Control method for heat pump system, heat pump system, and storage medium

Abstract

The application discloses a kind of control method of heat pump system, heat pump system and storage medium.Therein, in the heat pump system, compression device, four-way valve, outdoor heat exchanger, gas supplement supercooling unit and indoor heat exchanger are sequentially connected, gas supplement supercooling unit is communicated with the gas supplement port of compression device or secondary compression suction port by gas supplement branch, one end of liquid injection branch is connected between indoor heat exchanger and gas supplement supercooling unit or connected between outdoor heat exchanger and gas supplement supercooling unit, the other end of liquid injection branch is communicated with gas supplement branch, gas supplement branch is provided with gas supplement valve, and liquid injection branch is provided with liquid injection valve, and the method comprises: controlling heat pump system to heat operation, obtains the first state parameter of heat pump system;When the first state parameter satisfies gas supplement enthalpy-increasing condition, control gas supplement valve to open and obtain the second state parameter of heat pump system;When the second state parameter satisfies liquid injection condition, control liquid injection valve to open.The application aims at improving system energy efficiency while ensuring the operation reliability of compression device.

Description

Technical Field

[0001] This invention relates to the field of heat pump technology, and more particularly to a control method for a heat pump system, a heat pump system, and a storage medium. Background Technology

[0002] When heat pump systems are used for low-temperature heating, they typically employ a flash evaporator. Flash gas from the flash evaporator is introduced into the compressor unit via a make-up gas branch to provide sufficient make-up gas and boost its pressure, thereby improving system efficiency. However, the make-up gas volume is not adjustable, which can easily lead to excessively high exhaust temperatures from the compressor unit, affecting its operational reliability. Summary of the Invention

[0003] The main objective of this invention is to provide a control method for a heat pump system, a heat pump system, and a storage medium, aiming to improve system energy efficiency while ensuring the reliability of the compression device.

[0004] To achieve the above objectives, the present invention provides a control method for a heat pump system. The heat pump system includes a compressor, a four-way valve, an outdoor heat exchanger, a gas-injection subcooling unit, an indoor heat exchanger, a gas-injection branch, and a liquid injection branch. The compressor, the four-way valve, the outdoor heat exchanger, the gas-injection subcooling unit, and the indoor heat exchanger are connected sequentially. The gas-injection subcooling unit is connected to the gas-injection port or the secondary compressor intake port of the compressor through the gas-injection branch. One end of the liquid injection branch is connected between the indoor heat exchanger and the gas-injection subcooling unit or between the outdoor heat exchanger and the gas-injection subcooling unit. The other end of the liquid injection branch is connected to the gas-injection branch. The gas-injection branch is equipped with a gas-injection valve, and the liquid injection branch is equipped with a liquid injection valve. The control method for the heat pump system includes the following steps:

[0005] Control the heat pump system to operate in heating mode and obtain the first state parameters of the heat pump system;

[0006] When the first state parameter meets the gas replenishment and enthalpy increase condition, the gas replenishment valve is controlled to open and the second state parameter of the heat pump system is obtained.

[0007] When the second state parameter meets the spraying conditions, the spraying valve is controlled to open.

[0008] Optionally, the second state parameter includes the condensing temperature of the heat pump system and the exhaust superheat of the compression device, and the liquid injection conditions include at least one of the following conditions:

[0009] The condensing temperature of the heat pump system is not greater than the first preset condensing temperature;

[0010] The exhaust superheat of the compression device is not less than the preset superheat.

[0011] Optionally, after the step of controlling the opening of the injection valve, the method further includes:

[0012] Obtain the change value of the exhaust superheat corresponding to the compression device;

[0013] The opening degree of the injection valve is adjusted according to the change value.

[0014] Optionally, the step of controlling the opening of the injection valve according to the change value includes:

[0015] When the change value is greater than a preset change threshold, the spray valve is controlled to increase its opening.

[0016] When the change value is less than the preset change threshold, the opening of the spray valve is reduced.

[0017] Optionally, the gas replenishment subcooling unit includes a flash evaporator, and the heat pump system further includes a throttling valve, which is disposed between the outdoor heat exchanger and the flash evaporator or between the indoor heat exchanger and the flash evaporator. The gas replenishment branch is connected to the gas outlet of the flash evaporator. After the step of controlling the opening of the gas replenishment valve, the system further includes:

[0018] Obtain the intermediate pressure of the compression device;

[0019] The opening degree of the throttle valve is adjusted according to the intermediate pressure.

[0020] Optionally, the step of controlling the opening of the throttle valve according to the intermediate pressure includes:

[0021] When the intermediate pressure is greater than the target pressure, the throttle valve is controlled to increase its opening.

[0022] When the intermediate pressure is less than the target pressure, the throttle valve is controlled to reduce its opening.

[0023] Optionally, before the step of controlling the throttle valve opening according to the intermediate pressure, the method further includes:

[0024] Obtain the exhaust pressure and compression frequency of the compression device;

[0025] The target pressure is determined based on the exhaust pressure and the compression frequency.

[0026] Optionally, the first state parameters include the ambient temperature corresponding to the heat pump system, the operating frequency of the compression device, and the condensing temperature of the heat pump system, and the gas replenishment enthalpy increase conditions include at least one of the following conditions:

[0027] The ambient temperature corresponding to the heat pump system is not greater than the preset ambient temperature;

[0028] The difference between the operating frequency of the compression device and the set frequency is not greater than a preset value;

[0029] The condensing temperature of the heat pump system is not greater than the second preset condensing temperature.

[0030] Optionally, the heat pump system further includes a throttling valve and a control valve, the gas replenishment subcooling unit includes a flash evaporator, the throttling valve is disposed between the outdoor heat exchanger and the flash evaporator, the control valve is disposed between the indoor heat exchanger and the flash evaporator, and the control method of the heat pump system further includes:

[0031] Control the heat pump system to operate in heating mode and obtain the exhaust superheat of the compression device;

[0032] The opening degree of the throttle valve and / or the control valve is adjusted according to the exhaust superheat, and the step of obtaining the first state parameters of the heat pump system is performed.

[0033] Optionally, the step of controlling the opening of the throttle valve and / or the control valve according to the exhaust superheat includes:

[0034] Adjust the opening of the throttle valve according to the exhaust superheat until the opening of the throttle valve exceeds the preset opening range or triggers the protection conditions of the heat pump system.

[0035] Adjust the opening of the control valve according to the exhaust superheat.

[0036] Optionally, the step of adjusting the opening of the throttle valve according to the exhaust superheat includes:

[0037] When the exhaust superheat is less than the target superheat, control the throttle valve to reduce its opening.

[0038] When the exhaust superheat is greater than the target superheat, the throttle valve is controlled to increase its opening.

[0039] Optionally, the step of adjusting the opening of the control valve according to the exhaust superheat includes:

[0040] When the exhaust superheat is less than the target superheat, the control valve is controlled to reduce its opening.

[0041] When the exhaust superheat is greater than the target superheat, the control valve is controlled to increase its opening.

[0042] Furthermore, to achieve the above objectives, this application also proposes a heat pump system, which includes a control device, a compression device, a four-way valve, an outdoor heat exchanger, a gas replenishment subcooling unit, an indoor heat exchanger, a gas replenishment branch, and a liquid injection branch. The compression device, the four-way valve, the outdoor heat exchanger, the gas replenishment subcooling unit, and the indoor heat exchanger are connected in sequence. The gas replenishment subcooling unit is connected to the gas replenishment port or the secondary compression intake port of the compression device through the gas replenishment branch. One end of the liquid injection branch is connected between the indoor heat exchanger and the gas replenishment subcooling unit or between the outdoor heat exchanger and the gas replenishment subcooling unit. The other end of the liquid injection branch is connected to the gas replenishment branch. The gas replenishment branch is equipped with a gas replenishment valve, and the liquid injection branch is equipped with a liquid injection valve.

[0043] Both the gas replenishment valve and the liquid injection valve are connected to the control device, which includes a memory, a processor, and a control program for the heat pump system stored in the memory and executable on the processor. When the control program for the heat pump system is executed by the processor, it implements the steps of the control method for the heat pump system as described above.

[0044] Optionally, the heat pump system further includes a throttling valve and a control valve. The gas replenishment subcooling unit includes a flash evaporator. The throttling valve is disposed between the outdoor heat exchanger and the flash evaporator or between the indoor heat exchanger and the flash evaporator. The control valve is disposed between the indoor heat exchanger and the flash evaporator and is connected to the control device.

[0045] In addition, to achieve the above objectives, this application also proposes a storage medium storing a control program for a heat pump system, which, when executed by a processor, implements the steps of the control method for the heat pump system as described in any of the preceding claims.

[0046] This invention proposes a control method for a heat pump system. Based on a heat pump system equipped with a gas replenishment branch and a liquid injection branch, the method first opens the gas replenishment valve to replenish the enthalpy of the compressor through the gas replenishment branch when the first state parameter meets the gas replenishment enthalpy increase condition during the heating operation of the heat pump system. If, during the gas replenishment enthalpy increase process, a second state parameter determines that there is a reliability risk to the compressor, the liquid injection valve is then opened to spray liquid into the gas replenishment branch through the liquid injection branch to cool the gas in the gas replenishment branch. The cooled gas then enters the compressor through the gas replenishment port for gas replenishment enthalpy increase, which helps to quickly reduce the exhaust temperature of the compressor. This method can replenish the enthalpy while avoiding excessively high compressor exhaust temperature, thereby improving system energy efficiency and the operational reliability of the compressor. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the refrigerant flow path in an embodiment of the heat pump system of the present invention;

[0048] Figure 2 This is a schematic diagram of the hardware structure involved in the operation of an embodiment of the heat pump system of the present invention;

[0049] Figure 3 This is a flowchart illustrating an embodiment of the control method for the heat pump system of the present invention;

[0050] Figure 4 This is a pressure-enthalpy diagram related to an embodiment of the control method for the heat pump system of the present invention;

[0051] Figure 5 This is a schematic flowchart of another embodiment of the control method for the heat pump system of the present invention;

[0052] Figure 6 This is a flowchart illustrating another embodiment of the control method for the heat pump system of the present invention;

[0053] Figure 7 This is a flowchart illustrating another embodiment of the control method for the heat pump system of the present invention.

[0054] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0055] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0056] This invention provides a heat pump system.

[0057] In this embodiment, refer to Figure 1 The heat pump system includes a control device 100, a compression device 200, a four-way valve 900, an indoor heat exchanger 500, a gas replenishment subcooling unit 302, an outdoor heat exchanger 700, a gas replenishment branch 300, and a liquid injection branch 400. The compression device 200, the four-way valve 900, the outdoor heat exchanger 700, the gas replenishment subcooling unit 302, and the indoor heat exchanger 500 are connected in sequence. The gas replenishment branch 300 and the gas replenishment subcooling unit 302 are connected via... The gas supply branch 300 is connected to the gas supply port of the compression device 200. One end of the liquid injection branch 400 is connected between the indoor heat exchanger 500 and the gas supply subcooling unit 302 or between the outdoor heat exchanger 700 and the gas supply subcooling unit 302. The other end of the liquid injection branch 400 is connected to the gas supply branch 300. The gas supply branch 300 is equipped with a gas supply valve 301, and the liquid injection branch 400 is equipped with a liquid injection valve 401.

[0058] The exhaust port of the compressor 200, the return port of the compressor 200, the indoor heat exchanger 500, and the outdoor heat exchanger 700 are all connected to the four-way valve 900. The four-way valve 900 can be used to switch the operating state of the heat pump system between cooling operation and heating operation.

[0059] The gas supply branch 300 is used to introduce the medium-pressure gas generated by the gas supply subcooling unit 302 into the gas supply port or the secondary compression intake port of the compression device 200 to supply gas and increase the enthalpy of the compression device 200.

[0060] The liquid injection branch 400 is used to introduce the throttled liquid in the system into the gas supply branch 300 to cool the saturated gas in the gas supply branch 300 to supersaturated gas, thereby reducing the exhaust temperature of the compressor 200.

[0061] In this embodiment, the air replenishment valve 301 is a solenoid valve, and the liquid injection valve 401 is an electronic expansion valve. In other embodiments, both the air replenishment valve 301 and the liquid injection valve 401 are electronic expansion valves, or both the air replenishment valve 301 and the liquid injection valve 401 are solenoid valves.

[0062] In this embodiment, the gas replenishment subcooling unit 302 is a flash evaporator, which includes a first refrigerant port, a second refrigerant port, and an outlet. The first refrigerant port is connected to the indoor heat exchanger 500, and the second refrigerant port is connected to the outdoor heat exchanger 700. In other embodiments, the gas replenishment subcooling unit 302 may also include an economizer. The gas replenishment branch 300 is connected to the economizer, and one end of the gas replenishment branch 300 is connected between the outdoor heat exchanger 700 and the economizer. The other end of the gas replenishment branch 300 is connected to the gas replenishment port or the secondary compression intake port of the compression device 200. The gas replenishment valve 301 is an electronic expansion valve and is disposed between one end of the gas replenishment branch and the economizer.

[0063] In this embodiment, the compression device 200 is a two-stage compression device 200. The compression device 200 may include a primary compressor and a secondary compressor connected to the primary compressor. The inlet of the primary compressor is the return port of the compression device 200, and the outlet of the primary compressor is connected to the inlet of the secondary compressor. The communication channel between the outlet of the primary compressor and the inlet of the secondary compressor is connected to the supplementary air subcooling unit 302 through the supplementary air branch 300. The outlet of the secondary compressor is the exhaust port of the compression device 200. Alternatively, the compressor system may be a compressor including a primary compression cylinder and a secondary compression cylinder. The return port of the compressor, the primary compression cylinder, the secondary compression cylinder, and the exhaust port of the compression cylinder are sequentially connected. The connection channel between the primary compression cylinder and the secondary compression cylinder is connected to the supplementary air subcooling unit 302 through the supplementary air branch 300.

[0064] In other embodiments, the compression device 200 may also be a single-stage compression device. The compression device 200 is provided with a return air port, a make-up air port and an exhaust air port. The make-up air port is connected to the make-up air subcooling unit 302 through the make-up air branch 300.

[0065] Furthermore, in this embodiment, referring to Figure 1 The heat pump system further includes a throttling valve 600 and a control valve 800. The throttling valve 600 is disposed between the outdoor heat exchanger 700 and the flash evaporator or between the indoor heat exchanger 500 and the flash evaporator. The gas replenishment subcooling unit 302 includes a flash evaporator. The gas replenishment branch 300 is connected to the outlet of the flash evaporator. The control valve 800 is disposed between the indoor heat exchanger 500 and the flash evaporator. The liquid injection branch 400 is provided with a throttling component 402 connected in series with the liquid injection valve 401. The control valve 800 is disposed on the pipeline between the flash evaporator 302 and the gas replenishment branch 300.

[0066] In this embodiment, the throttling component 402 is a capillary tube, and the injection valve 401 is an electronic expansion valve. In other embodiments, the throttling component 402 and the injection valve 401 may also be integrated into an electronic expansion valve, or both the throttling component 402 and the injection valve 401 may be electronic expansion valves.

[0067] When the heat pump system is in heating mode, the exhaust port of the compressor 200 is connected to the indoor heat exchanger 500, and the return port of the compressor 200 is connected to the outdoor heat exchanger 700. The refrigerant discharged by the compressor flows sequentially through the indoor heat exchanger 500, control valve 800, flash evaporator, expansion valve 600, and outdoor heat exchanger 700 before returning to the compressor. The indoor heat exchanger 500 is in a condensing state, and the outdoor heat exchanger 700 is in an evaporating state. The saturated gas separated from the refrigerant after condensation and entering the flash evaporator can be discharged from the outlet. When the gas supply valve 301 is opened, the saturated gas discharged from the outlet can flow through the gas supply branch 300 and enter the gas supply port to supply gas to the compression device 200 and increase its enthalpy. When the liquid injection valve 401 is opened, part of the condensed refrigerant will enter the flash evaporator, and the other part will enter the liquid injection branch 400. The liquid refrigerant after being throttled by the throttling component 402 can enter the gas supply branch 300 and mix with the saturated gas in the gas supply branch 300. The supersaturated gas formed after mixing will enter the medium-pressure area of ​​the compression device 200 from the gas supply port or the secondary compression suction port.

[0068] Furthermore, refer to Figure 1 and Figure 2 The heat pump system also includes a pressure sensor 01 connected to the control device 100, which can be located at the exhaust port of the compressor 200 to detect the exhaust pressure of the compressor 200.

[0069] Furthermore, refer to Figure 2The heat pump system also includes an environmental detection module 02 connected to the control device 100. The environmental detection module 02 is located in the environment where the heat pump system is located to detect the ambient temperature of the environment where the heat pump system is located. In this embodiment, the environmental detection module 02 is used to detect the outdoor ambient temperature.

[0070] Furthermore, refer to Figure 1 and Figure 2 The heat pump system also includes a temperature sensor 03 connected to the control device 100, which can be installed at the exhaust port of the compressor 200 or on the pipeline connected to the exhaust port of the compressor 200, for detecting the exhaust temperature of the compressor 200.

[0071] In this embodiment of the invention, reference is made to Figure 2 The control device 100 of the heat pump system includes a processor 1001, such as a CPU, a memory 1002, and a timer 1003. These components communicate with each other via a communication bus. The memory 1002 can be a high-speed RAM or a stable, non-volatile memory, such as a disk drive. Optionally, the memory 1002 can also be a storage device independent of the aforementioned processor 1001.

[0072] Those skilled in the art will understand that Figure 2 The device structure shown does not constitute a limitation on the device and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0073] like Figure 2 As shown, the memory 1002, which serves as a computer storage medium, may include a control program for a heat pump system.

[0074] exist Figure 2 In the device shown, the processor 1001 can be used to call the control program of the heat pump system stored in the memory 1002 and execute the relevant steps of the control method of the heat pump system in the following embodiments.

[0075] This invention also provides a control method for a heat pump system, applied to the aforementioned heat pump system.

[0076] Reference Figure 3 This application proposes an embodiment of a control method for a heat pump system. In this embodiment, the control method for the heat pump system includes:

[0077] Step S10: Control the heat pump system to operate in heating mode and obtain the first state parameters of the heat pump system;

[0078] During the heating operation of the heat pump system, the refrigerant discharged by the compressor flows sequentially through the indoor heat exchanger, the expansion valve, and the outdoor heat exchanger before returning to the compressor. The indoor heat exchanger is in a condensing state, while the outdoor heat exchanger is in an evaporating state.

[0079] The first state parameter can be any parameter characterizing the output capacity of the heat pump system under the current environment. The first state parameter may include the heat pump system's own operating parameters (e.g., compressor frequency) and / or state characteristic parameters of the heat pump system's operation process detected by the detection module (e.g., temperature and / or pressure) and / or environmental parameters of the environment in which the heat pump system is located (e.g., ambient temperature and / or humidity). In this embodiment, the first state parameter includes, but is not limited to, at least one of the following parameters: condensing temperature, condensing pressure, exhaust superheat, exhaust pressure, ambient temperature, compressor operating frequency, exhaust pressure change, exhaust temperature change, etc.

[0080] The first state parameter can be detected when the heat pump system starts heating or when the heat pump system reaches a preset state during heating.

[0081] Specifically, the first state parameter can be detected in real time or at preset intervals.

[0082] Step S20: When the first state parameter meets the gas replenishment enthalpy increase condition, control the gas replenishment valve to open and obtain the second state parameter of the heat pump system;

[0083] The enthalpy enhancement condition is specifically a preset condition that the first state parameter must meet when the current heating output capacity of the heat pump system is insufficient and enthalpy enhancement is needed to improve the system's energy efficiency.

[0084] The conditions for replenishing gas and increasing enthalpy may include the target parameter range that the above-mentioned operating parameters and / or state characteristic parameters and / or environmental parameters need to achieve, or the quantitative or magnitude relationship that the above-mentioned operating parameters and / or state characteristic parameters and / or environmental parameters need to satisfy with the preset parameter values, etc.

[0085] In one implementation, when the first state parameter satisfies the gas replenishment enthalpy condition, the gas replenishment valve and the liquid injection valve can be opened simultaneously.

[0086] In another implementation, when the first state parameter satisfies the gas replenishment enthalpy condition, the gas replenishment valve is opened first, followed by the liquid injection valve.

[0087] In this embodiment, "opening the air supply valve" means switching the air supply valve from a closed state to an open state, and "opening the liquid injection valve" means switching the liquid injection valve from a closed state to an open state.

[0088] When the make-up air valve is an adjustable fluid valve, it can be controlled to open at a corresponding initial opening. This initial opening can be a pre-set fixed opening, or it can be determined based on the actual operating parameters of the heat pump system. For example, it can be determined based on the exhaust temperature and / or exhaust pressure and / or make-up air port temperature and / or make-up air port pressure and / or ambient temperature, to ensure energy efficiency while improving the reliability of compressor operation.

[0089] The second state parameter can be any parameter characterizing the compressor reliability of the heat pump system after enthalpy increase due to gas replenishment. The second state parameter may include the heat pump system's own operating parameters (e.g., compressor frequency) and / or state characteristic parameters of the heat pump system's operation detected by the detection module (e.g., temperature and / or pressure) and / or environmental parameters of the environment in which the heat pump system is located (e.g., ambient temperature and / or humidity). In this embodiment, the second state parameter includes, but is not limited to, at least one of the following parameters: condensing temperature, condensing pressure, exhaust superheat, exhaust pressure, ambient temperature, compressor operating frequency, exhaust pressure change, exhaust temperature change, etc.

[0090] During the process of the air replenishment valve opening and the liquid injection valve closing, the second state parameter can be detected at set intervals, in real time, or when the operation reaches a preset state. Alternatively, the second state parameter can be obtained when the air replenishment valve is open for a duration not less than a preset duration, or when the air replenishment valve opening degree is not less than a preset opening degree, and so on.

[0091] Step S30: When the second state parameter meets the liquid spraying conditions, control the liquid spraying valve to open.

[0092] The liquid injection condition is the condition that the second state parameter must meet when there is a reliability risk caused by excessively high exhaust temperature during the compressor's gas replenishment and enthalpy increase process, and liquid injection is needed to reduce the exhaust temperature.

[0093] The spraying conditions may include the target parameter range that the above-mentioned operating parameters and / or state characteristic parameters and / or environmental parameters need to achieve, or the quantitative or magnitude relationship that the above-mentioned operating parameters and / or state characteristic parameters and / or environmental parameters need to satisfy with the preset parameter values, etc.

[0094] The opening of the injection valve specifically refers to switching from the closed state to the open state.

[0095] The liquid injection valve can be opened at a preset initial opening degree, or it can be opened at an initial opening degree determined according to the actual state parameters of the heat pump system. For example, the initial opening degree can be determined according to the exhaust temperature and / or exhaust pressure and / or gas inlet temperature and / or gas inlet pressure and / or ambient temperature, so as to ensure energy efficiency and improve the reliability of compressor operation.

[0096] When the injection valve is an adjustable fluid valve, it can be controlled to open at a corresponding initial opening. This initial opening can be a pre-set fixed opening, or it can be determined based on the actual operating parameters of the heat pump system. For example, it can be determined based on the exhaust temperature and / or exhaust pressure and / or inlet temperature and / or inlet pressure and / or ambient temperature, to ensure energy efficiency while improving compressor operational reliability.

[0097] This invention proposes a control method for a heat pump system. During the heating operation of the heat pump system, when the first state parameter meets the enthalpy-increasing condition, the method first opens the gas injection valve to inject gas into the compressor via the gas injection branch to increase enthalpy. If, during the enthalpy-increasing process, a second state parameter determines that there is a reliability risk with the compressor, the method then opens the liquid injection valve to inject liquid into the gas injection branch to cool the gas in the gas injection branch. The cooled gas then enters the compressor through the gas injection port for enthalpy increase, thereby facilitating a rapid reduction in the exhaust temperature of the compressor. This method increases enthalpy while preventing the compressor exhaust temperature from becoming too high, thus improving both system energy efficiency and the operational reliability of the compressor.

[0098] Furthermore, in this embodiment, the first state parameter includes the ambient temperature corresponding to the heat pump system, the operating frequency of the compression device, and the condensation temperature of the heat pump system, and the gas replenishment enthalpy increase condition includes at least one of the following conditions:

[0099] The ambient temperature corresponding to the heat pump system is not greater than the preset ambient temperature;

[0100] The difference between the operating frequency of the compression device and the set frequency is not greater than a preset value;

[0101] The condensing temperature of the heat pump system is not greater than the second preset condensing temperature.

[0102] The ambient temperature is the outdoor ambient temperature, and the preset ambient temperature is greater than the freezing point temperature and the temperature difference between the ambient temperature and the freezing point temperature is less than the preset value.

[0103] The operating frequency of the compressor is its current compression frequency. The set frequency is the frequency that the compressor needs to reach to achieve the target energy efficiency under the current environment.

[0104] The condensation temperature is determined based on the current exhaust pressure of the compression unit. Specifically, the exhaust pressure is detected by the aforementioned pressure sensor, and the saturation temperature corresponding to the exhaust pressure is determined as the condensation temperature here.

[0105] In this embodiment, the heat pump system is considered to require gas injection to increase enthalpy when the first state parameter simultaneously meets the above three conditions. For example, when the ambient temperature is ≤2℃, the compressor frequency minus the set frequency is ≤5Hz, and the condensing temperature is ≤38℃.

[0106] In this embodiment, setting the gas replenishment enthalpy conditions according to the above conditions is beneficial to ensure that the insufficient output capacity of the heat pump system is detected in time during the heating operation, and gas replenishment enthalpy is performed in time to improve the output capacity of the system, thereby realizing the timely and effective improvement of the energy efficiency of the heat pump system.

[0107] Furthermore, in this embodiment, the second state parameter includes the condensing temperature of the heat pump system and the exhaust superheat of the compression device, and the liquid injection conditions include at least one of the following conditions:

[0108] The condensing temperature of the heat pump system is not greater than the first preset condensing temperature;

[0109] The exhaust superheat of the compression device is not less than the preset superheat.

[0110] The condensation temperature is determined based on the current exhaust pressure of the compression unit. Specifically, the exhaust pressure is detected by the aforementioned pressure sensor, and the saturation temperature corresponding to the exhaust pressure is determined as the condensation temperature here.

[0111] The exhaust superheat is specifically obtained by subtracting the condensing temperature from the compressor's exhaust temperature.

[0112] The first condensing temperature is specifically the minimum temperature that the condensing temperature can reach during reliable operation of the compression unit.

[0113] The preset superheat is specifically the maximum superheat that the exhaust gas can reach when the compression device is running reliably.

[0114] In this embodiment, when the second state parameter simultaneously meets the above conditions, it can be considered that the liquid injection condition is met, and the liquid injection valve can be controlled to open. For example, when the condensation temperature is ≤40℃ and the exhaust superheat is ≥15℃.

[0115] In this embodiment, setting the liquid spraying conditions according to the above conditions helps to ensure that reliability risks of the compression device are detected in a timely manner during the gas replenishment enthalpy increase process of the heat pump system. Liquid is sprayed into the gas replenishment branch in a timely manner to cool the gaseous refrigerant therein. The cooled gaseous refrigerant enters the compression device to achieve gas replenishment enthalpy increase, and the exhaust temperature of the compression device can be reduced rapidly. This enables the heat pump system to improve the energy efficiency in a timely and effective manner and enhance the operational reliability of the compression device.

[0116] To better understand the technical effects of improving energy efficiency and enhancing the operational reliability of the compression device achieved by the liquid injection branch of the liquid injection branch in the embodiments of the present invention after the liquid is injected into the gas replenishment branch, the following is combined with Figure 4 The pressure-enthalpy diagram is used for illustration:

[0117] In this embodiment, the gaseous refrigerant flowing into the injection branch is the saturated gaseous refrigerant from the outlet of the flash evaporator. When the injection valve is opened alone, the state point of the compressor's injection port is the saturated gaseous point B. After entering the intermediate cavity of the compression device through the injection port, it mixes with the exhaust gas H that has undergone primary compression to state point A. State point A is the intake state point of the secondary compression. After secondary compression, it reaches state point D. The AD segment is the compression process of the secondary cylinder.

[0118] In this state, the injection valve is opened to increase the amount of refrigerant entering the compressor. As can be seen from the pressure-enthalpy diagram, after the injection valve is opened, one stream of refrigerant passes through the injection valve and the throttling device, changing from state point F to a two-phase state point G. State point G and the saturated gaseous state point B first mix to the supersaturated state point C, then enter the compressor's intermediate chamber together, mixing with the first-stage exhaust gas H. This further lowers the exhaust temperature at the mixing point, shifting its state point to the left. To balance compression reliability (preventing liquid compression) and high energy efficiency, the theoretical optimal point is state point B. After compression by the second-stage cylinder, it reaches state point E; the BE segment represents the compression process of the second-stage cylinder.

[0119] Furthermore, based on any of the above embodiments, another embodiment of the control method for the heat pump system of this application is proposed. In this embodiment, reference is made to... Figure 5 After the step of controlling the opening of the injection valve, the method further includes:

[0120] Step S40: Obtain the change value of the exhaust superheat corresponding to the compression device;

[0121] The exhaust superheat is periodically measured, and the difference between the currently measured exhaust superheat and the previously measured exhaust superheat is determined as the variation value here. Alternatively, the variation value here can be determined based on the difference between the maximum and minimum values ​​of multiple exhaust superheat measurements within a preset time period.

[0122] Step S50: Control the opening degree of the spray valve according to the change value.

[0123] Different change values ​​correspond to different opening adjustment parameters of the injection valve.

[0124] In one implementation, the range of the changing value can be determined, and the opening adjustment parameter can be determined based on the range. The opening of the injection valve can then be adjusted according to the opening adjustment parameter. In another implementation, the opening adjustment parameter can be determined based on the magnitude or quantitative relationship between the changing value and a preset changing threshold. The opening of the injection valve can then be adjusted according to the opening adjustment parameter.

[0125] In this embodiment, the change in exhaust superheat can accurately reflect the reliability risk of the compression device. Therefore, adjusting the opening of the injection valve according to the change value helps to ensure that the injection branch can provide a precise amount of liquid to the gas injection branch, and ensures that the gas entering the compression device from the gas injection port after mixing can reach a supersaturated state. This allows the compressor's exhaust temperature to drop rapidly while increasing the enthalpy of the gas injection, thereby improving energy efficiency and effectively enhancing the operational reliability of the compression device.

[0126] Furthermore, in this embodiment, when the change value is greater than a preset change threshold, the opening of the injection valve is increased; when the change value is less than the preset change threshold, the opening of the injection valve is decreased. The preset change threshold is specifically the target value required for the change in exhaust superheat of the compressor to reliably operate during the liquid replenishment and enthalpy increase process. During the process of increasing or decreasing the opening of the injection valve, it can be adjusted according to a preset fixed opening adjustment value, or the opening adjustment value can be determined based on the actual operating parameters of the heat pump system, and the opening of the injection valve can be increased or decreased according to the opening adjustment value. For example, the refrigerant outlet temperature of the first-stage compressor can be predicted based on the compression frequency and return gas temperature of the compressor, and the opening adjustment value can be determined based on the refrigerant outlet temperature to ensure that the refrigerant discharged from the first-stage compressor and the refrigerant entering through the replenishment port can reach a saturated gaseous state after mixing, thereby effectively improving both the energy efficiency and operational reliability of the compressor.

[0127] In this embodiment, the opening of the injection valve is increased or decreased based on the relationship between the change value and the preset change threshold. This ensures that the change value of the exhaust superheat can reach the preset change value, thereby improving the compressor's energy efficiency and operational reliability.

[0128] Furthermore, based on any of the above embodiments, another embodiment of the control method for the heat pump system of this application is proposed. In this embodiment, the gas replenishment subcooling unit includes a flash evaporator, and the heat pump system further includes a throttling valve. The throttling valve is disposed between the outdoor heat exchanger and the flash evaporator or between the indoor heat exchanger and the flash evaporator. The gas replenishment branch is connected to the gas outlet of the flash evaporator. (Refer to...) Figure 6 After the step of controlling the opening of the air supply valve, the method further includes:

[0129] Step S60: Obtain the intermediate pressure of the compression device;

[0130] Intermediate pressure refers to the pressure of the gas discharged from the first stage of compression in the compression device when it is cooled into dry saturated gas.

[0131] The intermediate pressure of the compression device is detected with the air supply valve open.

[0132] Step S70: Adjust the opening of the throttle valve according to the intermediate pressure.

[0133] Different intermediate pressures correspond to different throttle valve opening adjustment parameters.

[0134] In one implementation, the pressure range containing the intermediate pressure can be determined, and the opening adjustment parameter can be determined based on the pressure range. The throttle valve is then controlled to adjust its opening according to the opening adjustment parameter. In another implementation, the opening adjustment parameter can be determined based on the magnitude or quantitative relationship between the intermediate pressure and the target pressure. The throttle valve is then controlled to adjust its opening according to the opening adjustment parameter.

[0135] In this embodiment, the magnitude of the intermediate pressure can accurately reflect the current energy efficiency of the compression device. Based on this, the opening of the throttle valve can be adjusted according to the intermediate pressure, which is beneficial to improve the energy efficiency of the heat pump system while replenishing gas and increasing enthalpy.

[0136] Furthermore, in this embodiment, the step of controlling the throttle valve to adjust its opening based on the intermediate pressure includes: when the intermediate pressure is greater than the target pressure, controlling the throttle valve to increase its opening; and when the intermediate pressure is less than the target pressure, controlling the throttle valve to decrease its opening.

[0137] The target pressure is specifically the target value that the heat pump system needs to reach when it achieves optimal energy efficiency. The target pressure can be a pre-set fixed value or a value determined based on the actual operating conditions of the heat pump system. In this embodiment, to ensure accurate and effective improvement of system energy efficiency, the exhaust pressure and compression frequency of the compression device are obtained before adjusting the throttle valve opening; the target pressure is then determined based on the exhaust pressure and the compression frequency. Different exhaust pressures and different compression frequencies correspond to different target pressures.

[0138] During the process of increasing or decreasing the opening degree of the throttle valve, it can be adjusted according to a preset fixed opening degree adjustment value, or the opening degree adjustment value can be determined based on the actual operating parameters of the heat pump system, and the opening degree of the throttle valve can be increased or decreased accordingly. For example, the opening degree adjustment value can be determined based on the current opening degree of the control valve, the current opening degree of the injection valve, the temperature of the air inlet, and the exhaust temperature, thereby improving the energy efficiency of the heat pump system while improving the operational reliability of the compression unit.

[0139] In this embodiment, the opening of the throttle valve is increased or decreased based on the relationship between the intermediate pressure and the target pressure, which can ensure that the intermediate pressure can accurately reach the target pressure, thereby effectively improving the compressor's energy efficiency.

[0140] Furthermore, based on any of the above embodiments, another embodiment of the control method for the heat pump system of this application is proposed. In this embodiment, the heat pump system further includes a throttling valve and a control valve, the gas replenishment subcooling unit includes a flash evaporator, the throttling valve is disposed between the outdoor heat exchanger and the flash evaporator, and the control valve is disposed between the indoor heat exchanger and the flash evaporator, as shown in the figure. Figure 7 The control method for the heat pump system further includes:

[0141] Step S101: Control the heat pump system to operate in heating mode and obtain the exhaust superheat of the compression device;

[0142] The process for detecting exhaust superheat is as follows: The exhaust temperature and exhaust pressure of the compression device are detected by the pressure sensor and temperature sensor mentioned above. The saturation temperature corresponding to the exhaust pressure is determined. The exhaust superheat is determined based on the difference between the exhaust temperature and the saturation temperature.

[0143] Step S102: Control the opening degree of the throttle valve and / or the control valve according to the exhaust superheat, and perform the step of obtaining the first state parameters of the heat pump system.

[0144] The first state parameter is detected during the process of adjusting the opening of the throttle valve and / or control valve according to the exhaust superheat.

[0145] In one implementation of this embodiment, the opening of the throttle valve is first adjusted according to the exhaust superheat. Once the throttle valve opening reaches a certain condition, the opening of the control valve is then adjusted according to the exhaust superheat. In this embodiment, the opening of the throttle valve is adjusted according to the exhaust superheat until it exceeds a preset range or triggers the protection condition of the heat pump system. The opening of the control valve is then adjusted according to the exhaust superheat. Here, adjusting the throttle valve opening is prioritized within the preset range or when the system protection condition is not triggered. Adjusting the control valve only when the range is exceeded or the system protection condition is triggered helps ensure stable pressure within the flash evaporator and allows for rapid input of saturated steam to the gas injection port after the enthalpy-boosting condition is triggered, thereby achieving a rapid increase in the energy efficiency of the heat pump system.

[0146] In another implementation of this embodiment, the opening degree can be adjusted by either the throttling valve or the control valve according to the exhaust superheat. The valve body whose opening degree needs to be adjusted can be a pre-set fixed valve body or a valve body determined according to the actual operation of the heat pump system. For example, the opening degree can be adjusted by either the throttling valve or the control valve according to the flash pressure range in the flash evaporator.

[0147] In another implementation of this embodiment, the openings of the throttle valve and the control valve can be adjusted simultaneously according to the exhaust superheat. Specifically, a target adjustment value and the adjustment ratio of the throttle valve and the control valve can be determined according to the exhaust superheat. A first adjustment value for the throttle valve and a second adjustment value for the control valve can be determined according to the target adjustment value and the adjustment ratio. The opening of the throttle valve is adjusted according to the first adjustment value, while the opening of the control valve is adjusted according to the second adjustment value.

[0148] In this embodiment, when the exhaust superheat is less than the target superheat, the throttle valve is controlled to decrease its opening; when the exhaust superheat is greater than the target superheat, the throttle valve is controlled to increase its opening. Based on this, it can be ensured that the exhaust superheat of the heat pump system can accurately reach the target superheat.

[0149] In this embodiment, when the exhaust superheat is less than the target superheat, the control valve is controlled to decrease its opening; when the exhaust superheat is greater than the target superheat, the control valve is controlled to increase its opening. Based on this, it can be ensured that the exhaust superheat of the heat pump system can accurately reach the target superheat.

[0150] In this embodiment, the exhaust superheat can accurately reflect whether the current heating capacity of the system can meet the demand. The exhaust superheat can be used to adjust the opening of the throttle valve and / or control valve to ensure that the current heating capacity of the system can meet the actual demand.

[0151] Furthermore, embodiments of the present invention also propose a storage medium storing a control program for a heat pump system. When the control program for the heat pump system is executed by a processor, it implements the relevant steps of any embodiment of the control method for the heat pump system described above.

[0152] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0153] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0154] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, heat pump system, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0155] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A control method for a heat pump system, characterized in that, The heat pump system includes a compressor, a four-way valve, an outdoor heat exchanger, a gas-injection subcooling unit, an indoor heat exchanger, a gas-injection branch, and a liquid injection branch. The compressor, the four-way valve, the outdoor heat exchanger, the gas-injection subcooling unit, and the indoor heat exchanger are connected sequentially. The gas-injection subcooling unit is connected to the gas-injection port or the secondary compressor intake port of the compressor via the gas-injection branch. One end of the liquid injection branch is connected between the indoor heat exchanger and the gas-injection subcooling unit, or between the outdoor heat exchanger and the gas-injection subcooling unit. The other end of the liquid injection branch is connected to the gas-injection branch. The gas-injection branch is equipped with a gas-injection valve, and the liquid injection branch is equipped with a liquid injection valve. The control method of the heat pump system includes the following steps: Control the heat pump system to operate in heating mode and obtain the first state parameters of the heat pump system; When the first state parameter meets the gas replenishment and enthalpy increase condition, the gas replenishment valve is controlled to open and the second state parameter of the heat pump system is obtained. When the second state parameter meets the spraying conditions, the spraying valve is controlled to open; The second state parameter includes the condensing temperature of the heat pump system and the exhaust superheat of the compression device, and the liquid injection conditions include the following: The condensing temperature of the heat pump system is not greater than the first preset condensing temperature, which is the minimum temperature that the condensing temperature can reach when the compression device is running reliably. The exhaust superheat of the compression device is not less than the preset superheat.

2. The control method for a heat pump system as described in claim 1, characterized in that, After the step of controlling the opening of the injection valve, the method further includes: Obtain the change value of the exhaust superheat corresponding to the compression device; The opening degree of the injection valve is adjusted according to the change value.

3. The control method for a heat pump system as described in claim 2, characterized in that, The step of controlling the opening of the injection valve according to the change value includes: When the change value is greater than a preset change threshold, the spray valve is controlled to increase its opening. When the change value is less than the preset change threshold, the opening of the spray valve is reduced.

4. The control method for a heat pump system as described in claim 1, characterized in that, The gas replenishment subcooling unit includes a flash evaporator, and the heat pump system further includes a throttling valve. The throttling valve is disposed between the outdoor heat exchanger and the flash evaporator or between the indoor heat exchanger and the flash evaporator. The gas replenishment branch is connected to the gas outlet of the flash evaporator. After the step of controlling the opening of the gas replenishment valve, the system further includes: Obtain the intermediate pressure of the compression device; The opening degree of the throttle valve is adjusted according to the intermediate pressure.

5. The control method for a heat pump system as described in claim 4, characterized in that, The step of controlling the opening of the throttle valve according to the intermediate pressure includes: When the intermediate pressure is greater than the target pressure, the throttle valve is controlled to increase its opening. When the intermediate pressure is less than the target pressure, the throttle valve is controlled to reduce its opening.

6. The control method for a heat pump system as described in claim 5, characterized in that, Before the step of controlling the throttle valve opening according to the intermediate pressure, the method further includes: Obtain the exhaust pressure and compression frequency of the compression device; The target pressure is determined based on the exhaust pressure and the compression frequency.

7. The control method for a heat pump system as described in claim 1, characterized in that, The first state parameters include the ambient temperature corresponding to the heat pump system, the operating frequency of the compression device, and the condensing temperature of the heat pump system. The gas replenishment and enthalpy increase conditions include at least one of the following conditions: The ambient temperature corresponding to the heat pump system is not greater than the preset ambient temperature; The difference between the operating frequency of the compression device and the set frequency is not greater than a preset value; The condensing temperature of the heat pump system is not greater than the second preset condensing temperature.

8. The control method for a heat pump system as described in any one of claims 1 to 7, characterized in that, The heat pump system further includes a throttling valve and a control valve. The gas replenishment subcooling unit includes a flash evaporator. The throttling valve is disposed between the outdoor heat exchanger and the flash evaporator. The control valve is disposed between the indoor heat exchanger and the flash evaporator. The control method of the heat pump system further includes: Control the heat pump system to operate in heating mode and obtain the exhaust superheat of the compression device; The opening degree of the throttle valve and / or the control valve is adjusted according to the exhaust superheat, and the step of obtaining the first state parameters of the heat pump system is performed.

9. The control method for a heat pump system as described in claim 8, characterized in that, The step of controlling the opening of the throttle valve and / or the control valve according to the exhaust superheat includes: Adjust the opening of the throttle valve according to the exhaust superheat until the opening of the throttle valve exceeds the preset opening range or triggers the protection conditions of the heat pump system. Adjust the opening of the control valve according to the exhaust superheat.

10. The control method for a heat pump system as described in claim 9, characterized in that, The step of adjusting the opening of the throttle valve according to the exhaust superheat includes: When the exhaust superheat is less than the target superheat, control the throttle valve to reduce its opening. When the exhaust superheat is greater than the target superheat, the throttle valve is controlled to increase its opening.

11. The control method for a heat pump system as described in claim 9, characterized in that, The step of adjusting the opening of the control valve according to the exhaust superheat includes: When the exhaust superheat is less than the target superheat, the control valve is controlled to reduce its opening. When the exhaust superheat is greater than the target superheat, the control valve is controlled to increase its opening.

12. A heat pump system, characterized in that, The heat pump system includes a control device, a compression device, a four-way valve, an outdoor heat exchanger, a gas replenishment subcooling unit, an indoor heat exchanger, a gas replenishment branch, and a liquid injection branch. The compression device, the four-way valve, the outdoor heat exchanger, the gas replenishment subcooling unit, and the indoor heat exchanger are connected in sequence. The gas replenishment subcooling unit is connected to the gas replenishment port or the secondary compression intake port of the compression device through the gas replenishment branch. One end of the liquid injection branch is connected between the indoor heat exchanger and the gas replenishment subcooling unit or between the outdoor heat exchanger and the gas replenishment subcooling unit. The other end of the liquid injection branch is connected to the gas replenishment branch. The gas replenishment branch is equipped with a gas replenishment valve, and the liquid injection branch is equipped with a liquid injection valve. Both the gas replenishment valve and the liquid injection valve are connected to the control device, which includes a memory, a processor, and a control program for the heat pump system stored in the memory and executable on the processor. When the control program for the heat pump system is executed by the processor, it implements the steps of the control method for the heat pump system as described in any one of claims 1 to 11.

13. The heat pump system as described in claim 12, characterized in that, The heat pump system further includes a throttling valve and a control valve. The gas replenishment subcooling unit includes a flash evaporator. The throttling valve is located between the outdoor heat exchanger and the flash evaporator or between the indoor heat exchanger and the flash evaporator. The control valve is located between the indoor heat exchanger and the flash evaporator and is connected to the control device.

14. A storage medium, characterized in that, The storage medium stores a control program for a heat pump system, which, when executed by a processor, implements the steps of the control method for the heat pump system as described in any one of claims 1 to 11.

Images