A control method and device of an air conditioning system, the air conditioning system and a storage medium

Abstract

The application discloses a control method and device of an air conditioning system, the air conditioning system and a storage medium, and relates to the technical field of air conditioning systems. The method comprises the following steps: after the air conditioning system is started, the target opening degree of a first-stage throttling device and the target opening degree of a second-stage throttling device are determined in the current operation mode of the air conditioning system, in combination with the outdoor environment temperature of the air conditioning system, the indoor return air relative humidity of the air conditioning system and the operation parameters of the air conditioning system, after the oil return operation of the air conditioning system is ended; then, the air conditioning system is operated according to the target opening degree of the first-stage throttling device and the target opening degree of the second-stage throttling device; wherein the current operation mode of the air conditioning system is a refrigeration mode or a reheating dehumidification mode. According to the scheme, a three-pipe parallel reheating dehumidification system is adopted in the air conditioning system, the double electronic expansion valves in the three-pipe parallel reheating dehumidification system are decoupled and controlled, active control of the opening degrees of the double electronic expansion valves is realized, and the energy efficiency and comfort of the air conditioning system during refrigeration and dehumidification operation are improved.

Description

Technical Field

[0001] This invention belongs to the field of air conditioning system technology, specifically relating to a control method, device, air conditioning system and storage medium for an air conditioning system, and particularly to a method, device, air conditioning system and storage medium for controlling the opening degree of a dual electronic expansion valve in an air conditioning system. Background Technology

[0002] Air conditioning systems (such as residential inverter heat pump air conditioners) are widely used in my country, serving both cooling and dehumidification in summer and heating in winter. To meet dehumidification requirements, the evaporation temperature of a residential inverter heat pump air conditioner needs to be lower than the return air dew point temperature; however, to meet comfort requirements, the return air temperature should not be too low. When a residential inverter heat pump air conditioner is running at low load, its evaporation temperature is typically higher. To maintain dehumidification, the indoor unit's airflow needs to be reduced to lower the evaporation temperature, thus achieving dehumidification. At this time (i.e., when reducing the indoor unit's airflow), both the cooling efficiency ratio and the dehumidification capacity per unit of energy consumption decrease.

[0003] In the middle and lower reaches of the Yangtze River and areas south of it, relative humidity is high during the transitional season (i.e., the season when household inverter heat pump air conditioners are not needed for cooling or heating), especially during the "plum rain season" and "return to spring" weather. Dehumidification is necessary to address the comfort and health issues caused by dampness. When household inverter heat pump air conditioners are cooling and dehumidifying during the transitional season, the indoor return air temperature and dew point gradually decrease, and the indoor relative humidity stops decreasing after reaching a certain level and may even increase, resulting in a cool but not dry indoor environment. On the other hand, the decrease in the evaporation temperature and dew point of the household inverter heat pump air conditioner significantly reduces the dehumidification capacity per unit of energy consumption. Therefore, during the humid weather of the transitional season, the cooling and dehumidification of household inverter heat pump air conditioners cannot meet the comfort requirements for dehumidification and are usually idle.

[0004] The above content is only used to help understand the technical solution of the present invention and does not represent an admission that the above content is prior art. Summary of the Invention

[0005] The purpose of this invention is to provide a control method, device, air conditioning system, and storage medium for an air conditioning system, in order to solve the problems of high energy consumption in air conditioning systems (such as household inverter heat pump air conditioners) during low-load operation for cooling and dehumidification in summer, and low comfort and high energy consumption during humid weather in transitional seasons. This is achieved by using a three-pipe parallel reheat dehumidification system in the air conditioning system, decoupling the dual electronic expansion valves in the three-pipe parallel reheat dehumidification system, and realizing active control of the opening degree of the dual electronic expansion valves, thereby improving the energy efficiency and comfort of the air conditioning system during cooling and dehumidification operation.

[0006] This invention provides a control method for an air conditioning system, wherein the air conditioning system employs a three-pipe parallel reheat dehumidification system; the three-pipe parallel reheat dehumidification system includes a compressor, a first-stage throttling device, a second-stage throttling device, an outdoor fan, and an indoor fan; the control method for the air conditioning system includes: after the air conditioning system is started, controlling the indoor unit's air guide vane to open, controlling the indoor fan to start at a set fan speed or an automatic fan speed, and controlling the air conditioning system to return oil; after the air conditioning system returns oil, acquiring the outdoor ambient temperature of the air conditioning system; and acquiring the operating parameters of the air conditioning system; and in the current operating mode of the air conditioning system, based on... Based on the outdoor ambient temperature of the air conditioning system, the frequency of the compressor and the speed of the outdoor fan are adjusted; and, in the current operating mode of the air conditioning system, combined with the outdoor ambient temperature of the air conditioning system, the indoor return air relative humidity of the air conditioning system, and the operating parameters of the air conditioning system, the target opening degree of the first-stage throttling device and the target opening degree of the second-stage throttling device are determined; then, the first-stage throttling device is controlled to operate at the target opening degree of the first-stage throttling device, and the second-stage throttling device is controlled to operate at the target opening degree of the second-stage throttling device; wherein, the current operating mode of the air conditioning system is either cooling mode or reheat dehumidification mode.

[0007] In some embodiments, the three-pipe parallel reheat dehumidification system further includes an outdoor heat exchanger, an indoor first heat exchanger, and an indoor second heat exchanger; the compressor has an exhaust port, a first suction port, and a second suction port; the operating parameters of the air conditioning system are acquired, including at least one of the following: acquiring the indoor ambient temperature of the air conditioning system; acquiring the indoor return air relative humidity of the air conditioning system; acquiring the indoor return air temperature of the air conditioning system; acquiring the frequency of the compressor; acquiring the pipe temperature of the indoor first heat exchanger, denoted as the indoor first pipe temperature of the air conditioning system; acquiring the pipe temperature of the indoor second heat exchanger, denoted as the indoor second pipe temperature of the air conditioning system; acquiring the pipe temperature of the outdoor heat exchanger, denoted as the outdoor pipe temperature of the air conditioning system; acquiring the refrigerant outlet temperature of the outdoor heat exchanger; acquiring the temperature of the first suction port of the compressor, denoted as the first suction temperature of the air conditioning system; acquiring the pipe temperature of the second suction port of the compressor, denoted as the second suction pipe temperature of the air conditioning system; and acquiring the temperature of the exhaust port of the compressor, denoted as the exhaust temperature of the air conditioning system.

[0008] In some embodiments, the current operating mode of the air conditioning system is cooling mode. In cooling mode, based on the outdoor ambient temperature of the air conditioning system, the indoor return air relative humidity of the air conditioning system, and the operating parameters of the air conditioning system, the target opening degree of the first-stage throttling device and the target opening degree of the second-stage throttling device are determined, including: determining the inlet and outlet pressure difference of the first-stage throttling device based on the outdoor pipe temperature of the air conditioning system, the indoor first pipe temperature of the air conditioning system, and a predetermined saturation temperature drop from the outlet of the first-stage throttling device to the indoor first heat exchanger tube; and determining the inlet and outlet pressure difference of the second-stage throttling device based on the indoor first pipe temperature, the indoor second pipe temperature of the air conditioning system, and a predetermined saturation temperature drop from the outlet of the second-stage throttling device to the indoor second heat exchanger tube; determining the inlet refrigerant density of the first-stage throttling device based on the outdoor pipe temperature of the air conditioning system; and determining the target opening degree of the first-stage throttling device based on the outdoor ambient temperature of the air conditioning system or the refrigerant outlet temperature of the outdoor heat exchanger, combined with a predetermined saturated liquid specific volume of the refrigerant in the air conditioning system and a predetermined air... The refrigerant saturated gas specific volume of the system is adjusted to determine the inlet refrigerant density of the second-stage throttling device. Based on the indoor first pipe temperature of the air conditioning system and the predetermined saturated temperature drop from the middle of the indoor first heat exchanger to the first suction port of the compressor, the saturated suction specific volume corresponding to the first suction cylinder of the compressor is calculated. Similarly, based on the indoor second pipe temperature of the air conditioning system and the predetermined saturated temperature drop from the middle of the indoor second heat exchanger to the second suction port of the compressor, the saturated suction specific volume corresponding to the second suction cylinder of the compressor is calculated. Then, combining the inlet and outlet pressure difference of the first-stage throttling device, the inlet refrigerant density of the first-stage throttling device, the saturated suction specific volume corresponding to the first suction cylinder of the compressor, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor, the opening degree of the first-stage throttling device is determined as the target opening degree. Finally, combining the inlet and outlet pressure difference of the second-stage throttling device, the inlet refrigerant density of the second-stage throttling device, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor, the opening degree of the second-stage throttling device is determined as the target opening degree.

[0009] In some embodiments, determining the inlet and outlet pressure difference of the first-stage throttling device based on the outdoor pipe temperature of the air conditioning system, the indoor first pipe temperature of the air conditioning system, and a predetermined saturation temperature drop from the outlet of the first-stage throttling device to the indoor first heat exchanger tube includes: using the outdoor pipe temperature of the air conditioning system as the saturation temperature corresponding to the refrigerant inlet pressure of the first-stage throttling device; and using the sum of the indoor first pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the outlet of the first-stage throttling device to the indoor first heat exchanger tube as the saturation temperature corresponding to the refrigerant outlet pressure of the first-stage throttling device; multiplying the sum of the saturation temperature corresponding to the refrigerant inlet pressure of the first-stage throttling device and the saturation temperature corresponding to the refrigerant outlet pressure of the first-stage throttling device by a first set coefficient multiple, and a first set value, and then multiplying the sum by the difference in saturation temperature corresponding to the refrigerant outlet pressure of the first-stage throttling device to obtain the inlet and outlet pressure difference of the first-stage throttling device; and / or, based on the indoor... Determining the inlet and outlet pressure difference of the second-stage throttling device based on the first pipe temperature, the indoor second pipe temperature of the air conditioning system, and the predetermined saturation temperature drop from the outlet of the second-stage throttling device to the indoor second heat exchanger tube includes: using the sum of the indoor first pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the outlet of the second-stage throttling device to the indoor second heat exchanger tube as the saturation temperature corresponding to the refrigerant inlet pressure of the second-stage throttling device; using the sum of the indoor second pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the outlet of the second-stage throttling device to the indoor second heat exchanger tube as the saturation temperature corresponding to the refrigerant outlet pressure of the second-stage throttling device; and multiplying the sum of the refrigerant inlet pressure corresponding to the saturation temperature of the second-stage throttling device and the refrigerant outlet pressure corresponding to the saturation temperature of the second-stage throttling device by a second set coefficient multiple, with a second set value, and then multiplying this sum with the difference in saturation temperature corresponding to the refrigerant outlet pressure of the second-stage throttling device to obtain the inlet and outlet pressure difference of the second-stage throttling device.

[0010] In some embodiments, determining the inlet refrigerant density of the first-stage throttling device based on the outdoor pipe temperature of the air conditioning system includes: determining the inlet refrigerant density of the first-stage throttling device based on the correspondence between a set outdoor pipe temperature and a set inlet refrigerant density, where the set outdoor pipe temperature is the same as the outdoor pipe temperature of the air conditioning system; and / or, determining the inlet refrigerant density of the second-stage throttling device based on the outdoor ambient temperature of the air conditioning system or the refrigerant outlet temperature of the outdoor heat exchanger, combined with a predetermined saturated liquid specific volume and a predetermined saturated gas specific volume of the refrigerant in the air conditioning system. The inlet refrigerant density of the device includes: determining the outlet refrigerant specific enthalpy of the outdoor heat exchanger based on the outdoor ambient temperature of the air conditioning system or the refrigerant outlet temperature of the outdoor heat exchanger; determining the inlet refrigerant dryness of the second-stage throttling device based on the outlet refrigerant specific enthalpy of the outdoor heat exchanger, a pre-determined refrigerant saturated gas specific enthalpy of the air conditioning system, and a pre-determined refrigerant saturated liquid specific enthalpy of the air conditioning system; and determining the inlet refrigerant density of the second-stage throttling device based on the inlet refrigerant dryness of the second-stage throttling device, a pre-determined refrigerant saturated liquid specific volume of the air conditioning system, and a pre-determined refrigerant saturated gas specific volume of the air conditioning system.

[0011] In some embodiments, calculating the saturated suction specific volume corresponding to the first suction cylinder of the compressor based on the indoor first pipe temperature of the air conditioning system and a predetermined saturation temperature drop from the middle of the indoor first heat exchanger to the first suction port of the compressor includes: using the difference between the indoor first pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the middle of the indoor first heat exchanger to the first suction port of the compressor as the suction saturation temperature of the first suction cylinder of the compressor; and determining the saturated suction specific volume corresponding to the first suction cylinder of the compressor based on the suction saturation temperature of the first suction cylinder of the compressor. Gas specific volume; and / or, based on the indoor second pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the middle of the indoor second heat exchanger to the second suction port of the compressor, calculate the saturated suction specific volume corresponding to the second suction cylinder of the compressor, including: taking the difference between the indoor second pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the middle of the indoor second heat exchanger to the second suction port of the compressor as the suction saturation temperature of the second suction cylinder of the compressor; determining the saturated suction specific volume corresponding to the second suction cylinder of the compressor based on the suction saturation temperature of the second suction cylinder of the compressor.

[0012] In some embodiments, the opening degree of the first-stage throttling device is determined by combining the inlet and outlet pressure difference of the first-stage throttling device, the inlet refrigerant density of the first-stage throttling device, the saturated suction specific volume corresponding to the first suction cylinder of the compressor, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor, as the target opening degree of the first-stage throttling device. This includes: multiplying the sum of a predetermined third set coefficient multiple of the saturated temperature drop from the middle of the first indoor heat exchanger to the first suction port of the compressor and a third set value, and then multiplying the product of the predetermined suction superheat of the first suction cylinder of the compressor, as the saturated suction specific volume corresponding to the first suction cylinder of the compressor; and multiplying the predetermined... The product of a fourth set coefficient multiple of the saturated temperature drop from the middle of the second indoor heat exchanger to the second suction port of the compressor, and a fourth set value, multiplied by a preset suction superheat of the second suction cylinder of the compressor, is used as the saturated suction specific volume corresponding to the second suction cylinder of the compressor; the ratio of a set calculation coefficient multiple of the compressor frequency to the saturated suction specific volume corresponding to the second suction cylinder of the compressor is used as the refrigerant mass flow rate of the second-stage throttling device; the ratio of a set calculation coefficient multiple of the compressor frequency to the saturated suction specific volume corresponding to the first suction cylinder of the compressor is used as the refrigerant mass flow rate of the first indoor heat exchanger; the second-stage throttling device... The sum of the refrigerant mass flow rate and the refrigerant mass flow rate of the first indoor heat exchanger is taken as the refrigerant mass flow rate of the first-stage throttling device; the ratio of the product of the predetermined flow correction coefficient of the first-stage throttling device and the refrigerant mass flow rate of the first-stage throttling device, to the inlet refrigerant density of the first-stage throttling device, and then to the square root of the inlet and outlet pressure difference of the first-stage throttling device, is taken as the air flow rate of the first-stage throttling device; the opening degree of the first-stage throttling device is determined based on the air flow rate of the first-stage throttling device, which is taken as the target opening degree of the first-stage throttling device; and / or, combined with the inlet and outlet pressure difference of the second-stage throttling device and the second-stage throttling... The inlet refrigerant density of the device and the saturated suction specific volume corresponding to the second suction cylinder of the compressor are used to determine the opening degree of the second-stage throttling device, which is used as the target opening degree of the second-stage throttling device. This includes: multiplying the sum of a predetermined fourth set coefficient multiple of the saturated temperature drop from the middle of the second indoor heat exchanger to the second suction port of the compressor and a fourth set value, and then multiplying the product of the preset suction superheat of the second suction cylinder of the compressor, as the saturated suction specific volume corresponding to the second suction cylinder of the compressor; and using the ratio of a set calculation coefficient multiple of the compressor frequency and the saturated suction specific volume corresponding to the second suction cylinder of the compressor as the refrigerant mass flow rate of the second-stage throttling device.The ratio of the product of the predetermined flow correction coefficient of the second-stage throttling device and the refrigerant mass flow rate of the second-stage throttling device, to the inlet refrigerant density of the second-stage throttling device, and then to the square root of the inlet-outlet pressure difference of the second-stage throttling device, is taken as the air flow rate of the second-stage throttling device. Based on the air flow rate of the second-stage throttling device, the opening degree of the second-stage throttling device is determined as the target opening degree of the second-stage throttling device.

[0013] In some embodiments, determining the opening degree of the first-stage throttling device as the target opening degree of the first-stage throttling device by combining the inlet and outlet pressure difference of the first-stage throttling device, the inlet refrigerant density of the first-stage throttling device, the saturated suction specific volume corresponding to the first suction cylinder of the compressor, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor, further includes: determining the relationship between the first-stage throttling device and the second-stage throttling device based on preset volumes of the first and second suction cylinders of the compressor, the saturated suction specific volume corresponding to the first suction cylinder of the compressor, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor. The refrigerant flow ratio between the flow devices; the product of a predetermined third set factor multiple of the saturated temperature drop from the middle of the first indoor heat exchanger to the first suction port of the compressor, and a third set value, plus a predetermined suction superheat of the first suction cylinder of the compressor, is used as the saturated suction specific volume corresponding to the first suction cylinder of the compressor; the product of a predetermined fourth set factor multiple of the saturated temperature drop from the middle of the second indoor heat exchanger to the second suction port of the compressor, and a fourth set value, plus a predetermined suction superheat of the second suction cylinder of the compressor, is used as the saturated suction specific volume corresponding to the second suction cylinder of the compressor; and the frequency of the compressor... The refrigerant mass flow rate of the first-stage throttling device is calculated by multiplying the product of the refrigerant flow rate ratio between the first-stage and second-stage throttling devices by a predetermined coefficient, and then by dividing this product by the ratio of the saturated suction specific volume corresponding to the second suction cylinder of the compressor. This ratio is used as the refrigerant mass flow rate of the first-stage throttling device. The air flow rate of the first-stage throttling device is calculated by multiplying the predetermined flow rate correction coefficient of the first-stage throttling device by the refrigerant mass flow rate of the first-stage throttling device, and then by dividing this product by the ratio of the inlet refrigerant density of the first-stage throttling device by the square root of the inlet and outlet pressure difference of the first-stage throttling device. Based on the air flow rate of the first-stage throttling device, the opening degree of the first-stage throttling device is determined. The target opening degree of the first-stage throttling device is determined by: and / or, in combination with the inlet and outlet pressure difference of the second-stage throttling device, the inlet refrigerant density of the second-stage throttling device, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor, the target opening degree of the second-stage throttling device is determined by: determining the refrigerant flow ratio between the first-stage throttling device and the second-stage throttling device based on the preset first suction cylinder volume of the compressor, the preset second suction cylinder volume of the compressor, the saturated suction specific volume corresponding to the first suction cylinder of the compressor, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor;Based on the refrigerant flow ratio between the first-stage and second-stage throttling devices, the predetermined flow correction coefficient of the first-stage throttling device, the inlet and outlet pressure difference of the first-stage throttling device, and the inlet refrigerant density of the first-stage throttling device, and the predetermined flow correction coefficient of the second-stage throttling device, the inlet and outlet pressure difference of the second-stage throttling device, and the inlet refrigerant density of the second-stage throttling device, the air flow ratio between the first-stage and second-stage throttling devices is determined. Based on the air flow ratio between the first-stage and second-stage throttling devices and the determined air flow of the first-stage throttling device, the air flow of the second-stage throttling device is determined. Based on the air flow of the second-stage throttling device, the opening degree of the second-stage throttling device is determined as the target opening degree of the second-stage throttling device.

[0014] In some embodiments, the current operating mode of the air conditioning system is reheat dehumidification mode. In this reheat dehumidification mode, based on the outdoor ambient temperature of the air conditioning system, the indoor return air relative humidity of the air conditioning system, and the operating parameters of the air conditioning system, the target opening degree of the first-stage throttling device and the target opening degree of the second-stage throttling device are determined, including: determining the inlet and outlet pressure difference of the first-stage throttling device based on the outdoor pipe temperature of the air conditioning system, the indoor first pipe temperature of the air conditioning system, and a predetermined saturation temperature drop from the outlet of the first-stage throttling device to the indoor first heat exchanger tube; and determining the inlet and outlet pressure difference of the first-stage throttling device based on the indoor first pipe temperature of the air conditioning system, the indoor second pipe temperature of the air conditioning system, and a predetermined... The pressure difference between the inlet and outlet of the second-stage throttling device is determined by the saturated temperature drop from the outlet of the second-stage throttling device to the tubes of the indoor second heat exchanger; the inlet refrigerant density of the first-stage throttling device is determined based on the outdoor pipe temperature of the air conditioning system; and the inlet refrigerant density of the second-stage throttling device is determined based on the outdoor ambient temperature of the air conditioning system or the refrigerant outlet temperature of the outdoor heat exchanger, combined with the pre-determined saturated liquid specific volume and the pre-determined saturated gas specific volume of the refrigerant in the air conditioning system; the inlet dew point temperature of the air conditioning system is determined based on the indoor return air temperature and the return air relative humidity of the air conditioning system; and the pressure difference between the inlet and outlet of the air conditioning system is determined based on the outdoor pipe temperature of the air conditioning system. The ratio of refrigerant flow rate of the first-stage throttling device to that of the second-stage throttling device is determined based on the inlet dew point temperature of the air conditioning system; the refrigerant mass flow rate of the first-stage throttling device and the refrigerant mass flow rate of the second-stage throttling device are determined based on the indoor first pipe temperature of the air conditioning system, the predetermined saturation temperature drop from the middle of the indoor first heat exchanger to the first suction port of the compressor, the indoor second pipe temperature of the air conditioning system, the ratio of refrigerant flow rate of the first-stage throttling device to that of the second-stage throttling device, and the predetermined saturation temperature drop from the middle of the indoor second heat exchanger to the second suction port of the compressor; then, the refrigerant mass flow rate of the first-stage throttling device and the refrigerant mass flow rate of the second-stage throttling device are determined based on the predetermined flow correction coefficient of the first-stage throttling device. The opening degree of the first-stage throttling device is determined based on the inlet and outlet pressure difference, the inlet refrigerant density of the first-stage throttling device, the refrigerant mass flow rate of the first-stage throttling device, and the ratio of the refrigerant flow rates of the first-stage throttling device to that of the second-stage throttling device, and is used as the target opening degree of the first-stage throttling device. The opening degree of the second-stage throttling device is also determined based on a predetermined flow correction coefficient, the inlet and outlet pressure difference of the second-stage throttling device, the inlet refrigerant density of the second-stage throttling device, the refrigerant mass flow rate of the second-stage throttling device, and the ratio of the refrigerant flow rates of the first-stage throttling device to that of the second-stage throttling device, and is used as the target opening degree of the second-stage throttling device.

[0015] In some embodiments, determining the inlet dew point temperature of the air conditioning system based on the indoor return air temperature and the return air relative humidity of the air conditioning system includes: determining the set return air temperature that is the same as the indoor return air temperature of the air conditioning system and the set inlet dew point temperature that is the same as the return air relative humidity of the air conditioning system as the inlet dew point temperature of the air conditioning system, based on the correspondence between the set return air temperature, the set return air relative humidity and the set inlet dew point temperature; and / or, determining the ratio of the refrigerant flow rate of the first-stage throttling device to the refrigerant flow rate of the second-stage throttling device based on the inlet dew point temperature of the air conditioning system includes: determining whether the inlet dew point temperature of the air conditioning system is less than or equal to the indoor first pipe temperature of the air conditioning system; if the inlet dew point temperature of the air conditioning system is determined to be less than or equal to the indoor first pipe temperature of the air conditioning system... If the first pipe temperature is determined, it is determined that the first indoor heat exchanger does not require dehumidification, and the frequency of the compressor is increased or the speed of the indoor fan is decreased. If it is determined that the inlet dew point temperature of the air conditioning system is greater than the first indoor pipe temperature of the air conditioning system, the inlet specific enthalpy of the air conditioning system is determined based on the indoor return air temperature and the return air relative humidity of the air conditioning system. The outlet specific enthalpy of the air conditioning system is determined based on the outlet dew point temperature and the outlet air relative humidity of the air conditioning system. The dehumidification latent heat ratio of the first indoor heat exchanger is determined based on the inlet specific enthalpy, the outlet specific enthalpy, and the phase change latent heat of the air conditioning system. The ratio of the refrigerant flow rate of the first-stage throttling device to that of the second-stage throttling device is determined based on the return air relative humidity, the dehumidification latent heat ratio of the first indoor heat exchanger, and the temperature regulation coefficient of the air conditioning system.

[0016] In some embodiments, determining the refrigerant mass flow rate of the first-stage throttling device and the refrigerant mass flow rate of the second-stage throttling device based on the indoor first pipe temperature of the air conditioning system, a predetermined saturation temperature drop from the middle of the indoor first heat exchanger to the first suction port of the compressor, the indoor second pipe temperature of the air conditioning system, the ratio of refrigerant flow rate of the first-stage throttling device to that of the second-stage throttling device, and a predetermined saturation temperature drop from the middle of the indoor second heat exchanger to the second suction port of the compressor includes: determining the refrigerant mass flow rate of the first-stage throttling device and the refrigerant mass flow rate of the second-stage throttling device based on the indoor first pipe temperature of the air conditioning system, the predetermined saturation temperature drop from the middle of the indoor first heat exchanger to the second suction port of the compressor. The difference in saturation temperature drop from the middle of the compressor to the first suction port is taken as the suction saturation temperature of the first suction cylinder of the compressor; and the indoor second pipe temperature of the air conditioning system and the predetermined difference in saturation temperature drop from the middle of the indoor second heat exchanger to the second suction port of the compressor are taken as the suction saturation temperature of the second suction cylinder of the compressor; the saturation suction specific volume corresponding to the first suction cylinder of the compressor is determined based on the suction saturation temperature of the first suction cylinder of the compressor; and the saturation suction specific volume corresponding to the second suction cylinder of the compressor is determined based on the suction saturation temperature of the second suction cylinder of the compressor. The product of a predetermined third set factor multiple of the saturated temperature drop from the middle of the first indoor heat exchanger to the first suction port of the compressor, and a third set value, plus a predetermined suction superheat of the first suction cylinder of the compressor, is used as the saturated suction specific volume corresponding to the first suction cylinder of the compressor; and the product of a predetermined fourth set factor multiple of the saturated temperature drop from the middle of the second indoor heat exchanger to the second suction port of the compressor, and a fourth set value, plus a predetermined suction superheat of the second suction cylinder of the compressor, is used as the saturated suction specific volume corresponding to the second suction cylinder of the compressor; the product of a predetermined frequency setting factor multiple of the compressor, plus the compressor... The ratio of the saturated suction specific volume corresponding to the first suction cylinder is used to obtain a first calculated value; the frequency setting calculation coefficient of the compressor is multiplied by a factor, and then the ratio of the saturated suction specific volume corresponding to the second suction cylinder of the compressor is used to obtain a second calculated value; the sum of the first calculated value and the second calculated value is determined as the total refrigerant mass flow rate of the first-stage throttling device and the second-stage throttling device; based on the total refrigerant mass flow rate of the first-stage throttling device and the second-stage throttling device, and the ratio of the refrigerant flow rate of the first-stage throttling device to the refrigerant flow rate of the second-stage throttling device, the refrigerant mass flow rate of the first-stage throttling device and the refrigerant mass flow rate of the second-stage throttling device are determined.

[0017] In some embodiments, the method further includes: after the first-stage throttling device operates at its target opening and the second-stage throttling device operates at its target opening for a set period of time, if the current operating mode of the air conditioning system is cooling mode, then, based on the difference between the first suction temperature of the air conditioning system and the first indoor pipe temperature of the air conditioning system, the target opening of the first-stage throttling device is adjusted to obtain a new target opening of the first-stage throttling device; and based on the difference between the second suction temperature of the air conditioning system and the second indoor pipe temperature of the air conditioning system, the target opening of the second-stage throttling device is adjusted to obtain a new second-stage throttling device. The target opening degree of the device; if the current operating mode of the air conditioning system is reheat dehumidification mode, the target opening degree of the first-stage throttling device is adjusted according to the difference between the first suction temperature of the air conditioning system and the first indoor pipe temperature of the air conditioning system to obtain a new target opening degree of the first-stage throttling device; and the target opening degree of the second-stage throttling device is adjusted according to the difference between the indoor return air temperature of the air conditioning system and the set temperature to obtain a new target opening degree of the second-stage throttling device; then, the first-stage throttling device is controlled to operate at the new target opening degree of the first-stage throttling device, and the second-stage throttling device is controlled to operate at the new target opening degree of the second-stage throttling device.

[0018] In conjunction with the above method, another aspect of the present invention provides a control device for an air conditioning system, wherein the air conditioning system employs a three-pipe parallel reheat dehumidification system; the three-pipe parallel reheat dehumidification system includes a compressor, a first-stage throttling device, a second-stage throttling device, an outdoor fan, and an indoor fan; the control device for the air conditioning system includes: a control unit configured to, after the air conditioning system is started, control the indoor unit's air guide vane to open, control the indoor fan to start at a set fan speed or an automatic fan speed, and control the air conditioning system to return oil; an acquisition unit configured to, after the air conditioning system returns oil, acquire the outdoor ambient temperature of the air conditioning system; and acquire the operating parameters of the air conditioning system; the control unit is further configured to, In the current operating mode of the air conditioning system, the frequency of the compressor and the speed of the outdoor fan are adjusted according to the outdoor ambient temperature of the air conditioning system. Furthermore, the control unit is configured to, in the current operating mode of the air conditioning system, determine the target opening degree of the first-stage throttling device and the target opening degree of the second-stage throttling device by combining the outdoor ambient temperature of the air conditioning system, the relative humidity of the indoor return air of the air conditioning system, and the operating parameters of the air conditioning system. Then, the control unit controls the first-stage throttling device to operate at its target opening degree, and controls the second-stage throttling device to operate at its target opening degree. The current operating mode of the air conditioning system is either cooling mode or reheat / dehumidification mode.

[0019] In some embodiments, the three-pipe parallel reheat dehumidification system further includes an outdoor heat exchanger, an indoor first heat exchanger, and an indoor second heat exchanger; the compressor has an exhaust port, a first suction port, and a second suction port; the acquisition unit acquires the operating parameters of the air conditioning system, including at least one of the following: acquiring the indoor ambient temperature of the air conditioning system; acquiring the indoor return air relative humidity of the air conditioning system; acquiring the indoor return air temperature of the air conditioning system; acquiring the frequency of the compressor; acquiring the pipe temperature of the indoor first heat exchanger, recorded as the indoor first pipe temperature of the air conditioning system; acquiring the pipe temperature of the indoor second heat exchanger, recorded as the indoor second pipe temperature of the air conditioning system; acquiring the pipe temperature of the outdoor heat exchanger, recorded as the outdoor pipe temperature of the air conditioning system; acquiring the refrigerant outlet temperature of the outdoor heat exchanger; acquiring the temperature of the first suction port of the compressor, recorded as the first suction temperature of the air conditioning system; acquiring the pipe temperature of the second suction port of the compressor, recorded as the second suction pipe temperature of the air conditioning system; and acquiring the temperature of the exhaust port of the compressor, recorded as the exhaust temperature of the air conditioning system.

[0020] In some embodiments, the current operating mode of the air conditioning system is cooling mode; the control unit, in the cooling mode, determines the target opening degree of the first-stage throttling device and the target opening degree of the second-stage throttling device by combining the outdoor ambient temperature of the air conditioning system, the indoor return air relative humidity of the air conditioning system, and the operating parameters of the air conditioning system, including: determining the inlet and outlet pressure difference of the first-stage throttling device based on the outdoor pipe temperature of the air conditioning system, the indoor first pipe temperature of the air conditioning system, and a predetermined saturation temperature drop from the outlet of the first-stage throttling device to the indoor first heat exchanger tube; and determining the inlet and outlet pressure difference of the second-stage throttling device based on the indoor first pipe temperature, the indoor second pipe temperature of the air conditioning system, and a predetermined saturation temperature drop from the outlet of the second-stage throttling device to the indoor second heat exchanger tube; determining the inlet refrigerant density of the first-stage throttling device based on the outdoor pipe temperature of the air conditioning system; and determining the target opening degree of the first-stage throttling device based on the outdoor ambient temperature of the air conditioning system or the refrigerant outlet temperature of the outdoor heat exchanger, combined with a predetermined saturated liquid specific volume of the refrigerant of the air conditioning system, and a predetermined... The refrigerant density at the inlet of the second-stage throttling device is determined based on the saturated gas specific volume of the refrigerant in the air conditioning system. The saturated suction specific volume of the first suction cylinder of the compressor is calculated based on the indoor first pipe temperature of the air conditioning system and the predetermined saturated temperature drop from the middle of the indoor first heat exchanger to the first suction port of the compressor. The saturated suction specific volume of the second suction cylinder of the compressor is calculated based on the indoor second pipe temperature of the air conditioning system and the predetermined saturated temperature drop from the middle of the indoor second heat exchanger to the second suction port of the compressor. Then, the opening degree of the first-stage throttling device is determined by combining the inlet and outlet pressure difference of the first-stage throttling device, the inlet refrigerant density of the first-stage throttling device, the saturated suction specific volume of the first suction cylinder of the compressor, and the saturated suction specific volume of the second suction cylinder of the compressor, as the target opening degree of the first-stage throttling device. Finally, the opening degree of the second-stage throttling device is determined by combining the inlet and outlet pressure difference of the second-stage throttling device, the inlet refrigerant density of the second-stage throttling device, and the saturated suction specific volume of the second suction cylinder of the compressor, as the target opening degree of the second-stage throttling device.

[0021] In some embodiments, the control unit determines the inlet and outlet pressure difference of the first-stage throttling device based on the outdoor pipe temperature of the air conditioning system, the indoor first pipe temperature of the air conditioning system, and a predetermined saturation temperature drop from the outlet of the first-stage throttling device to the indoor first heat exchanger tube. This includes: using the outdoor pipe temperature of the air conditioning system as the saturation temperature corresponding to the refrigerant inlet pressure of the first-stage throttling device; and using the sum of the indoor first pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the outlet of the first-stage throttling device to the indoor first heat exchanger tube as the saturation temperature corresponding to the refrigerant outlet pressure of the first-stage throttling device; multiplying the sum of the saturation temperature corresponding to the refrigerant inlet pressure of the first-stage throttling device and the sum of the saturation temperature corresponding to the refrigerant outlet pressure of the first-stage throttling device by a first set coefficient multiple, and a first set value, and then multiplying the sum by the difference in saturation temperature corresponding to the refrigerant outlet pressure of the first-stage throttling device to obtain the inlet and outlet pressure difference of the first-stage throttling device; and / or, the control unit, based on the... The method for determining the inlet and outlet pressure difference of the second-stage throttling device involves considering the indoor first pipe temperature of the air conditioning system, the indoor second pipe temperature of the air conditioning system, and a predetermined saturation temperature drop from the outlet of the second-stage throttling device to the indoor second heat exchanger tube. This includes: using the sum of the indoor first pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the outlet of the second-stage throttling device to the indoor second heat exchanger tube as the saturation temperature corresponding to the refrigerant inlet pressure of the second-stage throttling device; using the sum of the indoor second pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the outlet of the second-stage throttling device to the indoor second heat exchanger tube as the saturation temperature corresponding to the refrigerant outlet pressure of the second-stage throttling device; and multiplying the sum of the refrigerant inlet pressure corresponding to the saturation temperature of the second-stage throttling device and the refrigerant outlet pressure corresponding to the saturation temperature of the second-stage throttling device by a second set coefficient multiple, along with a second set value, and then multiplying this sum by the difference between the refrigerant outlet pressure and the saturation temperature corresponding to the refrigerant outlet pressure of the second-stage throttling device to obtain the inlet and outlet pressure difference of the second-stage throttling device.

[0022] In some embodiments, the control unit determines the inlet refrigerant density of the first-stage throttling device based on the outdoor pipe temperature of the air conditioning system, including: determining the inlet refrigerant density of the first-stage throttling device based on the correspondence between a set outdoor pipe temperature and a set inlet refrigerant density, where the set inlet refrigerant density corresponds to the same set outdoor pipe temperature as the outdoor pipe temperature of the air conditioning system; and / or, the control unit determines the inlet refrigerant density of the first-stage throttling device based on the outdoor ambient temperature of the air conditioning system or the refrigerant outlet temperature of the outdoor heat exchanger, combined with a predetermined saturated liquid specific volume and a predetermined saturated gas specific volume of the refrigerant in the air conditioning system. The inlet refrigerant density of the second-stage throttling device includes: determining the outlet refrigerant specific enthalpy of the outdoor heat exchanger based on the outdoor ambient temperature of the air conditioning system or the refrigerant outlet temperature of the outdoor heat exchanger; determining the inlet refrigerant dryness fraction of the second-stage throttling device based on the outlet refrigerant specific enthalpy of the outdoor heat exchanger, a predetermined saturated gas refrigerant specific enthalpy of the air conditioning system, and a predetermined saturated liquid refrigerant specific enthalpy of the air conditioning system; and determining the inlet refrigerant density of the second-stage throttling device based on the inlet refrigerant dryness fraction of the second-stage throttling device, a predetermined saturated liquid refrigerant specific volume of the air conditioning system, and a predetermined saturated gas refrigerant specific volume of the air conditioning system.

[0023] In some embodiments, the control unit calculates the saturated suction specific volume corresponding to the first suction cylinder of the compressor based on the indoor first pipe temperature of the air conditioning system and a predetermined saturation temperature drop from the middle of the indoor first heat exchanger to the first suction port of the compressor. This includes: using the difference between the indoor first pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the middle of the indoor first heat exchanger to the first suction port of the compressor as the suction saturation temperature of the first suction cylinder of the compressor; and determining the saturated suction specific volume corresponding to the first suction cylinder of the compressor based on the suction saturation temperature of the first suction cylinder of the compressor. Gas specific volume; and / or, the control unit calculates the saturated suction specific volume corresponding to the second suction cylinder of the compressor based on the indoor second pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the middle of the indoor second heat exchanger to the second suction port of the compressor, including: taking the difference between the indoor second pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the middle of the indoor second heat exchanger to the second suction port of the compressor as the suction saturation temperature of the second suction cylinder of the compressor; and determining the saturated suction specific volume corresponding to the second suction cylinder of the compressor based on the suction saturation temperature of the second suction cylinder of the compressor.

[0024] In some embodiments, the control unit, in conjunction with the inlet and outlet pressure difference of the first-stage throttling device, the inlet refrigerant density of the first-stage throttling device, the saturated suction specific volume corresponding to the first suction cylinder of the compressor, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor, determines the opening degree of the first-stage throttling device as the target opening degree of the first-stage throttling device. This includes: multiplying the sum of a predetermined third set coefficient multiple of the saturated temperature drop from the middle of the first indoor heat exchanger to the first suction port of the compressor and a third set value, and then multiplying the product of a predetermined suction superheat of the first suction cylinder of the compressor, as the saturated suction specific volume corresponding to the first suction cylinder of the compressor; and multiplying the predetermined... The product of the fourth set coefficient multiple of the saturated temperature drop from the middle of the second heat exchanger in the room to the second suction port of the compressor, and the fourth set value, and the preset suction superheat of the second suction cylinder of the compressor, is used as the saturated suction specific volume corresponding to the second suction cylinder of the compressor; the ratio of the set calculation coefficient multiple of the compressor frequency to the saturated suction specific volume corresponding to the second suction cylinder of the compressor is used as the refrigerant mass flow rate of the second-stage throttling device; the ratio of the set calculation coefficient multiple of the compressor frequency to the saturated suction specific volume corresponding to the first suction cylinder of the compressor is used as the refrigerant mass flow rate of the first heat exchanger in the room; the second-stage throttling device... The sum of the refrigerant mass flow rate and the refrigerant mass flow rate of the first indoor heat exchanger is taken as the refrigerant mass flow rate of the first-stage throttling device; the ratio of the product of the predetermined flow correction coefficient of the first-stage throttling device and the refrigerant mass flow rate of the first-stage throttling device, to the inlet refrigerant density of the first-stage throttling device, and then to the square root of the inlet and outlet pressure difference of the first-stage throttling device, is taken as the air flow rate of the first-stage throttling device; the opening degree of the first-stage throttling device is determined based on the air flow rate of the first-stage throttling device, as the target opening degree of the first-stage throttling device; and / or, the control unit, in conjunction with the inlet and outlet pressure difference of the second-stage throttling device, the first... The opening degree of the second-stage throttling device is determined by the inlet refrigerant density of the second-stage throttling device and the saturated suction specific volume corresponding to the second suction cylinder of the compressor. This is used as the target opening degree of the second-stage throttling device. This includes: multiplying the sum of a predetermined fourth set coefficient multiple of the saturated temperature drop from the middle of the second indoor heat exchanger to the second suction port of the compressor and a fourth set value, and then multiplying the product of the preset suction superheat of the second suction cylinder of the compressor, as the saturated suction specific volume corresponding to the second suction cylinder of the compressor; and using the ratio of a set calculation coefficient multiple of the compressor frequency and the saturated suction specific volume corresponding to the second suction cylinder of the compressor as the refrigerant mass flow rate of the second-stage throttling device.The ratio of the product of the predetermined flow correction coefficient of the second-stage throttling device and the refrigerant mass flow rate of the second-stage throttling device, to the inlet refrigerant density of the second-stage throttling device, and then to the square root of the inlet-outlet pressure difference of the second-stage throttling device, is taken as the air flow rate of the second-stage throttling device. Based on the air flow rate of the second-stage throttling device, the opening degree of the second-stage throttling device is determined as the target opening degree of the second-stage throttling device.

[0025] In some embodiments, the control unit, in conjunction with the inlet and outlet pressure difference of the first-stage throttling device, the inlet refrigerant density of the first-stage throttling device, the saturated suction specific volume corresponding to the first suction cylinder of the compressor, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor, determines the opening degree of the first-stage throttling device as the target opening degree of the first-stage throttling device. This further includes: determining the relationship between the first-stage throttling device and the first-stage throttling device based on preset volumes of the first and second suction cylinders of the compressor, preset volumes of the second and third suction cylinders of the compressor, the saturated suction specific volume corresponding to the first and second suction cylinders of the compressor. The refrigerant flow ratio between the two throttling devices; the product of a predetermined third set factor multiple of the saturated temperature drop from the middle of the first indoor heat exchanger to the first suction port of the compressor, and a third set value, plus a predetermined suction superheat of the first suction cylinder of the compressor, is used as the saturated suction specific volume corresponding to the first suction cylinder of the compressor; the product of a predetermined fourth set factor multiple of the saturated temperature drop from the middle of the second indoor heat exchanger to the second suction port of the compressor, and a fourth set value, plus a predetermined suction superheat of the second suction cylinder of the compressor, is used as the saturated suction specific volume corresponding to the second suction cylinder of the compressor; and the frequency of the compressor... The product of the refrigerant flow rate ratio between the first-stage throttling device and the second-stage throttling device, multiplied by a predetermined calculation factor, and then multiplied by the ratio of the saturated suction specific volume corresponding to the second suction cylinder of the compressor, is used as the refrigerant mass flow rate of the first-stage throttling device. The product of the predetermined flow correction factor of the first-stage throttling device and the refrigerant mass flow rate of the first-stage throttling device, multiplied by the ratio of the inlet refrigerant density of the first-stage throttling device, and then multiplied by the square root of the inlet and outlet pressure difference of the first-stage throttling device, is used as the air flow rate of the first-stage throttling device. Based on the air flow rate of the first-stage throttling device, the opening degree of the first-stage throttling device is determined as the... The target opening degree of the first-stage throttling device; and / or, the control unit, in conjunction with the inlet and outlet pressure difference of the second-stage throttling device, the inlet refrigerant density of the second-stage throttling device, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor, determines the opening degree of the second-stage throttling device as the target opening degree of the second-stage throttling device, and further includes: determining the refrigerant flow ratio between the first-stage throttling device and the second-stage throttling device based on the preset first suction cylinder volume of the compressor, the preset second suction cylinder volume of the compressor, the saturated suction specific volume corresponding to the first suction cylinder of the compressor, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor;Based on the refrigerant flow ratio between the first-stage and second-stage throttling devices, the predetermined flow correction coefficient of the first-stage throttling device, the inlet and outlet pressure difference of the first-stage throttling device, and the inlet refrigerant density of the first-stage throttling device, and the predetermined flow correction coefficient of the second-stage throttling device, the inlet and outlet pressure difference of the second-stage throttling device, and the inlet refrigerant density of the second-stage throttling device, the air flow ratio between the first-stage and second-stage throttling devices is determined. Based on the air flow ratio between the first-stage and second-stage throttling devices and the determined air flow of the first-stage throttling device, the air flow of the second-stage throttling device is determined. Based on the air flow of the second-stage throttling device, the opening degree of the second-stage throttling device is determined as the target opening degree of the second-stage throttling device.

[0026] In some embodiments, the current operating mode of the air conditioning system is a reheat dehumidification mode; the control unit, in the reheat dehumidification mode, determines the target opening degree of the first-stage throttling device and the target opening degree of the second-stage throttling device by combining the outdoor ambient temperature of the air conditioning system, the indoor return air relative humidity of the air conditioning system, and the operating parameters of the air conditioning system, including: determining the inlet and outlet pressure difference of the first-stage throttling device based on the outdoor pipe temperature of the air conditioning system, the indoor first pipe temperature of the air conditioning system, and a predetermined saturation temperature drop from the outlet of the first-stage throttling device to the indoor first heat exchanger tube; and determining the inlet and outlet pressure difference of the first-stage throttling device based on the indoor first pipe temperature, the indoor second pipe temperature of the air conditioning system, and the outdoor pipe temperature of the air conditioning system. The inlet and outlet pressure difference of the second-stage throttling device is determined based on the predetermined saturated temperature drop from the outlet of the second-stage throttling device to the tubes of the indoor second heat exchanger; the inlet refrigerant density of the first-stage throttling device is determined based on the outdoor pipe temperature of the air conditioning system; and the inlet refrigerant density of the second-stage throttling device is determined based on the outdoor ambient temperature of the air conditioning system or the refrigerant outlet temperature of the outdoor heat exchanger, combined with the predetermined saturated liquid specific volume and the predetermined saturated gas specific volume of the refrigerant in the air conditioning system; the inlet dew point temperature of the air conditioning system is determined based on the indoor return air temperature and the return air relative humidity of the air conditioning system; and the inlet dew point temperature of the air conditioning system is determined based on the air... The system's inlet dew point temperature is adjusted to determine the refrigerant flow rate ratio between the first-stage and second-stage throttling devices. Based on the indoor first pipe temperature of the air conditioning system, a predetermined saturation temperature drop from the middle of the indoor first heat exchanger to the first suction port of the compressor, the indoor second pipe temperature of the air conditioning system, the refrigerant flow rate ratio between the first-stage and second-stage throttling devices, and a predetermined saturation temperature drop from the middle of the indoor second heat exchanger to the second suction port of the compressor, the refrigerant mass flow rate of the first-stage throttling device and the refrigerant mass flow rate of the second-stage throttling device are determined. Then, based on the predetermined flow correction coefficient of the first-stage throttling device and the first-stage throttling device... The opening degree of the first-stage throttling device is determined based on the inlet and outlet pressure difference, the inlet refrigerant density of the first-stage throttling device, the refrigerant mass flow rate of the first-stage throttling device, and the ratio of the refrigerant flow rates of the first-stage throttling device to that of the second-stage throttling device, and is used as the target opening degree of the first-stage throttling device. The opening degree of the second-stage throttling device is also determined based on a predetermined flow correction coefficient, the inlet and outlet pressure difference of the second-stage throttling device, the inlet refrigerant density of the second-stage throttling device, the refrigerant mass flow rate of the second-stage throttling device, and the ratio of the refrigerant flow rates of the first-stage throttling device to that of the second-stage throttling device, and is used as the target opening degree of the second-stage throttling device.

[0027] In some embodiments, the control unit determines the inlet dew point temperature of the air conditioning system based on the indoor return air temperature and the return air relative humidity of the air conditioning system, including: determining the set return air temperature that is the same as the indoor return air temperature of the air conditioning system and the set inlet dew point temperature that is the same as the return air relative humidity of the air conditioning system as the inlet dew point temperature of the air conditioning system according to the correspondence between the set return air temperature, the set return air relative humidity and the set inlet dew point temperature; and / or, the control unit determines the ratio of the refrigerant flow rate of the first-stage throttling device to the refrigerant flow rate of the second-stage throttling device based on the inlet dew point temperature of the air conditioning system, including: determining whether the inlet dew point temperature of the air conditioning system is less than or equal to the indoor first pipe temperature of the air conditioning system; if the inlet dew point temperature of the air conditioning system is determined to be less than or equal to the indoor first pipe temperature of the air conditioning system; If the indoor first pipe temperature of the air conditioning system is determined, then the indoor first heat exchanger does not require dehumidification, and the frequency of the compressor is increased or the speed of the indoor fan is reduced. If the inlet dew point temperature of the air conditioning system is determined to be greater than the indoor first pipe temperature, then the inlet specific enthalpy of the air conditioning system is determined based on the indoor return air temperature and the return air relative humidity of the air conditioning system. The outlet specific enthalpy of the air conditioning system is determined based on the outlet dew point temperature and the outlet air relative humidity of the air conditioning system. The dehumidification latent heat ratio of the indoor first heat exchanger is determined based on the inlet specific enthalpy, the outlet specific enthalpy, and the phase change latent heat of the air conditioning system. The ratio of the refrigerant flow rate of the first-stage throttling device to that of the second-stage throttling device is determined based on the return air relative humidity, the dehumidification latent heat ratio of the indoor first heat exchanger, and the temperature regulation coefficient of the air conditioning system.

[0028] In some embodiments, the control unit determines the refrigerant mass flow rate of the first-stage throttling device and the refrigerant mass flow rate of the second-stage throttling device based on the indoor first pipe temperature of the air conditioning system, a predetermined saturation temperature drop from the middle of the indoor first heat exchanger to the first suction port of the compressor, the indoor second pipe temperature of the air conditioning system, the ratio of the refrigerant flow rate of the first-stage throttling device to the refrigerant flow rate of the second-stage throttling device, and a predetermined saturation temperature drop from the middle of the indoor second heat exchanger to the second suction port of the compressor. This includes: adjusting the indoor first pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the middle of the indoor first heat exchanger to the second suction port of the compressor. The difference in saturation temperature drop at the first suction port of the compressor is taken as the suction saturation temperature of the first suction cylinder of the compressor; and the difference in saturation temperature drop between the indoor second pipe temperature of the air conditioning system and the predetermined difference in saturation temperature drop from the middle of the indoor second heat exchanger to the second suction port of the compressor is taken as the suction saturation temperature of the second suction cylinder of the compressor; the saturation suction specific volume corresponding to the first suction cylinder of the compressor is determined based on the suction saturation temperature of the first suction cylinder of the compressor; and the saturation suction specific volume corresponding to the second suction cylinder of the compressor is determined based on the suction saturation temperature of the second suction cylinder of the compressor; the predetermined difference in saturation temperature drop from the middle of the indoor first heat exchanger to the second suction port of the compressor is taken as the suction saturation temperature of the second suction cylinder of the compressor; the difference in saturation temperature drop from the middle of the indoor first heat exchanger to the second suction port of the compressor is taken as the suction saturation temperature of the second suction cylinder of the compressor; the difference in saturation temperature drop from the second suction port of the air conditioning system and the predetermined difference in saturation temperature drop from the middle of the indoor second heat exchanger to the second suction port of the compressor is taken as the suction saturation temperature of the second suction cylinder of the compressor; the difference in saturation temperature drop from the second suction port of the air conditioning system and the predetermined difference in saturation temperature drop from the middle of the indoor first heat exchanger to the second suction port of the compressor is taken as the suction saturation temperature of the second suction cylinder of the compressor; the difference in saturation temperature drop from the second suction port of the air conditioning system and the predetermined difference in saturation temperature drop from the second suction port of the air conditioning system ... The product of a third set factor multiple of the saturation temperature drop from the middle of the second heat exchanger to the second suction port of the compressor, and a third set value, plus a preset suction superheat of the first suction cylinder of the compressor, is used as the saturation suction specific volume corresponding to the first suction cylinder of the compressor; and the product of a fourth set factor multiple of the predetermined saturation temperature drop from the middle of the second heat exchanger to the second suction port of the compressor, and a fourth set value, plus a preset suction superheat of the second suction cylinder of the compressor, is used as the saturation suction specific volume corresponding to the second suction cylinder of the compressor; the set factor multiple of the compressor frequency is then multiplied by the product of the frequency of the compressor and the first suction cylinder of the compressor. The ratio of the saturated suction specific volume to the compressor's frequency setting coefficient is used to obtain a first calculated value; the ratio of this coefficient to the saturated suction specific volume of the compressor's second suction cylinder is then used to obtain a second calculated value; the sum of the first and second calculated values ​​is determined as the total refrigerant mass flow rate of the first-stage throttling device and the second-stage throttling device; based on the total refrigerant mass flow rate of the first-stage and second-stage throttling devices and the ratio of the refrigerant flow rates of the first-stage and second-stage throttling devices, the refrigerant mass flow rate of the first-stage throttling device and the refrigerant mass flow rate of the second-stage throttling device are determined.

[0029] In some embodiments, the control unit is further configured to: after the first-stage throttling device operates at its target opening and the second-stage throttling device operates at its target opening for a set period of time, the control unit is further configured to: if the current operating mode of the air conditioning system is cooling mode, adjust the target opening of the first-stage throttling device according to the difference between the first suction temperature of the air conditioning system and the first indoor pipe temperature of the air conditioning system to obtain a new target opening of the first-stage throttling device; and adjust the target opening of the second-stage throttling device according to the difference between the second suction temperature of the air conditioning system and the second indoor pipe temperature of the air conditioning system to obtain a new second-stage throttling device. The control unit is further configured to, if the current operating mode of the air conditioning system is reheat dehumidification mode, adjust the target opening of the first-stage throttling device according to the difference between the first suction temperature of the air conditioning system and the first indoor pipe temperature of the air conditioning system to obtain a new target opening of the first-stage throttling device; and adjust the target opening of the second-stage throttling device according to the difference between the indoor return air temperature of the air conditioning system and the set temperature to obtain a new target opening of the second-stage throttling device; thereafter, the control unit is further configured to control the first-stage throttling device to operate at the new target opening of the first-stage throttling device, and control the second-stage throttling device to operate at the new target opening of the second-stage throttling device.

[0030] In conjunction with the above-described device, the present invention further provides an air conditioning system, comprising: the control device for the air conditioning system described above.

[0031] In conjunction with the above method, the present invention further provides a storage medium comprising a stored program, wherein, when the program is executed, the device on which the storage medium is located controls the execution of the control method of the air conditioning system described above.

[0032] Therefore, the solution of this invention, by employing a three-pipe parallel reheat dehumidification system in the air conditioning system, calculates the refrigerant mass flow ratio of the outdoor electronic expansion valve and the indoor electronic expansion valve for the two-stage throttling device (i.e., the first-stage throttling device, such as the outdoor electronic expansion valve) and the second-stage throttling device (i.e., the indoor electronic expansion valve) in the three-pipe parallel reheat dehumidification system, and calculates the inlet and outlet pressure difference of the outdoor and indoor electronic expansion valves; based on the refrigerant mass flow ratio of the outdoor and indoor electronic expansion valves and the inlet and outlet pressure difference of the outdoor and indoor electronic expansion valves, the air flow ratio of the outdoor and indoor electronic expansion valves is calculated; based on the electronic expansion valve... The relationship between the airflow rate and opening degree of the expansion valve is calculated based on the airflow rate ratio of the outdoor and indoor electronic expansion valves. The opening degrees of the outdoor and indoor electronic expansion valves are then adjusted according to their opening degrees. This allows for fine-tuning of the opening degrees of the outdoor and indoor electronic expansion valves. Furthermore, by employing a three-pipe parallel reheat dehumidification system in the air conditioning system, the dual electronic expansion valves within the system are decoupled, enabling active control of their opening degrees and improving the energy efficiency and comfort of the air conditioning system during cooling and dehumidification operation.

[0033] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention.

[0034] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0035] Figure 1 This is a flowchart illustrating an embodiment of the control method for an air conditioning system according to the present invention;

[0036] Figure 2 This is a flowchart illustrating an embodiment of calculating the target opening degree of the first-stage throttling device and the target opening degree of the second-stage throttling device in the cooling mode of the method of the present invention.

[0037] Figure 3 This is a schematic flowchart of an embodiment of determining the inlet and outlet pressure difference of the first-stage throttling device in the cooling mode of the method of the present invention;

[0038] Figure 4 This is a schematic flowchart of an embodiment of determining the inlet and outlet pressure difference of the second-stage throttling device in the refrigeration mode of the method of the present invention;

[0039] Figure 5 This is a schematic flowchart of an embodiment of determining the inlet refrigerant density of the second-stage throttling device in the refrigeration mode of the method of the present invention;

[0040] Figure 6 This is a flowchart illustrating an embodiment of calculating the saturated suction specific volume corresponding to the first suction cylinder of the compressor in the refrigeration mode of the method of the present invention.

[0041] Figure 7 This is a flowchart illustrating an embodiment of calculating the saturated suction specific volume corresponding to the second suction cylinder of the compressor in the refrigeration mode of the method of the present invention.

[0042] Figure 8 This is a flowchart illustrating an embodiment of determining the target opening degree of the first-stage throttling device in the cooling mode of the method of the present invention.

[0043] Figure 9 This is a flowchart illustrating an embodiment of determining the target opening degree of the second-stage throttling device in the cooling mode of the method of the present invention;

[0044] Figure 10 This is a flowchart illustrating another embodiment of determining the target opening degree of the first-stage throttling device in the cooling mode of the method of the present invention.

[0045] Figure 11 This is a flowchart illustrating another embodiment of determining the target opening degree of the second-stage throttling device in the cooling mode of the method of the present invention;

[0046] Figure 12 This is a flowchart illustrating an embodiment of calculating the target opening degree of the first-stage throttling device and the target opening degree of the second-stage throttling device in the reheat dehumidification mode of the method of the present invention.

[0047] Figure 13 This is a schematic flowchart of an embodiment of the method of the present invention for determining the ratio of refrigerant flow rate of the first-stage throttling device to that of the second-stage throttling device under reheat dehumidification mode;

[0048] Figure 14 This is a schematic flowchart of an embodiment of the method of the present invention for determining the refrigerant mass flow rate of the first-stage throttling device and the refrigerant mass flow rate of the second-stage throttling device under reheat dehumidification mode;

[0049] Figure 15 This is a flowchart illustrating an embodiment of the method of the present invention, which involves operating the first-stage throttling device at a target opening degree and fine-tuning the target opening degree of the second-stage throttling device.

[0050] Figure 16 This is a schematic diagram of the structure of an embodiment of the control device for the air conditioning system of the present invention;

[0051] Figure 17A schematic diagram of the refrigeration mode cycle of a three-pipe parallel reheat dehumidification system;

[0052] Figure 18 A schematic diagram of the refrigeration cycle enthalpy of a three-pipe parallel reheat dehumidification system;

[0053] Figure 19 A schematic flowchart of the first embodiment of the calculation process for the opening degree of the dual electronic expansion valve in cooling mode;

[0054] Figure 20 This is a schematic flowchart of the second embodiment of the calculation process for the opening degree of the dual electronic expansion valve in cooling mode;

[0055] Figure 21 A schematic diagram of the reheat dehumidification mode circulation of a three-pipe parallel reheat dehumidification system;

[0056] Figure 22 This is a schematic diagram of the pressure and enthalpy of the reheat dehumidification cycle in a three-pipe parallel reheat dehumidification system.

[0057] Figure 23 This is a schematic diagram illustrating the calculation process for the opening degree of the dual electronic expansion valves in reheat dehumidification mode.

[0058] Referring to the accompanying drawings, the reference numerals in the embodiments of the present invention are as follows:

[0059] 10-Compressor, 11-Compressor exhaust port, 12-Compressor first suction port, 13-Compressor second suction port, 20-Outdoor heat exchanger, 31-First stage flow device, 32-Second stage throttling device, 41-Indoor first heat exchanger, 42-Indoor second heat exchanger, 51-First four-way reversing valve, 52-Second four-way reversing valve, 61-Outdoor fan, 62-Indoor fan, 70-Check valve; 71, 72, 73, 74, 75, 76-Temperature sensor; 102-Acquisition unit; 104-Control unit. Detailed Implementation

[0060] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0061] Considering that approximately half of my country's population resides in the middle and lower reaches of the Yangtze River and areas south of it, the cumulative duration of summer cooling and the cumulative duration of humid weather during the transitional season are both relatively long, resulting in significant demand for cooling and dehumidification. To address the high energy consumption of air conditioning systems (such as household inverter heat pump air conditioners) during low-load operation in summer, and the low comfort and high energy consumption during humid weather in the transitional season, some solutions employ a dual-temperature parallel reheat dehumidification cycle technology. This technology can achieve efficient cooling, temperature regulation, dehumidification, and heating functions. However, the dual electronic expansion valves in this technology are coupled, and the scheme using parameters such as the compressor's suction superheat or exhaust superheat to control the opening of the dual electronic expansion valves may lead to instability in the air conditioning system or longer adjustment times due to the coupling of the dual electronic expansion valves.

[0062] The air conditioning systems in related solutions typically use only one electronic expansion valve, and its opening is usually controlled based on the compressor's exhaust superheat or exhaust temperature to ensure the performance and reliability of the refrigeration system. However, the refrigeration system in this invention employs a compressor with a dual-suction, single-exhaust structure to achieve dual-temperature cooling and reheat dehumidification functions. The indoor evaporators are connected in parallel, with electronic expansion valves installed at the condenser outlet and the inlet of the indoor leeward-side evaporator (i.e., the indoor second heat exchanger 42), respectively. In cooling mode, the outdoor electronic expansion valve throttles the condensing pressure to the evaporating pressure on the windward side, while simultaneously adjusting the suction superheat of the windward evaporator. The indoor leeward-side electronic expansion valve throttles the windward evaporating pressure to the leeward evaporating pressure, while also adjusting the suction superheat of the leeward evaporator. Because the two electronic expansion valves are coupled, controlling the compressor's exhaust superheat alone could lead to one evaporator overheating while the other evaporator outlet carries liquid, causing compressor liquid slugging and reduced energy efficiency.

[0063] Therefore, the present invention proposes a control method for an air conditioning system, specifically a method for controlling the opening of dual electronic expansion valves in an air conditioning system, and more specifically, a method for decoupling the opening of dual electronic expansion valves in a refrigeration cycle system under cooling and reheat dehumidification modes. This method involves calculating the refrigerant mass flow rate ratio of the outdoor and indoor electronic expansion valves, and then calculating the inlet and outlet pressure difference between the outdoor and indoor electronic expansion valves. Based on the refrigerant mass flow rate ratio and the inlet and outlet pressure difference, the air flow rate ratio of the outdoor and indoor electronic expansion valves is calculated. Based on the correspondence between the air flow rate and the opening of the electronic expansion valves, and according to the air flow rate ratio, the opening of the outdoor and indoor electronic expansion valves is calculated. Based on the opening of the outdoor and indoor electronic expansion valves, the discharge superheat and suction superheat of the compressor are adjusted to achieve fine-tuning of the opening of the outdoor and indoor electronic expansion valves, thereby ensuring the reliability and stability of the air conditioning system operation. This approach not only solves the problems of high energy consumption in air conditioning systems (such as household inverter heat pump air conditioners) during low-load cooling and dehumidification in summer, and low comfort and high energy consumption during humid weather in transitional seasons, but also addresses the issues of unstable operation or longer adjustment time in air conditioning systems caused by the coupling relationship between the two electronic expansion valves in related solutions that use parameters such as compressor suction superheat or exhaust superheat for dual electronic expansion valve opening control.

[0064] According to embodiments of the present invention, a control method for an air conditioning system is provided, such as... Figure 1The diagram shows a flow chart of an embodiment of the method of the present invention. The air conditioning system adopts a three-pipe parallel reheat dehumidification system; the three-pipe parallel reheat dehumidification system includes a compressor 10, a first-stage throttling device 31, a second-stage throttling device 32, an outdoor fan 61, and an indoor fan 62. Specifically, the air conditioning system includes: a compressor 10, an outdoor heat exchanger 20, an indoor first heat exchanger 41, an indoor second heat exchanger 42, a first-stage throttling device 31, a second-stage throttling device 32, a first four-way reversing valve 51 and a second four-way reversing valve 52, an outdoor fan 61 located at the outdoor heat exchanger 20, and an indoor fan 62 located at the indoor first heat exchanger 41; wherein, the exhaust port 11 of the compressor 10, after passing through the D and C ports of the first four-way reversing valve 51, the outdoor heat exchanger 20, and the first-stage throttling device 31, is divided into two paths: one path passes through the indoor first heat exchanger 41 and the E and S ports of the first four-way reversing valve 51, and returns to the first suction port 12 of the compressor 10; the other path passes through the second-stage throttling device 32 and the indoor second heat exchanger 42, and then through the E and S ports of the second four-way reversing valve 52, and returns to the second suction port 13 of the compressor 10.

[0065] In the solution of this invention, the air conditioning system adopts a three-pipe parallel reheat dehumidification system. Figure 17 This is a schematic diagram of the cooling mode cycle of a three-pipe parallel reheat dehumidification system. Figure 17 As shown, the three-pipe parallel reheat dehumidification system includes: a compressor 10, an outdoor heat exchanger 20, a first-stage throttling device 31, a second-stage throttling device 32, an indoor first heat exchanger 41, an indoor second heat exchanger 42, a first four-way reversing valve 51, a second four-way reversing valve 52, an outdoor fan 61 and an indoor fan 62, a one-way valve 70, and temperature sensors 71, 72, 73, 74, 75, and 76. Among them, as... Figure 17As shown, in cooling mode, the discharge port 11 of the compressor 10 is connected to port D of the first four-way reversing valve 51. Port C of the first four-way reversing valve 51, after passing through the outdoor heat exchanger 20 and the first-stage throttling device 31, splits into two paths: one path passes through the indoor first heat exchanger 41 and connects to port E of the first four-way reversing valve 51; the other path passes through the second-stage throttling device 32 and the indoor second heat exchanger 42 and connects to port E of the second four-way reversing valve 52. Port S of the second four-way reversing valve 52 is connected to the second suction port 13 of the compressor 10. Port S of the first four-way reversing valve 51 is connected to the first suction port 12 of the compressor 10. Temperature sensor 71 is installed on the heat exchange coil of the first indoor heat exchanger 41, temperature sensor 72 is installed on the heat exchange coil of the second indoor heat exchanger 42, temperature sensor 73 is installed on the heat exchange coil of the outdoor heat exchanger 20, temperature sensor 74 is installed on the pipeline where the first suction port 12 of the compressor 10 is located, temperature sensor 75 is installed on the pipeline where the second suction port 13 of the compressor 10 is located, and temperature sensor 76 is installed on the discharge port 11 of the compressor 10.

[0066] In the present invention, a compressor 10 with a dual-intake, single-exhaust structure is adopted, and the indoor evaporators, namely the first indoor heat exchanger 41 and the second indoor heat exchanger 42, are connected in parallel. Throttling devices are respectively provided at the outlet of the condenser (i.e., the outdoor heat exchanger 20) and the inlet of the indoor leeward side evaporator (i.e., the second indoor heat exchanger 42), such as a first-stage throttling device 31 (e.g., an outdoor electronic expansion valve) and a second-stage throttling device 32 (e.g., an indoor electronic expansion valve): In the cooling mode, the outdoor electronic expansion valve throttles the condensing pressure to the evaporating pressure on the windward side, and at the same time adjusts the suction superheat of the windward evaporator (i.e., the first indoor heat exchanger 41); the indoor leeward electronic expansion valve (i.e., the indoor electronic expansion valve) throttles the windward evaporating pressure to the leeward evaporating pressure, and at the same time adjusts the suction superheat of the leeward evaporator (i.e., the second indoor heat exchanger 42).

[0067] Figure 21 This is a schematic diagram of the reheat dehumidification mode cycle of a three-pipe parallel reheat dehumidification system. Figure 21As shown, in reheat dehumidification mode, the discharge port 11 of compressor 10 is connected to port D of the first four-way reversing valve 51. The discharge port 11 of compressor 10 is also connected to port D of the second four-way reversing valve 52. Port C of the first four-way reversing valve 51, after passing through the outdoor heat exchanger 20 and the first-stage throttling device 31, connects to port E of the first four-way reversing valve 51 after passing through the indoor first heat exchanger 41. Port E of the second four-way reversing valve 52, after passing through the indoor second heat exchanger 42 and the second-stage throttling device 32, flows into the indoor first heat exchanger 41, and then connects to port E of the first four-way reversing valve 51. Port S of the second four-way reversing valve 52 is connected to the second suction port 13 of compressor 10. Port C of the second four-way reversing valve 52 is connected to the outlet of check valve 70. The first suction port 12 of compressor 10 is connected to the inlet of check valve 70. The control method for the air conditioning system includes steps S110 to S140.

[0068] In step S110, after the air conditioning system is started, the indoor unit's air guide vane is opened, the indoor fan 62 is started at a set fan speed or automatic fan speed, and the air conditioning system is controlled to perform oil return operation. Specifically, during the oil return operation, according to a preset oil return operation logic, the outdoor fan 62's speed is set to the oil return speed, the compressor 10's frequency is set to the oil return frequency, the first-stage throttling device 31's opening degree is set to the first oil return opening degree, and the second-stage throttling device 32's opening degree is set to the second oil return opening degree, thereby controlling the air conditioning system to perform oil return operation. In the preset oil return operation logic, the outdoor fan 62's speed, the compressor 10's frequency, the first-stage throttling device 31's opening degree, and the second-stage throttling device 32's opening degree correspond to the set oil return parameters.

[0069] In step S120, after the air conditioning system completes its oil return operation, the outdoor ambient temperature of the air conditioning system is obtained, such as the ambient temperature t. w And obtain the operating parameters of the air conditioning system.

[0070] In some embodiments, the three-pipe parallel reheat dehumidification system further includes an outdoor heat exchanger 20, an indoor first heat exchanger 41, and an indoor second heat exchanger 42; the compressor 10 has an exhaust port 11, a first intake port 12, and a second intake port 13.

[0071] Step S120 involves obtaining the operating parameters of the air conditioning system, including at least one of the following:

[0072] Obtain the indoor ambient temperature of the air conditioning system, such as the inner ambient temperature t. N ; Obtain the indoor return air relative humidity of the air conditioning system, such as the indoor return air relative humidity RH. NThe system obtains the indoor return air temperature of the air conditioning system. It also obtains the frequency of the compressor 10, such as the frequency f of the compressor 10. Finally, it obtains the pipe temperature of the indoor first heat exchanger 41, denoted as the indoor first pipe temperature of the air conditioning system, such as the pipe temperature t of the indoor first heat exchanger 41. eH The pipe temperature of the indoor second heat exchanger 42 is obtained and recorded as the indoor second pipe temperature of the air conditioning system, such as the pipe temperature t of the indoor second heat exchanger 42. eL The pipe temperature of the outdoor heat exchanger 20 is obtained and recorded as the outdoor pipe temperature of the air conditioning system, such as the pipe temperature t of the outdoor heat exchanger 20. c The refrigerant outlet temperature of the outdoor heat exchanger 20 is obtained. For example, in cooling mode, a refrigerant outlet temperature sensor is added to the outdoor condenser outlet pipe to detect the condenser outlet temperature in cooling mode. The temperature of the first suction port 12 of the compressor 10 is obtained and recorded as the first suction temperature of the air conditioning system. For example, the temperature t of the first suction port 12 of the compressor 10 is... suc1 The temperature of the second suction port 13 of the compressor 10 is obtained and recorded as the second suction port temperature of the air conditioning system, such as suction temperature 2, which is the temperature t of the second suction port 13 of the compressor 10. suc2 And, the temperature of the exhaust port 11 of the compressor 10 is obtained and recorded as the exhaust temperature of the air conditioning system, such as the temperature t of the exhaust port 11 of the compressor 10. dis .

[0073] In the solution of this invention, see Figure 19 , Figure 20 and Figure 23 In the example shown, while obtaining the operating parameters of the air conditioning system, it is also necessary to obtain the preset values ​​and fitted parameters of the air conditioning system. After obtaining the detected values ​​(i.e., the operating parameters of the air conditioning system), preset values, and fitted values, the opening degree of the dual electronic expansion valve in cooling mode is determined based on these parameters. Specifically, the detected values, preset values, and fitted values ​​are required when calculating the opening degree (i.e., the target opening degree) of the dual electronic expansion valve; therefore, it is necessary to obtain these parameters.

[0074] The acquired detection values ​​include at least one of the following: inner pipe temperature 1, i.e., the pipe temperature t of the first indoor heat exchanger 41. eH The inner pipe temperature 2 is the pipe temperature t of the second indoor heat exchanger 42. eL The external pipe temperature is the pipe temperature t of the outdoor heat exchanger 20. c The suction temperature 1 is the temperature t of the first suction port 12 of the compressor 10. suc1 The suction temperature 2 is the temperature t of the second suction port 13 of the compressor 10. suc2 The exhaust temperature is the temperature t at the exhaust port 11 of the compressor 10.dis The frequency f of compressor 10, and the ambient temperature t w Inner ring temperature t N Indoor return air relative humidity (RH) N .

[0075] The preset values ​​obtained include at least one of the following: the high-temperature cylinder volume V of compressor 10 rev，H The cryogenic cylinder volume V of compressor 10 rev，L The leeward side suction superheat setpoint dt of compressor 10 suc，sh，l .

[0076] The parameters that need to be fitted during prototype matching include at least one of the following: the cryogenic cylinder volumetric efficiency η of compressor 10. v，L The flow correction factor K of main valve 1 (i.e., outdoor electronic expansion valve) c1 The flow correction factor K of the indoor unit reheat valve 2 (i.e., indoor electronic expansion valve) c2 The saturation temperature drop dt from the middle of the evaporator on the windward side (i.e., the first heat exchanger 41 in the room) to the suction port sat，suc1 The saturation temperature drop dt from the middle of the evaporator on the leeward side (i.e., the second indoor heat exchanger 42) to the suction port sat，suc2 The saturated temperature drop dt from the outlet of main valve 1 (i.e., outdoor electronic expansion valve) to the high-temperature evaporator tube sat1 The saturated temperature drop dt from the outlet of the indoor unit valve (i.e., indoor unit reheat valve 2) to the low-temperature evaporator tube sat2 Outdoor valve opening Pulse1 = f(V) a，1 ), the opening degree of the indoor valve (i.e., indoor unit reheat valve 2) Pulse2 = f(V a 2), Main valve 1 flow correction coefficient K c1 Flow correction coefficient K for indoor reheat valve 2 c2 .

[0077] The saturation temperature drop from the middle of the evaporator to the suction port refers to the difference between the saturation temperature corresponding to the pressure at the middle of the evaporator and the saturation temperature corresponding to the suction pressure of the compressor. The low-temperature cylinder of the compressor 10 refers to the cylinder corresponding to the second suction port 13 of the compressor 10 connected to the indoor leeward side heat exchanger (i.e., the indoor second heat exchanger 42); correspondingly, the high-temperature cylinder of the compressor 10 refers to the cylinder corresponding to the first suction port 12 of the compressor 10 connected to the windward side evaporator (i.e., the indoor first heat exchanger 41). The high-temperature evaporator is the indoor first heat exchanger 41, and the low-temperature evaporator is the indoor second heat exchanger 42.

[0078] In step S130, under the current operating mode of the air conditioning system, the frequency of the compressor 10 and the speed of the outdoor fan 61 are adjusted according to the outdoor ambient temperature of the air conditioning system. And,

[0079] In step S140, under the current operating mode of the air conditioning system, the target opening degree of the first-stage throttling device 31 and the target opening degree of the second-stage throttling device 32 are determined by combining the outdoor ambient temperature of the air conditioning system, the indoor return air relative humidity of the air conditioning system, and the operating parameters of the air conditioning system. Then, under the current operating mode of the air conditioning system, the first-stage throttling device 31 is controlled to operate at the target opening degree of the first-stage throttling device 31, and the second-stage throttling device 32 is controlled to operate at the target opening degree of the second-stage throttling device 32. The current operating mode of the air conditioning system is either cooling mode or reheat dehumidification mode. That is, in the current operating mode of the air conditioning system, the current opening of the first-stage throttling device 31 and the current opening of the second-stage throttling device 32 are adjusted according to the target opening of the first-stage throttling device 31 and the target opening of the second-stage throttling device 32. Specifically, the current opening of the first-stage throttling device 31 is adjusted according to the target opening of the first-stage throttling device 31, and at the same time, the current opening of the second-stage throttling device 32 is adjusted according to the target opening of the second-stage throttling device 32, so as to improve the energy efficiency of the air conditioning system and the user's comfort experience in the current operating mode of the air conditioning system.

[0080] The present invention proposes a method for controlling the opening degree of dual electronic expansion valves in an air conditioning system. This method calculates the refrigerant mass flow rate ratio between the outdoor main electronic expansion valve (i.e., the outdoor electronic expansion valve) and the indoor reheat electronic expansion valve (i.e., the indoor electronic expansion valve), and calculates the inlet and outlet pressure difference between the main electronic expansion valve (i.e., the outdoor electronic expansion valve) and the reheat electronic expansion valve (i.e., the indoor electronic expansion valve) based on the temperature parameters detected by the pipe temperature sensor. Finally, the method calculates the opening degree of the dual electronic expansion valves using the refrigerant mass flow rate ratio between the main valve 1 (i.e., the outdoor electronic expansion valve) and the reheat electronic expansion valve, and the pressure difference across the valves (i.e., the inlet and outlet pressure difference). The airflow ratio is determined by fitting the corresponding relationship between the airflow and opening degree of the selected electronic expansion valve. This yields the fitting formulas for the airflow-opening degree and opening degree-airflow ratio of the valve. Knowing the opening degree of one valve allows calculation of its airflow, and vice versa, enabling the correlated control of the two valve openings. Based on the calculated electronic expansion valve opening, appropriate feedback adjustments, such as compressor exhaust superheat and intake superheat, are used to fine-tune the opening of the dual electronic expansion valves, thus ensuring the reliability and stability of the air conditioning system. However, the control method for the opening of the electronic expansion valve in the relevant scheme cannot meet the decoupling control requirements of the dual electronic expansion valves in a three-pipe parallel reheat dehumidification system, thus failing to address the issue of active control of the dual electronic expansion valve opening. By decoupling the dual electronic expansion valves in the three-pipe parallel reheat dehumidification system, active control of the dual electronic expansion valve opening is achieved, along with rapid adjustment, improving the stability and reliability of the air conditioning system. Therefore, this not only solves the problems of high energy consumption in air conditioning systems (such as household inverter heat pump air conditioners) during low-load operation for cooling and dehumidification in summer, and low comfort and high energy consumption during humid weather in transitional seasons, but also solves the problems of unstable operation of air conditioning systems or longer adjustment time caused by the coupling relationship between the two electronic expansion valves in related solutions that use parameters such as compressor suction superheat or exhaust superheat for dual electronic expansion valve opening control.

[0081] In some implementations, the current operating mode of the air conditioning system is cooling mode.

[0082] In step S140, under the cooling mode, the target opening degree of the first-stage throttling device 31 and the target opening degree of the second-stage throttling device 32 are determined by combining the outdoor ambient temperature of the air conditioning system, the indoor return air relative humidity of the air conditioning system, and the operating parameters of the air conditioning system. This includes the process of calculating the target opening degree of the first-stage throttling device 31 and the target opening degree of the second-stage throttling device 32 under the cooling mode.

[0083] The following is combined with Figure 2The flowchart shown is a schematic diagram of an embodiment of the method of the present invention for calculating the target opening degree of the first-stage throttling device 31 and the target opening degree of the second-stage throttling device 32 in the cooling mode. It further illustrates the specific process of calculating the target opening degree of the first-stage throttling device 31 and the target opening degree of the second-stage throttling device 32 in the cooling mode in step S140, including steps S210 to S250.

[0084] Step S210: Based on the outdoor pipe temperature of the air conditioning system, the indoor first pipe temperature of the air conditioning system, and the predetermined saturation temperature drop from the outlet of the first-stage throttling device 31 to the pipe of the first indoor heat exchanger 41, determine the inlet and outlet pressure difference of the first-stage throttling device 31, such as based on the pipe temperature t of the outdoor heat exchanger 20. c The tube temperature t of the first heat exchanger 41 in the room eH The saturated temperature drop dt from the outlet of main valve 1 to the high-temperature evaporator tube sat1 Calculate the refrigerant inlet and outlet pressure difference ΔP of main valve 1. r1 The high-temperature evaporator is the indoor first heat exchanger 41; and the inlet and outlet pressure difference of the second-stage throttling device 32 is determined based on the indoor first pipe temperature of the air conditioning system, the indoor second pipe temperature of the air conditioning system, and the predetermined saturation temperature drop from the outlet of the second-stage throttling device 32 to the pipe of the indoor second heat exchanger 42, such as based on the pipe temperature t of the indoor first heat exchanger 41. eH The tube temperature t of the second heat exchanger 42 in the room eL The saturated temperature drop dt from the outlet of indoor unit valve 2 to the low-temperature evaporator tube sat2 Calculate the refrigerant inlet and outlet pressure difference ΔP of main valve 1. r2 Among them, the low-temperature evaporator is the second heat exchanger in the room 42.

[0085] In some embodiments, the specific process of determining the inlet and outlet pressure difference of the first-stage throttling device 31 in step S210 based on the outdoor pipe temperature of the air conditioning system, the indoor first pipe temperature of the air conditioning system, and the predetermined saturation temperature drop from the outlet of the first-stage throttling device 31 to the pipe of the indoor first indoor heat exchanger 41 is described in the following exemplary description.

[0086] The following is combined with Figure 3 The schematic diagram shows an embodiment of determining the inlet and outlet pressure difference of the first-stage throttling device in the cooling mode of the method of the present invention. It further illustrates the specific process of determining the inlet and outlet pressure difference of the first-stage throttling device 31 in the cooling mode in step S210, including steps S310 to S320.

[0087] Step S310: The outdoor pipe temperature of the air conditioning system is used as the saturation temperature corresponding to the refrigerant inlet pressure of the first-stage throttling device 31, such as the refrigerant inlet saturation temperature of the main valve 1 being t. i1 =t c ; and, the sum of the indoor first pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the outlet of the first-stage throttling device 31 to the pipe of the first indoor heat exchanger 41 is taken as the saturation temperature corresponding to the refrigerant outlet pressure of the first-stage throttling device 31, such as the refrigerant outlet saturation temperature of the main valve 1 being t o1 =t eH +dt sat1 .

[0088] Step S320: The sum of the refrigerant inlet pressure corresponding to the saturation temperature and the refrigerant outlet pressure corresponding to the saturation temperature of the first-stage throttling device 31, multiplied by a first set coefficient, is added to a first set value. This sum is then multiplied by the difference between the refrigerant outlet pressure and the saturation temperature of the first-stage throttling device 31 to obtain the inlet and outlet pressure difference of the first-stage throttling device 31, such as the refrigerant inlet and outlet pressure difference ΔP of the main valve 1. r1 =[509.46(t)] i1 +t o1 )+20853](t i1 -t o1 ).

[0089] In some embodiments, the specific process of determining the inlet and outlet pressure difference of the second-stage throttling device 32 in step S210 based on the indoor first pipe temperature of the air conditioning system, the indoor second pipe temperature of the air conditioning system, and the predetermined saturation temperature drop from the outlet of the second-stage throttling device 32 to the pipe of the indoor second heat exchanger 42 is described in the following exemplary description.

[0090] The following is combined with Figure 4 The schematic diagram shown is a flowchart of an embodiment of determining the inlet and outlet pressure difference of the second-stage throttling device 32 in the refrigeration mode in the method of the present invention. It further illustrates the specific process of determining the inlet and outlet pressure difference of the second-stage throttling device 32 in the refrigeration mode in step S210, including steps S410 to S420.

[0091] Step S410: The sum of the indoor first pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the outlet of the second-stage throttling device 32 to the pipe of the indoor second heat exchanger 42 is taken as the saturation temperature corresponding to the refrigerant inlet pressure of the second-stage throttling device 32. For example, the refrigerant inlet saturation temperature of the indoor unit valve 2 is t. i2 =t eH +dt sat2; and, the sum of the indoor second pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the outlet of the second-stage throttling device 32 to the pipe of the indoor second heat exchanger 42 is taken as the saturation temperature corresponding to the refrigerant outlet pressure of the second-stage throttling device 32, such as the refrigerant outlet saturation temperature of the indoor unit valve 2 being t o2 =t eL +dt sat2 .

[0092] Step S420: The second set coefficient multiple of the sum of the refrigerant inlet pressure corresponding to the saturation temperature of the second-stage throttling device 32 and the refrigerant outlet pressure corresponding to the saturation temperature of the second-stage throttling device 32 is added to a second set value, and then multiplied by the difference between the refrigerant outlet pressure and the saturation temperature of the second-stage throttling device 32 to obtain the inlet and outlet pressure difference of the second-stage throttling device 32, such as the refrigerant inlet and outlet pressure difference ΔP of the main valve 1. r2 =[509.46(t)] i2 +t o2 )+20853](t i2 -t o2 ).

[0093] Specifically, Figure 19 This is a schematic flowchart of the first embodiment of the calculation process for the opening degree of the dual electronic expansion valve in cooling mode. Figure 19 As shown, the calculation process for the opening degree of the dual electronic expansion valve in cooling mode includes:

[0094] Step 11: After the air conditioning system receives the command to operate in cooling mode, it first opens the air deflector of the indoor unit and starts the indoor fan according to the user-set fan speed or automatic fan speed. The outdoor fan speed, compressor frequency, and the opening of the outdoor and indoor electronic expansion valves will initially operate at the outdoor fan speed, compressor frequency, and the opening of the outdoor and indoor electronic expansion valves corresponding to the set oil return parameters. After the oil return operation is completed, proceed to step 12. The oil return parameters include the compressor frequency, outdoor fan speed, indoor fan speed, and the opening of the two electronic expansion valves in this mode.

[0095] Step 12: The compressor frequency and outdoor fan speed are determined based on the ambient temperature detected by the outdoor ambient temperature sensor (i.e., the outdoor ambient temperature t). w The system operates based on user-defined temperature parameters, and the opening degrees of the outdoor and indoor electronic expansion valves are calculated based on the temperature parameters detected by the temperature sensor. For example, when the outdoor ambient temperature is high and the indoor set temperature is low, the compressor needs to operate at high frequency and the outdoor fan at high speed.

[0096] The calculation process for the opening degree of main valve 1 (i.e., outdoor electronic expansion valve) and indoor reheat valve 2 (i.e., indoor electronic expansion valve) in cooling mode is as follows:

[0097] Step 121: Calculate the refrigerant inlet and outlet pressure difference of the main valve 1 (i.e., the outdoor electronic expansion valve) and the indoor unit valve (i.e., the indoor unit reheat valve 2).

[0098] Figure 18 This is a schematic diagram of the pressure and enthalpy of the refrigeration cycle in a three-pipe parallel reheat dehumidification system. Figure 18 This can display the pressure and enthalpy relationship of a three-pipe parallel reheat dehumidification system in cooling mode. Here, h represents the specific enthalpy at the state point, P represents the pressure, and lg represents the logarithm down to 10; the numbers represent different state points: 1 represents compressor suction, 2 represents compressor discharge, 3' represents the outlet of outdoor condenser 20, 3 represents the outlet of reheat condenser 4, and 4 represents the inlet refrigerant state point of dehumidification evaporator 4. From... Figure 18 The pressure-enthalpy diagram for cooling mode shows that the inlet pressure of main valve 1 (i.e., outdoor electronic expansion valve) is the saturation pressure corresponding to the condenser tube temperature, and the outlet pressure of main valve 1 (i.e., outdoor electronic expansion valve) is the saturation pressure corresponding to the sum of the high-temperature evaporator tube temperature and the saturation temperature drop from the valve outlet to the high-temperature evaporator tube; the inlet pressure of indoor unit valve (i.e., indoor unit reheat valve 2) is the sum of the high-temperature evaporator tube temperature and the saturation temperature drop from the valve outlet to the high-temperature evaporator tube, and the outlet pressure of indoor unit valve (i.e., indoor unit reheat valve 2) is the saturation pressure corresponding to the sum of the low-temperature evaporator tube temperature and the saturation temperature drop from the outlet of indoor unit valve (i.e., indoor unit reheat valve 2) to the low-temperature evaporator tube.

[0099] Given the refrigerant used in the air conditioning system, the correlation between the refrigerant's saturated vapor pressure P and the corresponding saturated temperature t can be fitted using the refrigerant property software NIST, as shown by the equation P = f(t). Taking R32, the mainstream refrigerant for household inverter heat pump air conditioners, as an example, the fitted equation for the saturated vapor pressure P (Pa) of R32 under normal cooling conditions, such as an ambient temperature of 0-50℃, is as follows:

[0100] P=509.46*t*t+20853*t+839607.

[0101] The pressure difference between the inlet and outlet of the valve can be expressed as:

[0102] Δp r =[509.46(t)] i +t o )+20853](t i -t o ).

[0103] Among them, t i and t o These represent the saturation temperatures corresponding to the valve's inlet and outlet pressures, respectively. The refrigerant inlet and outlet saturation temperatures of main valve 1 (i.e., the outdoor electronic expansion valve) are tin and toutlet, respectively. i1 =t c , to1 =t eH +dt sat1 The refrigerant inlet and outlet saturation temperatures of the indoor unit valve (i.e., indoor unit reheat valve 2) are t and t, respectively. i2 =t eH +dt sat2 , t o2 =t eL +dt sat2 .

[0104] Step S220: Determine the inlet refrigerant density of the first-stage throttling device 31 based on the outdoor pipe temperature of the air conditioning system, such as based on the pipe temperature t of the outdoor heat exchanger 20. c Calculate the refrigerant density ρ at the inlet of main valve 1. 1i Furthermore, based on the outdoor ambient temperature of the air conditioning system or the refrigerant outlet temperature of the outdoor heat exchanger 20, and in conjunction with the predetermined saturated liquid specific volume and the predetermined saturated gas specific volume of the refrigerant in the air conditioning system, the inlet refrigerant density of the second-stage throttling device 32 is determined, such as based on the refrigerant dryness x at the indoor unit valve inlet and the saturated gas specific volume v of the refrigerant. g Specific volume of refrigerant in saturated liquid (v) l Calculate the refrigerant density ρ at the inlet of valve 2 in the indoor unit. 1i .

[0105] In some embodiments, determining the inlet refrigerant density of the first-stage throttling device 31 based on the outdoor pipe temperature of the air conditioning system in step S220 includes: determining the inlet refrigerant density of the first-stage throttling device 31 based on the correspondence between the set outdoor pipe temperature and the set inlet refrigerant density, where the set outdoor pipe temperature in the correspondence is the same as the outdoor pipe temperature of the air conditioning system. For example, ρ 1i =f(t) c ).

[0106] In some embodiments, the specific process of determining the inlet refrigerant density of the second-stage throttling device 32 in step S220 based on the outdoor ambient temperature of the air conditioning system or the refrigerant outlet temperature of the outdoor heat exchanger 20, combined with the predetermined saturated liquid specific volume and the predetermined saturated gas specific volume of the refrigerant in the air conditioning system, is described in the following exemplary description.

[0107] The following is combined with Figure 5The schematic diagram shows an embodiment of determining the inlet refrigerant density of the second-stage throttling device 32 in the refrigeration mode of the method of the present invention. It further illustrates the specific process of determining the inlet refrigerant density of the second-stage throttling device 32 in the refrigeration mode in step S220, including steps S510 to S530.

[0108] Step S510: Determine the specific enthalpy of the refrigerant at the outlet of the outdoor heat exchanger 20 based on the outdoor ambient temperature of the air conditioning system or the refrigerant outlet temperature of the outdoor heat exchanger 20, such as the specific enthalpy of the refrigerant at the condenser outlet h. c,out =f(t) c，out ), condenser outlet temperature t c，out It can be obtained through two calculation methods: one is using the ambient temperature t w Make corrections, i.e., t c , out =(t w +△t), where △t is selected according to the different configurations of the refrigeration system, usually between 2 and 5℃; another method is to add a cold outlet temperature sensor at the outdoor condenser outlet pipe to detect the condenser outlet temperature in refrigeration mode.

[0109] Step S520: Based on the outlet refrigerant specific enthalpy of the outdoor heat exchanger 20, the predetermined refrigerant saturated gas specific enthalpy of the air conditioning system, and the predetermined refrigerant saturated liquid specific enthalpy of the air conditioning system, determine the inlet refrigerant dryness of the second-stage throttling device 32, such as the inlet refrigerant dryness x of the indoor unit valve 2 = (h c,out -h l ) / (h g -h l ), the saturated gas enthalpy h of R32 g The saturated liquid specific enthalpy h of R32 l .

[0110] Step S530: Based on the inlet refrigerant dryness of the second-stage throttling device 32, the predetermined saturated liquid specific volume of the refrigerant in the air conditioning system, and the predetermined saturated gas specific volume of the refrigerant in the air conditioning system, determine the inlet refrigerant density of the second-stage throttling device 32, such as the refrigerant density ρ at the inlet of the indoor unit valve 2. 2i =1 / (x*v) g +(1-x)*v L ), the saturated gas specific volume v of the refrigerant g Specific volume of refrigerant in saturated liquid (v) l .

[0111] Specifically, such as Figure 19As shown, the calculation process for the opening of the dual electronic expansion valve in cooling mode also includes: step 122, calculating the refrigerant density at the inlet of the dual electronic expansion valve.

[0112] In cooling mode, the inlet of main valve 1 (i.e., the outdoor electronic expansion valve) contains subcooled liquid refrigerant, the density of which can be approximated as the density of a saturated liquid. This density can be calculated using the correlation between the saturated liquid density and the saturated temperature corresponding to the pressure, fitted by the refrigerant property calculation software NIST. In other words, the refrigerant density ρ at the inlet of main valve 1 (i.e., the outdoor electronic expansion valve) is... 1i =f(t) c ).

[0113] The inlet of the indoor valve (i.e., indoor unit reheat valve 2) is in a two-phase refrigerant state after throttling by the outdoor main valve 1 (i.e., outdoor electronic expansion valve). Its inlet density can be approximately calculated using the relationship between the inlet refrigerant dryness fraction, saturated liquid density, and saturated gas density. The refrigerant density ρ at the inlet of the indoor valve (i.e., indoor unit reheat valve 2) is... 2i =1 / (x*v) g +(1-x)*v L The refrigerant dryness fraction at the inlet of the indoor unit valve (i.e., indoor unit reheat valve 2) can be calculated using the relationship between the condenser outlet specific enthalpy and the specific enthalpy of the saturated gas and saturated liquid refrigerant at the inlet of the indoor unit valve (i.e., indoor unit reheat valve 2), x = (h c，out -h l ) / (h g -h l ), where the enthalpy of the refrigerant at the condenser outlet is h c，out =f(t) c，out ), condenser outlet temperature t c，out It can be obtained through two calculation methods: one is using the ambient temperature t w Make corrections, i.e., t c，out =(t w +△t), where △t is selected according to the different configurations of the refrigeration system, usually between 2 and 5℃; another method is to add a cold outlet temperature sensor at the outdoor condenser outlet pipe to detect the condenser outlet temperature in cooling mode. Taking R32, the mainstream refrigerant for household inverter heat pump air conditioners, as an example, in the ambient temperature range of 0-40℃: the saturated liquid density ρ (kg / m³) of R32 3 The fitting formula for ) is:

[0114] ρ=-0.031*t*t-2.7548*t+1051.3.

[0115] Specific volume of saturated gas of R32 v g (m 3 The fitted formula for ( / kg) is:

[0116] v g=10 -5 *t 2 -0.0013*t+0.045.

[0117] Specific volume of saturated liquid R32 v l (m 3 The fitted formula for ( / kg) is:

[0118] v l =3*10 -8 *t 2 +3*10 -6 *t+0.0009.

[0119] Specific enthalpy h of saturated liquid of R32 l The fitting formula for (kJ / kg) is:

[0120] h l =1.8414*t+199.51.

[0121] Enthalpy of saturated gas of R32 (h) g The fitting formula for (kJ / kg) is:

[0122] h g = -0.0063*t 2 +0.2075*t+515.24.

[0123] Step S230: Based on the indoor first pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the middle of the indoor first heat exchanger 41 to the first suction port 12 of the compressor 10, calculate the saturation suction specific volume corresponding to the first suction cylinder of the compressor 10, such as based on the pipe temperature t of the indoor first heat exchanger 41. eH The saturated temperature drop dt from the middle of the evaporator on the windward side to the first suction port of the compressor 10 sat，suc1 Calculate the saturated intake specific volume v corresponding to the first intake port of compressor 10. suc,sat,H Based on the indoor second pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the middle of the indoor second heat exchanger 42 to the second suction port 13 of the compressor 10, the saturation suction specific volume corresponding to the second suction cylinder of the compressor 10 is calculated, such as based on the pipe temperature t of the indoor second heat exchanger 42. eL The saturated temperature drop dt from the middle of the evaporator on the leeward side to the second suction port of the compressor 10 sat，suc2 Calculate the saturated intake specific volume v corresponding to the second intake port of compressor 10. suc,sat,L .

[0124] In some embodiments, the specific process of calculating the saturated suction specific volume corresponding to the first suction cylinder of the compressor 10 in step S230 based on the indoor first pipe temperature of the air conditioning system and the predetermined saturated temperature drop from the middle of the indoor first heat exchanger 41 to the first suction port 12 of the compressor 10 is described in the following exemplary description.

[0125] The following is combined with Figure 6 The flowchart shown is a schematic diagram of an embodiment of the method of the present invention for calculating the saturated suction specific volume corresponding to the first suction cylinder of the compressor 10 in the refrigeration mode. The specific process of calculating the saturated suction specific volume corresponding to the first suction cylinder of the compressor 10 in the refrigeration mode in step S230 is further explained, including steps S610 to S620.

[0126] In step S610, the difference between the indoor first pipe temperature of the air conditioning system and the pre-determined saturation temperature drop between the middle of the indoor first heat exchanger 41 and the first suction port 12 of the compressor 10 is taken as the suction saturation temperature of the first suction cylinder of the compressor 10.

[0127] Step S620: Based on the suction saturation temperature of the first suction cylinder of the compressor 10, determine the saturated suction specific volume corresponding to the first suction cylinder of the compressor 10. For example, calculate the saturated suction specific volume v corresponding to the high-temperature cylinder based on the correlation relationship. suc，sat，H .

[0128] In some embodiments, the specific process of calculating the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10 in step S230 based on the indoor second pipe temperature of the air conditioning system and the predetermined saturated temperature drop from the middle of the indoor second heat exchanger 42 to the second suction port 13 of the compressor 10 is described in the following exemplary description.

[0129] The following is combined with Figure 7 The flowchart shown is a schematic diagram of an embodiment of the method of the present invention for calculating the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10 in the refrigeration mode. The specific process of calculating the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10 in the refrigeration mode in step S230 is further explained, including steps S710 to S720.

[0130] In step S710, the difference between the indoor second pipe temperature of the air conditioning system and the pre-determined saturation temperature drop between the middle of the indoor second heat exchanger 42 and the second suction port 13 of the compressor 10 is taken as the suction saturation temperature of the second suction cylinder of the compressor 10.

[0131] Step S720: Based on the suction saturation temperature of the second suction cylinder of the compressor 10, determine the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10. For example, calculate the saturated suction specific volume v corresponding to the low-temperature cylinder based on the correlation relationship. suc，sat，L .

[0132] Specifically, such as Figure 19 As shown, the calculation process for the opening of the dual electronic expansion valve in refrigeration mode also includes: step 123, calculating the saturated suction specific volume corresponding to the two cylinders of the compressor.

[0133] The compressor cylinder connected to the indoor windward heat exchanger (i.e., the indoor first heat exchanger 41) has an intake saturation temperature of t. sat1 =t eH -dt sat，suc1 The leeward-side compressor cylinder is connected to the indoor leeward-side heat exchanger (i.e., the indoor second heat exchanger 42), and its intake saturation temperature is t. sat2 =t eL -dt sat，suc2 The saturated suction specific volume (v) of the compressor's two suction cylinders can be calculated using the fitting formula between the saturated suction specific volume and the suction saturation temperature. Specifically, the saturated suction specific volume v of the high-temperature cylinder can be obtained from this formula. suc，sat，H The saturated intake specific volume v corresponding to the cryogenic cylinder suc，sat，L Here, the saturated suction volume is a physical property parameter of the refrigerant itself, which can be calculated using refrigerant property calculation software such as NIST based on the saturation temperature. Then, within the system operating range, a calculation correlation between the saturated suction volume and the saturation temperature is fitted.

[0134] Then, in step S240, the opening degree of the first-stage throttling device 31 is determined by combining the inlet and outlet pressure difference of the first-stage throttling device 31, the inlet refrigerant density of the first-stage throttling device 31, the saturated suction specific volume corresponding to the first suction cylinder of the compressor 10, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10. This is used as the target opening degree of the first-stage throttling device 31, such as calculating the opening degree Pulse1 of the main valve 1.

[0135] In some embodiments, step S240 combines the inlet and outlet pressure difference of the first-stage throttling device 31, the inlet refrigerant density of the first-stage throttling device 31, the saturated suction specific volume corresponding to the first suction cylinder of the compressor 10, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10 to determine the opening degree of the first-stage throttling device 31 as the specific process of the target opening degree of the first-stage throttling device 31. See the following exemplary description.

[0136] The following is combined with Figure 8The flowchart shown is a schematic diagram of an embodiment of the method of the present invention for determining the target opening degree of the first-stage throttling device 31 in the cooling mode. The specific process of determining the target opening degree of the first-stage throttling device 31 in the cooling mode in step S240 is further explained, including steps S810 to S860.

[0137] Step S810: The sum of the third predetermined coefficient multiple of the saturation temperature drop from the middle of the first indoor heat exchanger 41 to the first suction port 12 of the compressor 10, and the third predetermined value, is multiplied by the predetermined suction superheat of the first suction cylinder of the compressor 10. This product is used as the saturation suction specific volume corresponding to the first suction cylinder of the compressor 10, such as the suction specific volume v corresponding to the high-temperature cylinder. suc，H Among them, the intake specific volume v corresponding to the high-temperature cylinder suc，H =v suc，sat，H *(1+2.2*10 -4 *dt suc，sh The preset intake superheat of the second intake cylinder of the compressor 10 is dt. suc，sh .

[0138] Step S820: The sum of the fourth predetermined coefficient multiple of the saturation temperature drop from the middle of the second indoor heat exchanger 42 to the second suction port 13 of the compressor 10, and the fourth predetermined value, is multiplied by the predetermined suction superheat of the second suction cylinder of the compressor 10. This product is used as the saturation suction specific volume corresponding to the second suction cylinder of the compressor 10, such as the suction specific volume v corresponding to the low-temperature cylinder. suc，L Among them, the specific volume of the intake air corresponding to the cryogenic cylinder is v. suc，L =v suc，sat，L *(1+2.2*10 -4 *dt suc，sh The preset intake superheat of the second intake cylinder of the compressor 10 is dt. suc，sh .

[0139] Step S830: The ratio of the frequency setting calculation factor of the compressor 10 to the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10 is used as the refrigerant mass flow rate of the second-stage throttling device 32, such as the refrigerant mass flow rate M2 of the indoor unit valve 2 = a*f / v suc，L .

[0140] Step S840: The ratio of the frequency setting calculation factor of the compressor 10 to the saturated suction specific volume corresponding to the first suction cylinder of the compressor 10 is used as the refrigerant mass flow rate of the indoor first heat exchanger 41, such as the refrigerant mass flow rate M of the evaporator on the windward side (i.e., the indoor first heat exchanger 41). H =a*f / v suc，HThe refrigerant mass flow rate of the second-stage throttling device 32 and the refrigerant mass flow rate of the indoor first heat exchanger 41 are taken as the refrigerant mass flow rate of the first-stage throttling device 31. For example, the refrigerant mass flow rate M1 of the outdoor unit main valve 1 is the sum of the refrigerant mass flow rates of the leeward side evaporator (i.e., the indoor second heat exchanger 42) and the windward side evaporator (i.e., the indoor first heat exchanger 41), that is: M1=M2+a*f / v suc，H , where 'a' is a coefficient related to compressor performance.

[0141] Step S850: The ratio of the product of the predetermined flow correction coefficient of the first-stage throttling device 31 and the refrigerant mass flow rate of the first-stage throttling device 31, to the inlet refrigerant density of the first-stage throttling device 31, and then to the square root of the inlet and outlet pressure difference of the first-stage throttling device 31, is taken as the air flow rate of the first-stage throttling device 31, such as the air flow rate V of the outdoor main valve 1. a，1 =K c1 *M1 / (ρ 1，i *sqrt(△P r1 ).

[0142] Step S860: Based on the airflow rate of the first-stage throttling device 31, determine the opening degree of the first-stage throttling device 31 as the target opening degree of the first-stage throttling device 31, such as the opening degree of the main valve 1, Pulse1 = f(V a1 ).

[0143] Step S250: Combining the inlet and outlet pressure difference of the second-stage throttling device 32, the inlet refrigerant density of the second-stage throttling device 32, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10, determine the opening degree of the second-stage throttling device 32 as the target opening degree of the second-stage throttling device 32, such as calculating the opening degree Pulse2 of the indoor unit valve 2.

[0144] In some embodiments, step S250 combines the inlet and outlet pressure difference of the second-stage throttling device 32, the inlet refrigerant density of the second-stage throttling device 32, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10 to determine the opening degree of the second-stage throttling device 32 as the specific process of determining the target opening degree of the second-stage throttling device 32. See the following exemplary description.

[0145] The following is combined with Figure 9 The flowchart shown is a schematic diagram of an embodiment of the method of the present invention for determining the target opening degree of the second-stage throttling device 32 in the cooling mode. The specific process of determining the target opening degree of the second-stage throttling device 32 in the cooling mode in step S250 is further explained, including steps S910 to S940.

[0146] Step S910: The sum of the predetermined fourth set coefficient multiple of the saturation temperature drop from the middle of the second indoor heat exchanger 42 to the second suction port 13 of the compressor 10 and the fourth set value, and then multiplied by the preset suction superheat of the second suction cylinder of the compressor 10, is taken as the saturation suction specific volume corresponding to the second suction cylinder of the compressor 10, such as the suction specific volume v corresponding to the low-temperature cylinder. suc，L Among them, the specific volume of the intake air corresponding to the cryogenic cylinder is v. suc，L =v suc，sat，L *(1+2.2*10 -4 *dt suc，sh The preset intake superheat of the second intake cylinder of the compressor 10 is dt. suc，sh .

[0147] Step S920: The ratio of the frequency setting calculation factor of the compressor 10 to the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10 is used as the refrigerant mass flow rate of the second-stage throttling device 32, such as the refrigerant mass flow rate M2 of the indoor unit valve 2 = a*f / v suc，L .

[0148] Step S930: The ratio of the product of the predetermined flow correction coefficient of the second-stage throttling device 32 and the refrigerant mass flow rate of the second-stage throttling device 32, to the inlet refrigerant density of the second-stage throttling device 32, and then to the square root of the inlet and outlet pressure difference of the second-stage throttling device 32, is taken as the air flow rate of the second-stage throttling device 32, such as the air flow rate V of the indoor unit valve (i.e., the indoor unit reheat valve 2). a，2 =K c2 *M2 / (ρ 2，i *sqrt(△P r2 ).

[0149] Step S940: Based on the airflow of the second-stage throttling device 32, determine the opening degree of the second-stage throttling device 32 as the target opening degree of the second-stage throttling device 32, such as the opening degree of the indoor unit valve 2, Pulse2 = f(V a2 ).

[0150] Specifically, such as Figure 19 As shown, the calculation process for the opening degree of the dual electronic expansion valve in cooling mode also includes:

[0151] Given the saturated intake specific volume of the two compression cylinders of the compressor, i.e., the saturated intake specific volume v corresponding to the high-temperature cylinder. suc，sat，H The saturated intake specific volume v corresponding to the cryogenic cylinder suc，sat，L and the preset intake superheat dt suc，shThe suction specific volume v of the two compression cylinders of compressor 10, i.e., the suction specific volume v of the high-temperature cylinder, can be calculated. suc，H The intake specific volume v corresponding to the cryogenic cylinder suc，L Taking R32, the mainstream refrigerant for household inverter heat pump air conditioners, as an example: the suction specific volume v of R32... suc (m 3 The fitting formula for ( / kg) is:

[0152] v suc =v suc，sat *(1+2.2*10 -4 *dt suc，sh ).

[0153] The specific suction volume of the two compression cylinders of compressor 10, i.e., the specific suction volume v corresponding to the high-temperature cylinder, is known. suc，H The intake specific volume v corresponding to the cryogenic cylinder suc，L Based on the compressor parameters, the refrigerant mass flow rates of the indoor unit valve (i.e., indoor unit reheat valve 2) and main valve 1 (i.e., outdoor electronic expansion valve) can be calculated, where the refrigerant mass flow rate M2 of the indoor unit valve (i.e., indoor unit reheat valve 2) is:

[0154] M2 = a * f / v suc，L .

[0155] The refrigerant mass flow rate M1 of the outdoor unit main valve 1 (i.e., the outdoor electronic expansion valve) is the sum of the refrigerant mass flow rates of the leeward side evaporator (i.e., the indoor second heat exchanger 42) and the windward side evaporator (i.e., the indoor first heat exchanger 41), that is:

[0156] M1 = M2 + a * f / v suc，H , where 'a' is a coefficient related to compressor performance.

[0157] Given the pressure difference ΔP between the inlet and outlet of the dual electronic expansion valve. r1 and △P r2 Based on the mass flow rate and inlet density, the air flow rate (L / min) corresponding to 0.1 MPa for the electronic expansion valve can be calculated, where the air flow rate V of the outdoor main valve 1 (i.e., the outdoor electronic expansion valve) is... a，1 :

[0158] V a，1 =K c1 *M1 / (ρ 1，i *sqrt(△P r1 ).

[0159] Airflow V of the indoor unit valve (i.e., indoor unit reheat valve 2) a，2 :

[0160] V a，2 =K c2 *M2 / (ρ 2，i*sqrt(△P r2 ).

[0161] Here, sqrt represents the radical sign, referring to the calculation of square roots.

[0162] It is known that the main valve 1 (i.e., the outdoor electronic expansion valve) and the indoor unit valve (i.e., the indoor unit reheat valve 2) correspond to an air flow rate V of 0.1 MPa. a1 and V a2 Calculate the opening degree of main valve 1 (i.e., outdoor electronic expansion valve) and indoor unit valve (i.e., indoor unit reheat valve 2) respectively: Pulse1 = f(V a1 ) and Pulse2 = f(V a2 ).

[0163] In other embodiments, the opening degree of the first-stage throttling device 31 is determined in step S240 by combining the inlet and outlet pressure difference of the first-stage throttling device 31, the inlet refrigerant density of the first-stage throttling device 31, the saturated suction specific volume corresponding to the first suction cylinder of the compressor 10, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10. As a specific process for determining the target opening degree of the first-stage throttling device 31, please also refer to the following exemplary description.

[0164] The following is combined with Figure 10 The flowchart shown is another embodiment of the method of the present invention for determining the target opening degree of the first-stage throttling device 31 in the cooling mode. It further illustrates another specific process of determining the target opening degree of the first-stage throttling device 31 in the cooling mode in step S240, including steps S1010 to S1060.

[0165] Step S1010: Based on the preset first suction cylinder volume of the compressor 10, the preset second suction cylinder volume of the compressor 10, the saturated suction specific volume corresponding to the first suction cylinder of the compressor 10, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10, determine the refrigerant flow ratio between the first-stage throttling device 31 and the second-stage throttling device 32, such as the refrigerant flow ratio r between the outdoor main valve 1 (i.e., the outdoor electronic expansion valve) and the indoor reheat valve 2. Mr =1+V rev，H *v suc，sat，L / V rev，L *v suc，sat，H The preset volume of the first suction cylinder of the compressor 10 is, for example, the volume of the high-temperature cylinder V. rev,H The preset volume of the second suction cylinder of the compressor 10 is, for example, the volume of the cryogenic cylinder V. rev,L .

[0166] Step S1020: The sum of the third predetermined coefficient multiple of the saturation temperature drop from the middle of the first indoor heat exchanger 41 to the first suction port 12 of the compressor 10, and the third predetermined value, is multiplied by the predetermined suction superheat of the first suction cylinder of the compressor 10. This product is used as the saturation suction specific volume corresponding to the first suction cylinder of the compressor 10, such as the suction specific volume v corresponding to the high-temperature cylinder. suc，H Among them, the intake specific volume v corresponding to the high-temperature cylinder suc，H =v suc，sat，H *(1+2.2*10 -4 *dt suc，sh The preset intake superheat of the second intake cylinder of the compressor 10 is dt. suc，sh .

[0167] Step S1030: The sum of the fourth predetermined coefficient multiple of the saturation temperature drop from the middle of the second indoor heat exchanger 42 to the second suction port 13 of the compressor 10, and the fourth predetermined value, is multiplied by the predetermined suction superheat of the second suction cylinder of the compressor 10. This product is used as the saturation suction specific volume corresponding to the second suction cylinder of the compressor 10, such as the suction specific volume v corresponding to the low-temperature cylinder. suc，L Among them, the specific volume of the intake air corresponding to the cryogenic cylinder is v. suc，L =v suc，sat，L *(1+2.2*10 -4 *dt suc，sh The preset intake superheat of the second intake cylinder of the compressor 10 is dt. suc，sh .as well as,

[0168] Step S1040: The product of the frequency of the compressor 10 and the refrigerant flow ratio between the first-stage throttling device 31 and the second-stage throttling device 32 is multiplied by a set calculation factor, and then the ratio of this product to the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10 is used as the refrigerant mass flow rate of the first-stage throttling device 31. For example, the mass flow rate M1 (g / min) of the main valve 1 is M1 = a*r Mr *f / v suc,L .

[0169] Step S1050: The ratio of the product of the predetermined flow correction coefficient of the first-stage throttling device 31 and the refrigerant mass flow rate of the first-stage throttling device 31, to the inlet refrigerant density of the first-stage throttling device 31, and then to the square root of the inlet and outlet pressure difference of the first-stage throttling device 31, is taken as the air flow rate of the first-stage throttling device 31, such as the air flow rate V of the outdoor main valve 1. a，1 =K c1 *M1 / (ρ 1，i *sqrt(△P r1 ).

[0170] Step S1060: Based on the airflow rate of the first-stage throttling device 31, determine the opening degree of the first-stage throttling device 31 as the target opening degree of the first-stage throttling device 31, such as the opening degree of the main valve 1, Pulse1 = f(V a1 ).

[0171] In other embodiments, in step S250, the opening degree of the second-stage throttling device 32 is determined by combining the inlet and outlet pressure difference of the second-stage throttling device 32, the inlet refrigerant density of the second-stage throttling device 32, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10. As a specific process for determining the target opening degree of the second-stage throttling device 32, please also refer to the following exemplary description.

[0172] The following is combined with Figure 11 The flowchart shown is a schematic diagram of another embodiment of the method of the present invention for determining the target opening degree of the second-stage throttling device 32 in the cooling mode. It further illustrates another specific process of determining the target opening degree of the second-stage throttling device 32 in the cooling mode in step S250, including steps S1110 to S1140.

[0173] Step S1110: Based on the preset first suction cylinder volume of the compressor 10, the preset second suction cylinder volume of the compressor 10, the saturated suction specific volume corresponding to the first suction cylinder of the compressor 10, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10, determine the refrigerant flow ratio between the first-stage throttling device 31 and the second-stage throttling device 32, such as the refrigerant flow ratio r between the outdoor main valve 1 (i.e., the outdoor electronic expansion valve) and the indoor reheat valve 2. Mr =1+V rev，H *v suc，sat，L / V rev，L *v suc，sat，H The preset volume of the first suction cylinder of the compressor 10 is, for example, the volume of the high-temperature cylinder V. rev,H The preset volume of the second suction cylinder of the compressor 10 is, for example, the volume of the cryogenic cylinder V. rev,L .

[0174] Step S1120: Based on the refrigerant flow ratio between the first-stage throttling device 31 and the second-stage throttling device 32, the predetermined flow correction coefficient of the first-stage throttling device 31, the inlet and outlet pressure difference of the first-stage throttling device 31, the inlet refrigerant density of the first-stage throttling device 31, and the predetermined flow correction coefficient of the second-stage throttling device 32, the inlet and outlet pressure difference of the second-stage throttling device 32, and the inlet refrigerant density of the second-stage throttling device 32, determine the air flow ratio between the first-stage throttling device 31 and the second-stage throttling device 32, such as the air flow ratio between the main valve 1 and the indoor unit valve 2, rVa=rMr*[(Kc1 / (ρ1,i*sqrt(△Pr1))) / (Kc2 / (ρ2i*sqrt(△Pr2)))].

[0175] Step S1130: Based on the airflow ratio between the first-stage throttling device 31 and the second-stage throttling device 32, and the already determined airflow of the first-stage throttling device 31, determine the airflow of the second-stage throttling device 32. For example, the indoor unit reheat valve 2 corresponds to an airflow of 0.1 MPa, Va2:V a，2 =V a，1 / r Va .

[0176] Step S1140: Based on the airflow of the second-stage throttling device 32, determine the opening degree of the second-stage throttling device 32 as the target opening degree of the second-stage throttling device 32, such as the opening degree of the indoor unit valve 2, Pulse2 = f(V a2 ).

[0177] Specifically, Figure 20 This is a schematic flowchart of a second embodiment of the calculation process for the opening degree of the dual electronic expansion valve in cooling mode. Figure 20 As shown, the calculation process for the opening degree of the dual electronic expansion valve in cooling mode includes:

[0178] Step 21: Add a cold outlet temperature sensor to the outdoor unit's condenser outlet to detect the condenser outlet temperature in cooling mode. The condenser outlet temperature can be used to calculate the condenser outlet specific enthalpy.

[0179] Step 22: In the calculation process of the opening degree of the main valve 1 (i.e., the outdoor electronic expansion valve) and the indoor reheat valve 2 (i.e., the indoor electronic expansion valve) in the cooling mode, the refrigerant mass flow rate ratio of the outdoor main valve 1 (i.e., the outdoor electronic expansion valve) and the indoor reheat valve 2 and the refrigerant mass flow rate of the indoor reheat valve can be calculated first to calculate the air flow rate corresponding to the two valves, thereby determining the opening degree of the two valves.

[0180] The calculation includes the refrigerant flow ratio between the outdoor main valve 1 (i.e., the outdoor electronic expansion valve) and the indoor reheat valve 2.

[0181] r Mr =1+V rev，H *v suc，sat，L / V rev，L *v suc，sat，H .

[0182] Given the pressure difference, flow rate, and inlet density of the refrigerant at the inlet and outlet of main valve 1 (i.e., the outdoor electronic expansion valve), the corresponding air flow rate (L / min) at 0.1 MPa can be calculated as follows:

[0183] V a，1 =K c1 *M1 / (ρ 1，i *sqrt(△P r1 ).

[0184] The refrigerant mass flow ratio r of the indoor unit valve (i.e., indoor unit reheat valve 2) and the main valve 1 (i.e., outdoor electronic expansion valve) is known. Mr Parameters such as the pressure difference between the valve inlet and outlet and the density before the valve can be used to calculate the air flow ratio r between the main valve 1 (i.e., the outdoor electronic expansion valve) and the indoor unit valve (i.e., the indoor unit reheat valve 2). Va Then the indoor unit valve (i.e., indoor unit reheat valve 2) corresponds to an air flow rate Va2 of 0.1 MPa:

[0185] V a，2 =V a，1 / r Va .

[0186] It is known that the main valve 1 (i.e., the outdoor electronic expansion valve) and the indoor unit valve (i.e., the indoor unit reheat valve 2) correspond to an air flow rate V of 0.1 MPa. a1 and V a2 Calculate the opening degree of main valve 1 (i.e., outdoor electronic expansion valve) and indoor unit valve (i.e., indoor unit reheat valve 2) respectively: Pulse1 = f(V a1 ) and Pulse2 = f(V a2 ).

[0187] In some implementations, the current operating mode of the air conditioning system is reheat dehumidification mode.

[0188] In step S140, under the reheat dehumidification mode, the target opening degree of the first-stage throttling device 31 and the target opening degree of the second-stage throttling device 32 are determined by combining the outdoor ambient temperature of the air conditioning system, the indoor return air relative humidity of the air conditioning system, and the operating parameters of the air conditioning system. This includes the process of calculating the target opening degree of the first-stage throttling device 31 and the target opening degree of the second-stage throttling device 32 under the reheat dehumidification mode.

[0189] The following is combined with Figure 12 The flowchart shown is a schematic diagram of an embodiment of the method of the present invention for calculating the target opening degree of the first-stage throttling device 31 and the target opening degree of the second-stage throttling device 32 in the reheat dehumidification mode. It further illustrates the specific process of calculating the target opening degree of the first-stage throttling device 31 and the target opening degree of the second-stage throttling device 32 in the reheat dehumidification mode in step S140, including steps S1210 to S1260.

[0190] Step S1210: Based on the outdoor pipe temperature of the air conditioning system, the indoor first pipe temperature of the air conditioning system, and the predetermined saturation temperature drop from the outlet of the first-stage throttling device 31 to the pipe of the first indoor heat exchanger 41, determine the inlet and outlet pressure difference of the first-stage throttling device 31, such as based on the pipe temperature t of the outdoor heat exchanger 20. c The tube temperature t of the first heat exchanger 41 in the room eH The saturated temperature drop dt from the outlet of main valve 1 to the high-temperature evaporator tube sat1 Calculate the refrigerant inlet and outlet pressure difference ΔP of main valve 1. r1 The high-temperature evaporator is the indoor first heat exchanger 41; and the inlet and outlet pressure difference of the second-stage throttling device 32 is determined based on the indoor first pipe temperature of the air conditioning system, the indoor second pipe temperature of the air conditioning system, and the predetermined saturation temperature drop from the outlet of the second-stage throttling device 32 to the pipe of the indoor second heat exchanger 42, such as based on the pipe temperature t of the indoor first heat exchanger 41. eH The tube temperature t of the second heat exchanger 42 in the room eL The saturated temperature drop dt from the outlet of indoor unit valve 2 to the low-temperature evaporator tube sat2 Calculate the refrigerant inlet and outlet pressure difference ΔP of main valve 1. r2 Among them, the low-temperature evaporator is the second heat exchanger in the room 42.

[0191] The specific methods for determining the inlet and outlet pressure difference of the first-stage throttling device 31 and the inlet and outlet pressure difference of the second-stage throttling device 32 in the reheat dehumidification mode are the same as those for determining the inlet and outlet pressure difference of the first-stage throttling device 31 and the inlet and outlet pressure difference of the second-stage throttling device 32 in the refrigeration mode.

[0192] Step S1220: Determine the inlet refrigerant density of the first-stage throttling device 31 based on the outdoor pipe temperature of the air conditioning system, such as based on the pipe temperature t of the outdoor heat exchanger 20. c Calculate the refrigerant density ρ at the inlet of main valve 1. 1iFurthermore, based on the outdoor ambient temperature of the air conditioning system or the refrigerant outlet temperature of the outdoor heat exchanger 20, and in conjunction with the predetermined saturated liquid specific volume and the predetermined saturated gas specific volume of the refrigerant in the air conditioning system, the inlet refrigerant density of the second-stage throttling device 32 is determined, such as based on the refrigerant dryness x at the indoor unit valve inlet and the saturated gas specific volume v of the refrigerant. g Specific volume of refrigerant in saturated liquid (v) l Calculate the refrigerant density ρ at the inlet of valve 2 in the indoor unit. 1i .

[0193] The specific methods for determining the inlet refrigerant density of the first-stage throttling device 31 and the inlet refrigerant density of the second-stage throttling device 32 under reheat dehumidification mode are the same as those for determining the inlet refrigerant density of the first-stage throttling device 31 and the inlet refrigerant density of the second-stage throttling device 32 under cooling mode.

[0194] Step S1230: Determine the inlet dew point temperature of the air conditioning system based on the indoor return air temperature and the relative humidity of the return air of the air conditioning system, such as the evaporator inlet dew point temperature t. dew =f(t) N ,RH N Based on the inlet dew point temperature of the air conditioning system, the ratio of refrigerant flow rate of the first-stage throttling device 31 to that of the second-stage throttling device 32 is determined, such as the ratio r of the refrigerant flow rate of the first-stage throttling device 31 to that of the second-stage throttling device 32. Mr =f(RH) N ,k t LHR).

[0195] In some embodiments, determining the inlet dew point temperature of the air conditioning system based on the indoor return air temperature and the return air relative humidity of the air conditioning system in step S1230 includes: determining the set return air temperature that is the same as the indoor return air temperature of the air conditioning system and the set inlet dew point temperature that is the same as the return air relative humidity of the air conditioning system as the inlet dew point temperature of the air conditioning system, based on the correspondence between the set return air temperature, the set return air relative humidity, and the set inlet dew point temperature, as the inlet dew point temperature of the air conditioning system, such as the evaporator inlet dew point temperature t. dew =f(t) N ,RH N ).

[0196] The specific process of determining the refrigerant flow ratio of the first-stage throttling device 31 to the second-stage throttling device 32 based on the inlet dew point temperature of the air conditioning system in step S1230 is illustrated in the following exemplary description.

[0197] The following is combined with Figure 13 The schematic diagram shows an embodiment of the method of the present invention for determining the ratio of refrigerant flow rate of the first-stage throttling device 31 to the second-stage throttling device 32 in the reheat dehumidification mode. It further illustrates the specific process of determining the ratio of refrigerant flow rate of the first-stage throttling device 31 to the second-stage throttling device 32 in the reheat dehumidification mode in step S1230, including steps S1310 to S1340.

[0198] Step S1310: Determine whether the inlet dew point temperature of the air conditioning system is less than or equal to the indoor first pipe temperature of the air conditioning system.

[0199] In step S1320, if it is determined that the inlet dew point temperature of the air conditioning system is less than or equal to the indoor first pipe temperature of the air conditioning system, then it is determined that the indoor first heat exchanger 41 does not need dehumidification, and the frequency of the compressor 10 is increased or the speed of the indoor fan 62 is reduced.

[0200] Step S1330: If it is determined that the inlet dew point temperature of the air conditioning system is greater than the indoor first pipe temperature of the air conditioning system, then the inlet specific enthalpy of the air conditioning system is determined based on the indoor return air temperature and the return air relative humidity of the air conditioning system, such as calculating the inlet saturated vapor pressure p. v,sat,i =f(t) N ), calculate the moisture content of the incoming air: d a,in =f(RH) N ,p v,sat,i (B), where B represents atmospheric pressure, is used to calculate the intake air specific enthalpy h. a,in =f(t) N ,d a,in Based on the outlet dew point temperature and the outlet relative humidity of the air conditioning system, determine the outlet enthalpy of the air conditioning system, such as calculating the outlet saturated vapor pressure p. v,sat,o =f(t) dew,o ), calculate the wind moisture content d a,o =f(RH) o ,p v,sat,o B), calculate the air-to-air ratio enthalpy h. a,o =f(t) dew,o ,d a,o ), t dew,o The outlet dew point temperature, RH o The relative humidity of the outlet air; t dew,o For the outlet dew point temperature and RH oThe relative humidity of the outlet air is used as the outlet air state parameter; based on the inlet air enthalpy, the outlet air enthalpy, and the latent heat of phase change of the air conditioning system, the dehumidification latent heat ratio of the first indoor heat exchanger 41 is determined, such as the evaporator dehumidification latent heat ratio LHR = r w，t *(d a，in -d a，o ) / (h a，in -h a，o ), where r w，t The latent heat of phase transition (kJ / kg). w，t = f(t), where t is the outlet dew point temperature or approximately the evaporator tube temperature t eH , ℃.

[0201] Step S1340: Based on the return air relative humidity of the air conditioning system, the latent heat ratio of the indoor first heat exchanger 41, and the temperature regulation coefficient of the air conditioning system, determine the refrigerant flow ratio of the first-stage throttling device 31 to the second-stage throttling device 32, such as the refrigerant flow ratio r of the first-stage throttling device 31 to the second-stage throttling device 32. Mr =f(RH) N ,k t ,LHR), k t This is the temperature control coefficient. Wherein, the latent heat ratio LHR = 0 indicates that the evaporation temperature is greater than or equal to the inlet dew point temperature. At this point, the evaporator does not dehumidify, and the latent heat of vaporization used for dehumidification is 0.

[0202] Specifically, such as Figure 23 As shown, the calculation process for the opening degree of the dual electronic expansion valves in reheat dehumidification mode also includes: Step 32. The calculation process for the opening degree of the main valve 1 (i.e., the outdoor electronic expansion valve) and the indoor reheat valve 2 in reheat dehumidification mode also includes: based on the detected indoor return air temperature t N and return air relative humidity RH N Calculate the evaporator inlet dew point temperature t dew =f(t) N RH N Based on the calculated inlet dew point temperature and evaporator tube temperature t eH (i.e., the tube temperature t of the first heat exchanger 41 in the room) eH The latent heat ratio of dehumidification of the evaporator (i.e., the first heat exchanger 41 in the room) is calculated by comparing it with that of the evaporator.

[0203] When the evaporator inlet dew point temperature t dew ≤Pipe temperature t of the first heat exchanger 41 in the room eHAt this time, the evaporator (i.e., the first indoor heat exchanger 41) is not dehumidifying. Therefore, it is necessary to increase the operating frequency of the compressor 10 or decrease the speed of the indoor fan (i.e., the speed of the indoor fan 62). For example, increasing the compressor frequency or decreasing the indoor fan speed will reduce the inlet dew point temperature t. dew >Indoor first heat exchanger tube temperature t eH +2℃.

[0204] When the evaporator inlet dew point temperature t dew >Pipe temperature t of the first indoor heat exchanger 41 eH At this time, the inlet air moisture content and inlet air specific enthalpy need to be calculated based on the detected return air temperature and relative humidity. When calculating the evaporator outlet air moisture content and outlet air specific enthalpy, it is assumed that the dehumidifying evaporator outlet air is saturated (i.e., relative humidity 100%) and the outlet air dew point temperature is close to the evaporator tube temperature t. eH (i.e., the tube temperature t of the first heat exchanger 41 in the room) eH The difference between them is zero.

[0205] Evaporator latent heat ratio for dehumidification: LHR = r w，t *(d a，in -d a，o ) / (h a，in -h a，o ), where r w，t The latent heat of phase transition (kJ / kg). w，t = f(t), where t is the outlet dew point temperature or approximately the evaporator tube temperature t eH , ℃.

[0206] Analysis of the refrigerant thermodynamic cycle and the latent heat ratio of moist air revealed that when the relative humidity (RH) of the inlet air to the dehumidifying evaporator (i.e., the first indoor heat exchanger 41) is between 0.4 and 1, the ratio of the reheat valve flow rate to the total flow rate at the optimal reheat dehumidification evaporation temperature can be fitted with a calculation correlation formula based on the inlet relative humidity, the latent heat ratio of dehumidification, and the temperature regulation coefficient, i.e., r Mr =f(RH) N k t (LHR). First, the total flow rate and flow ratio are calculated, and then the refrigerant flow rates of the two cylinders are calculated separately.

[0207] Step S1240: Based on the indoor first pipe temperature of the air conditioning system, the predetermined saturation temperature drop from the middle of the indoor first heat exchanger 41 to the first suction port 12 of the compressor 10, the indoor second pipe temperature of the air conditioning system, the ratio of refrigerant flow rates of the first-stage throttling device 31 to the second-stage throttling device 32, and the predetermined saturation temperature drop from the middle of the indoor second heat exchanger 42 to the second suction port 13 of the compressor 10, determine the refrigerant mass flow rate of the first-stage throttling device 31 and the refrigerant mass flow rate of the second-stage throttling device 32, such as determining the refrigerant mass flow rate M1 of the main valve 1 and the refrigerant mass flow rate M2 of the indoor unit valve 2.

[0208] In some embodiments, the specific process of determining the refrigerant mass flow rate of the first-stage throttling device 31 and the refrigerant mass flow rate of the second-stage throttling device 32 in step S1240 based on the indoor first pipe temperature of the air conditioning system, the predetermined saturation temperature drop from the middle of the indoor first heat exchanger 41 to the first suction port 12 of the compressor 10, the indoor second pipe temperature of the air conditioning system, the ratio of the refrigerant flow rate of the first-stage throttling device 31 to the refrigerant flow rate of the second-stage throttling device 32, and the predetermined saturation temperature drop from the middle of the indoor second heat exchanger 42 to the second suction port 13 of the compressor 10, is described in the following exemplary description.

[0209] The following is combined with Figure 14 The schematic diagram shows an embodiment of the method of the present invention for determining the refrigerant mass flow rate of the first-stage throttling device 31 and the refrigerant mass flow rate of the second-stage throttling device 32 in the reheat dehumidification mode. It further illustrates the specific process of determining the refrigerant mass flow rate of the first-stage throttling device 31 and the refrigerant mass flow rate of the second-stage throttling device 32 in the reheat dehumidification mode in step S1240, including steps S1410 to S1460.

[0210] In step S1410, the indoor first pipe temperature of the air conditioning system and the difference between the predetermined saturation temperature drop from the middle of the indoor first heat exchanger 41 to the first suction port 12 of the compressor 10 are taken as the suction saturation temperature of the first suction cylinder of the compressor 10; and the indoor second pipe temperature of the air conditioning system and the difference between the predetermined saturation temperature drop from the middle of the indoor second heat exchanger 42 to the second suction port 13 of the compressor 10 are taken as the suction saturation temperature of the second suction cylinder of the compressor 10.

[0211] Step S1420: Based on the suction saturation temperature of the first suction cylinder of the compressor 10, determine the saturated suction specific volume corresponding to the first suction cylinder of the compressor 10. For example, calculate the saturated suction specific volume v corresponding to the high-temperature cylinder based on the correlation relationship. suc，sat，H; and, based on the suction saturation temperature of the second suction cylinder of the compressor 10, determine the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10, such as calculating the saturated suction specific volume v corresponding to the low-temperature cylinder based on the correlation relationship. suc，sat，L .

[0212] Step S1430: The sum of the third predetermined coefficient multiple of the saturation temperature drop from the middle of the first indoor heat exchanger 41 to the first suction port 12 of the compressor 10, and the third predetermined value, is multiplied by the predetermined suction superheat of the first suction cylinder of the compressor 10. This product is used as the saturation suction specific volume corresponding to the first suction cylinder of the compressor 10, such as the suction specific volume v corresponding to the high-temperature cylinder. suc，H Among them, the intake specific volume v corresponding to the high-temperature cylinder suc，H =v suc，sat，H *(1+2.2*10 -4 *dt suc，sh The preset intake superheat of the second intake cylinder of the compressor 10 is dt. suc，sh ; and, the product of the fourth predetermined coefficient multiple of the saturation temperature drop from the middle of the second indoor heat exchanger 42 to the second suction port 13 of the compressor 10, and the fourth predetermined value, and the product of this fourth predetermined coefficient multiple and the predetermined suction superheat of the second suction cylinder of the compressor 10, is taken as the saturation suction specific volume corresponding to the second suction cylinder of the compressor 10, such as the suction specific volume v corresponding to the low-temperature cylinder. suc，L Among them, the specific volume of the intake air corresponding to the cryogenic cylinder is v. suc，L =v suc，sat，L *(1+2.2*10 -4 *dt suc，sh The preset intake superheat of the second intake cylinder of the compressor 10 is dt. suc，sh .

[0213] Step S1440: The frequency setting calculation factor of the compressor 10 is multiplied by the ratio of the saturated intake specific volume corresponding to the first intake cylinder of the compressor 10 to obtain the first calculated value.

[0214] Step S1450: The frequency setting calculation factor of the compressor 10 is multiplied by the ratio of the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10 to obtain a second calculated value. The sum of the first calculated value and the second calculated value is determined as the total refrigerant mass flow rate of the first-stage throttling device 31 and the second-stage throttling device 32. For example, the total refrigerant mass flow rate M (g / min) is calculated using the compressor suction specific volume and compressor parameters: M = a * f / v suc +a*f / v suc , where 'a' is a coefficient related to compressor performance and 'f' is the compressor frequency.

[0215] Step S1460: Based on the total refrigerant mass flow rate of the first-stage throttling device 31 and the second-stage throttling device 32, and the ratio of the refrigerant flow rates of the first-stage throttling device 31 to the second-stage throttling device 32, determine the refrigerant mass flow rate of the first-stage throttling device 31 and the refrigerant mass flow rate of the second-stage throttling device 32. For example, calculate the refrigerant mass flow rate M2 of the indoor unit reheat valve 2 as M2 = M / (1+r Mr The refrigerant mass flow rate of outdoor main valve 1 is M1 = M - M2.

[0216] like Figure 23 As shown, the calculation process for the opening degree of the dual electronic expansion valves in reheat dehumidification mode also includes: the calculation process for the opening degree of main valve 1 (i.e., outdoor electronic expansion valve) and indoor reheat valve 2 in reheat dehumidification mode, including: similar to the cooling mode, the total refrigerant mass flow rate M (g / min) is calculated using the compressor suction specific volume and compressor parameters: M=a*f / v suc +a*f / v suc 'a' is a coefficient related to compressor performance, and 'f' is the compressor frequency. The refrigerant mass flow rate M2 of the indoor unit valve (i.e., indoor unit reheat valve 2) is calculated as M / (1+r). Mr The refrigerant mass flow rate of outdoor main valve 1 (i.e., outdoor electronic expansion valve) is M1 = M - M2.

[0217] Based on the refrigerant mass flow rate and flow correction factor K of the indoor and outdoor electronic expansion valves. c Based on the inlet refrigerant density and the pressure difference across the valve, calculate the air flow rate (L / min) at 0.1 MPa corresponding to the indoor unit reheat valve 2: V a，2 =K c2 *M2 / (ρ i *sqrt(△P r The outdoor unit main valve 1 (i.e., the outdoor electronic expansion valve) corresponds to an air flow rate of 0.1 MPa (L / min): V a，1 =K c1 *M1 / (ρ i *sqrt(△P r Finally, based on the airflow of the indoor and outdoor electronic expansion valves, the corresponding opening degree Pulse1 is calculated: Pulse1 = f(V a，1 ) and Pulse2 = f(V a，2 ).

[0218] Then, in step S1250, based on the predetermined flow correction coefficient of the first-stage throttling device 31, the inlet and outlet pressure difference of the first-stage throttling device 31, the inlet refrigerant density of the first-stage throttling device 31, the refrigerant mass flow rate of the first-stage throttling device 31, and the ratio of the refrigerant flow rate of the first-stage throttling device 31 to that of the second-stage throttling device 32, the opening degree of the first-stage throttling device 31 is determined as the target opening degree of the first-stage throttling device 31, such as calculating the opening degree Pulse1 of the main valve 1.

[0219] In the reheat dehumidification mode, the target opening degree of the first-stage throttling device 31 is determined based on the predetermined flow correction coefficient of the first-stage throttling device 31, the inlet and outlet pressure difference of the first-stage throttling device 31, the inlet refrigerant density of the first-stage throttling device 31, the refrigerant mass flow rate of the first-stage throttling device 31, and the ratio of the refrigerant flow rates of the first-stage throttling device 31 to the second-stage throttling device 32. This method is the same as the method used in the cooling mode to determine the target opening degree of the first-stage throttling device 31 based on the predetermined flow correction coefficient of the first-stage throttling device 31, the inlet and outlet pressure difference of the first-stage throttling device 31, the inlet refrigerant density of the first-stage throttling device 31, the refrigerant mass flow rate of the first-stage throttling device 31, and the ratio of the refrigerant flow rates of the first-stage throttling device 31 to the second-stage throttling device 32.

[0220] Step S1260: Based on the predetermined flow correction coefficient of the second-stage throttling device 32, the inlet and outlet pressure difference of the second-stage throttling device 32, the inlet refrigerant density of the second-stage throttling device 32, the refrigerant mass flow rate of the second-stage throttling device 32, and the ratio of the refrigerant flow rates of the first-stage throttling device 31 to the second-stage throttling device 32, the opening degree of the second-stage throttling device 32 is determined as the target opening degree of the second-stage throttling device 32, such as calculating the opening degree Pulse2 of the indoor unit valve 2.

[0221] In the reheat dehumidification mode, the target opening degree of the second-stage throttling device 32 is determined based on the predetermined flow correction coefficient of the second-stage throttling device 32, the inlet and outlet pressure difference of the second-stage throttling device 32, the inlet refrigerant density of the second-stage throttling device 32, the refrigerant mass flow rate of the second-stage throttling device 32, and the ratio of the refrigerant flow rates of the first-stage throttling device 31 to the second-stage throttling device 32. This method is the same as the method used in the cooling mode to determine the target opening degree of the second-stage throttling device 32 based on the predetermined flow correction coefficient of the second-stage throttling device 32, the inlet and outlet pressure difference of the second-stage throttling device 32, the inlet refrigerant density of the second-stage throttling device 32, the refrigerant mass flow rate of the second-stage throttling device 32, and the ratio of the refrigerant flow rates of the first-stage throttling device 31 to the second-stage throttling device 32.

[0222] Figure 22 This is a schematic diagram of the pressure and enthalpy of the reheat dehumidification cycle in a three-pipe parallel reheat dehumidification system. Figure 22 It can display the correspondence between pressure and enthalpy values ​​of a three-pipe parallel reheat dehumidification system in reheat dehumidification mode. Here, h represents the specific enthalpy of the state point, P represents pressure, and lg represents the logarithm with 10 as the minimum; the numbers represent different state points: 1 represents compressor suction, 2 represents compressor discharge, 3' represents the outlet of outdoor condenser 20, 3 represents the outlet of reheat condenser 4, and 4 represents the inlet refrigerant state point of dehumidification evaporator 4. Figure 21 and Figure 22 The diagrams show the reheat dehumidification cycle and corresponding pressure-enthalpy diagram of the dual-temperature parallel reheat dehumidification system. The pressure-enthalpy diagram shows that during constant-temperature dehumidification, the reheat heat of the reheat heat exchanger (i.e., the second indoor heat exchanger 42) is equal to the sensible heat of the dehumidification evaporator (i.e., the first indoor heat exchanger 41). If the reheat heat is greater than or less than the sensible heat, i.e., the ratio is greater than or less than 1, then it is either heating dehumidification or cooling dehumidification. Therefore:

[0223] k t (M1+M2)Δh e (1-LHR)=M2Δh c，2。

[0224] In the formula, k t K is the temperature regulation coefficient, which is used for constant temperature dehumidification. t The value is 1, and the k value is 1 when heating and dehumidifying. t When k is greater than 1, it indicates cooling and dehumidification. t Less than 1; M1 and M2 are the mass flow rates, g / min, of the main valve 1 (i.e., the outdoor electronic expansion valve) and the indoor reheat valve (i.e., the indoor reheat valve 2), respectively; Δh eΔh is the enthalpy difference (unit mass cooling capacity) between the outlet and inlet of the dehumidifying evaporator (i.e., the first indoor heat exchanger 41), expressed in kJ / kg; LHR is the latent heat ratio; Δh c，2 The specific enthalpy difference (unit mass reheat) between the inlet and outlet of the reheat heat exchanger (i.e., the second heat exchanger 42 in the room) is kJ / kg.

[0225] Figure 23 This is a schematic diagram illustrating the calculation process for the opening degree of the dual electronic expansion valves in reheat dehumidification mode. (Example:) Figure 23 As shown, the calculation process for the opening degree of the dual electronic expansion valves in reheat dehumidification mode includes: Step 31: When the air conditioner receives the reheat dehumidification mode operation command, it first opens the indoor unit air guide plate and starts the indoor fan according to the user-set fan speed or automatic fan speed. The outdoor fan speed, compressor frequency, and opening degree of the outdoor electronic expansion valve and indoor electronic expansion valve are initially operated with the set oil return parameters. After the oil return operation is completed, the compressor frequency and outdoor fan speed are operated according to the ambient temperature detected by the outdoor ambient temperature sensor and the user-set temperature parameters. The opening degree of the outdoor electronic expansion valve and indoor electronic expansion valve is calculated based on the temperature parameters detected by the sensor.

[0226] In some embodiments, the control method for the air conditioning system described in the present invention further includes, after step S140, a process of fine-tuning the target opening degree of the first-stage throttling device 31 and the target opening degree of the second-stage throttling device 32.

[0227] The following is combined Figure 15 The schematic diagram shows an embodiment of the method of the present invention in which the target opening of the first-stage throttling device 31 is operated and the target opening of the second-stage throttling device 32 is finely adjusted. The specific process of operating the target opening of the first-stage throttling device 31 and finely adjusting the target opening of the second-stage throttling device 32 is further explained, including steps S1510 to S1540.

[0228] Step S1510: In the current operating mode of the air conditioning system, such as in cooling mode or reheat / dehumidification mode, after controlling the first-stage throttling device 31 to operate at its target opening and the second-stage throttling device 32 to operate at its target opening, specifically after the first-stage throttling device 31 and the second-stage throttling device 32 have been operating at their target opening for a set duration, the following measures are performed.

[0229] Step S1520: If the current operating mode of the air conditioning system is cooling mode, then the target opening of the first-stage throttling device 31 is adjusted according to the difference between the first suction temperature of the air conditioning system and the first indoor pipe temperature of the air conditioning system to obtain a new target opening of the first-stage throttling device 31; and the target opening of the second-stage throttling device 32 is adjusted according to the difference between the second suction temperature of the air conditioning system and the second indoor pipe temperature of the air conditioning system to obtain a new target opening of the second-stage throttling device 32.

[0230] Step S1530: If the current operating mode of the air conditioning system is reheat dehumidification mode, then the target opening of the first-stage throttling device 31 is adjusted according to the difference between the first suction temperature of the air conditioning system and the first indoor pipe temperature of the air conditioning system to obtain a new target opening of the first-stage throttling device 31; and the target opening of the second-stage throttling device 32 is adjusted according to the difference between the indoor return air temperature and the set temperature of the air conditioning system to obtain a new target opening of the second-stage throttling device 32.

[0231] Then, in step S1540, under the current operating mode of the air conditioning system, the first-stage throttling device 31 is controlled to operate at the new target opening degree of the first-stage throttling device 31, and the second-stage throttling device 32 is controlled to operate at the new target opening degree of the second-stage throttling device 32.

[0232] Specifically, such as Figure 19 and Figure 20 As shown, the calculation process for the opening degree of the dual electronic expansion valve in cooling mode also includes: after the dual electronic expansion valve has been running at the calculated opening degree for a period of time, the suction temperature t can be used to determine the opening degree. suc1 and inner tube temperature t eH The difference △t sh1 Intake temperature t suc2 and inner tube temperature t eL The difference △t sh2 Fine-tuning the opening of the electronic expansion valve so that Δt sh1 =(t suc1 -t eH ) and △t sh2 =(t suc2 -t eL When the temperature is between 2 and 6℃, the opening degree remains unchanged to ensure reliable operation. Fine-tuning can be achieved by adjusting Δt. sh1 =(t suc1 -t eH When ) < 2, reduce the opening value of electronic expansion valve 31 and Δt. sh1 =(t suc1 -t eHWhen Δt > 6, increase the opening of the electronic expansion valve 31; sh2 =(t suc2 -t eL When Δt < 2, decrease the opening value of the electronic expansion valve 32, Δt sh2 =(t suc2 -t eL When the value is greater than 6, increase the opening value of the electronic expansion valve 32.

[0233] like Figure 23 As shown, the calculation process for the opening degree of the dual electronic expansion valve in reheat dehumidification mode also includes: after the dual electronic expansion valve runs at the calculated opening degree for a period of time (e.g., 5 min to 10 min), the opening degree can be determined by the suction temperature t. suc1 and inner tube temperature t eH and indoor return air temperature t N The opening of the dual electronic expansion valve is fine-tuned based on the difference from the set temperature value to ensure the reliability of the air conditioning system. This fine-tuning can be: Δt sh1 =(t suc1 -t eH When ) < 2, reduce the opening value of electronic expansion valve 31 or 32, Δt sh1 =(t suc1 -t eH When the value is greater than 6, increase the opening value of electronic expansion valve 31 or 32.

[0234] In this invention, based on the operating characteristics of a dual-temperature parallel reheat dehumidification system (i.e., a three-pipe parallel reheat dehumidification system), the opening degrees of the two interconnected electronic expansion valves are decoupled for calculation, achieving stable calculation of the opening degree of the dual electronic expansion valves. Specifically, when calculating the opening degree of the dual electronic expansion valves, the calculation is performed using temperature measuring points based on the pressure difference across the valves. Thus, through the decoupled control of the dual electronic expansion valves in the three-pipe parallel reheat dehumidification system, active control of the valve opening degree is achieved, along with rapid adjustment of the valves, improving the stability and reliability of the air conditioning system.

[0235] The technical solution of this embodiment employs a three-pipe parallel reheat dehumidification system in the air conditioning system. For the dual electronic expansion valves in the three-pipe parallel reheat dehumidification system—namely, the first-stage throttling device (such as the outdoor electronic expansion valve) and the second-stage throttling device (such as the indoor electronic expansion valve)—the refrigerant mass flow ratio of the outdoor and indoor electronic expansion valves is calculated, as well as the inlet and outlet pressure difference between the outdoor and indoor electronic expansion valves. Based on the refrigerant mass flow ratio of the outdoor and indoor electronic expansion valves and the inlet and outlet pressure difference, the air flow ratio of the outdoor and indoor electronic expansion valves is calculated. The relationship between the airflow rate and opening degree of the expansion valve is calculated based on the airflow rate ratio of the outdoor and indoor electronic expansion valves. The opening degrees of the outdoor and indoor electronic expansion valves are then adjusted according to their opening degrees. This allows for fine-tuning of the opening degrees of the outdoor and indoor electronic expansion valves. Furthermore, by employing a three-pipe parallel reheat dehumidification system in the air conditioning system, the dual electronic expansion valves within the system are decoupled, enabling active control of their opening degrees and improving the energy efficiency and comfort of the air conditioning system during cooling and dehumidification operation.

[0236] According to an embodiment of the present invention, a control device for an air conditioning system corresponding to a control method for an air conditioning system is also provided. See also Figure 16 The diagram shows a structural schematic of an embodiment of the device of the present invention. The air conditioning system adopts a three-pipe parallel reheat dehumidification system; the three-pipe parallel reheat dehumidification system includes a compressor 10, a first-stage throttling device 31, a second-stage throttling device 32, an outdoor fan 61, and an indoor fan 62. Specifically, the air conditioning system includes: a compressor 10, an outdoor heat exchanger 20, an indoor first heat exchanger 41, an indoor second heat exchanger 42, a first-stage throttling device 31, a second-stage throttling device 32, a first four-way reversing valve 51 and a second four-way reversing valve 52, an outdoor fan 61 located at the outdoor heat exchanger 20, and an indoor fan 62 located at the indoor first heat exchanger 41; wherein, the exhaust port 11 of the compressor 10, after passing through the D and C ports of the first four-way reversing valve 51, the outdoor heat exchanger 20, and the first-stage throttling device 31, is divided into two paths: one path passes through the indoor first heat exchanger 41 and the E and S ports of the first four-way reversing valve 51, and returns to the first suction port 12 of the compressor 10; the other path passes through the second-stage throttling device 32 and the indoor second heat exchanger 42, and then through the E and S ports of the second four-way reversing valve 52, and returns to the second suction port 13 of the compressor 10.

[0237] In the solution of this invention, the air conditioning system adopts a three-pipe parallel reheat dehumidification system. Figure 17 This is a schematic diagram of the cooling mode cycle of a three-pipe parallel reheat dehumidification system. Figure 17 As shown, the three-pipe parallel reheat dehumidification system includes: a compressor 10, an outdoor heat exchanger 20, a first-stage throttling device 31, a second-stage throttling device 32, an indoor first heat exchanger 41, an indoor second heat exchanger 42, a first four-way reversing valve 51, a second four-way reversing valve 52, an outdoor fan 61 and an indoor fan 62, a one-way valve 70, and temperature sensors 71, 72, 73, 74, 75, and 76. Among them, as... Figure 17 As shown, in cooling mode, the discharge port 11 of the compressor 10 is connected to port D of the first four-way reversing valve 51. Port C of the first four-way reversing valve 51, after passing through the outdoor heat exchanger 20 and the first-stage throttling device 31, splits into two paths: one path passes through the indoor first heat exchanger 41 and connects to port E of the first four-way reversing valve 51; the other path passes through the second-stage throttling device 32 and the indoor second heat exchanger 42 and connects to port E of the second four-way reversing valve 52. Port S of the second four-way reversing valve 52 is connected to the second suction port 13 of the compressor 10. Port S of the first four-way reversing valve 51 is connected to the first suction port 12 of the compressor 10. Temperature sensor 71 is installed on the heat exchange coil of the first indoor heat exchanger 41, temperature sensor 72 is installed on the heat exchange coil of the second indoor heat exchanger 42, temperature sensor 73 is installed on the heat exchange coil of the outdoor heat exchanger 20, temperature sensor 74 is installed on the pipeline where the first suction port 12 of the compressor 10 is located, temperature sensor 75 is installed on the pipeline where the second suction port 13 of the compressor 10 is located, and temperature sensor 76 is installed on the discharge port 11 of the compressor 10.

[0238] In the present invention, a compressor 10 with a dual-intake, single-exhaust structure is adopted, and the indoor evaporators, namely the first indoor heat exchanger 41 and the second indoor heat exchanger 42, are connected in parallel. Throttling devices are respectively provided at the outlet of the condenser (i.e., the outdoor heat exchanger 20) and the inlet of the indoor leeward side evaporator (i.e., the second indoor heat exchanger 42), such as a first-stage throttling device 31 (e.g., an outdoor electronic expansion valve) and a second-stage throttling device 32 (e.g., an indoor electronic expansion valve): In the cooling mode, the outdoor electronic expansion valve throttles the condensing pressure to the evaporating pressure on the windward side, and at the same time adjusts the suction superheat of the windward evaporator (i.e., the first indoor heat exchanger 41); the indoor leeward electronic expansion valve (i.e., the indoor electronic expansion valve) throttles the windward evaporating pressure to the leeward evaporating pressure, and at the same time adjusts the suction superheat of the leeward evaporator (i.e., the second indoor heat exchanger 42).

[0239] Figure 21 This is a schematic diagram of the reheat dehumidification mode cycle of a three-pipe parallel reheat dehumidification system. Figure 21As shown, in reheat dehumidification mode, the discharge port 11 of compressor 10 is connected to port D of the first four-way reversing valve 51. The discharge port 11 of compressor 10 is also connected to port D of the second four-way reversing valve 52. Port C of the first four-way reversing valve 51, after passing through the outdoor heat exchanger 20 and the first-stage throttling device 31, connects to port E of the first four-way reversing valve 51 after passing through the indoor first heat exchanger 41. Port E of the second four-way reversing valve 52, after passing through the indoor second heat exchanger 42 and the second-stage throttling device 32, flows into the indoor first heat exchanger 41, and then connects to port E of the first four-way reversing valve 51. Port S of the second four-way reversing valve 52 is connected to the second suction port 13 of compressor 10. Port C of the second four-way reversing valve 52 is connected to the outlet of check valve 70. The first suction port 12 of compressor 10 is connected to the inlet of check valve 70. The control device for the air conditioning system includes: an acquisition unit 102 and a control unit 104.

[0240] The control unit 104 is configured to, after the air conditioning system is started, control the indoor unit's air guide vane to open, control the indoor fan 62 to start at a set fan speed or automatic fan speed, and control the air conditioning system to perform oil return operation. Specifically, during the oil return operation, according to a preset oil return operation logic, the outdoor fan 62's speed is controlled to be the oil return speed, the compressor 10's frequency is controlled to be the oil return frequency, the first-stage throttling device 31's opening degree is controlled to be the first oil return opening degree, and the second-stage throttling device 32's opening degree is controlled to be the second oil return opening degree, thereby controlling the air conditioning system to perform oil return operation. In the preset oil return operation logic, the outdoor fan 62's speed, the compressor 10's frequency, the first-stage throttling device 31's opening degree, and the second-stage throttling device 32's opening degree correspond to the set oil return parameters. For the specific functions and processing of this control unit 104, please refer to step S110.

[0241] The acquisition unit 102 is configured to acquire the outdoor ambient temperature of the air conditioning system, such as the ambient temperature t, after the oil return operation of the air conditioning system is completed. w The operating parameters of the air conditioning system are obtained; the specific functions and processing of the acquisition unit 102 are described in step S120.

[0242] In some embodiments, the three-pipe parallel reheat dehumidification system further includes an outdoor heat exchanger 20, an indoor first heat exchanger 41, and an indoor second heat exchanger 42; the compressor 10 has an exhaust port 11, a first intake port 12, and a second intake port 13.

[0243] The acquisition unit 102 acquires the operating parameters of the air conditioning system, including at least one of the following:

[0244] The acquisition unit 102 is further configured to acquire the indoor ambient temperature of the air conditioning system, such as the inner ambient temperature t. N ; Obtain the indoor return air relative humidity of the air conditioning system, such as the indoor return air relative humidity RH. N The unit 102 is further configured to acquire the indoor return air temperature of the air conditioning system. Specifically, the acquisition unit 102 is also configured to acquire the frequency of the compressor 10, such as the frequency f of the compressor 10. The acquisition unit 102 is also specifically configured to acquire the pipe temperature of the indoor first heat exchanger 41, denoted as the indoor first pipe temperature of the air conditioning system, such as the pipe temperature t of the indoor first heat exchanger 41. eH The acquisition unit 102 is further configured to acquire the pipe temperature of the indoor second heat exchanger 42, denoted as the indoor second pipe temperature of the air conditioning system, such as the pipe temperature t of the indoor second heat exchanger 42. eL The acquisition unit 102 is further configured to acquire the pipe temperature of the outdoor heat exchanger 20, denoted as the outdoor pipe temperature of the air conditioning system, such as the pipe temperature t of the outdoor heat exchanger 20. c The refrigerant outlet temperature of the outdoor heat exchanger 20 is obtained. For example, in cooling mode, a refrigerant outlet temperature sensor is added to the outdoor condenser outlet pipe to detect the condenser outlet temperature in cooling mode. Specifically, the acquisition unit 102 is further configured to acquire the temperature of the first suction port 12 of the compressor 10, denoted as the first suction temperature of the air conditioning system, such as the temperature t of the first suction port 12 of the compressor 10. suc1 The acquisition unit 102 is further configured to acquire the pipe temperature of the second suction port 13 of the compressor 10, denoted as the second suction pipe temperature of the air conditioning system, such as suction temperature 2, which is the temperature t of the second suction port 13 of the compressor 10. suc2 Furthermore, the acquisition unit 102 is specifically configured to acquire the temperature of the exhaust port 11 of the compressor 10, denoted as the exhaust temperature of the air conditioning system, such as the temperature t of the exhaust port 11 of the compressor 10. dis .

[0245] In the solution of this invention, see Figure 19 , Figure 20 and Figure 23 In the example shown, while obtaining the operating parameters of the air conditioning system, it is also necessary to obtain the preset values ​​and fitted parameters of the air conditioning system. After obtaining the detected values ​​(i.e., the operating parameters of the air conditioning system), preset values, and fitted values, the opening degree of the dual electronic expansion valve in cooling mode is determined based on these parameters. Specifically, the detected values, preset values, and fitted values ​​are required when calculating the opening degree (i.e., the target opening degree) of the dual electronic expansion valve; therefore, it is necessary to obtain these parameters.

[0246] The acquired detection values ​​include at least one of the following: inner pipe temperature 1, i.e., the pipe temperature t of the first indoor heat exchanger 41. eH The inner pipe temperature 2 is the pipe temperature t of the second heat exchanger 42 in the room. eL The external pipe temperature is the pipe temperature t of the outdoor heat exchanger 20. c The suction temperature 1 is the temperature t of the first suction port 12 of the compressor 10. suc1 The suction temperature 2 is the temperature t of the second suction port 13 of the compressor 10. suc2 The exhaust temperature is the temperature t at the exhaust port 11 of the compressor 10. dis The frequency f of compressor 10, and the ambient temperature t w Inner ring temperature t N Indoor return air relative humidity (RH) N .

[0247] The preset values ​​obtained include at least one of the following: the high-temperature cylinder volume V of compressor 10 rev，H The cryogenic cylinder volume V of compressor 10 rev，L The setpoint dt of the leeward side intake superheat of compressor 10 suc，sh，l .

[0248] The parameters that need to be fitted during prototype matching include at least one of the following: the cryogenic cylinder volumetric efficiency η of compressor 10. v，L The flow correction factor K of main valve 1 (i.e., outdoor electronic expansion valve) c1 The flow correction factor K of the indoor unit reheat valve 2 (i.e., indoor electronic expansion valve) c2 The saturation temperature drop dt from the middle of the evaporator on the windward side (i.e., the first heat exchanger 41 in the room) to the suction port sat，suc1 The saturation temperature drop dt from the middle of the evaporator on the leeward side (i.e., the second indoor heat exchanger 42) to the suction port sat，suc2 The saturated temperature drop dt from the outlet of main valve 1 (i.e., outdoor electronic expansion valve) to the high-temperature evaporator tube sat1 The saturated temperature drop dt from the outlet of the indoor unit valve (i.e., indoor unit reheat valve 2) to the low-temperature evaporator tube sat2 Outdoor valve opening Pulse1 = f(V) a，1 ), the opening degree of the indoor valve (i.e., indoor unit reheat valve 2) Pulse2 = f(V a，2 ), Main valve 1 flow correction coefficient K c1 Flow correction coefficient K for indoor reheat valve 2 c2 .

[0249] In this context, the low-temperature cylinder of compressor 10 refers to the cylinder corresponding to the second suction port 13 of compressor 10, which is connected to the indoor leeward side heat exchanger (i.e., the indoor second heat exchanger 42); correspondingly, the high-temperature cylinder of compressor 10 refers to the cylinder corresponding to the first suction port 12 of compressor 10, which is connected to the windward side evaporator (i.e., the indoor first heat exchanger 41). The high-temperature evaporator is the indoor first heat exchanger 41, and the low-temperature evaporator is the indoor second heat exchanger 42.

[0250] The control unit 104 is also configured to adjust the frequency of the compressor 10 and the speed of the outdoor fan 61 according to the outdoor ambient temperature of the air conditioning system in the current operating mode of the air conditioning system. The specific functions and processing of the control unit 104 are further described in step S130.

[0251] The control unit 104 is further configured to, in the current operating mode of the air conditioning system, determine the target opening degree of the first-stage throttling device 31 and the target opening degree of the second-stage throttling device 32 by combining the outdoor ambient temperature of the air conditioning system, the indoor return air relative humidity of the air conditioning system, and the operating parameters of the air conditioning system; then, in the current operating mode of the air conditioning system, control the first-stage throttling device 31 to operate at the target opening degree of the first-stage throttling device 31, and control the second-stage throttling device 32 to operate at the target opening degree of the second-stage throttling device 32; wherein, the current operating mode of the air conditioning system is a cooling mode or a reheat dehumidification mode. That is, in the current operating mode of the air conditioning system, the current opening degrees of the first-stage throttling device 31 and the second-stage throttling device 32 are adjusted according to the target opening degree of the first-stage throttling device 31 and the target opening degree of the second-stage throttling device 32. Specifically, the current opening degree of the first-stage throttling device 31 is adjusted according to its target opening degree, and simultaneously, the current opening degree of the second-stage throttling device 32 is adjusted according to its target opening degree, so as to improve the energy efficiency of the air conditioning system and the user's comfort experience in the current operating mode of the air conditioning system. The specific functions and processing of this control unit 104 are also described in step S140.

[0252] The present invention proposes an opening control device for dual electronic expansion valves in an air conditioning system. This device calculates the refrigerant mass flow ratio between the outdoor main electronic expansion valve (i.e., the outdoor electronic expansion valve) and the indoor reheat electronic expansion valve (i.e., the indoor electronic expansion valve), and calculates the inlet and outlet pressure difference between the main electronic expansion valve (i.e., the outdoor electronic expansion valve) and the reheat electronic expansion valve (i.e., the indoor electronic expansion valve) based on the temperature parameters detected by the pipe temperature sensor. Finally, it calculates the opening degree of the dual electronic expansion valves using the refrigerant mass flow ratio between the main valve 1 (i.e., the outdoor electronic expansion valve) and the reheat electronic expansion valve, and the pressure difference across the valves (i.e., the inlet and outlet pressure difference). The airflow ratio is determined by fitting the corresponding relationship between the airflow and opening degree of the selected electronic expansion valve. This yields the fitting formulas for the airflow-opening degree and opening degree-airflow ratio of the valve. Knowing the opening degree of one valve allows calculation of its airflow, and vice versa, enabling the correlated control of the two valve openings. Based on the calculated electronic expansion valve opening, appropriate feedback adjustments, such as compressor exhaust superheat and intake superheat, are used to fine-tune the opening of the dual electronic expansion valves, thus ensuring the reliability and stability of the air conditioning system. However, the control device for the opening of the electronic expansion valve in the relevant scheme cannot meet the decoupling control requirements of the dual electronic expansion valves in a three-pipe parallel reheat dehumidification system, thus failing to achieve active control of the dual electronic expansion valve opening. By decoupling the dual electronic expansion valves in the three-pipe parallel reheat dehumidification system, active control of the dual electronic expansion valve opening is achieved, along with rapid adjustment, improving the stability and reliability of the air conditioning system. Therefore, this not only solves the problems of high energy consumption in air conditioning systems (such as household inverter heat pump air conditioners) during low-load operation for cooling and dehumidification in summer, and low comfort and high energy consumption during humid weather in transitional seasons, but also solves the problems of unstable operation of air conditioning systems or longer adjustment time caused by the coupling relationship between the two electronic expansion valves in related solutions that use parameters such as compressor suction superheat or exhaust superheat for dual electronic expansion valve opening control.

[0253] In some implementations, the current operating mode of the air conditioning system is cooling mode.

[0254] The control unit 104, in the cooling mode, determines the target opening degree of the first-stage throttling device 31 and the target opening degree of the second-stage throttling device 32 by combining the outdoor ambient temperature of the air conditioning system, the indoor return air relative humidity of the air conditioning system, and the operating parameters of the air conditioning system. This includes the process of calculating the target opening degree of the first-stage throttling device 31 and the target opening degree of the second-stage throttling device 32 in the cooling mode, as detailed below:

[0255] The control unit 104 is further configured to determine the inlet and outlet pressure difference of the first-stage throttling device 31 based on the outdoor pipe temperature of the air conditioning system, the indoor first pipe temperature of the air conditioning system, and a predetermined saturation temperature drop from the outlet of the first-stage throttling device 31 to the pipe of the first indoor heat exchanger 41, such as based on the pipe temperature t of the outdoor heat exchanger 20. c The tube temperature t of the first heat exchanger 41 in the room eH The saturated temperature drop dt from the outlet of main valve 1 to the high-temperature evaporator tube sat1 Calculate the refrigerant inlet and outlet pressure difference ΔP of main valve 1. r1 The high-temperature evaporator is the indoor first heat exchanger 41; and the inlet and outlet pressure difference of the second-stage throttling device 32 is determined based on the indoor first pipe temperature of the air conditioning system, the indoor second pipe temperature of the air conditioning system, and the predetermined saturation temperature drop from the outlet of the second-stage throttling device 32 to the pipe of the indoor second heat exchanger 42, such as based on the pipe temperature t of the indoor first heat exchanger 41. eH The tube temperature t of the second heat exchanger 42 in the room eL The saturated temperature drop dt from the outlet of indoor unit valve 2 to the low-temperature evaporator tube sat2 Calculate the refrigerant inlet and outlet pressure difference ΔP of main valve 1. r2 The low-temperature evaporator is the second indoor heat exchanger 42. For the specific functions and processing of the control unit 104, please refer to step S210.

[0256] In some embodiments, the control unit 104 determines the inlet and outlet pressure difference of the first-stage throttling device 31 based on the outdoor pipe temperature of the air conditioning system, the indoor first pipe temperature of the air conditioning system, and a predetermined saturation temperature drop from the outlet of the first-stage throttling device 31 to the pipe of the first indoor heat exchanger 41, including:

[0257] The control unit 104 is further configured to use the outdoor pipe temperature of the air conditioning system as the saturation temperature corresponding to the refrigerant inlet pressure of the first-stage throttling device 31, such as the refrigerant inlet saturation temperature of the main valve 1 being t. i1 =t c ; and, the sum of the indoor first pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the outlet of the first-stage throttling device 31 to the pipe of the first indoor heat exchanger 41 is taken as the saturation temperature corresponding to the refrigerant outlet pressure of the first-stage throttling device 31, such as the refrigerant outlet saturation temperature of the main valve 1 being t o1 =t eH +dt sat1 For details on the specific functions and processing of the control unit 104, please refer to step S310.

[0258] The control unit 104 is further configured to multiply the sum of the refrigerant inlet pressure corresponding to the saturation temperature of the first-stage throttling device 31 and the refrigerant outlet pressure corresponding to the saturation temperature of the first-stage throttling device 31 by a first set coefficient multiple, and then multiply the sum by the difference between the refrigerant outlet pressure and the saturation temperature of the first-stage throttling device 31 to obtain the inlet and outlet pressure difference of the first-stage throttling device 31, such as the refrigerant inlet and outlet pressure difference ΔP of the main valve 1. r1 =[509.46(t)] i1 +t o1 )+20853](t i1 -t o1 For details on the specific functions and processing of the control unit 104, please refer to step S320.

[0259] In some embodiments, the control unit 104 determines the inlet and outlet pressure difference of the second-stage throttling device 32 based on the indoor first pipe temperature of the air conditioning system, the indoor second pipe temperature of the air conditioning system, and a predetermined saturation temperature drop from the outlet of the second-stage throttling device 32 to the pipe of the indoor second heat exchanger 42, including:

[0260] The control unit 104 is further configured to use the sum of the indoor first pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the outlet of the second-stage throttling device 32 to the pipe of the indoor second heat exchanger 42 as the saturation temperature corresponding to the refrigerant inlet pressure of the second-stage throttling device 32, such as the refrigerant inlet saturation temperature of the indoor unit valve 2 being t. i2 =t eH +dt sat2 ; and, the sum of the indoor second pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the outlet of the second-stage throttling device 32 to the pipe of the indoor second heat exchanger 42 is taken as the saturation temperature corresponding to the refrigerant outlet pressure of the second-stage throttling device 32, such as the refrigerant outlet saturation temperature of the indoor unit valve 2 being t o2 =t eL +dt sat2 For details on the specific functions and processing of the control unit 104, please refer to step S410.

[0261] The control unit 104 is further configured to multiply a second set coefficient (a multiple of the sum of the refrigerant inlet pressure corresponding to the saturation temperature of the second-stage throttling device 32 and the refrigerant outlet pressure corresponding to the saturation temperature of the second-stage throttling device 32) by a second set value, and then multiply this sum by the difference between the refrigerant outlet pressure and the saturation temperature of the second-stage throttling device 32 to obtain the inlet and outlet pressure difference of the second-stage throttling device 32, such as the refrigerant inlet and outlet pressure difference ΔP of the main valve 1. r2 =[509.46(t)] i2+t o2 )+20853](t i2 -t o2 For details on the specific functions and processing of the control unit 104, please refer to step S420.

[0262] Specifically, Figure 19 This is a schematic flowchart of the first embodiment of the calculation process for the opening degree of the dual electronic expansion valve in cooling mode. Figure 19 As shown, the calculation process for the opening degree of the dual electronic expansion valve in cooling mode includes:

[0263] Step 11: After the air conditioning system receives the operation command for cooling mode, first open the air guide plate of the indoor unit, start the indoor fan according to the user-set fan speed or automatic fan speed, and set the outdoor fan speed, compressor frequency, outdoor electronic expansion valve and indoor electronic expansion valve opening degree. First, run at the outdoor fan speed, compressor frequency, outdoor electronic expansion valve and indoor electronic expansion valve opening degree corresponding to the set oil return parameters. After the oil return operation is completed, proceed to step 12.

[0264] Step 12: The compressor frequency and outdoor fan speed are determined based on the ambient temperature detected by the outdoor ambient temperature sensor (i.e., the outdoor ambient temperature t). w The system operates based on user-defined temperature parameters, and the opening degrees of the outdoor and indoor electronic expansion valves are calculated based on the temperature parameters detected by the temperature sensor.

[0265] The calculation process for the opening degree of main valve 1 (i.e., outdoor electronic expansion valve) and indoor reheat valve 2 (i.e., indoor electronic expansion valve) in cooling mode is as follows:

[0266] Step 121: Calculate the refrigerant inlet and outlet pressure difference of the main valve 1 (i.e., the outdoor electronic expansion valve) and the indoor unit valve (i.e., the indoor unit reheat valve 2).

[0267] Figure 18 This is a schematic diagram of the pressure and enthalpy of the refrigeration cycle in a three-pipe parallel reheat dehumidification system. Figure 18 It can display the pressure and enthalpy relationship of a three-pipe parallel reheat dehumidification system in cooling mode. From Figure 18 The pressure-enthalpy diagram for cooling mode shows that the inlet pressure of main valve 1 (i.e., outdoor electronic expansion valve) is the saturation pressure corresponding to the condenser tube temperature, and the outlet pressure of main valve 1 (i.e., outdoor electronic expansion valve) is the saturation pressure corresponding to the sum of the high-temperature evaporator tube temperature and the saturation temperature drop from the valve outlet to the high-temperature evaporator tube; the inlet pressure of indoor unit valve (i.e., indoor unit reheat valve 2) is the sum of the high-temperature evaporator tube temperature and the saturation temperature drop from the valve outlet to the high-temperature evaporator tube, and the outlet pressure of indoor unit valve (i.e., indoor unit reheat valve 2) is the saturation pressure corresponding to the sum of the low-temperature evaporator tube temperature and the saturation temperature drop from the outlet of indoor unit valve (i.e., indoor unit reheat valve 2) to the low-temperature evaporator tube.

[0268] Given the refrigerant used in the air conditioning system, the correlation between the refrigerant's saturated vapor pressure P and the corresponding saturated temperature t can be fitted using the refrigerant property software NIST, as shown by the equation P = f(t). Taking R32, the mainstream refrigerant for household inverter heat pump air conditioners, as an example, the fitted equation for the saturated vapor pressure P (Pa) of R32 under normal cooling conditions, such as an ambient temperature of 0-50℃, is as follows:

[0269] P=509.46*t*t+20853*t+839607.

[0270] The pressure difference between the inlet and outlet of the valve can be expressed as:

[0271] Δp r =[509.46(t)] i +t o )+20853](t i -t o ).

[0272] Among them, t i and t o These represent the saturation temperatures corresponding to the valve's inlet and outlet pressures, respectively. The refrigerant inlet and outlet saturation temperatures of main valve 1 (i.e., the outdoor electronic expansion valve) are tin and toutlet, respectively. i1 =t c , t o1 =t eH +dt sat1 The refrigerant inlet and outlet saturation temperatures of the indoor unit valve (i.e., indoor unit reheat valve 2) are t and t, respectively. i2 =t eH +dt sat2 , t o2 =t eL +dt sat2 .

[0273] The control unit 104 is further configured to determine the inlet refrigerant density of the first-stage throttling device 31 based on the outdoor pipe temperature of the air conditioning system, such as based on the pipe temperature t of the outdoor heat exchanger 20. c Calculate the refrigerant density ρ at the inlet of main valve 1. 1i Furthermore, based on the outdoor ambient temperature of the air conditioning system or the refrigerant outlet temperature of the outdoor heat exchanger 20, and in conjunction with the predetermined saturated liquid specific volume and the predetermined saturated gas specific volume of the refrigerant in the air conditioning system, the inlet refrigerant density of the second-stage throttling device 32 is determined, such as based on the refrigerant dryness x at the indoor unit valve inlet and the saturated gas specific volume v of the refrigerant. g Specific volume of refrigerant in saturated liquid (v) l Calculate the refrigerant density ρ at the inlet of valve 2 in the indoor unit. 1iFor details on the specific functions and processing of the control unit 104, please refer to step S220.

[0274] In some embodiments, the control unit 104 determines the inlet refrigerant density of the first-stage throttling device 31 based on the outdoor pipe temperature of the air conditioning system. Specifically, the control unit 104 is further configured to determine the inlet refrigerant density of the first-stage throttling device 31 based on the correspondence between a set outdoor pipe temperature and a set inlet refrigerant density, where the set inlet refrigerant density corresponds to the same set outdoor pipe temperature as the outdoor pipe temperature of the air conditioning system. For example, ρ 1i =f(t) c ).

[0275] In some embodiments, the control unit 104 determines the inlet refrigerant density of the second-stage throttling device 32 based on the outdoor ambient temperature of the air conditioning system or the refrigerant outlet temperature of the outdoor heat exchanger 20, and in conjunction with a predetermined saturated liquid specific volume and a predetermined saturated gas specific volume of the refrigerant in the air conditioning system, including:

[0276] The control unit 104 is further configured to determine the refrigerant specific enthalpy at the outlet of the outdoor heat exchanger 20, such as the condenser outlet refrigerant specific enthalpy h, based on the outdoor ambient temperature of the air conditioning system or the refrigerant outlet temperature of the outdoor heat exchanger 20. c,out =f(t) c，out ), condenser outlet temperature t c，out It can be obtained through two types of computing devices: one is by utilizing the ambient temperature t w Make corrections, i.e., t c，out =(t w +△t), where △t is selected according to the different configurations of the refrigeration system, usually between 2 and 5℃; another method is to add a cold outlet temperature sensor at the outdoor condenser outlet pipe to detect the condenser outlet temperature in refrigeration mode. For the specific functions and processing of this control unit 104, please refer to step S510.

[0277] The control unit 104 is further configured to determine the inlet refrigerant dryness of the second-stage throttling device 32 based on the outlet refrigerant specific enthalpy of the outdoor heat exchanger 20, the pre-determined refrigerant saturated gas specific enthalpy of the air conditioning system, and the pre-determined refrigerant saturated liquid specific enthalpy of the air conditioning system. For example, the inlet refrigerant dryness x of the indoor unit valve 2 is calculated as x = (h... c,out -h l ) / (h g -h l ), the saturated gas enthalpy h of R32 g The saturated liquid specific enthalpy h of R32l For details on the specific functions and processing of the control unit 104, please refer to step S520.

[0278] The control unit 104 is further configured to determine the inlet refrigerant density of the second-stage throttling device 32, such as the refrigerant density ρ at the inlet of the indoor unit valve 2, based on the inlet refrigerant dryness of the second-stage throttling device 32, the pre-determined saturated liquid specific volume of the refrigerant in the air conditioning system, and the pre-determined saturated gas specific volume of the refrigerant in the air conditioning system. 2i =1 / (x*v) g +(1-x)*v L ), the saturated gas specific volume v of the refrigerant g Specific volume of refrigerant in saturated liquid (v) l For details on the specific functions and processing of the control unit 104, please refer to step S530.

[0279] Specifically, such as Figure 19 As shown, the calculation process for the opening of the dual electronic expansion valve in cooling mode also includes: step 122, calculating the refrigerant density at the inlet of the dual electronic expansion valve.

[0280] In cooling mode, the inlet of main valve 1 (i.e., the outdoor electronic expansion valve) contains subcooled liquid refrigerant, the density of which can be approximated as the density of a saturated liquid. This density can be calculated using the correlation between the saturated liquid density and the saturated temperature corresponding to the pressure, fitted by the refrigerant property calculation software NIST. In other words, the refrigerant density ρ at the inlet of main valve 1 (i.e., the outdoor electronic expansion valve) is... 1i =f(t) c ).

[0281] The inlet of the indoor valve (i.e., indoor unit reheat valve 2) is in a two-phase refrigerant state after throttling by the outdoor main valve 1 (i.e., outdoor electronic expansion valve). Its inlet density can be approximately calculated using the relationship between the inlet refrigerant dryness fraction, saturated liquid density, and saturated gas density. The refrigerant density ρ at the inlet of the indoor valve (i.e., indoor unit reheat valve 2) is... 2i =1 / (x*v) g +(1-x)*v L The refrigerant dryness fraction at the inlet of the indoor unit valve (i.e., indoor unit reheat valve 2) can be calculated using the relationship between the condenser outlet specific enthalpy and the specific enthalpy of the saturated gas and saturated liquid refrigerant at the inlet of the indoor unit valve (i.e., indoor unit reheat valve 2), x = (h c，out -h l ) / (h g -h l ), where the enthalpy of the refrigerant at the condenser outlet is h c，out =f(t) c，out ), condenser outlet temperature t c，out It can be obtained through two calculation devices: one is by using the ambient temperature tw Make corrections, i.e., t c，out =(t w +△t), where △t is selected according to the different configurations of the refrigeration system, usually between 2 and 5℃; another method is to add a cold outlet temperature sensor at the outdoor condenser outlet pipe to detect the condenser outlet temperature in cooling mode. Taking R32, the mainstream refrigerant for household inverter heat pump air conditioners, as an example, in the ambient temperature range of 0-40℃: the saturated liquid density ρ (kg / m³) of R32 3 The fitting formula for ) is:

[0282] ρ=-0.031*t*t-2.7548*t+1051.3.

[0283] Specific volume of saturated gas of R32 v g (m 3 The fitted formula for ( / kg) is:

[0284] v g =10 -5 *t 2 -0.0013*t+0.045.

[0285] Specific volume of saturated liquid R32 v l (m 3 The fitted formula for ( / kg) is:

[0286] v l =3*10 -8 *t 2 +3*10 -6 *t+0.0009.

[0287] Specific enthalpy h of saturated liquid of R32 l The fitting formula for (kJ / kg) is:

[0288] h l =1.8414*t+199.51.

[0289] Enthalpy of saturated gas of R32 (h) g The fitting formula for (kJ / kg) is:

[0290] h g = -0.0063*t 2 +0.2075*t+515.24.

[0291] The control unit 104 is further configured to calculate the saturated suction specific volume corresponding to the first suction cylinder of the compressor 10 based on the indoor first pipe temperature of the air conditioning system and the predetermined saturated temperature drop from the middle of the indoor first heat exchanger 41 to the first suction port 12 of the compressor 10, such as based on the pipe temperature t of the indoor first heat exchanger 41.eH The saturated temperature drop dt from the middle of the evaporator on the windward side to the first suction port of the compressor 10 sat，suc1 Calculate the saturated intake specific volume v corresponding to the first intake port of compressor 10. suc,sat,H Based on the indoor second pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the middle of the indoor second heat exchanger 42 to the second suction port 13 of the compressor 10, the saturation suction specific volume corresponding to the second suction cylinder of the compressor 10 is calculated, such as based on the pipe temperature t of the indoor second heat exchanger 42. eL The saturated temperature drop dt from the middle of the evaporator on the leeward side to the second suction port of the compressor 10 sat，suc2 Calculate the saturated intake specific volume v corresponding to the second intake port of compressor 10. suc,sat,L For details on the specific functions and processing of the control unit 104, please refer to step S230.

[0292] In some embodiments, the control unit 104 calculates the saturated suction specific volume corresponding to the first suction cylinder of the compressor 10 based on the indoor first pipe temperature of the air conditioning system and the predetermined saturated temperature drop from the middle of the indoor first heat exchanger 41 to the first suction port 12 of the compressor 10, including:

[0293] The control unit 104 is further configured to use the difference between the indoor first pipe temperature of the air conditioning system and the predetermined saturation temperature drop between the middle of the indoor first heat exchanger 41 and the first suction port 12 of the compressor 10 as the suction saturation temperature of the first suction cylinder of the compressor 10. The specific functions and processing of this control unit 104 are further described in step S610.

[0294] The control unit 104 is further configured to determine the saturated suction specific volume corresponding to the first suction cylinder of the compressor 10 based on the suction saturation temperature of the first suction cylinder, such as calculating the saturated suction specific volume v corresponding to the high-temperature cylinder based on the correlation relationship. suc，sat，H For details on the specific functions and processing of the control unit 104, please refer to step S620.

[0295] In some embodiments, the control unit 104 calculates the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10 based on the indoor second pipe temperature of the air conditioning system and the predetermined saturated temperature drop from the middle of the indoor second heat exchanger 42 to the second suction port 13 of the compressor 10, including:

[0296] The control unit 104 is further configured to use the difference between the indoor second pipe temperature of the air conditioning system and the predetermined saturation temperature drop between the middle of the indoor second heat exchanger 42 and the second suction port 13 of the compressor 10 as the suction saturation temperature of the second suction cylinder of the compressor 10. The specific functions and processing of this control unit 104 are further described in step S710.

[0297] The control unit 104 is further configured to determine the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10 based on the suction saturation temperature of the second suction cylinder, such as calculating the saturated suction specific volume v corresponding to the low-temperature cylinder based on the correlation relationship. suc，sat，L For details on the specific functions and processing of the control unit 104, please refer to step S720.

[0298] Specifically, such as Figure 19 As shown, the calculation process for the opening of the dual electronic expansion valve in refrigeration mode also includes: step 123, calculating the saturated suction specific volume corresponding to the two cylinders of the compressor.

[0299] The compressor cylinder connected to the indoor windward heat exchanger (i.e., the indoor first heat exchanger 41) has an intake saturation temperature of t. sat1 =t eH -dt sat，suc1 The leeward-side compressor cylinder is connected to the indoor leeward-side heat exchanger (i.e., the indoor second heat exchanger 42), and its intake saturation temperature is t. sat2 =t eL -dt sat，suc2 The saturated suction specific volume (v) of the compressor's two suction cylinders can be calculated using the fitting formula between the saturated suction specific volume and the suction saturation temperature. Specifically, the saturated suction specific volume v of the high-temperature cylinder can be obtained from this formula. suc，sat，H The saturated intake specific volume v corresponding to the cryogenic cylinder suc，sat，L .

[0300] Subsequently, the control unit 104 is further configured to determine the opening degree of the first-stage throttling device 31 by combining the inlet and outlet pressure difference of the first-stage throttling device 31, the inlet refrigerant density of the first-stage throttling device 31, the saturated suction specific volume corresponding to the first suction cylinder of the compressor 10, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10. This target opening degree of the first-stage throttling device 31 is then calculated, such as by calculating the opening degree Pulse1 of the main valve 1. The specific functions and processing of this control unit 104 are further described in step S240.

[0301] In some embodiments, the control unit 104, in conjunction with the inlet and outlet pressure difference of the first-stage throttling device 31, the inlet refrigerant density of the first-stage throttling device 31, the saturated suction specific volume corresponding to the first suction cylinder of the compressor 10, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10, determines the opening degree of the first-stage throttling device 31 as the target opening degree of the first-stage throttling device 31, including:

[0302] The control unit 104 is further configured to multiply the sum of a predetermined third set coefficient (multiplied by a third set value) of the saturation temperature drop from the middle of the indoor first heat exchanger 41 to the first suction port 12 of the compressor 10, and a predetermined suction superheat of the first suction cylinder of the compressor 10, as the saturation suction specific volume corresponding to the first suction cylinder of the compressor 10, such as the suction specific volume v corresponding to the high-temperature cylinder. suc，H Among them, the intake specific volume v corresponding to the high-temperature cylinder suc，H =v suc，sat，H *(1+2.2*10 -4 *dt suc，sh The preset intake superheat of the second intake cylinder of the compressor 10 is dt. suc，sh For details on the specific functions and processing of the control unit 104, please refer to step S810.

[0303] The control unit 104 is further configured to multiply the sum of a predetermined fourth set coefficient (multiple of the saturation temperature drop from the middle of the indoor second heat exchanger 42 to the second suction port 13 of the compressor 10) and a fourth set value, and then multiply the product of the preset suction superheat of the second suction cylinder of the compressor 10, as the saturation suction specific volume corresponding to the second suction cylinder of the compressor 10, such as the suction specific volume v corresponding to the low-temperature cylinder. suc，L Among them, the specific volume of the intake air corresponding to the cryogenic cylinder is v. suc，L =v suc，sat，L *(1+2.2*10 -4 *dt suc，sh The preset intake superheat of the second intake cylinder of the compressor 10 is dt. suc，sh For details on the specific functions and processing of the control unit 104, please refer to step S820.

[0304] The control unit 104 is further configured to calculate the ratio of the set frequency multiplier of the compressor 10 to the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10, and use this ratio as the refrigerant mass flow rate of the second-stage throttling device 32, such as the refrigerant mass flow rate M2 of the indoor unit valve 2 = a*f / v suc，L For details on the specific functions and processing of the control unit 104, please refer to step S830.

[0305] The control unit 104 is further configured to calculate the ratio of the set frequency of the compressor 10 to the saturated suction specific volume corresponding to the first suction cylinder of the compressor 10, and use this ratio as the refrigerant mass flow rate of the indoor first heat exchanger 41, such as the refrigerant mass flow rate M of the evaporator on the windward side (i.e., the indoor first heat exchanger 41). H =a*f / v suc，H The refrigerant mass flow rate of the second-stage throttling device 32 and the refrigerant mass flow rate of the indoor first heat exchanger 41 are taken as the refrigerant mass flow rate of the first-stage throttling device 31. For example, the refrigerant mass flow rate M1 of the outdoor unit main valve 1 is the sum of the refrigerant mass flow rates of the leeward side evaporator (i.e., the indoor second heat exchanger 42) and the windward side evaporator (i.e., the indoor first heat exchanger 41), that is: M1=M2+a*f / v suc，H 'a' is a coefficient related to compressor performance. For the specific functions and processing of this control unit 104, please refer to step S840.

[0306] The control unit 104 is further configured to take the ratio of the product of the predetermined flow correction coefficient of the first-stage throttling device 31 and the refrigerant mass flow rate of the first-stage throttling device 31, to the ratio of the inlet refrigerant density of the first-stage throttling device 31, and then to the square root of the inlet and outlet pressure difference of the first-stage throttling device 31, as the air flow rate V of the outdoor main valve 1. a，1 =K c1 *M1 / (ρ 1，i *sqrt(△P r1 For details on the specific functions and processing of the control unit 104, please refer to step S850.

[0307] The control unit 104 is further configured to determine the opening degree of the first-stage throttling device 31 based on the air flow rate of the first-stage throttling device 31, as the target opening degree of the first-stage throttling device 31, such as the opening degree of the main valve 1, Pulse1 = f(V a1 For details on the specific functions and processing of the control unit 104, please refer to step S860.

[0308] The control unit 104 is further configured to determine the opening degree of the second-stage throttling device 32 by combining the inlet and outlet pressure difference of the second-stage throttling device 32, the inlet refrigerant density of the second-stage throttling device 32, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10. This target opening degree of the second-stage throttling device 32 is used, such as calculating the opening degree Pulse2 of the indoor unit valve 2. The specific functions and processing of this control unit 104 are further described in step S250.

[0309] In some embodiments, the control unit 104, in conjunction with the inlet and outlet pressure difference of the second-stage throttling device 32, the inlet refrigerant density of the second-stage throttling device 32, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10, determines the opening degree of the second-stage throttling device 32 as the target opening degree of the second-stage throttling device 32, including:

[0310] The control unit 104 is further configured to multiply the sum of a predetermined fourth set coefficient (multiple of the saturation temperature drop from the middle of the indoor second heat exchanger 42 to the second suction port 13 of the compressor 10) and a fourth set value, and then multiply the product of the preset suction superheat of the second suction cylinder of the compressor 10, as the saturation suction specific volume corresponding to the second suction cylinder of the compressor 10, such as the suction specific volume v corresponding to the low-temperature cylinder. suc，L Among them, the specific volume of the intake air corresponding to the cryogenic cylinder is v. suc，L =v suc，sat，L *(1+2.2*10 -4 *dt suc，sh The preset intake superheat of the second intake cylinder of the compressor 10 is dt. suc，sh For details on the specific functions and processing of the control unit 104, please refer to step S910.

[0311] The control unit 104 is further configured to calculate the ratio of the set frequency multiplier of the compressor 10 to the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10, and use this ratio as the refrigerant mass flow rate of the second-stage throttling device 32, such as the refrigerant mass flow rate M2 of the indoor unit valve 2 = a*f / v suc，L For details on the specific functions and processing of the control unit 104, please refer to step S920.

[0312] The control unit 104 is further configured to take the ratio of the product of the predetermined flow correction coefficient of the second-stage throttling device 32 and the refrigerant mass flow rate of the second-stage throttling device 32, to the ratio of the inlet refrigerant density of the second-stage throttling device 32, and then to the square root of the inlet and outlet pressure difference of the second-stage throttling device 32, as the air flow rate V of the indoor unit valve (i.e., the indoor unit reheat valve 2). a，2 =K c2 *M2 / (ρ2, i *sqrt(△P r2 For details on the specific functions and processing of the control unit 104, please refer to step S930.

[0313] The control unit 104 is further configured to determine the opening degree of the second-stage throttling device 32 based on the airflow of the second-stage throttling device 32, as the target opening degree of the second-stage throttling device 32, such as the opening degree of the indoor unit valve 2, Pulse2 = f(V a2 For details on the specific functions and processing of the control unit 104, please refer to step S940.

[0314] Specifically, such as Figure 19 As shown, the calculation process for the opening degree of the dual electronic expansion valve in cooling mode also includes:

[0315] Given the saturated intake specific volume of the two compression cylinders of the compressor, i.e., the saturated intake specific volume v corresponding to the high-temperature cylinder. suc，sat，H The saturated intake specific volume v corresponding to the cryogenic cylinder suc，sat，L and the preset intake superheat dt suc，sh The suction specific volume v of the two compression cylinders of compressor 10, i.e., the suction specific volume v of the high-temperature cylinder, can be calculated. suc，H The intake specific volume v corresponding to the cryogenic cylinder suc，L Taking R32, the mainstream refrigerant for household inverter heat pump air conditioners, as an example: the suction specific volume v of R32... suc (m 3 The fitting formula for ( / kg) is:

[0316] v suc =v suc，sat *(1+2.2*10 -4 *dt suc，sh ).

[0317] The specific suction volume of the two compression cylinders of compressor 10, i.e., the specific suction volume v corresponding to the high-temperature cylinder, is known. suc，H The intake specific volume v corresponding to the cryogenic cylinder suc，L Based on the compressor parameters, the refrigerant mass flow rates of the indoor unit valve (i.e., indoor unit reheat valve 2) and main valve 1 (i.e., outdoor electronic expansion valve) can be calculated, where the refrigerant mass flow rate M2 of the indoor unit valve (i.e., indoor unit reheat valve 2) is:

[0318] M2 = a * f / v suc，L .

[0319] The refrigerant mass flow rate M1 of the outdoor unit main valve 1 (i.e., the outdoor electronic expansion valve) is the sum of the refrigerant mass flow rates of the leeward side evaporator (i.e., the indoor second heat exchanger 42) and the windward side evaporator (i.e., the indoor first heat exchanger 41), that is:

[0320] M1 = M2 + a * f / v suc，H , where 'a' is a coefficient related to compressor performance.

[0321] Given the pressure difference ΔP between the inlet and outlet of the dual electronic expansion valve.r1 and △P r2 Based on the mass flow rate and inlet density, the air flow rate (L / min) corresponding to 0.1 MPa for the electronic expansion valve can be calculated, where the air flow rate V of the outdoor main valve 1 (i.e., the outdoor electronic expansion valve) is... a，1 :

[0322] V a，1 =K c1 *M1 / (ρ 1，i *sqrt(△P r1 ).

[0323] Airflow V of the indoor unit valve (i.e., indoor unit reheat valve 2) a，2 :

[0324] V a，2 =K c2 *M2 / (ρ 2，i *sqrt(△P r2 ).

[0325] Here, sqrt represents the radical sign, referring to the calculation of square roots.

[0326] It is known that the main valve 1 (i.e., the outdoor electronic expansion valve) and the indoor unit valve (i.e., the indoor unit reheat valve 2) correspond to an air flow rate V of 0.1 MPa. a1 and V a2 Calculate the opening degree of main valve 1 (i.e., outdoor electronic expansion valve) and indoor unit valve (i.e., indoor unit reheat valve 2) respectively: Pulse1 = f(V a1 ) and Pulse2 = f(V a2 ).

[0327] In other embodiments, the control unit 104, in conjunction with the inlet and outlet pressure difference of the first-stage throttling device 31, the inlet refrigerant density of the first-stage throttling device 31, the saturated suction specific volume corresponding to the first suction cylinder of the compressor 10, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10, determines the opening degree of the first-stage throttling device 31 as the target opening degree of the first-stage throttling device 31, and further includes:

[0328] The control unit 104 is further configured to determine the refrigerant flow ratio between the first-stage throttling device 31 and the second-stage throttling device 32 based on the preset first suction cylinder volume of the compressor 10, the preset second suction cylinder volume of the compressor 10, the saturated suction specific volume corresponding to the first suction cylinder of the compressor 10, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10. For example, the refrigerant flow ratio r between the outdoor main valve 1 (i.e., the outdoor electronic expansion valve) and the indoor reheat valve 2. Mr =1+V rev，H *v suc，sat，L / V rev，L *v suc，sat，H The preset volume of the first suction cylinder of the compressor 10 is such as the volume of the high-temperature cylinder V. rev,H The preset volume of the second suction cylinder of the compressor 10 is, for example, the volume of the cryogenic cylinder V. rev,L For details on the specific functions and processing of the control unit 104, please refer to step S1010.

[0329] The control unit 104 is further configured to multiply the sum of a predetermined third set coefficient (multiplied by a third set value) of the saturation temperature drop from the middle of the indoor first heat exchanger 41 to the first suction port 12 of the compressor 10, and a predetermined suction superheat of the first suction cylinder of the compressor 10, as the saturation suction specific volume corresponding to the first suction cylinder of the compressor 10, such as the suction specific volume v corresponding to the high-temperature cylinder. suc，H Among them, the intake specific volume v corresponding to the high-temperature cylinder suc，H =v suc，sat，H *(1+2.2*10 -4 *dt suc，sh The preset intake superheat of the second intake cylinder of the compressor 10 is dt. suc，sh For details on the specific functions and processing of the control unit 104, please refer to step S1020.

[0330] The control unit 104 is further configured to multiply the sum of a predetermined fourth set coefficient (multiple of the saturation temperature drop from the middle of the indoor second heat exchanger 42 to the second suction port 13 of the compressor 10) and a fourth set value, and then multiply the product of the preset suction superheat of the second suction cylinder of the compressor 10, as the saturation suction specific volume corresponding to the second suction cylinder of the compressor 10, such as the suction specific volume v corresponding to the low-temperature cylinder. suc，L Among them, the specific volume of the intake air corresponding to the cryogenic cylinder is v. suc，L =v suc，sat，L *(1+2.2*10 -4 *dt suc，sh The preset intake superheat of the second intake cylinder of the compressor 10 is dt. suc，sh For details on the specific functions and processing of the control unit 104, please refer to step S1030.

[0331] The control unit 104 is further configured to take the product of the frequency of the compressor 10 and the refrigerant flow ratio between the first-stage throttling device 31 and the second-stage throttling device 32 as a set calculation factor, and then take the ratio of the product of the frequency of the compressor 10 and the product of the refrigerant flow ratio between the first-stage throttling device 31 and the second-stage throttling device 32 as the refrigerant mass flow rate of the first-stage throttling device 31, such as the mass flow rate of the main valve 1 M1 (g / min) = a*r Mr *f / v suc,LFor details on the specific functions and processing of the control unit 104, please refer to step S1040.

[0332] The control unit 104 is further configured to take the ratio of the product of the predetermined flow correction coefficient of the first-stage throttling device 31 and the refrigerant mass flow rate of the first-stage throttling device 31, to the ratio of the inlet refrigerant density of the first-stage throttling device 31, and then to the square root of the inlet and outlet pressure difference of the first-stage throttling device 31, as the air flow rate V of the outdoor main valve 1. a，1 =K c1 *M1 / (ρ 1，i *sqrt(△P r1 For details on the specific functions and processing of the control unit 104, please refer to step S1050.

[0333] The control unit 104 is further configured to determine the opening degree of the first-stage throttling device 31 based on the air flow rate of the first-stage throttling device 31, as the target opening degree of the first-stage throttling device 31, such as the opening degree of the main valve 1, Pulse1 = f(V a1 For details on the specific functions and processing of the control unit 104, please refer to step S1060.

[0334] In other embodiments, the control unit 104, in conjunction with the inlet and outlet pressure difference of the second-stage throttling device 32, the inlet refrigerant density of the second-stage throttling device 32, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10, determines the opening degree of the second-stage throttling device 32 as the target opening degree of the second-stage throttling device 32, and further includes:

[0335] The control unit 104 is further configured to determine the refrigerant flow ratio between the first-stage throttling device 31 and the second-stage throttling device 32 based on the preset first suction cylinder volume of the compressor 10, the preset second suction cylinder volume of the compressor 10, the saturated suction specific volume corresponding to the first suction cylinder of the compressor 10, and the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10. For example, the refrigerant flow ratio r between the outdoor main valve 1 (i.e., the outdoor electronic expansion valve) and the indoor reheat valve 2. Mr =1+V rev，H *v suc，sat，L / V rev，L *v suc，sat，H The preset volume of the first suction cylinder of the compressor 10 is such as the volume of the high-temperature cylinder V. rev,H The preset volume of the second suction cylinder of the compressor 10 is, for example, the volume of the cryogenic cylinder V. rev,L For details on the specific functions and processing of the control unit 104, please refer to step S1110.

[0336] The control unit 104 is further configured to determine the air flow ratio between the first-stage throttling device 31 and the second-stage throttling device 32 based on the refrigerant flow ratio between the first-stage throttling device 31 and the second-stage throttling device 32, the pre-determined flow correction coefficient of the first-stage throttling device 31, the inlet and outlet pressure difference of the first-stage throttling device 31, and the inlet refrigerant density of the first-stage throttling device 31, as well as the pre-determined flow correction coefficient of the second-stage throttling device 32, the inlet and outlet pressure difference of the second-stage throttling device 32, and the inlet refrigerant density of the second-stage throttling device 32, such as the air flow ratio rVa between the main valve 1 and the indoor unit valve 2, which is rVa = rMr * [(Kc1 / (ρ1,i*sqrt(△Pr1))) / (Kc2 / (ρ2i*sqrt(△Pr2)))]. The specific functions and processing of this control unit 104 are further described in step S1120.

[0337] The control unit 104 is further configured to determine the airflow rate of the second-stage throttling device 32 based on the airflow ratio between the first-stage throttling device 31 and the second-stage throttling device 32, and the already determined airflow rate of the first-stage throttling device 31. For example, the indoor unit reheat valve 2 corresponds to an airflow rate Va2 of 0.1 MPa. a，2 =V a，1 / r Va For details on the specific functions and processing of the control unit 104, please refer to step S1130.

[0338] The control unit 104 is further configured to determine the opening degree of the second-stage throttling device 32 based on the airflow of the second-stage throttling device 32, as the target opening degree of the second-stage throttling device 32, such as the opening degree of the indoor unit valve 2, Pulse2 = f(V a2 For details on the specific functions and processing of the control unit 104, please refer to step S1140.

[0339] Specifically, Figure 20 This is a schematic flowchart of the second embodiment of the calculation process for the opening degree of the dual electronic expansion valve in cooling mode. Figure 20 As shown, the calculation process for the opening degree of the dual electronic expansion valve in cooling mode includes:

[0340] Step 21: Add a cold outlet temperature sensor to the outdoor unit at the condenser outlet to detect the condenser outlet temperature in cooling mode.

[0341] Step 22: In the calculation process of the opening degree of the main valve 1 (i.e., the outdoor electronic expansion valve) and the indoor reheat valve 2 (i.e., the indoor electronic expansion valve) in the cooling mode, the refrigerant mass flow rate ratio of the outdoor main valve 1 (i.e., the outdoor electronic expansion valve) and the indoor reheat valve 2 and the refrigerant mass flow rate of the indoor reheat valve can be calculated first to calculate the air flow rate corresponding to the two valves, thereby determining the opening degree of the two valves.

[0342] The calculation includes the refrigerant flow ratio between the outdoor main valve 1 (i.e., the outdoor electronic expansion valve) and the indoor reheat valve 2.

[0343] r Mr =1+V rev，H *v suc，sat，L / V rev，L *v suc，sat，H .

[0344] Given the pressure difference, flow rate, and inlet density of the refrigerant at the inlet and outlet of main valve 1 (i.e., the outdoor electronic expansion valve), the corresponding air flow rate (L / min) at 0.1 MPa can be calculated as follows:

[0345] V a，1 =K c1 *M1 / (ρ 1，i *sqrt(△P r1 ).

[0346] The refrigerant mass flow ratio r of the indoor unit valve (i.e., indoor unit reheat valve 2) and the main valve 1 (i.e., outdoor electronic expansion valve) is known. Mr Parameters such as the pressure difference between the valve inlet and outlet and the density before the valve can be used to calculate the air flow ratio r between the main valve 1 (i.e., the outdoor electronic expansion valve) and the indoor unit valve (i.e., the indoor unit reheat valve 2). Va Then the indoor unit valve (i.e., indoor unit reheat valve 2) corresponds to an air flow rate Va2 of 0.1 MPa:

[0347] V a，2 =V a，1 / r Va .

[0348] It is known that the main valve 1 (i.e., the outdoor electronic expansion valve) and the indoor unit valve (i.e., the indoor unit reheat valve 2) correspond to an air flow rate V of 0.1 MPa. a1 and V a2 Calculate the opening degree of main valve 1 (i.e., outdoor electronic expansion valve) and indoor unit valve (i.e., indoor unit reheat valve 2) respectively: Pulse1 = f(V a1 ) and Pulse2 = f(V a2 ).

[0349] In some implementations, the current operating mode of the air conditioning system is reheat dehumidification mode.

[0350] The control unit 104, in the reheat dehumidification mode, determines the target opening degree of the first-stage throttling device 31 and the target opening degree of the second-stage throttling device 32 by combining the outdoor ambient temperature of the air conditioning system, the indoor return air relative humidity of the air conditioning system, and the operating parameters of the air conditioning system. This includes the process of calculating the target opening degree of the first-stage throttling device 31 and the second-stage throttling device 32 in the reheat dehumidification mode, as detailed below:

[0351] The control unit 104 is further configured to determine the inlet and outlet pressure difference of the first-stage throttling device 31 based on the outdoor pipe temperature of the air conditioning system, the indoor first pipe temperature of the air conditioning system, and a predetermined saturation temperature drop from the outlet of the first-stage throttling device 31 to the pipe of the first indoor heat exchanger 41, such as based on the pipe temperature t of the outdoor heat exchanger 20. c The tube temperature t of the first heat exchanger 41 in the room eH The saturated temperature drop dt from the outlet of main valve 1 to the high-temperature evaporator tube sat1 Calculate the refrigerant inlet and outlet pressure difference ΔP of main valve 1. r1 The high-temperature evaporator is the indoor first heat exchanger 41; and the inlet and outlet pressure difference of the second-stage throttling device 32 is determined based on the indoor first pipe temperature of the air conditioning system, the indoor second pipe temperature of the air conditioning system, and the predetermined saturation temperature drop from the outlet of the second-stage throttling device 32 to the pipe of the indoor second heat exchanger 42, such as based on the pipe temperature t of the indoor first heat exchanger 41. eH The tube temperature t of the second heat exchanger 42 in the room eL The saturated temperature drop dt from the outlet of indoor unit valve 2 to the low-temperature evaporator tube sat2 Calculate the refrigerant inlet and outlet pressure difference ΔP of main valve 1. r2 Among them, the low-temperature evaporator is the second heat exchanger in the room 42.

[0352] The specific methods for determining the inlet and outlet pressure difference of the first-stage throttling device 31 and the inlet and outlet pressure difference of the second-stage throttling device 32 in reheat dehumidification mode are the same as those for determining the inlet and outlet pressure difference of the first-stage throttling device 31 and the second-stage throttling device 32 in cooling mode. The specific functions and processing of the control unit 104 are also described in step S1210.

[0353] The control unit 104 is further configured to determine the inlet refrigerant density of the first-stage throttling device 31 based on the outdoor pipe temperature of the air conditioning system, such as based on the pipe temperature t of the outdoor heat exchanger 20. c Calculate the refrigerant density ρ at the inlet of main valve 1. 1iFurthermore, based on the outdoor ambient temperature of the air conditioning system or the refrigerant outlet temperature of the outdoor heat exchanger 20, and in conjunction with the predetermined saturated liquid specific volume and the predetermined saturated gas specific volume of the refrigerant in the air conditioning system, the inlet refrigerant density of the second-stage throttling device 32 is determined, such as based on the refrigerant dryness x at the indoor unit valve inlet and the saturated gas specific volume v of the refrigerant. g Specific volume of refrigerant in saturated liquid (v) l Calculate the refrigerant density ρ at the inlet of valve 2 in the indoor unit. 1i .

[0354] The specific methods for determining the inlet refrigerant density of the first-stage throttling device 31 and the inlet refrigerant density of the second-stage throttling device 32 in reheat dehumidification mode are the same as those for determining the inlet refrigerant density of the first-stage throttling device 31 and the inlet refrigerant density of the second-stage throttling device 32 in cooling mode. The specific functions and processing of the control unit 104 are also described in step S1220.

[0355] The control unit 104 is further configured to determine the inlet dew point temperature of the air conditioning system, such as the evaporator inlet dew point temperature t, based on the indoor return air temperature and the return air relative humidity of the air conditioning system. dew =f(t) N ,RH N Based on the inlet dew point temperature of the air conditioning system, the ratio of refrigerant flow rate of the first-stage throttling device 31 to that of the second-stage throttling device 32 is determined, such as the ratio r of the refrigerant flow rate of the first-stage throttling device 31 to that of the second-stage throttling device 32. Mr =f(RH) N ,k t (LHR). For the specific functions and processing of the control unit 104, please refer to step S1230.

[0356] In some embodiments, the control unit 104 determines the inlet dew point temperature of the air conditioning system based on the indoor return air temperature and the return air relative humidity of the air conditioning system. Specifically, the control unit 104 is further configured to determine the inlet dew point temperature of the air conditioning system as the set inlet dew point temperature, such as the evaporator inlet dew point temperature t, based on the correspondence between the set return air temperature, the set return air relative humidity, and the set inlet dew point temperature. This is achieved by setting the set return air temperature that is the same as the indoor return air temperature of the air conditioning system, and the set inlet dew point temperature that is the same as the return air relative humidity of the air conditioning system. dew =f(t) N ,RH N ).

[0357] In some embodiments, the control unit 104 determines the refrigerant flow ratio of the first-stage throttling device 31 to the second-stage throttling device 32 based on the inlet dew point temperature of the air conditioning system, including:

[0358] The control unit 104 is further configured to determine whether the inlet dew point temperature of the air conditioning system is less than or equal to the indoor first pipe temperature of the air conditioning system. The specific functions and processing of the control unit 104 are also described in step S1310.

[0359] The control unit 104 is further configured to determine that the indoor first heat exchanger 41 does not need dehumidification if the inlet dew point temperature of the air conditioning system is less than or equal to the indoor first pipe temperature of the air conditioning system, and to increase the frequency of the compressor 10 or reduce the speed of the indoor fan 62. The specific functions and processing of the control unit 104 are also described in step S1320.

[0360] The control unit 104 is further configured to, if it is determined that the inlet dew point temperature of the air conditioning system is greater than the indoor first pipe temperature of the air conditioning system, determine the inlet specific enthalpy of the air conditioning system based on the indoor return air temperature and the return air relative humidity of the air conditioning system, such as calculating the inlet saturated vapor pressure p. v,sat,i =f(t) N ), calculate the moisture content of the incoming air: d a,in =f(RH) N ,p v,sat,i B), Calculate the inlet air ratio enthalpy h a,in =f(t) N ,d a,in Based on the outlet dew point temperature and the outlet relative humidity of the air conditioning system, determine the outlet enthalpy of the air conditioning system, such as calculating the outlet saturated vapor pressure p. v,sat,o =f(t) dew,o ), calculate the wind moisture content d a,o =f(RH) o ,p v,sat,o B), calculate the air-to-air ratio enthalpy h. a,o =f(t) dew,o ,d a,o ), t dew,o The outlet dew point temperature, RH o The relative humidity of the outlet air; based on the inlet air enthalpy, the outlet air enthalpy, and the latent heat of phase change of the air conditioning system, the latent heat ratio of the first indoor heat exchanger 41 is determined, such as the latent heat ratio of the evaporator LHR = r w，t *(d a，in -d a，o ) / (h a，in -h a，o), where r w，t The latent heat of phase transition (kJ / kg). w，t = f(t), where t is the outlet dew point temperature or approximately the evaporator tube temperature t eH ,℃. For the specific functions and processing of the control unit 104, please refer to step S1330.

[0361] The control unit 104 is further configured to determine the refrigerant flow ratio of the first-stage throttling device 31 to the second-stage throttling device 32 based on the return air relative humidity of the air conditioning system, the latent heat ratio of the indoor first heat exchanger 41, and the temperature regulation coefficient of the air conditioning system, such as the refrigerant flow ratio r of the first-stage throttling device 31 to the second-stage throttling device 32. Mr =f(RH) N ,k t ,LHR), k t This refers to the temperature control coefficient. For the specific functions and processing of this control unit 104, please refer to step S1340.

[0362] Specifically, such as Figure 23 As shown, the calculation process for the opening degree of the dual electronic expansion valves in reheat dehumidification mode also includes: Step 32. The calculation process for the opening degree of the main valve 1 (i.e., the outdoor electronic expansion valve) and the indoor reheat valve 2 in reheat dehumidification mode also includes: based on the detected indoor return air temperature t N and return air relative humidity (RH) N Calculate the evaporator inlet dew point temperature t dew =f(t) N RH N Based on the calculated inlet dew point temperature and evaporator tube temperature t eH (i.e., the tube temperature t of the first heat exchanger 41 in the room) eH The latent heat ratio of dehumidification of the evaporator (i.e., the first heat exchanger 41 in the room) is calculated by comparing it with that of the evaporator.

[0363] When the evaporator inlet dew point temperature t dew ≤Pipe temperature t of the first heat exchanger 41 in the room eH At this time, the evaporator (i.e., the first heat exchanger 41 in the room) does not dehumidify. At this time, it is necessary to increase the operating frequency of the compressor 10 or reduce the speed of the indoor fan (i.e., the speed of the indoor fan 62).

[0364] When the evaporator inlet dew point temperature t dew >Pipe temperature t of the first indoor heat exchanger 41 eH At this time, the inlet air moisture content and inlet air specific enthalpy need to be calculated based on the detected return air temperature and relative humidity. When calculating the evaporator outlet air moisture content and outlet air specific enthalpy, it is assumed that the dehumidifying evaporator outlet air is saturated (i.e., relative humidity 100%) and the outlet air dew point temperature is close to the evaporator tube temperature t. eH(i.e., the tube temperature t of the first heat exchanger 41 in the room) eH The difference between them is zero.

[0365] Evaporator latent heat ratio for dehumidification: LHR = r w，t *(d a，in -d a，o ) / (h a，in -h a，o ), where r w，t The latent heat of phase transition (kJ / kg). w，t = f(t), where t is the outlet dew point temperature or approximately the evaporator tube temperature t eH , ℃.

[0366] Analysis of the refrigerant thermodynamic cycle and the latent heat ratio of moist air revealed that when the relative humidity (RH) of the inlet air to the dehumidifying evaporator (i.e., the first indoor heat exchanger 41) is between 0.4 and 1, the ratio of the reheat valve flow rate to the total flow rate at the optimal reheat dehumidification evaporation temperature can be fitted with a calculation correlation formula based on the inlet relative humidity, the latent heat ratio of dehumidification, and the temperature regulation coefficient, i.e., r Mr =f(RH) N k t LHR).

[0367] The control unit 104 is further configured to determine the refrigerant mass flow rate of the first-stage throttling device 31 and the refrigerant mass flow rate of the second-stage throttling device 32 based on the indoor first pipe temperature of the air conditioning system, the predetermined saturation temperature drop from the middle of the indoor first heat exchanger 41 to the first suction port 12 of the compressor 10, the indoor second pipe temperature of the air conditioning system, the ratio of the refrigerant flow rates of the first-stage throttling device 31 to the second-stage throttling device 32, and the predetermined saturation temperature drop from the middle of the indoor second heat exchanger 42 to the second suction port 13 of the compressor 10, such as determining the refrigerant mass flow rate M1 of the main valve 1 and the refrigerant mass flow rate M2 of the indoor unit valve 2. The specific functions and processing of this control unit 104 are further described in step S1240.

[0368] In some embodiments, the control unit 104 determines the refrigerant mass flow rate of the first-stage throttling device 31 and the refrigerant mass flow rate of the second-stage throttling device 32 based on the indoor first pipe temperature of the air conditioning system, a predetermined saturation temperature drop from the middle of the indoor first heat exchanger 41 to the first suction port 12 of the compressor 10, the indoor second pipe temperature of the air conditioning system, the ratio of the refrigerant flow rates of the first-stage throttling device 31 to the second-stage throttling device 32, and a predetermined saturation temperature drop from the middle of the indoor second heat exchanger 42 to the second suction port 13 of the compressor 10, including:

[0369] The control unit 104 is further configured to use the indoor first pipe temperature of the air conditioning system and the predetermined difference between the saturation temperature drop from the middle of the indoor first heat exchanger 41 to the first suction port 12 of the compressor 10 as the suction saturation temperature of the first suction cylinder of the compressor 10; and to use the indoor second pipe temperature of the air conditioning system and the predetermined difference between the saturation temperature drop from the middle of the indoor second heat exchanger 42 to the second suction port 13 of the compressor 10 as the suction saturation temperature of the second suction cylinder of the compressor 10. The specific functions and processing of this control unit 104 are further described in step S1410.

[0370] The control unit 104 is further configured to determine the saturated suction specific volume corresponding to the first suction cylinder of the compressor 10 based on the suction saturation temperature of the first suction cylinder, such as calculating the saturated suction specific volume v corresponding to the high-temperature cylinder based on the correlation relationship. suc，sat，H ; and, based on the suction saturation temperature of the second suction cylinder of the compressor 10, determine the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10, such as calculating the saturated suction specific volume v corresponding to the low-temperature cylinder based on the correlation relationship. suc，sat，L For details on the specific functions and processing of the control unit 104, please refer to step S1420.

[0371] The control unit 104 is further configured to multiply the sum of a predetermined third set coefficient (multiplied by a third set value) of the saturation temperature drop from the middle of the indoor first heat exchanger 41 to the first suction port 12 of the compressor 10, and a predetermined suction superheat of the first suction cylinder of the compressor 10, as the saturation suction specific volume corresponding to the first suction cylinder of the compressor 10, such as the suction specific volume v corresponding to the high-temperature cylinder. suc，H Among them, the intake specific volume v corresponding to the high-temperature cylinder suc，H =v suc，sat，H *(1+2.2*10 -4 *dt suc，sh The preset intake superheat of the second intake cylinder of the compressor 10 is dt. suc，sh ; and, the product of the fourth predetermined coefficient multiple of the saturation temperature drop from the middle of the second indoor heat exchanger 42 to the second suction port 13 of the compressor 10, and the fourth predetermined value, and the product of this fourth predetermined coefficient multiple and the predetermined suction superheat of the second suction cylinder of the compressor 10, is taken as the saturation suction specific volume corresponding to the second suction cylinder of the compressor 10, such as the suction specific volume v corresponding to the low-temperature cylinder. suc，L Among them, the specific volume of the intake air corresponding to the cryogenic cylinder is v. suc，L =v suc，sat，L *(1+2.2*10 -4 *dt suc，shThe preset intake superheat of the second intake cylinder of the compressor 10 is dt. suc，sh For details on the specific functions and processing of the control unit 104, please refer to step S1430.

[0372] The control unit 104 is further configured to calculate a first value by multiplying the set frequency calculation factor of the compressor 10 by the ratio of the saturated suction specific volume corresponding to the first suction cylinder of the compressor 10. The specific functions and processing of this control unit 104 are further described in step S1440.

[0373] The control unit 104 is further configured to calculate a second value by multiplying the set frequency of the compressor 10 by a factor and then by the ratio of the saturated suction specific volume corresponding to the second suction cylinder of the compressor 10; the sum of the first calculated value and the second calculated value is determined as the total refrigerant mass flow rate of the first-stage throttling device 31 and the second-stage throttling device 32, such as calculating the total refrigerant mass flow rate M (g / min) using the compressor suction specific volume and compressor parameters: M = a * f / v suc +a*f / v suc 'a' is a coefficient related to compressor performance, and 'f' is the compressor frequency. For the specific functions and processing of this control unit 104, please refer to step S1450.

[0374] The control unit 104 is further configured to determine the refrigerant mass flow rate of the first-stage throttling device 31 and the refrigerant mass flow rate of the second-stage throttling device 32 based on the total refrigerant mass flow rate of the first-stage throttling device 31 and the second-stage throttling device 32, and the ratio of the refrigerant flow rates of the first-stage throttling device 31 and the second-stage throttling device 32, such as calculating the refrigerant mass flow rate M2 of the indoor unit reheat valve 2 as M2 = M / (1+r Mr The refrigerant mass flow rate of the outdoor main valve 1 is M1 = M - M2. For the specific functions and processing of this control unit 104, please refer to step S1460.

[0375] like Figure 23 As shown, the calculation process for the opening degree of the dual electronic expansion valves in reheat dehumidification mode also includes: the calculation process for the opening degree of main valve 1 (i.e., outdoor electronic expansion valve) and indoor reheat valve 2 in reheat dehumidification mode, including: similar to the cooling mode, the total refrigerant mass flow rate M (g / min) is calculated using the compressor suction specific volume and compressor parameters: M=a*f / v suc +a*f / v suc 'a' is a coefficient related to compressor performance, and 'f' is the compressor frequency. The refrigerant mass flow rate M2 of the indoor unit valve (i.e., indoor unit reheat valve 2) is calculated as M / (1+r). MrThe refrigerant mass flow rate of outdoor main valve 1 (i.e., outdoor electronic expansion valve) is M1 = M - M2.

[0376] Based on the refrigerant mass flow rate and flow correction factor K of the indoor and outdoor electronic expansion valves. c Based on the inlet refrigerant density and the pressure difference across the valve, calculate the air flow rate (L / min) at 0.1 MPa corresponding to the indoor unit reheat valve 2: V a ,2=K c2 *M2 / (ρ i *sqrt(△P r The outdoor unit main valve 1 (i.e., the outdoor electronic expansion valve) corresponds to an air flow rate of 0.1 MPa (L / min): V a，1 =K c1 *M1 / (ρ i *sqrt(△P r Finally, based on the airflow of the indoor and outdoor electronic expansion valves, the corresponding opening degree Pulse1 is calculated: Pulse1 = f(V a，1 ) and Pulse2 = f(V a，2 ).

[0377] Subsequently, the control unit 104 is further configured to determine the opening degree of the first-stage throttling device 31 based on the predetermined flow correction coefficient of the first-stage throttling device 31, the inlet and outlet pressure difference of the first-stage throttling device 31, the inlet refrigerant density of the first-stage throttling device 31, the refrigerant mass flow rate of the first-stage throttling device 31, and the ratio of the refrigerant flow rate of the first-stage throttling device 31 to that of the second-stage throttling device 32, as the target opening degree of the first-stage throttling device 31, such as calculating the opening degree Pulse1 of the main valve 1.

[0378] In the reheat dehumidification mode, the target opening degree of the first-stage throttling device 31 is determined based on the predetermined flow correction coefficient of the first-stage throttling device 31, the inlet and outlet pressure difference of the first-stage throttling device 31, the inlet refrigerant density of the first-stage throttling device 31, the refrigerant mass flow rate of the first-stage throttling device 31, and the ratio of the refrigerant flow rates of the first-stage throttling device 31 to the second-stage throttling device 32. This method is the same as the method used in the cooling mode to determine the target opening degree of the first-stage throttling device 31 based on the predetermined flow correction coefficient of the first-stage throttling device 31, the inlet and outlet pressure difference of the first-stage throttling device 31, the inlet refrigerant density of the first-stage throttling device 31, the refrigerant mass flow rate of the first-stage throttling device 31, and the ratio of the refrigerant flow rates of the first-stage throttling device 31 to the second-stage throttling device 32. The specific functions and processing of the control unit 104 are also described in step S1250.

[0379] The control unit 104 is further configured to determine the opening degree of the second-stage throttling device 32 based on a predetermined flow correction coefficient of the second-stage throttling device 32, the inlet and outlet pressure difference of the second-stage throttling device 32, the inlet refrigerant density of the second-stage throttling device 32, the refrigerant mass flow rate of the second-stage throttling device 32, and the ratio of the refrigerant flow rates of the first-stage throttling device 31 to the second-stage throttling device 32, as the target opening degree of the second-stage throttling device 32, such as calculating the opening degree Pulse2 of the indoor unit valve 2.

[0380] In the reheat dehumidification mode, the target opening degree of the second-stage throttling device 32 is determined based on the predetermined flow correction coefficient of the second-stage throttling device 32, the inlet and outlet pressure difference of the second-stage throttling device 32, the inlet refrigerant density of the second-stage throttling device 32, the refrigerant mass flow rate of the second-stage throttling device 32, and the ratio of the refrigerant flow rates of the first-stage throttling device 31 to the second-stage throttling device 32. This method is the same as the method used in the cooling mode to determine the target opening degree of the second-stage throttling device 32 based on the predetermined flow correction coefficient of the second-stage throttling device 32, the inlet and outlet pressure difference of the second-stage throttling device 32, the inlet refrigerant density of the second-stage throttling device 32, the refrigerant mass flow rate of the second-stage throttling device 32, and the ratio of the refrigerant flow rates of the first-stage throttling device 31 to the second-stage throttling device 32. The specific functions and processing of the control unit 104 are also described in step S1260.

[0381] Figure 22 This is a schematic diagram of the pressure and enthalpy of the reheat dehumidification cycle in a three-pipe parallel reheat dehumidification system. Figure 22 It can display the relationship between pressure and enthalpy in a three-pipe parallel reheat dehumidification system under reheat dehumidification mode. Figure 21 and Figure 22 The diagrams show the reheat dehumidification cycle and corresponding pressure-enthalpy diagram of the dual-temperature parallel reheat dehumidification system. The pressure-enthalpy diagram shows that during constant-temperature dehumidification, the reheat heat of the reheat heat exchanger (i.e., the second indoor heat exchanger 42) is equal to the sensible heat of the dehumidification evaporator (i.e., the first indoor heat exchanger 41). If the reheat heat is greater than or less than the sensible heat, i.e., the ratio is greater than or less than 1, then it is either heating dehumidification or cooling dehumidification. Therefore:

[0382] k t (M1+M2)Δh e (1-LHR)=M2Δh c，2。

[0383] In the formula, k t K is the temperature regulation coefficient, which is used for constant temperature dehumidification.t The value is 1, and the k value is 1 when heating and dehumidifying. t When k is greater than 1, it indicates cooling and dehumidification. t Less than 1; M1 and M2 are the mass flow rates, g / min, of the main valve 1 (i.e., the outdoor electronic expansion valve) and the indoor reheat valve (i.e., the indoor reheat valve 2), respectively; Δh e Δh is the enthalpy difference (unit mass cooling capacity) between the outlet and inlet of the dehumidifying evaporator (i.e., the first indoor heat exchanger 41), expressed in kJ / kg; LHR is the latent heat ratio; Δh c，2 The specific enthalpy difference (unit mass reheat) between the inlet and outlet of the reheat heat exchanger (i.e., the second heat exchanger 42 in the room) is kJ / kg.

[0384] Figure 23 This is a schematic diagram illustrating the calculation process for the opening degree of the dual electronic expansion valves in reheat dehumidification mode. (Example:) Figure 23 As shown, the calculation process for the opening degree of the dual electronic expansion valves in reheat dehumidification mode includes: Step 31: When the air conditioner receives the reheat dehumidification mode operation command, it first opens the indoor unit air guide plate and starts the indoor fan according to the user-set fan speed or automatic fan speed. The outdoor fan speed, compressor frequency, and opening degree of the outdoor electronic expansion valve and indoor electronic expansion valve are initially operated with the set oil return parameters. After the oil return operation is completed, the compressor frequency and outdoor fan speed are operated according to the ambient temperature detected by the outdoor ambient temperature sensor and the user-set temperature parameters. The opening degree of the outdoor electronic expansion valve and indoor electronic expansion valve is calculated based on the temperature parameters detected by the sensor.

[0385] In some embodiments, the control device for the air conditioning system described in this invention further includes a process of fine-tuning the target opening degree of the first-stage throttling device 31 and the target opening degree of the second-stage throttling device 32, as detailed below:

[0386] The control unit 104 is further configured to, under the current operating mode of the air conditioning system (e.g., cooling mode or reheat / dehumidification mode), after controlling the first-stage throttling device 31 to operate at its target opening and the second-stage throttling device 32 to operate at its target opening, specifically after a set duration of operation of both the first-stage throttling device 31 and the second-stage throttling device 32, perform the following fine-tuning measures. The specific functions and processing of this control unit 104 are further described in step S1510.

[0387] The control unit 104 is further configured to, if the current operating mode of the air conditioning system is cooling mode, adjust the target opening of the first-stage throttling device 31 according to the difference between the first suction temperature of the air conditioning system and the first indoor pipe temperature of the air conditioning system, to obtain a new target opening of the first-stage throttling device 31; and adjust the target opening of the second-stage throttling device 32 according to the difference between the second suction temperature of the air conditioning system and the second indoor pipe temperature of the air conditioning system, to obtain a new target opening of the second-stage throttling device 32. The specific functions and processing of this control unit 104 are further described in step S1520.

[0388] The control unit 104 is further configured to, if the current operating mode of the air conditioning system is reheat dehumidification mode, adjust the target opening of the first-stage throttling device 31 according to the difference between the first suction temperature of the air conditioning system and the first indoor pipe temperature of the air conditioning system to obtain a new target opening of the first-stage throttling device 31; and adjust the target opening of the second-stage throttling device 32 according to the difference between the indoor return air temperature of the air conditioning system and the set temperature to obtain a new target opening of the second-stage throttling device 32. The specific functions and processing of this control unit 104 are further described in step S1530.

[0389] Subsequently, the control unit 104 is further configured to contro...

Claims

1. A control method for an air conditioning system, characterized in that, The air conditioning system adopts a three-pipe parallel reheat dehumidification system; the three-pipe parallel reheat dehumidification system has a compressor (10), a first-stage throttling device (31), a second-stage throttling device (32), an outdoor fan (61), and an indoor fan (62); the control method of the air conditioning system includes: After the air conditioning system is started, the indoor unit air guide plate of the air conditioning system is opened, the indoor fan (62) is started, and the air conditioning system is put into oil return operation. After the air conditioning system completes its oil return cycle, the outdoor ambient temperature of the air conditioning system is obtained; and the operating parameters of the air conditioning system are also obtained. In the current operating mode of the air conditioning system, the frequency of the compressor (10) and the speed of the outdoor fan (61) are adjusted according to the outdoor ambient temperature of the air conditioning system; and, In the current operating mode of the air conditioning system, the target opening degree of the first-stage throttling device (31) and the target opening degree of the second-stage throttling device (32) are determined by combining the outdoor ambient temperature of the air conditioning system, the indoor return air relative humidity of the air conditioning system, and the operating parameters of the air conditioning system; then, the first-stage throttling device (31) is controlled to operate at the target opening degree of the first-stage throttling device (31), and the second-stage throttling device (32) is controlled to operate at the target opening degree of the second-stage throttling device (32); wherein, the current operating mode of the air conditioning system is either cooling mode or reheat dehumidification mode; Specifically, the refrigerant mass flow rate ratio of the first-stage throttling device (31) and the second-stage throttling device (32) is calculated, and the inlet and outlet pressure difference between the first-stage throttling device (31) and the second-stage throttling device (32) is calculated. Based on the refrigerant mass flow rate ratio and the inlet and outlet pressure difference between the first-stage throttling device (31) and the second-stage throttling device (32), the air flow rate ratio between the first-stage throttling device (31) and the second-stage throttling device (32) is calculated. The correspondence between the air flow rate and the opening degree of the selected throttling device is fitted to obtain the fitting relationship between the air flow rate and the opening degree and the air flow rate corresponding to the throttling device. Then, the air flow rate of the throttling device can be calculated if the opening degree of one of the throttling devices is known. The air flow rate and the opening degree of the other throttling device are calculated in turn to realize the associated control of the two throttling devices.

2. The control method for the air conditioning system according to claim 1, characterized in that, The three-pipe parallel reheat dehumidification system also includes an outdoor heat exchanger (20), an indoor first heat exchanger (41), and an indoor second heat exchanger (42); the compressor (10) has an exhaust port (11), a first intake port (12), and a second intake port (13). Obtaining the operating parameters of the air conditioning system includes at least one of the following: Obtain the indoor ambient temperature of the air conditioning system; obtain the indoor return air relative humidity of the air conditioning system; obtain the indoor return air temperature of the air conditioning system; Obtain the frequency of the compressor (10); The pipe temperature of the indoor first heat exchanger (41) is obtained and recorded as the indoor first pipe temperature of the air conditioning system; Obtain the pipe temperature of the indoor second heat exchanger (42) and record it as the indoor second pipe temperature of the air conditioning system; Obtain the pipe temperature of the outdoor heat exchanger (20) and record it as the outdoor pipe temperature of the air conditioning system; obtain the refrigerant outlet temperature of the outdoor heat exchanger (20); The temperature of the first suction port (12) of the compressor (10) is obtained and recorded as the first suction temperature of the air conditioning system; The pipe temperature of the second suction port (13) of the compressor (10) is obtained and recorded as the second suction pipe temperature of the air conditioning system; as well as, The temperature of the exhaust port (11) of the compressor (10) is obtained and recorded as the exhaust temperature of the air conditioning system.

3. The control method for the air conditioning system according to claim 2, characterized in that, The current operating mode of the air conditioning system is cooling mode; In the cooling mode, based on the outdoor ambient temperature of the air conditioning system, the indoor return air relative humidity of the air conditioning system, and the operating parameters of the air conditioning system, the target opening degree of the first-stage throttling device (31) and the target opening degree of the second-stage throttling device (32) are determined, including: The inlet and outlet pressure difference of the first-stage throttling device (31) is determined based on the outdoor pipe temperature of the air conditioning system, the indoor first pipe temperature of the air conditioning system, and the predetermined saturation temperature drop from the outlet of the first-stage throttling device (31) to the pipe of the indoor first heat exchanger (41); and the inlet and outlet pressure difference of the second-stage throttling device (32) is determined based on the indoor first pipe temperature of the air conditioning system, the indoor second pipe temperature of the air conditioning system, and the predetermined saturation temperature drop from the outlet of the second-stage throttling device (32) to the pipe of the indoor second heat exchanger (42). Based on the outdoor pipe temperature of the air conditioning system, the inlet refrigerant density of the first-stage throttling device (31) is determined; and based on the outdoor ambient temperature of the air conditioning system or the refrigerant outlet temperature of the outdoor heat exchanger (20), and in conjunction with the pre-determined specific volume of the refrigerant saturated liquid of the air conditioning system and the pre-determined specific volume of the refrigerant saturated gas of the air conditioning system, the inlet refrigerant density of the second-stage throttling device (32) is determined. Based on the indoor first pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the middle of the indoor first heat exchanger (41) to the first suction port (12) of the compressor (10), calculate the saturated suction specific volume corresponding to the first suction cylinder of the compressor (10); and based on the indoor second pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the middle of the indoor second heat exchanger (42) to the second suction port (13) of the compressor (10), calculate the saturated suction specific volume corresponding to the second suction cylinder of the compressor (10). after, The opening degree of the first-stage throttling device (31) is determined by combining the inlet and outlet pressure difference of the first-stage throttling device (31), the inlet refrigerant density of the first-stage throttling device (31), the saturated suction specific volume corresponding to the first suction cylinder of the compressor (10), and the saturated suction specific volume corresponding to the second suction cylinder of the compressor (10), and is used as the target opening degree of the first-stage throttling device (31). By combining the inlet and outlet pressure difference of the second-stage throttling device (32), the inlet refrigerant density of the second-stage throttling device (32), and the saturated suction specific volume corresponding to the second suction cylinder of the compressor (10), the opening degree of the second-stage throttling device (32) is determined as the target opening degree of the second-stage throttling device (32).

4. The control method for the air conditioning system according to claim 3, characterized in that, in, Based on the outdoor pipe temperature of the air conditioning system, the indoor first pipe temperature of the air conditioning system, and the predetermined saturation temperature drop from the outlet of the first-stage throttling device (31) to the pipe of the indoor first heat exchanger (41), the inlet and outlet pressure difference of the first-stage throttling device (31) is determined, including: The outdoor pipe temperature of the air conditioning system is used as the saturation temperature corresponding to the refrigerant inlet pressure of the first-stage throttling device (31); and the indoor first pipe temperature of the air conditioning system and the sum of the predetermined saturation temperature drop from the outlet of the first-stage throttling device (31) to the pipe of the indoor first heat exchanger (41) are used as the saturation temperature corresponding to the refrigerant outlet pressure of the first-stage throttling device (31). The first set coefficient multiple of the sum of the refrigerant inlet pressure corresponding to the saturation temperature of the first stage throttling device (31) and the refrigerant outlet pressure corresponding to the saturation temperature of the first stage throttling device (31) is multiplied by the first set value, and then multiplied by the difference between the refrigerant outlet pressure corresponding to the saturation temperature of the first stage throttling device (31) to obtain the inlet and outlet pressure difference of the first stage throttling device (31). And / or, Based on the indoor first pipe temperature of the air conditioning system, the indoor second pipe temperature of the air conditioning system, and the predetermined saturation temperature drop from the outlet of the second-stage throttling device (32) to the pipe of the indoor second heat exchanger (42), the inlet and outlet pressure difference of the second-stage throttling device (32) is determined, including: The sum of the indoor first pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the outlet of the second-stage throttling device (32) to the indoor second heat exchanger (42) is taken as the saturation temperature corresponding to the refrigerant inlet pressure of the second-stage throttling device (32); and the sum of the indoor second pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the outlet of the second-stage throttling device (32) to the indoor second heat exchanger (42) is taken as the saturation temperature corresponding to the refrigerant outlet pressure of the second-stage throttling device (32). The second set coefficient multiple of the sum of the refrigerant inlet pressure corresponding to the saturation temperature of the second-stage throttling device (32) and the refrigerant outlet pressure corresponding to the saturation temperature of the second-stage throttling device (32) is multiplied by the second set value, and then multiplied by the difference between the refrigerant outlet pressure corresponding to the saturation temperature of the second-stage throttling device (32) to obtain the inlet and outlet pressure difference of the second-stage throttling device (32).

5. The control method for an air conditioning system according to claim 3, characterized in that, in, Based on the outdoor pipe temperature of the air conditioning system, the inlet refrigerant density of the first-stage throttling device (31) is determined, including: Based on the correspondence between the set outdoor pipe temperature and the set inlet refrigerant density, the set inlet refrigerant density corresponding to the set outdoor pipe temperature that is the same as the outdoor pipe temperature of the air conditioning system is determined as the inlet refrigerant density of the first-stage throttling device (31). And / or, Based on the outdoor ambient temperature of the air conditioning system or the refrigerant outlet temperature of the outdoor heat exchanger (20), and in conjunction with the predetermined saturated liquid specific volume and the predetermined saturated gas specific volume of the refrigerant in the air conditioning system, the inlet refrigerant density of the second-stage throttling device (32) is determined, including: The specific enthalpy of the refrigerant at the outlet of the outdoor heat exchanger (20) is determined based on the outdoor ambient temperature of the air conditioning system or the refrigerant outlet temperature of the outdoor heat exchanger (20). The refrigerant dryness of the second-stage throttling device (32) is determined based on the refrigerant specific enthalpy at the outlet of the outdoor heat exchanger (20), the refrigerant saturated gas specific enthalpy of the air conditioning system as determined in advance, and the refrigerant saturated liquid specific enthalpy of the air conditioning system as determined in advance. The inlet refrigerant density of the second-stage throttling device (32) is determined based on the inlet refrigerant dryness of the second-stage throttling device (32), the pre-determined specific volume of the refrigerant saturated liquid in the air conditioning system, and the pre-determined specific volume of the refrigerant saturated gas in the air conditioning system.

6. The control method for the air conditioning system according to claim 3, characterized in that, in, Based on the indoor first pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the middle of the indoor first heat exchanger (41) to the first suction port (12) of the compressor (10), the saturation suction specific volume corresponding to the first suction cylinder of the compressor (10) is calculated, including: The difference between the indoor first pipe temperature of the air conditioning system and the pre-determined saturation temperature drop between the middle of the indoor first heat exchanger (41) and the first suction port (12) of the compressor (10) is taken as the suction saturation temperature of the first suction cylinder of the compressor (10). Based on the intake saturation temperature of the first intake cylinder of the compressor (10), determine the saturated intake specific volume corresponding to the first intake cylinder of the compressor (10); And / or, Based on the indoor second pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the middle of the indoor second heat exchanger (42) to the second suction port (13) of the compressor (10), the saturation suction specific volume corresponding to the second suction cylinder of the compressor (10) is calculated, including: The difference between the indoor second pipe temperature of the air conditioning system and the pre-determined saturation temperature drop between the middle of the indoor second heat exchanger (42) and the second suction port (13) of the compressor (10) is taken as the suction saturation temperature of the second suction cylinder of the compressor (10). Based on the intake saturation temperature of the second intake cylinder of the compressor (10), determine the saturated intake specific volume corresponding to the second intake cylinder of the compressor (10).

7. The control method for an air conditioning system according to any one of claims 3 to 6, characterized in that, in, Based on the inlet and outlet pressure difference of the first-stage throttling device (31), the inlet refrigerant density of the first-stage throttling device (31), the saturated suction specific volume corresponding to the first suction cylinder of the compressor (10), and the saturated suction specific volume corresponding to the second suction cylinder of the compressor (10), the opening degree of the first-stage throttling device (31) is determined as the target opening degree of the first-stage throttling device (31), including: The product of the third set coefficient multiple of the saturated temperature drop from the middle of the first heat exchanger (41) to the first suction port (12) of the compressor (10) and the third set value, and the product of the preset suction superheat of the first suction cylinder of the compressor (10), is taken as the saturated suction specific volume corresponding to the first suction cylinder of the compressor (10). The product of the fourth set coefficient multiple of the saturated temperature drop from the middle of the second heat exchanger (42) to the second suction port (13) of the compressor (10) and the fourth set value, and the product of the preset suction superheat of the second suction cylinder of the compressor (10), is taken as the saturated suction specific volume corresponding to the second suction cylinder of the compressor (10). The frequency setting calculation factor of the compressor (10) is multiplied by the ratio of the saturated suction specific volume corresponding to the second suction cylinder of the compressor (10) to the refrigerant mass flow rate of the second stage throttling device (32). The ratio of the frequency setting calculation factor of the compressor (10) to the saturated suction specific volume corresponding to the first suction cylinder of the compressor (10) is used as the refrigerant mass flow rate of the first indoor heat exchanger (41); the sum of the refrigerant mass flow rate of the second stage throttling device (32) and the refrigerant mass flow rate of the first indoor heat exchanger (41) is used as the refrigerant mass flow rate of the first stage throttling device (31). The ratio of the product of the predetermined flow correction coefficient of the first-stage throttling device (31) and the refrigerant mass flow rate of the first-stage throttling device (31), to the inlet refrigerant density of the first-stage throttling device (31), and then to the square root of the inlet and outlet pressure difference of the first-stage throttling device (31), is taken as the air flow rate of the first-stage throttling device (31). Based on the air flow rate of the first-stage throttling device (31), the opening degree of the first-stage throttling device (31) is determined as the target opening degree of the first-stage throttling device (31). And / or, Based on the inlet and outlet pressure difference of the second-stage throttling device (32), the inlet refrigerant density of the second-stage throttling device (32), and the saturated suction specific volume corresponding to the second suction cylinder of the compressor (10), the opening degree of the second-stage throttling device (32) is determined as the target opening degree of the second-stage throttling device (32), including: The product of the fourth set coefficient multiple of the saturated temperature drop from the middle of the second heat exchanger (42) to the second suction port (13) of the compressor (10) and the fourth set value, and the product of the preset suction superheat of the second suction cylinder of the compressor (10), is taken as the saturated suction specific volume corresponding to the second suction cylinder of the compressor (10). The frequency setting calculation factor of the compressor (10) is multiplied by the ratio of the saturated suction specific volume corresponding to the second suction cylinder of the compressor (10) to the refrigerant mass flow rate of the second stage throttling device (32). The ratio of the product of the predetermined flow correction coefficient of the second-stage throttling device (32) and the refrigerant mass flow rate of the second-stage throttling device (32), to the inlet refrigerant density of the second-stage throttling device (32), and then to the square root of the inlet and outlet pressure difference of the second-stage throttling device (32), is taken as the air flow rate of the second-stage throttling device (32). Based on the air flow rate of the second-stage throttling device (32), the opening degree of the second-stage throttling device (32) is determined as the target opening degree of the second-stage throttling device (32).

8. The control method for an air conditioning system according to any one of claims 3 to 6, characterized in that, in, Based on the inlet and outlet pressure difference of the first-stage throttling device (31), the inlet refrigerant density of the first-stage throttling device (31), the saturated suction specific volume corresponding to the first suction cylinder of the compressor (10), and the saturated suction specific volume corresponding to the second suction cylinder of the compressor (10), the opening degree of the first-stage throttling device (31) is determined as the target opening degree of the first-stage throttling device (31), and further includes: Based on the preset first suction cylinder volume of the compressor (10), the preset second suction cylinder volume of the compressor (10), the saturated suction specific volume corresponding to the first suction cylinder of the compressor (10), and the saturated suction specific volume corresponding to the second suction cylinder of the compressor (10), the refrigerant flow ratio between the first stage throttling device (31) and the second stage throttling device (32) is determined. The product of the third set coefficient multiple of the saturated temperature drop from the middle of the first heat exchanger (41) to the first suction port (12) of the compressor (10) and the third set value, and the product of the preset suction superheat of the first suction cylinder of the compressor (10), is taken as the saturated suction specific volume corresponding to the first suction cylinder of the compressor (10). The product of the fourth predetermined coefficient multiple of the saturation temperature drop from the middle of the second indoor heat exchanger (42) to the second suction port (13) of the compressor (10), the sum of the fourth predetermined value and the predetermined suction superheat of the second suction cylinder of the compressor (10), is taken as the saturation suction specific volume corresponding to the second suction cylinder of the compressor (10); and, The product of the frequency of the compressor (10) and the refrigerant flow ratio between the first-stage throttling device (31) and the second-stage throttling device (32) is multiplied by a set calculation coefficient, and then the ratio of this product to the saturated suction specific volume corresponding to the second suction cylinder of the compressor (10) is used as the refrigerant mass flow rate of the first-stage throttling device (31). The ratio of the product of the predetermined flow correction coefficient of the first-stage throttling device (31) and the refrigerant mass flow rate of the first-stage throttling device (31), to the inlet refrigerant density of the first-stage throttling device (31), and then to the square root of the inlet and outlet pressure difference of the first-stage throttling device (31), is taken as the air flow rate of the first-stage throttling device (31). Based on the air flow rate of the first-stage throttling device (31), the opening degree of the first-stage throttling device (31) is determined as the target opening degree of the first-stage throttling device (31). And / or, Based on the inlet and outlet pressure difference of the second-stage throttling device (32), the inlet refrigerant density of the second-stage throttling device (32), and the saturated suction specific volume corresponding to the second suction cylinder of the compressor (10), the opening degree of the second-stage throttling device (32) is determined as the target opening degree of the second-stage throttling device (32), and further includes: Based on the preset first suction cylinder volume of the compressor (10), the preset second suction cylinder volume of the compressor (10), the saturated suction specific volume corresponding to the first suction cylinder of the compressor (10), and the saturated suction specific volume corresponding to the second suction cylinder of the compressor (10), the refrigerant flow ratio between the first stage throttling device (31) and the second stage throttling device (32) is determined. Based on the refrigerant flow ratio between the first-stage throttling device (31) and the second-stage throttling device (32), the predetermined flow correction coefficient of the first-stage throttling device (31), the inlet and outlet pressure difference of the first-stage throttling device (31), the inlet refrigerant density of the first-stage throttling device (31), and the predetermined flow correction coefficient of the second-stage throttling device (32), the inlet and outlet pressure difference of the second-stage throttling device (32), and the inlet refrigerant density of the second-stage throttling device (32), the air flow ratio between the first-stage throttling device (31) and the second-stage throttling device (32) is determined. Based on the air flow ratio between the first-stage throttling device (31) and the second-stage throttling device (32), and the already determined air flow of the first-stage throttling device (31), the air flow of the second-stage throttling device (32) is determined; Based on the air flow rate of the second-stage throttling device (32), the opening degree of the second-stage throttling device (32) is determined as the target opening degree of the second-stage throttling device (32).

9. The control method for an air conditioning system according to claim 2, characterized in that, The current operating mode of the air conditioning system is reheat dehumidification mode; In the reheat dehumidification mode, based on the outdoor ambient temperature of the air conditioning system, the indoor return air relative humidity of the air conditioning system, and the operating parameters of the air conditioning system, the target opening degree of the first-stage throttling device (31) and the target opening degree of the second-stage throttling device (32) are determined, including: The inlet and outlet pressure difference of the first-stage throttling device (31) is determined based on the outdoor pipe temperature of the air conditioning system, the indoor first pipe temperature of the air conditioning system, and the predetermined saturation temperature drop from the outlet of the first-stage throttling device (31) to the pipe of the indoor first heat exchanger (41); and the inlet and outlet pressure difference of the second-stage throttling device (32) is determined based on the indoor first pipe temperature of the air conditioning system, the indoor second pipe temperature of the air conditioning system, and the predetermined saturation temperature drop from the outlet of the second-stage throttling device (32) to the pipe of the indoor second heat exchanger (42). Based on the outdoor pipe temperature of the air conditioning system, the inlet refrigerant density of the first-stage throttling device (31) is determined; and based on the outdoor ambient temperature of the air conditioning system or the refrigerant outlet temperature of the outdoor heat exchanger (20), and in conjunction with the pre-determined specific volume of the refrigerant saturated liquid of the air conditioning system and the pre-determined specific volume of the refrigerant saturated gas of the air conditioning system, the inlet refrigerant density of the second-stage throttling device (32) is determined. Based on the indoor return air temperature and the return air relative humidity of the air conditioning system, the inlet dew point temperature of the air conditioning system is determined; and based on the inlet dew point temperature of the air conditioning system, the ratio of the refrigerant flow rate of the first-stage throttling device (31) to that of the second-stage throttling device (32) is determined. Based on the indoor first pipe temperature of the air conditioning system, the predetermined saturation temperature drop from the middle of the indoor first heat exchanger (41) to the first suction port (12) of the compressor (10), the indoor second pipe temperature of the air conditioning system, the ratio of the refrigerant flow rate of the first-stage throttling device (31) to the refrigerant flow rate of the second-stage throttling device (32), and the predetermined saturation temperature drop from the middle of the indoor second heat exchanger (42) to the second suction port (13) of the compressor (10), the refrigerant mass flow rate of the first-stage throttling device (31) and the refrigerant mass flow rate of the second-stage throttling device (32) are determined. after, Based on the predetermined flow correction coefficient of the first-stage throttling device (31), the inlet and outlet pressure difference of the first-stage throttling device (31), the inlet refrigerant density of the first-stage throttling device (31), the refrigerant mass flow rate of the first-stage throttling device (31), and the ratio of the refrigerant flow rate of the first-stage throttling device (31) to that of the second-stage throttling device (32), the opening degree of the first-stage throttling device (31) is determined as the target opening degree of the first-stage throttling device (31). Based on the predetermined flow correction coefficient of the second-stage throttling device (32), the inlet and outlet pressure difference of the second-stage throttling device (32), the inlet refrigerant density of the second-stage throttling device (32), the refrigerant mass flow rate of the second-stage throttling device (32), and the ratio of the refrigerant flow rates of the first-stage throttling device (31) to the second-stage throttling device (32), the opening degree of the second-stage throttling device (32) is determined as the target opening degree of the second-stage throttling device (32).

10. The control method for an air conditioning system according to claim 9, characterized in that, in, Determining the inlet dew point temperature of the air conditioning system based on the indoor return air temperature and the return air relative humidity of the air conditioning system includes: Based on the correspondence between the set return air temperature, the set return air relative humidity and the set inlet air dew point temperature, the set return air temperature that is the same as the indoor return air temperature of the air conditioning system and the set inlet air dew point temperature that is the same as the return air relative humidity of the air conditioning system are determined as the inlet air dew point temperature of the air conditioning system. And / or, Based on the inlet dew point temperature of the air conditioning system, the ratio of refrigerant flow rate of the first-stage throttling device (31) to that of the second-stage throttling device (32) is determined, including: Determine whether the inlet dew point temperature of the air conditioning system is less than or equal to the indoor first pipe temperature of the air conditioning system; If it is determined that the inlet dew point temperature of the air conditioning system is less than or equal to the indoor first pipe temperature of the air conditioning system, then it is determined that the indoor first heat exchanger (41) does not need dehumidification, and the frequency of the compressor (10) is increased or the speed of the indoor fan (62) is reduced. If it is determined that the inlet dew point temperature of the air conditioning system is greater than the indoor first pipe temperature of the air conditioning system, then the inlet enthalpy of the air conditioning system is determined based on the indoor return air temperature and the return air relative humidity of the air conditioning system; the outlet enthalpy of the air conditioning system is determined based on the outlet dew point temperature and the outlet relative humidity of the air conditioning system; and the dehumidification latent heat ratio of the indoor first heat exchanger (41) is determined based on the inlet enthalpy, the outlet enthalpy, and the phase change latent heat of the air conditioning system. The ratio of refrigerant flow rate of the first-stage throttling device (31) to that of the second-stage throttling device (32) is determined based on the relative humidity of the return air of the air conditioning system, the latent heat ratio of the first indoor heat exchanger (41), and the temperature regulation coefficient of the air conditioning system.

11. The control method for an air conditioning system according to claim 9 or 10, characterized in that, Based on the indoor first pipe temperature of the air conditioning system, the predetermined saturation temperature drop from the middle of the indoor first heat exchanger (41) to the first suction port (12) of the compressor (10), the indoor second pipe temperature of the air conditioning system, the ratio of the refrigerant flow rate of the first-stage throttling device (31) to the refrigerant flow rate of the second-stage throttling device (32), and the predetermined saturation temperature drop from the middle of the indoor second heat exchanger (42) to the second suction port (13) of the compressor (10), the refrigerant mass flow rate of the first-stage throttling device (31) and the refrigerant mass flow rate of the second-stage throttling device (32) are determined, including: The difference between the indoor first pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the middle of the indoor first heat exchanger (41) to the first suction port (12) of the compressor (10) is taken as the suction saturation temperature of the first suction cylinder of the compressor (10); and the difference between the indoor second pipe temperature of the air conditioning system and the predetermined saturation temperature drop from the middle of the indoor second heat exchanger (42) to the second suction port (13) of the compressor (10) is taken as the suction saturation temperature of the second suction cylinder of the compressor (10). Based on the suction saturation temperature of the first suction cylinder of the compressor (10), determine the saturated suction specific volume corresponding to the first suction cylinder of the compressor (10); and based on the suction saturation temperature of the second suction cylinder of the compressor (10), determine the saturated suction specific volume corresponding to the second suction cylinder of the compressor (10). The product of the third set coefficient multiple of the saturated temperature drop from the middle of the first indoor heat exchanger (41) to the first suction port (12) of the compressor (10) and the third set value, and the product of the third set value and the preset suction superheat of the first suction cylinder of the compressor (10), is taken as the saturated suction specific volume corresponding to the first suction cylinder of the compressor (10); and the product of the fourth set coefficient multiple of the saturated temperature drop from the middle of the second indoor heat exchanger (42) to the second suction port (13) of the compressor (10) and the fourth set value, and the product of the fourth set coefficient multiple of the saturated temperature drop and the preset suction superheat of the second suction cylinder of the compressor (10), is taken as the saturated suction specific volume corresponding to the second suction cylinder of the compressor (10). The first calculated value is obtained by multiplying the frequency setting calculation coefficient of the compressor (10) by the ratio of the saturated intake specific volume corresponding to the first intake cylinder of the compressor (10); The frequency setting calculation factor of the compressor (10) is multiplied by the ratio of the saturated suction specific volume corresponding to the second suction cylinder of the compressor (10) to obtain the second calculated value; the sum of the first calculated value and the second calculated value is determined as the total refrigerant mass flow rate of the first stage throttling device (31) and the second stage throttling device (32); Based on the total refrigerant mass flow rate of the first-stage throttling device (31) and the second-stage throttling device (32), and the ratio of the refrigerant flow rate of the first-stage throttling device (31) to the refrigerant flow rate of the second-stage throttling device (32), the refrigerant mass flow rate of the first-stage throttling device (31) and the refrigerant mass flow rate of the second-stage throttling device (32) are determined.

12. The control method for an air conditioning system according to any one of claims 1 to 6, 9, and 10, characterized in that, Also includes: After the first-stage throttling device (31) operates at its target opening and the second-stage throttling device (32) operates at its target opening for a set period of time, If the current operating mode of the air conditioning system is cooling mode, the target opening of the first-stage throttling device (31) is adjusted according to the difference between the first suction temperature of the air conditioning system and the first indoor pipe temperature of the air conditioning system to obtain a new target opening of the first-stage throttling device (31); and the target opening of the second-stage throttling device (32) is adjusted according to the difference between the second suction temperature of the air conditioning system and the second indoor pipe temperature of the air conditioning system to obtain a new target opening of the second-stage throttling device (32). If the current operating mode of the air conditioning system is reheat dehumidification mode, the target opening of the first-stage throttling device (31) is adjusted according to the difference between the first suction temperature of the air conditioning system and the first indoor pipe temperature of the air conditioning system to obtain a new target opening of the first-stage throttling device (31); and the target opening of the second-stage throttling device (32) is adjusted according to the difference between the indoor return air temperature of the air conditioning system and the set temperature to obtain a new target opening of the second-stage throttling device (32). Then, the first-stage throttling device (31) is controlled to operate at the new target opening of the first-stage throttling device (31), and the second-stage throttling device (32) is controlled to operate at the new target opening of the second-stage throttling device (32).

13. A control device for an air conditioning system that uses the control method of any one of claims 1 to 12 to control the air conditioning system, characterized in that, The air conditioning system adopts a three-pipe parallel reheat dehumidification system; the three-pipe parallel reheat dehumidification system has a compressor (10), a first-stage throttling device (31), a second-stage throttling device (32), an outdoor fan (61), and an indoor fan (62); the control device of the air conditioning system includes: The control unit is configured to, after the air conditioning system is started, control the indoor unit air deflector of the air conditioning system to open, control the indoor fan (62) to start, and control the air conditioning system to return oil operation; The acquisition unit is configured to acquire the outdoor ambient temperature of the air conditioning system after the oil return operation of the air conditioning system is completed; and to acquire the operating parameters of the air conditioning system. The control unit is further configured to adjust the frequency of the compressor (10) and the speed of the outdoor fan (61) according to the outdoor ambient temperature of the air conditioning system in the current operating mode of the air conditioning system; and, The control unit is further configured to, in the current operating mode of the air conditioning system, determine the target opening degree of the first-stage throttling device (31) and the target opening degree of the second-stage throttling device (32) by combining the outdoor ambient temperature of the air conditioning system, the indoor return air relative humidity of the air conditioning system, and the operating parameters of the air conditioning system; then, control the first-stage throttling device (31) to operate at the target opening degree of the first-stage throttling device (31), and control the second-stage throttling device (32) to operate at the target opening degree of the second-stage throttling device (32); wherein, the current operating mode of the air conditioning system is a cooling mode or a reheat dehumidification mode.

14. An air conditioning system, characterized in that, include: The control device for the air conditioning system as described in claim 13.

15. A storage medium, characterized in that, The storage medium includes a stored program, wherein, when the program is executed, the device containing the storage medium is controlled to perform the control method of the air conditioning system according to any one of claims 1 to 12.

Images