A high-efficiency heating control system and method for a wide temperature range air source heat pump hot and cold water machine

Abstract

The present invention discloses a high-efficiency heating control system and method for a wide-temperature-range air source heat pump cold and hot water machine. A water-to-water plate heat exchanger is used to directly exchange heat between engine cooling water and water to heat air-conditioning water. A refrigerant branch is designed on the low-pressure side of the system, and a water-to-fluorine plate heat exchanger and an electronic expansion valve are installed to control the heat exchange between the refrigerant and the engine cooling water to increase the low pressure of the system. The engine cooling water side of the water-to-water plate heat exchanger is connected in series with the engine cooling water side of the water-to-fluorine plate heat exchanger. During heating operation, the high-temperature engine cooling water first passes through the water-to-water plate heat exchanger and then flows to the water-to-fluorine plate heat exchanger. The waste heat of the engine is efficiently recovered. By efficiently utilizing the waste heat of the engine, the heating capacity of the system is improved and the defrosting effect of the system is enhanced.

Description

Technical Field

[0001] The invention discloses a wide temperature range air source heat pump control system and method, in particular a wide temperature range air source heat pump hot and cold water machine high-efficiency heating control system and method, belonging to the technical field of heat pumps. Background Art

[0002] The heating capacity and energy efficiency of the common electric air source heat pumps on the market are greatly affected by the ambient temperature. When operating at low temperature, the heat exchange between the refrigerant and the air is reduced, the system operating low pressure is low, the high-low pressure ratio of the compressor is large, the exhaust temperature is high and the compressor operating efficiency is low. In addition, too low low pressure will cause frequent frosting of the outdoor fin heat exchanger. After frosting, the existence of the frost layer will increase the heat exchange thermal resistance between the refrigerant and the air; at the same time, the fin gap will be blocked, and the heat exchange air volume will be greatly attenuated, resulting in extremely poor heat exchange effect. The electric air source heat pump system usually uses a reverse cycle defrosting method to defrost, and uses high-temperature exhaust gas to melt the frost layer on the surface of the heat exchanger through the outdoor heat exchanger. At this time, due to the reversal of the system's four-way valve, the system switches to cooling mode, which will greatly affect the comfort of the heated room. Summary of the invention

[0003] In view of the shortcomings of the prior art electric air source heat pumps, which have poor performance during use, the present invention provides a new wide temperature range air source heat pump hot and cold water heater efficient heating control system and method, which uses a water-to-water plate heat exchanger to directly exchange heat between engine cooling water and water to heat air-conditioning water, designs a refrigerant branch on the low-pressure side of the system, and adds a water-fluorine plate heat exchanger and an electronic expansion valve to control the heat exchange between the refrigerant and the engine cooling water to increase the low pressure of the system, and connects the engine cooling water side of the water-to-water plate heat exchanger and the engine cooling water side of the water-fluorine plate heat exchanger in series. During heating operation, the high-temperature engine cooling water first passes through the water-to-water plate heat exchanger and then flows to the water-fluorine plate heat exchanger, so that the engine waste heat is efficiently recovered. By efficiently utilizing the engine waste heat, the system heating capacity is improved and the system defrosting effect is enhanced.

[0004] The technical solution adopted by the present invention to solve the technical problem is: a high-efficiency heating control system for a wide temperature range air source heat pump cold and hot water machine, the system includes an air conditioning side system and an engine side system, wherein:

[0005] The air conditioning side system includes an engine, a compressor, an oil separator, a four-way valve, a main water-fluorine plate heat exchanger, a first heat exchanger and a gas-liquid separator. The compressor is connected to the engine, and the compressor is driven by the engine. The compressor outlet is connected to the oil separator, and the oil separator is connected to the main water-fluorine plate heat exchanger through the four-way valve. The main water-fluorine plate heat exchanger output is connected to the first heat exchanger, and the first heat exchanger is connected to the gas-liquid separator through the four-way valve. The gas-liquid separator output is connected to the compressor, and the oil output end of the oil separator is connected to the compressor inlet;

[0006] The engine side system includes a branch water-water plate heat exchanger, a branch water-fluorine plate heat exchanger, a flue gas waste heat recovery device and a cooling water radiator. The input end water inlet of the branch water-water plate heat exchanger is connected to the air conditioning water outlet of the main water-fluorine plate heat exchanger, the input end water outlet of the branch water-water plate heat exchanger is connected to the air conditioning water inlet of the main water-fluorine plate heat exchanger, the output end inlet of the branch water-water plate heat exchanger is connected to the engine cooling water output end, and the output end of the branch water-water plate heat exchanger is connected to the thermostat input end. The first output end of the thermostat is connected to the cooling water radiator, the second output end of the thermostat is connected to the output inlet of the branch water-fluorine plate heat exchanger, the output end of the branch water-fluorine plate heat exchanger and the output end of the cooling water radiator are both connected to the cooling water input end of the flue gas waste heat recovery device, the cooling water output end of the flue gas waste heat recovery device is connected to the cooling water input end of the engine, the engine flue gas output end is connected to the flue gas input end of the flue gas waste heat recovery device, and the flue gas output end of the flue gas waste heat recovery device discharges the cooled flue gas.

[0007] A high-efficiency heating control method for a wide-temperature-range air source heat pump hot and cold water machine, wherein the control method is as follows: when the unit is started for heating, the high-temperature and high-pressure gaseous refrigerant output from the first compressor and / or the second compressor first enters the main water-fluorine plate heat exchanger, exchanges heat with the air-conditioning water therein, and heats the air-conditioning water in the main water-fluorine plate heat exchanger; the cooled refrigerant passes through the main electronic expansion valve of the air-conditioning side system for throttling and pressure reduction, and the formed low-temperature and low-pressure refrigerant enters the first heat exchanger, absorbs heat from the air, and then returns to the first compressor and / or the second compressor; after the waste heat recovery solenoid valve is opened, the air-conditioning water is divided into two parts, one part enters the main water-fluorine plate heat exchanger, exchanges heat with the high-temperature refrigerant, and the other part enters the branch water-water plate heat exchanger, exchanges heat with the engine cooling water, and the heated air-conditioning water is mixed and discharged together.

[0008] The technical solution adopted by the present invention to solve the technical problem further includes:

[0009] There are two compressors, namely the first compressor and the second compressor, which are connected to the engine through belts, the outlets of the first compressor and the second compressor are respectively connected to the oil separator, and the outputs of the gas-liquid separator are respectively connected to the first compressor and the second compressor.

[0010] A high-pressure switch is connected to the pipeline between the outlet of the first compressor and the second compressor and the input end of the oil separator, a high-pressure pressure sensor is connected between the four-way valves at the output end of the oil separator, and an air-conditioning side system main electronic expansion valve is connected between the main water-fluorine plate heat exchanger and the first heat exchanger.

[0011] The front and rear ends of the main electronic expansion valve of the air-conditioning side system are respectively connected to filters, namely the first filter and the second filter. A fin temperature sensor is provided on the pipeline of the first heat exchanger. The pipeline between the main water-fluorine plate heat exchanger and the main electronic expansion valve of the air-conditioning side system is connected to the refrigerant inlet end of the branch water-fluorine plate heat exchanger through the branch electronic expansion valve of the air-conditioning side system. The pipeline between the main water-fluorine plate heat exchanger and the main electronic expansion valve of the air-conditioning side system is connected to the gas-liquid separator through the liquid bypass electronic expansion valve.

[0012] A low-pressure switch and a low-pressure sensor are connected to the pipeline connecting the gas-liquid separator and the compressor, a second temperature sensor is connected to the pipeline between the four-way valve and the gas-liquid separator, a main temperature sensor is arranged on the main water-fluorine plate heat exchanger, an inlet temperature sensor is connected to the air-conditioning water inlet pipeline of the main water-fluorine plate heat exchanger; an outlet temperature sensor is connected to the air-conditioning water outlet pipeline of the main water-fluorine plate heat exchanger, a waste heat recovery solenoid valve is connected between the air-conditioning water inlet pipeline of the main water-fluorine plate heat exchanger and the branch water-water plate heat exchanger, when the waste heat recovery solenoid valve is opened, the air-conditioning water is divided into two parts, one part enters the main water-fluorine plate heat exchanger, and the other part enters the branch water-water plate heat exchanger.

[0013] The pipeline between the cooling water radiator and the flue gas waste heat recovery device is connected with an engine cooling water pump, and the pipeline at the front end or rear end of the engine cooling water pump is connected with a cooling water filter.

[0014] The thermostat adopts an 83°C thermostat. When the engine cooling water temperature is lower than 83°C, the cooling water flows to the branch water-fluorine plate heat exchanger. When the cooling water temperature is greater than or equal to 83°C, the cooling water can flow to the branch water-fluorine plate heat exchanger and the cooling water radiator at the same time.

[0015] The control method of the waste heat recovery solenoid valve includes the following steps:

[0016] Step S1: When the unit receives a heating start command, when the system detects that the engine cooling water temperature reaches 65°C, the waste heat recovery solenoid valve opens;

[0017] Step S2: the unit receives a heating shutdown command, and the waste heat recovery solenoid valve is closed;

[0018] Step S3: In cooling mode, the waste heat recovery solenoid valve remains in a normally closed state.

[0019] The control method also includes air-conditioning side system branch electronic expansion valve control, and the air-conditioning side system branch electronic expansion valve control includes the following modes:

[0020] (1) Control in cooling mode: The unit is in the closed state during operation, that is, the opening is 0P, and the standby opening is maintained at 352P for the rest of the time;

[0021] (2) Control in heating mode includes the following control methods:

[0022] A. In heating mode standby and when the engine starts, maintain the standby opening of 352P within 2 minutes;

[0023] B. During normal operation of the heating mode, when the following conditions are met at the same time, the electronic expansion valve of the air-conditioning side system branch opens, and the rest of the time it is closed, that is, the opening degree is 0P:

[0024] a. The ambient temperature T4 is detected to be less than -5℃ for 30 minutes;

[0025] b. Low pressure PL < 0.6MPa is detected and lasts for 5min;

[0026] c. The high and low pressure difference PH-PL is detected to be greater than 0.5MPa and lasts for 5 minutes;

[0027] After the electronic expansion valve of the air-conditioning system branch is opened, it is first adjusted to the predetermined opening according to the ambient temperature:

[0028] -10≤T4<-5℃, the electronic expansion valve of the air-conditioning system branch is opened to 80P;

[0029] -15≤T4<-10℃, the electronic expansion valve of the air-conditioning side system branch is opened to 100P;

[0030] -20≤T4<-15℃, the electronic expansion valve of the air-conditioning system branch is opened to 120P;

[0031] T4<-20℃, the electronic expansion valve of the air-conditioning system branch is opened to 140P;

[0032] After 2 minutes, the electronic expansion valve of the air-conditioning system branch adjusts the opening according to the low-pressure change value. The low-pressure change value △PL = △PL2-△PL1. Every 30 seconds is a detection cycle. △PL1 is the PL value 15 seconds ago, and △PL2 is the PL value 15 seconds later.

[0033] When △PL>0.25MPa, the adjustment step of the electronic expansion valve of the air-conditioning side system branch is -10P;

[0034] When 0.15MPa<△PL≤0.25MPa, the electronic expansion valve of the air-conditioning side system branch adjusts the number of steps +0P;

[0035] When 0MPa<△PL≤0.15MPa, the electronic expansion valve of the air-conditioning side system branch adjusts the number of steps +5P;

[0036] When -0.2MPa<△PL≤0MPa, the electronic expansion valve of the air-conditioning side system branch adjusts the number of steps +10P;

[0037] When △PL≤-0.2MPa, the electronic expansion valve of the air-conditioning side system branch adjusts the number of steps +15P;

[0038] The air-conditioning side system branch electronic expansion valve is closed after opening. When one of the following conditions is met, the air-conditioning side system branch electronic expansion valve is closed and the opening degree is 0P:

[0039] a. The ambient temperature T4 ≥ -5°C is detected for 30 minutes, and the low pressure PL ≥ 0.8MPa is detected for 5 minutes;

[0040] b. Low pressure PL ≥ 1.2MPa is detected for 2 minutes;

[0041] (3) When running in defrost mode, when the four-way valve is switched to OFF, the step number of the electronic expansion valve of the air-conditioning side system branch is adjusted to 80P, which lasts for 2 minutes or until the defrost is completed. When the four-way valve is switched to ON 10 seconds before, the electronic expansion valve of the air-conditioning side system branch is adjusted to 0P.

[0042] The beneficial effects of the present invention are as follows: the wide temperature range air source heat pump in the present invention is an equipment system that uses a gas engine to drive a compressor to realize a refrigeration / heating cycle, wherein the mechanical efficiency of the engine driving the compressor is only about 35%, and the remaining 65% or so of energy exists in the form of heat. By recycling waste heat, a distributed energy system is constructed to utilize energy in a cascade manner. During heating, the heating capacity of the wide temperature range air source heat pump is partly derived from the air and partly from the engine waste heat. The engine waste heat can not only be directly exchanged with the air-conditioning water to significantly improve the heating capacity, but also can be exchanged with the low-pressure refrigerant side of the system to increase the system operating low pressure, reduce the operating compression ratio, improve the compressor efficiency, and enhance the heating energy efficiency and system defrosting effect.

[0043] The present invention uses a water-water plate heat exchanger to directly exchange heat between engine cooling water and water to heat air-conditioning water; a refrigerant branch is designed on the low-pressure side of the system, and a water-fluorine plate heat exchanger and an electronic expansion valve are installed to control the heat exchange between the refrigerant and the engine cooling water to increase the low pressure of the system; the engine cooling water side of the water-water plate heat exchanger is connected in series with the engine cooling water side of the water-fluorine plate heat exchanger. During heating operation, the high-temperature engine cooling water first passes through the water-water plate heat exchanger and then flows to the water-fluorine plate heat exchanger, so that the waste heat of the engine is efficiently recovered.

[0044] The present invention improves the heating capacity of the system and strengthens the defrosting effect of the system by efficiently utilizing the waste heat of the engine.

[0045] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a schematic diagram of the air conditioning side system of the wide temperature range air source heat pump in the present invention.

[0047] Figure 2 This is a schematic diagram of the water side system of the multi-energy high-efficiency heat pump in the present invention.

[0048] Figure 3 This is the control logic diagram of the waste heat recovery solenoid valve in the present invention. DETAILED DESCRIPTION

[0049] This embodiment is a preferred implementation mode of the present invention. Other embodiments whose principles and basic structures are the same or similar to those of this embodiment are within the protection scope of the present invention.

[0050] Please refer to the attached Figure 1 , Attachment Figure 2 and attached Figure 3 The present invention mainly protects a wide temperature range air source heat pump hot and cold water machine high efficiency heating control system, which is mainly divided into an air conditioning side system and an engine side system. The air conditioning side system belongs to an air-cooled air source heat pump system, and the engine drives the compressor to compress the refrigerant medium to circulate to achieve refrigeration and heating. The engine side system is mainly an engine cooling water circulation system, in which,

[0051] The air conditioning side system includes an engine, a compressor, an oil separator, a four-way valve, a main water-fluorine plate heat exchanger (i.e., PHE1), a first heat exchanger and a gas-liquid separator. The compressor is connected to the engine, and the compressor is driven by the engine. The compressor outlet is connected to the oil separator, and the oil separator is connected to the main water-fluorine plate heat exchanger through a four-way valve. The main water-fluorine plate heat exchanger output is connected to the first heat exchanger, and the first heat exchanger is connected to the gas-liquid separator through a four-way valve. The gas-liquid separator output is connected to the compressor, and the oil output end of the oil separator is connected to the inlet of the compressor.

[0052] In this embodiment, two compressors are provided, namely, a first compressor and a second compressor. The two compressors are connected to the engine through belts, and the engine drives the two compressors to operate simultaneously through the belts. The outlets of the first compressor and the second compressor are respectively connected to the oil separators, and the outputs of the gas-liquid separators are respectively connected to the first compressor and the second compressor.

[0053] The engine side system includes a branch water-water plate heat exchanger (i.e., PHE2), a branch water-fluorine plate heat exchanger (i.e., PHE3), a flue gas waste heat recovery device (i.e., PHE4) and a cooling water radiator. The input end water inlet of the branch water-water plate heat exchanger is connected to the air conditioning water outlet of the main water-fluorine plate heat exchanger, the input end water outlet of the branch water-water plate heat exchanger is connected to the air conditioning water inlet of the main water-fluorine plate heat exchanger, the output end inlet of the branch water-water plate heat exchanger is connected to the engine cooling water output end, and the output of the branch water-water plate heat exchanger is connected to the cooling water output end of the engine. The end is connected to the input end of the thermostat (i.e., SV5), the first output end of the thermostat is connected to the cooling water radiator, the second output end of the thermostat is connected to the output inlet of the branch water-fluorine plate heat exchanger, the output end of the branch water-fluorine plate heat exchanger and the output end of the cooling water radiator are both connected to the cooling water input end of the flue gas waste heat recovery device, the cooling water output end of the flue gas waste heat recovery device is connected to the cooling water input end of the engine, the engine fuel gas output end is connected to the flue gas input end of the flue gas waste heat recovery device, and the flue gas output end of the flue gas waste heat recovery device discharges the cooled flue gas.

[0054] In this embodiment, the engine is a gas engine.

[0055] In this embodiment, a high-pressure switch (i.e., HPS) is connected to the pipeline between the outlet of the first compressor and the second compressor and the input end of the oil separator. When the system high-pressure pressure reaches a certain value (this value is the initial setting value of the system, which is set according to different systems, and the highest value is based on not damaging the system), the high-pressure switch is automatically disconnected.

[0056] In this embodiment, a high-pressure pressure sensor (ie, PH) is connected between the output end of the oil separator and the four-way valve to detect the system high-pressure pressure PH.

[0057] In this embodiment, a main electronic expansion valve (ie, EXV1) of the air-conditioning system is connected between the main water-fluorine plate heat exchanger and the first heat exchanger to adjust the refrigerant flow of the air-conditioning system.

[0058] In this embodiment, filters are connected to the front and rear ends of the main electronic expansion valve of the air-conditioning system, which are the first filter and the second filter respectively.

[0059] In this embodiment, a fin temperature sensor (ie, T3) is provided on the pipeline of the first heat exchanger for detecting the temperature of the fin heat exchanger tube of the unit.

[0060] In this embodiment, the pipeline between the main water-fluorine plate heat exchanger and the main electronic expansion valve of the air-conditioning side system is connected to the refrigerant inlet end of the branch water-fluorine plate heat exchanger through the branch electronic expansion valve of the air-conditioning side system (i.e., EXV2), which is used to adjust the refrigerant flow of the air-conditioning side system.

[0061] In this embodiment, the pipeline between the main water-fluorine plate heat exchanger and the main electronic expansion valve of the air-conditioning side system is connected to the gas-liquid separator through a liquid bypass electronic expansion valve (ie, EXV3) to reduce the exhaust temperature of the compressor.

[0062] In this embodiment, a low-pressure switch (i.e., LPS) and a low-pressure sensor (i.e., PL) are connected to the pipeline connecting the gas-liquid separator and the compressor. The low-pressure switch is used to automatically disconnect when the system low-pressure reaches a certain value, and the low-pressure sensor is used to detect the system low-pressure PL.

[0063] In this embodiment, a second temperature sensor Th2 is connected to the pipeline between the four-way valve and the gas-liquid separator to detect the temperature on the pipeline.

[0064] In this embodiment, a main temperature sensor (ie, Tf) is provided on the main water-fluorine plate heat exchanger for detecting the operating temperature of the main water-fluorine plate heat exchanger.

[0065] In this embodiment, an inlet temperature sensor (i.e., Twi) is connected to the air-conditioning water inlet pipe of the main water-fluorine plate heat exchanger, which is used to detect the air-conditioning water inlet temperature of the main water-fluorine plate heat exchanger; an outlet temperature sensor (i.e., Two) is connected to the air-conditioning water outlet pipe of the main water-fluorine plate heat exchanger, which is used to detect the air-conditioning water outlet temperature of the main water-fluorine plate heat exchanger.

[0066] In this embodiment, a waste heat recovery solenoid valve (i.e., SV10) is connected between the air-conditioning water inlet pipeline of the main water-fluorine plate heat exchanger and the branch water-water plate heat exchanger, which is used to control the air-conditioning water inlet of the branch water-water plate heat exchanger. When the waste heat recovery solenoid valve is turned on, the air-conditioning water is divided into two parts, one part enters the main water-fluorine plate heat exchanger to exchange heat with the high-temperature refrigerant, and the other part enters the branch water-water plate heat exchanger to exchange heat with the engine cooling water. The heated air-conditioning water is mixed and discharged together.

[0067] In this embodiment, an engine cooling water pump is connected to the pipeline between the cooling water radiator and the flue gas waste heat recovery device to ensure the smooth operation of the cooling water. A cooling water filter is connected to the pipeline at the front end or rear end of the engine cooling water pump to filter the cooling water. In this embodiment, it is preferably connected to the front end of the engine cooling water pump so that the water entering the engine cooling water pump can be clean water, thereby extending the service life of the engine cooling water pump.

[0068] In this embodiment, the thermostat adopts an 83°C thermostat. When the engine cooling water temperature is lower than 83°C, the cooling water will only flow to the branch water-fluorine plate heat exchanger. When the cooling water temperature is greater than or equal to 83°C, the cooling water can flow to the branch water-fluorine plate heat exchanger and the cooling water radiator at the same time.

[0069] In this embodiment, fans are respectively installed on the cooling water radiator and the first heat exchanger to accelerate heat dissipation.

[0070] The present invention also protects an efficient heating control method for a wide temperature range air source heat pump hot and cold water heater. When the unit is started for heating, the high-temperature and high-pressure gaseous refrigerant output from the first compressor and / or the second compressor first enters the main water-fluorine plate heat exchanger, exchanges heat with the air-conditioning water therein, and heats the air-conditioning water in the main water-fluorine plate heat exchanger. The cooled refrigerant is throttled and reduced in pressure by the main electronic expansion valve of the air-conditioning side system, and the formed low-temperature and low-pressure refrigerant enters the first heat exchanger, absorbs heat from the air, and then returns to the first compressor and / or the second compressor. This is the conventional operating mode of the air-conditioning side system.

[0071] After the waste heat recovery solenoid valve is opened, the air-conditioning water is divided into two parts. One part enters the main water-fluorine plate heat exchanger to exchange heat with the high-temperature refrigerant, and the other part enters the branch water-water plate heat exchanger to exchange heat with the engine cooling water. The heated air-conditioning water is mixed and discharged together.

[0072] In this embodiment, the control method of the waste heat recovery solenoid valve, that is, the working method of the waste heat recovery solenoid valve includes the following steps:

[0073] Step S1: When the unit receives a heating start command, when the system detects that the engine cooling water temperature reaches 65°C, the waste heat recovery solenoid valve opens;

[0074] Step S2: the unit receives a heating shutdown command, and the waste heat recovery solenoid valve is closed;

[0075] Step S3: In cooling mode, the waste heat recovery solenoid valve remains in a normally closed state.

[0076] In this embodiment, the gas engine used in the wide temperature range air source heat pump is an internal combustion engine, which has a better thermal efficiency when the internal temperature is 80~90℃. Therefore, when the engine is just started, if the engine cooling water temperature is not high, the waste heat recovery solenoid valve is not opened first.

[0077] In this embodiment, the control method further includes air-conditioning side system branch electronic expansion valve control, and the air-conditioning side system branch electronic expansion valve control includes the following modes:

[0078] (1) Control in cooling mode: The unit is in the closed state during operation, that is, the opening is 0P, and the standby opening is maintained at 352P for the rest of the time.

[0079] (2) Control in heating mode includes the following control methods:

[0080] A. In heating mode standby and when the engine starts, maintain the standby opening at 352P for 2 minutes.

[0081] B. During normal operation of the heating mode (non-defrosting, oil return, etc.), when the following conditions are met at the same time, the electronic expansion valve of the air-conditioning side system branch is opened, and the rest of the time it is closed, that is, the opening is 0P:

[0082] a. The ambient temperature (i.e. T4) is detected to be less than -5°C for 30 minutes;

[0083] b. Low pressure PL < 0.6MPa is detected and lasts for 5min;

[0084] c. The high and low pressure difference PH-PL was detected to be greater than 0.5MPa and lasted for 5 minutes.

[0085] After the electronic expansion valve of the air-conditioning system branch is opened, it is first adjusted to the predetermined opening according to the ambient temperature:

[0086] -10≤T4<-5℃, the electronic expansion valve of the air-conditioning system branch is opened to 80P;

[0087] -15≤T4<-10℃, the electronic expansion valve of the air-conditioning side system branch is opened to 100P;

[0088] -20≤T4<-15℃, the electronic expansion valve of the air-conditioning system branch is opened to 120P;

[0089] T4<-20℃, the electronic expansion valve of the air-conditioning system branch is opened to 140P;

[0090] After 2 minutes, the electronic expansion valve of the air-conditioning side system branch adjusts the opening according to the low-pressure change value. The low-pressure change value △PL=△PL2-△PL1. Every 30 seconds is a detection cycle. △PL1 is the PL value 15 seconds ago, and △PL2 is the PL value 15 seconds later.

[0091] When △PL>0.25MPa, the adjustment step of the electronic expansion valve of the air-conditioning side system branch is -10P;

[0092] When 0.15MPa<△PL≤0.25MPa, the electronic expansion valve of the air-conditioning side system branch adjusts the number of steps +0P;

[0093] When 0MPa<△PL≤0.15MPa, the electronic expansion valve of the air-conditioning side system branch adjusts the number of steps +5P;

[0094] When -0.2MPa<△PL≤0MPa, the electronic expansion valve of the air-conditioning side system branch adjusts the number of steps +10P;

[0095] When △PL≤-0.2MPa, the adjustment steps of the electronic expansion valve of the air-conditioning side system branch are +15P.

[0096] The air-conditioning side system branch electronic expansion valve is closed after opening. When one of the following conditions is met, the air-conditioning side system branch electronic expansion valve is closed and the opening degree is 0P:

[0097] a. The ambient temperature T4 ≥ -5°C is detected for 30 minutes, and the low pressure PL ≥ 0.8MPa is detected for 5 minutes;

[0098] b. Low pressure PL ≥ 1.2 MPa is detected for 2 min.

[0099] (3) When running in defrost mode, when the four-way valve is switched to OFF, the step number of the electronic expansion valve of the air-conditioning side system branch is adjusted to 80P, which lasts for 2 minutes or until the defrost is completed. When the four-way valve is switched to ON 10 seconds before, the electronic expansion valve of the air-conditioning side system branch is adjusted to 0P.

[0100] The invention makes efficient cascade utilization of waste heat from a wide temperature range air source heat pump engine, utilizing the engine waste heat to increase the system low pressure, reduce the compression ratio, and improve the heating performance and defrosting effect.

[0101] The wide temperature range air source heat pump in the present invention is an equipment system that uses a gas engine to drive a compressor to achieve a refrigeration / heating cycle, in which the mechanical efficiency of the engine driving the compressor is only about 35%, and the remaining 65% of the energy exists in the form of heat. By recovering and utilizing waste heat, a distributed energy system is constructed to utilize energy in a cascade manner. During heating, the heating capacity of the wide temperature range air source heat pump comes partly from the air and partly from the engine waste heat. The engine waste heat can not only be used to directly exchange heat with the air-conditioning water to significantly improve the heating capacity, but also can be used to exchange heat with the low-pressure refrigerant side of the system to increase the system operating low pressure, reduce the operating compression ratio, improve the compressor efficiency, and enhance the heating energy efficiency and system defrosting effect.

[0102] The present invention uses a water-water plate heat exchanger to directly exchange heat between engine cooling water and water to heat air-conditioning water; a refrigerant branch is designed on the low-pressure side of the system, and a water-fluorine plate heat exchanger and an electronic expansion valve are installed to control the heat exchange between the refrigerant and the engine cooling water to increase the low pressure of the system; the engine cooling water side of the water-water plate heat exchanger is connected in series with the engine cooling water side of the water-fluorine plate heat exchanger. During heating operation, the high-temperature engine cooling water first passes through the water-water plate heat exchanger and then flows to the water-fluorine plate heat exchanger, so that the waste heat of the engine is efficiently recovered.

[0103] The present invention improves the heating capacity of the system and strengthens the defrosting effect of the system by efficiently utilizing the waste heat of the engine.

Claims

1. A high-efficiency heating control system for a wide temperature range air source heat pump cold and hot water machine, characterized by: The system includes an air conditioning side system and an engine side system, wherein: The air conditioning side system includes an engine, a compressor, an oil separator, a four-way valve, a main water-fluorine plate heat exchanger, a first heat exchanger and a gas-liquid separator. The compressor is connected to the engine, and the compressor is driven by the engine. The compressor outlet is connected to the oil separator, and the oil separator is connected to the main water-fluorine plate heat exchanger through the four-way valve. The main water-fluorine plate heat exchanger output is connected to the first heat exchanger, and the first heat exchanger is connected to the gas-liquid separator through the four-way valve. The gas-liquid separator output is connected to the compressor, and the oil output end of the oil separator is connected to the compressor inlet; A low-pressure switch and a low-pressure sensor are connected to the pipeline connecting the gas-liquid separator and the compressor, a second temperature sensor is connected to the pipeline between the four-way valve and the gas-liquid separator, a main temperature sensor is arranged on the main water-fluorine plate heat exchanger, an inlet temperature sensor is connected to the air-conditioning water inlet pipeline of the main water-fluorine plate heat exchanger; an outlet temperature sensor is connected to the air-conditioning water outlet pipeline of the main water-fluorine plate heat exchanger, a waste heat recovery solenoid valve is connected between the air-conditioning water inlet pipeline of the main water-fluorine plate heat exchanger and the branch water-water plate heat exchanger, when the waste heat recovery solenoid valve is turned on, the air-conditioning water is divided into two parts, one part enters the main water-fluorine plate heat exchanger, and the other part enters the branch water-water plate heat exchanger; The engine side system includes a branch water-water plate heat exchanger, a branch water-fluorine plate heat exchanger, a flue gas waste heat recovery device and a cooling water radiator. The input end water inlet of the branch water-water plate heat exchanger is connected to the air conditioning water outlet of the main water-fluorine plate heat exchanger, the input end water outlet of the branch water-water plate heat exchanger is connected to the air conditioning water inlet of the main water-fluorine plate heat exchanger, the output end inlet of the branch water-water plate heat exchanger is connected to the engine cooling water output end, and the output end of the branch water-water plate heat exchanger is connected to the thermostat input end. The first output end of the thermostat is connected to the cooling water radiator, the second output end of the thermostat is connected to the output inlet of the branch water-fluorine plate heat exchanger, the output end of the branch water-fluorine plate heat exchanger and the output end of the cooling water radiator are both connected to the cooling water input end of the flue gas waste heat recovery device, the cooling water output end of the flue gas waste heat recovery device is connected to the cooling water input end of the engine, the engine fuel gas output end is connected to the flue gas input end of the flue gas waste heat recovery device, and the flue gas output end of the flue gas waste heat recovery device discharges the cooled flue gas.

2. The high-efficiency heating control system for a wide temperature range air source heat pump cold and hot water machine according to claim 1 is characterized by: There are two compressors, namely the first compressor and the second compressor, which are connected to the engine through belts, the outlets of the first compressor and the second compressor are respectively connected to the oil separator, and the outputs of the gas-liquid separator are respectively connected to the first compressor and the second compressor.

3. The high-efficiency heating control system for a wide temperature range air source heat pump cold and hot water machine according to claim 2 is characterized by: A high-pressure switch is connected to the pipeline between the outlets of the first compressor and the second compressor and the input end of the oil separator, a high-pressure pressure sensor is connected between the output end of the oil separator and the four-way valve, and an air-conditioning side system main electronic expansion valve is connected between the main water-fluorine plate heat exchanger and the first heat exchanger.

4. The high-efficiency heating control system for a wide temperature range air source heat pump cold and hot water machine according to claim 1 is characterized by: The front and rear ends of the main electronic expansion valve of the air-conditioning side system are respectively connected to filters, namely the first filter and the second filter. A fin temperature sensor is provided on the pipeline of the first heat exchanger. The pipeline between the main water-fluorine plate heat exchanger and the main electronic expansion valve of the air-conditioning side system is connected to the refrigerant inlet end of the branch water-fluorine plate heat exchanger through the branch electronic expansion valve of the air-conditioning side system. The pipeline between the main water-fluorine plate heat exchanger and the main electronic expansion valve of the air-conditioning side system is connected to the gas-liquid separator through the liquid bypass electronic expansion valve.

5. The high-efficiency heating control system for a wide temperature range air source heat pump cold and hot water heater according to claim 1 is characterized by: The pipeline between the cooling water radiator and the flue gas waste heat recovery device is connected with an engine cooling water pump, and the pipeline at the front end or rear end of the engine cooling water pump is connected with a cooling water filter.

6. The high-efficiency heating control system for a wide temperature range air source heat pump cold and hot water machine according to claim 1 is characterized by: The thermostat adopts an 83°C thermostat. When the engine cooling water temperature is lower than 83°C, the cooling water flows to the branch water-fluorine plate heat exchanger. When the cooling water temperature is greater than or equal to 83°C, the cooling water can flow to the branch water-fluorine plate heat exchanger and the cooling water radiator at the same time.

7. A method for realizing a high-efficiency heating control system for a wide temperature range air source heat pump cold and hot water heater using the high-efficiency heating control system for a wide temperature range air source heat pump cold and hot water heater as claimed in any one of claims 1 to 6, characterized in that: The control method is as follows: when the unit is turned on for heating, the high-temperature and high-pressure gaseous refrigerant output from the first compressor and / or the second compressor first enters the main water-fluorine plate heat exchanger, exchanges heat with the air-conditioning water therein, heats the air-conditioning water in the main water-fluorine plate heat exchanger, and the cooled refrigerant passes through the main electronic expansion valve of the air-conditioning side system for throttling and pressure reduction, and the formed low-temperature and low-pressure refrigerant enters the first heat exchanger, absorbs heat from the air and returns to the first compressor and / or the second compressor, and after the waste heat recovery solenoid valve is opened, the air-conditioning water is divided into two parts, one part enters the main water-fluorine plate heat exchanger, exchanges heat with the high-temperature refrigerant, and the other part enters the branch water-water plate heat exchanger, exchanges heat with the engine cooling water, and the heated air-conditioning water is mixed and discharged together; The control method of the waste heat recovery solenoid valve includes the following steps: Step S1: When the unit receives a heating start command, when the system detects that the engine cooling water temperature reaches 65°C, the waste heat recovery solenoid valve opens; Step S2: the unit receives a heating shutdown command, and the waste heat recovery solenoid valve is closed; The control method also includes air-conditioning side system branch electronic expansion valve control, and the air-conditioning side system branch electronic expansion valve control includes the following modes: (1) Control in cooling mode: The unit is in the closed state during operation, that is, the opening is 0P, and the standby opening is maintained at 352P for the rest of the time; (2) Control in heating mode includes the following control methods: A. In heating mode standby and when the engine starts, maintain the standby opening of 352P within 2 minutes; B. During normal operation of the heating mode, when the following conditions are met at the same time, the electronic expansion valve of the air-conditioning side system branch opens, and the rest of the time it is closed, that is, the opening degree is 0P: a. The ambient temperature T4 is detected to be less than -5℃ for 30 minutes; b. Low pressure PL < 0.6MPa is detected and lasts for 5min; c. The high and low pressure difference PH-PL is detected to be greater than 0.5MPa and lasts for 5 minutes; After the electronic expansion valve of the air-conditioning system branch is opened, it is first adjusted to the predetermined opening according to the ambient temperature: -10≤T4<-5℃, the electronic expansion valve of the air-conditioning system branch is opened to 80P; -15≤T4<-10℃, the electronic expansion valve of the air-conditioning side system branch is opened to 100P; -20≤T4<-15℃, the electronic expansion valve of the air-conditioning system branch is opened to 120P; T4<-20℃, the electronic expansion valve of the air-conditioning system branch is opened to 140P; After 2 minutes, the electronic expansion valve of the air-conditioning system branch adjusts the opening according to the low-pressure change value. The low-pressure change value △PL = △PL2-△PL1. Every 30 seconds is a detection cycle. △PL1 is the PL value 15 seconds ago, and △PL2 is the PL value 15 seconds later. When △PL>0.25MPa, the adjustment step of the electronic expansion valve of the air-conditioning side system branch is -10P; When 0.15MPa<△PL≤0.25MPa, the electronic expansion valve of the air-conditioning side system branch adjusts the number of steps +0P; When 0MPa<△PL≤0.15MPa, the electronic expansion valve of the air-conditioning side system branch adjusts the number of steps +5P; When -0.2MPa<△PL≤0MPa, the electronic expansion valve of the air-conditioning side system branch adjusts the number of steps +10P; When △PL≤-0.2MPa, the electronic expansion valve of the air-conditioning side system branch adjusts the number of steps +15P; The air-conditioning side system branch electronic expansion valve is closed after opening. When one of the following conditions is met, the air-conditioning side system branch electronic expansion valve is closed and the opening degree is 0P: a. The ambient temperature T4 ≥ -5°C is detected for 30 minutes, and the low pressure PL ≥ 0.8MPa is detected for 5 minutes; b. Low pressure PL ≥ 1.2MPa is detected for 2 minutes; (3) When running in defrost mode, when the four-way valve is switched to OFF, the step number of the electronic expansion valve of the air-conditioning side system branch is adjusted to 80P, which lasts for 2 minutes or until the defrost is completed. When the four-way valve is switched to ON 10 seconds before, the electronic expansion valve of the air-conditioning side system branch is adjusted to 0P.

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