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

Abstract

The invention discloses a control method of a heat pump system, the heat pump system and a storage medium. In the heat pump system, a compression device, a four-way valve, an outdoor heat exchanger, an air supply supercooling unit and an indoor heat exchanger are sequentially connected, and the air supply supercooling unit communicates with an air supply port or a secondary compression air suction port of the compression device through an air supply branch. One end of the liquid spraying branch is connected between the indoor heat exchanger and the air supply supercooling unit or between the outdoor heat exchanger and the air supply supercooling unit, the other end of the liquid spraying branch communicates with the air supply branch, the air supply branch is provided with an air supply valve, and the liquid spraying branch is provided with a liquid spraying valve. Acquiring a first state parameter of the heat pump system; when the first state parameter meets the air supply enthalpy increasing condition, an air supply valve is controlled to be opened, and a second state parameter of the heat pump system is obtained; and when the second state parameter meets the liquid spraying condition, the liquid spraying valve is controlled to be opened. The invention aims to improve the energy efficiency of the system and ensure the operation reliability of the compression device.

Description

Technical Field

[0001] The present invention relates to the technical field of heat pumps, and in particular to a control method for a heat pump system, a heat pump system and a storage medium. Background Art

[0002] When the heat pump system is heating at low temperature, a flash evaporator is generally installed. The flash gas in the flash evaporator is introduced into the compression device through the air supply branch for air supply and pressure increase, so as to provide sufficient air supply volume for the compression device and improve the energy efficiency of the system. However, the air supply volume cannot be adjusted, which easily leads to excessively high exhaust temperature of the compression device, affecting the operational reliability of the compression device. Summary of the invention

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

[0004] To achieve the above-mentioned object, the present invention provides a control method for a heat pump system, the heat pump system comprising a compression device, a four-way valve, an outdoor heat exchanger, an air-supplementing subcooling unit, an indoor heat exchanger, an air-supplementing branch and a liquid-spraying branch, the compression device, the four-way valve, the outdoor heat exchanger, the air-supplementing subcooling unit and the indoor heat exchanger are connected in sequence, the air-supplementing subcooling unit is communicated with an air-supplementing port or a secondary compression air suction port of the compression device through the air-supplementing branch, one end of the liquid-spraying branch is connected between the indoor heat exchanger and the air-supplementing subcooling unit or between the outdoor heat exchanger and the air-supplementing subcooling unit, the other end of the liquid-spraying branch is communicated with the air-supplementing branch, the air-supplementing branch is provided with an air-supplementing valve, the liquid-spraying branch is provided with a liquid-spraying valve, and the control method for the heat pump system comprises the following steps:

[0005] Controlling the heating operation of the heat pump system and obtaining a first state parameter of the heat pump system;

[0006] When the first state parameter satisfies the air supply enthalpy increase condition, controlling the air supply valve to open and obtaining the second state parameter of the heat pump system;

[0007] When the second state parameter meets the liquid injection condition, the liquid injection 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 condition includes at least one of the following conditions:

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

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

[0011] Optionally, after the step of controlling the liquid spray valve to open, the method further comprises:

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

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

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

[0015] When the change value is greater than a preset change threshold, controlling the liquid injection valve to increase its opening;

[0016] When the change value is less than the preset change threshold, the liquid injection valve is controlled to reduce the opening degree.

[0017] Optionally, the air-supplementing subcooling unit includes a flash evaporator, the heat pump system further includes a throttle valve, the throttle valve is arranged between the outdoor heat exchanger and the flash evaporator or between the indoor heat exchanger and the flash evaporator, the air-supplementing branch is connected to the air outlet of the flash evaporator, and after the step of controlling the opening of the air-supplementing valve, the step further includes:

[0018] obtaining an intermediate pressure of the compression device;

[0019] The throttle valve is controlled to adjust its opening according to the intermediate pressure.

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

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

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

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

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

[0025] The target pressure is determined according to the exhaust pressure and the compression frequency.

[0026] Optionally, the first state parameter includes 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 air supplement enthalpy increase condition includes 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 a second preset condensing temperature.

[0030] Optionally, the heat pump system further includes a throttle valve and a control valve, the air supplement subcooling unit includes a flash evaporator, the throttle valve is arranged between the outdoor heat exchanger and the flash evaporator, the control valve is arranged between the indoor heat exchanger and the flash evaporator, and the control method of the heat pump system further includes:

[0031] Controlling the heating operation of the heat pump system and obtaining the exhaust superheat of the compression device;

[0032] The throttle valve and / or the control valve are controlled to adjust the opening according to the exhaust gas superheat, and the step of obtaining the first state parameter of the heat pump system is performed.

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

[0034] adjusting the opening of the throttle valve according to the exhaust gas superheat until the opening of the throttle valve exceeds a preset opening range or triggers a protection condition of the heat pump system;

[0035] The control valve opening is adjusted according to the exhaust gas superheat.

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

[0037] When the exhaust gas superheat is less than the target superheat, controlling the throttle valve to reduce the opening;

[0038] When the exhaust gas 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 comprises:

[0040] When the exhaust gas superheat is less than the target superheat, controlling the control valve to reduce the opening;

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

[0042] In addition, in order to achieve the above-mentioned purpose, the present application also proposes a heat pump system, which includes a control device, a compression device, a four-way valve, an outdoor heat exchanger, an air-supplementing subcooling unit, an indoor heat exchanger, an air-supplementing branch and a liquid injection branch, wherein the compression device, the four-way valve, the outdoor heat exchanger, the air-supplementing subcooling unit and the indoor heat exchanger are connected in sequence, the air-supplementing subcooling unit is connected to the air-supplementing port or the secondary compression air suction port of the compression device through the air-supplementing branch, one end of the liquid injection branch is connected between the indoor heat exchanger and the air-supplementing subcooling unit or between the outdoor heat exchanger and the air-supplementing subcooling unit, the other end of the liquid injection branch is connected to the air-supplementing branch, the air-supplementing branch is provided with an air-supplementing valve, and the liquid injection branch is provided with a liquid injection valve;

[0043] The air supply valve and the liquid injection valve are both 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, the steps of the control method for the heat pump system as described in any one of the above items are implemented.

[0044] Optionally, the heat pump system also includes a throttle valve and a control valve, the air supplement subcooling unit includes a flash evaporator, the throttle valve is arranged between the outdoor heat exchanger and the flash evaporator or between the indoor heat exchanger and the flash evaporator, the control valve is arranged between the indoor heat exchanger and the flash evaporator, and the control valve is connected to the control device.

[0045] In addition, in order to achieve the above-mentioned purpose, the present application also proposes a storage medium, on which a control program of a heat pump system is stored. When the control program of the heat pump system is executed by a processor, the steps of the control method of the heat pump system as described in any of the above items are implemented.

[0046] A control method for a heat pump system proposed in the present invention is based on a heat pump system provided with an air supply branch and a liquid injection branch. When a first state parameter meets an air supply and enthalpy increase condition during the heating operation of the heat pump system, the method first opens the air supply valve to supply air to the compression device through the air supply branch to increase enthalpy. When it is determined based on the second state parameter that there is a reliability risk in the compression device during the air supply and enthalpy increase process, the liquid injection valve is opened again to spray liquid to the air supply branch through the liquid injection branch to cool the gas in the air supply branch. The cooled gas enters the compressor through the air supply port to supply air to increase enthalpy, which is beneficial to the rapid reduction of the exhaust temperature of the compression device. While supplying air to increase enthalpy, the compressor exhaust temperature can be prevented from being too high, thereby improving the system energy efficiency and the operating reliability of the compression device at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A schematic diagram of the structure of a refrigerant flow path of a heat pump system according to an embodiment of the present invention;

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

[0049] Figure 3 A schematic flow chart of an embodiment of a control method for a heat pump system of the present invention;

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

[0051] Figure 5 A schematic flow chart of another embodiment of a control method for a heat pump system of the present invention;

[0052] Figure 6 A schematic flow chart of another embodiment of a control method for a heat pump system of the present invention;

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

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

[0055] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0056] An embodiment of the present 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, an air supply subcooling unit 302, an outdoor heat exchanger 700, an air supply branch 300 and a liquid injection branch 400. The compression device 200, the four-way valve 900, the outdoor heat exchanger 700, the air supply subcooling unit 302 and the indoor heat exchanger 500 are connected in sequence. The air supply branch 300 and the air supply subcooling unit 302 are connected in sequence. The air supply branch 300 is connected to the air 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 air supply subcooling unit 302 or between the outdoor heat exchanger 700 and the air supply subcooling unit 302, the other end of the liquid injection branch 400 is connected to the air supply branch 300, the air supply branch 300 is provided with an air supply valve 301, and the liquid injection branch 400 is provided with a liquid injection valve 401.

[0058] The exhaust port of the compression device 200, the return port of the compression device 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 air supply branch 300 is used to introduce the medium-pressure gas generated by the air supply subcooling unit 302 into the air supply port or the secondary compression suction port of the compression device 200 to supply air and increase 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 supplement branch 300 to cool the saturated gas in the gas supplement branch 300 to supersaturated gas, thereby reducing the exhaust temperature of the compression device 200.

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

[0062] In this embodiment, the air-supplement subcooling unit 302 is a flash evaporator, which includes a first refrigerant port, a second refrigerant port, and an air outlet, wherein 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 air-supplement subcooling unit 302 may also include an economizer, wherein the air-supplement branch 300 is connected to the economizer, and one end of the air-supplement branch 300 is connected between the outdoor heat exchanger 700 and the economizer, and the other end of the air-supplement branch 300 is connected to the air-supplement port or the secondary compression suction port of the compression device 200, and the air-supplement valve 301 is an electronic expansion valve and is arranged between one end of the air-supplement branch and the economizer.

[0063] In this embodiment, the compression device 200 is a two-stage compression device 200, and the compression device 200 may include a primary compressor and a secondary compressor connected to the primary compressor, the air inlet of the primary compressor is the return air inlet of the compression device 200, the air outlet of the primary compressor is connected to the air inlet of the secondary compressor, the connecting passage between the air outlet of the primary compressor and the air inlet of the secondary compressor is connected to the air supplementary subcooling unit 302 through the air supplementary branch 300, and the air 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 air return port of the compressor, the primary compression cylinder, the secondary compression cylinder and the exhaust port of the compression cylinder are connected in sequence, and the connecting passage between the primary compression cylinder and the secondary compression cylinder is connected to the air supplementary subcooling unit 302 through the air supplementary 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 an air return port, an air supply port and an air exhaust port. The air supply port is connected to the air supply subcooling unit 302 through the air supply branch 300.

[0065] Further, in this embodiment, referring to Figure 1 The heat pump system further comprises a throttle valve 600 and a control valve 800. The throttle valve 600 is arranged between the outdoor heat exchanger 700 and the flash evaporator or between the indoor heat exchanger 500 and the flash evaporator. The air-supplementing subcooling unit 302 comprises a flash evaporator. The air-supplementing branch 300 is connected to the air outlet of the flash evaporator. The control valve 800 is arranged between the indoor heat exchanger 500 and the flash evaporator. The liquid injection branch 400 is provided with a throttle component 402 connected in series with the liquid injection valve 401. The pipeline between the flash evaporator 302 and the air-supplementing branch 300 is provided with a control valve 800.

[0066] In this embodiment, the throttling component 402 is a capillary tube, and the liquid spraying valve 401 is an electronic expansion valve. In other embodiments, the throttling component 402 and the liquid spraying valve 401 can also be combined into one electronic expansion valve, or the throttling component 402 and the liquid spraying valve 401 are both electronic expansion valves.

[0067] When the heat pump system is in heating operation, the exhaust port of the compression device 200 is connected to the indoor heat exchanger 500, and the return air port of the compression device 200 is connected to the outdoor heat exchanger 700. The refrigerant discharged from the compressor flows through the indoor heat exchanger 500, the control valve 800, the flash evaporator, the throttle valve 600, and the outdoor heat exchanger 700 in sequence and then flows back to the compressor. The indoor heat exchanger 500 is in a condensing state, and the outdoor heat exchanger 700 is in an evaporating state. Among them, the saturated gas separated by flash evaporation of the refrigerant entering the flash evaporator after being condensed can be discharged from the air outlet. When the air supply valve 301 is opened, the saturated gas discharged from the air outlet can flow through the air supply branch 300 and enter the air supply port to replenish air and increase the enthalpy of the compression device 200; 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 throttling by the throttling component 402 can enter the air supply branch 300 and mix with the saturated gas in the air supply branch 300. The supersaturated gas formed after mixing will enter the medium-pressure area of ​​the compression device 200 from the air supply port or the secondary compression suction port.

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

[0069] Further, see Figure 2The heat pump system further includes an environment detection module 02 connected to the control device 100. The environment detection module 02 is disposed 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 environment detection module 02 is used to detect the outdoor ambient temperature.

[0070] Further, see Figure 1 and Figure 2 The heat pump system also includes a temperature sensor 03 connected to the control device 100, which can be arranged at the exhaust port of the compression device 200 or on a pipeline connected to the exhaust port of the compression device 200 to detect the exhaust temperature of the compression device 200.

[0071] In the embodiment of the present invention, refer 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. Among them, these components are connected and communicated through a communication bus. The memory 1002 can be a high-speed RAM memory or a stable memory (non-volatile memory), such as a disk memory. 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 in the figure does not constitute a limitation of the device, and may include more or less components than shown in the figure, or combine certain components, or arrange the components differently.

[0073] like Figure 2 As shown, the memory 1002 as a computer storage medium may include a control program for the 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 step operations of the control method of the heat pump system in the following embodiment.

[0075] An embodiment of the present invention further provides a control method for a heat pump system, which is applied to the above-mentioned heat pump system.

[0076] Reference Figure 3 , an embodiment of a control method of a heat pump system of the present application is proposed. In this embodiment, the control method of the heat pump system includes:

[0077] Step S10, controlling the heat pump system to perform heating operation, and obtaining a first state parameter of the heat pump system;

[0078] During the heating operation of the heat pump system, the refrigerant discharged from the compressor flows through the indoor heat exchanger, the throttle valve, the outdoor heat exchanger in sequence, and then flows back to the compressor. The indoor heat exchanger is in a condensing state, and the outdoor heat exchanger is in an evaporating state.

[0079] The first state parameter may be any parameter that characterizes the output capacity of the heat pump system under the current environment. The first state parameter may include operating parameters of the heat pump system itself (such as compressor frequency, etc.) and / or state characteristic parameters of the heat pump system operation process detected by the detection module (such as temperature and / or pressure, etc.) and / or environmental parameters of the environment where the heat pump system is located (such as ambient temperature and / or humidity, etc.). 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 value, exhaust temperature change value, etc.

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

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

[0082] Step S20, when the first state parameter meets the air-injection enthalpy-increasing condition, control the air-injection valve to open and obtain the second state parameter of the heat pump system;

[0083] The air replenishment and enthalpy increase condition is specifically a preset condition that the first state parameter needs to satisfy when it is characterized that the current heating output capacity of the heat pump system is insufficient and air replenishment and enthalpy increase are needed to improve the system energy efficiency.

[0084] The air replenishment and enthalpy increase conditions may include the target parameter range that the above-mentioned operating parameters and / or state characteristic parameters and / or environmental parameters need to reach, or the quantitative relationship or size 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 air-injection enthalpy increase condition, the air-injection valve and the liquid injection valve may be opened simultaneously.

[0086] In another implementation, when the first state parameter satisfies the air-injection enthalpy-increasing condition, the air-injection valve is opened first, and then the liquid injection valve is opened.

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

[0088] Wherein, when the air supply valve is a fluid valve with adjustable opening, the air supply valve can be controlled to open at a corresponding initial opening. The initial opening here can be a preset fixed opening, or an opening determined according to actual operating parameters of the heat pump system, for example, the initial opening here can be determined according to exhaust temperature and / or exhaust pressure and / or air supply port temperature and / or air supply port pressure and / or ambient temperature, etc., so as to ensure energy efficiency and improve compressor operation reliability.

[0089] The second state parameter may be any parameter related to the reliability of the compressor of the heat pump system after the air is supplemented and the enthalpy is increased. The second state parameter may include the operating parameters of the heat pump system itself (such as compressor frequency, etc.) and / or the state characteristic parameters of the heat pump system operation process detected by the detection module (such as temperature and / or pressure, etc.) and / or the environmental parameters of the environment where the heat pump system is located (such as ambient temperature and / or humidity, etc.). 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 value, exhaust temperature change value, etc.

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

[0091] Step S30: When the second state parameter satisfies the liquid injection condition, the liquid injection valve is controlled to open.

[0092] The liquid injection condition is the condition that the second state parameter needs to meet when there is a reliability risk caused by excessive exhaust temperature during the compressor air replenishment enthalpy increase process and liquid injection is required 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 reach, or the quantitative relationship or size 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 liquid injection valve specifically refers to switching from a closed state to an open state.

[0095] The injection valve can be opened at a preset initial opening, or it can be opened at an initial opening determined according to actual state parameters of the heat pump system. For example, the initial opening here can be determined based on the exhaust temperature and / or exhaust pressure and / or air inlet temperature and / or air inlet pressure and / or ambient temperature, so as to ensure energy efficiency while improving the operating reliability of the compressor.

[0096] Wherein, when the liquid injection valve is a fluid valve with adjustable opening, the liquid injection valve can be controlled to open at a corresponding initial opening. The initial opening here can be a preset fixed opening, or an opening determined according to actual operating parameters of the heat pump system, for example, the initial opening here can be determined according to exhaust temperature and / or exhaust pressure and / or air inlet temperature and / or air inlet pressure and / or ambient temperature, so as to ensure energy efficiency and improve compressor operation reliability.

[0097] A control method for a heat pump system is proposed in an embodiment of the present invention. When a first state parameter satisfies an air-inflation and enthalpy-increasing condition during the heating operation of the heat pump system, the method first opens an air-inflation valve to inflate and increase enthalpy of a compression device through an air-inflation branch. When it is determined based on a second state parameter that there is a reliability risk in the compression device during the air-inflation and enthalpy-increasing process, the liquid injection valve is opened to spray liquid into the air-inflation branch through the liquid injection branch to cool the gas in the air-inflation branch. The cooled gas enters the compressor through an air-inflation port to inflate and increase enthalpy, which is beneficial to quickly reduce the exhaust temperature of the compression device. While inflation and enthalpy-increasing, the compressor exhaust temperature can be prevented from being too high, thereby improving the system energy efficiency and the operating reliability of the compression device at the same time.

[0098] Further, 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 condensing temperature of the heat pump system, and the air 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 a 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 compression device is the current compression frequency of the compression device. The set frequency is the frequency that the compression device needs to reach when it reaches the target energy efficiency under the current environment.

[0104] The condensing temperature is determined according to the current exhaust pressure of the compression device. Specifically, the exhaust pressure is detected by the above-mentioned pressure sensor, and the saturation temperature corresponding to the exhaust pressure is determined as the condensing temperature here.

[0105] In this embodiment, when the first state parameter satisfies the above three conditions at the same time, it can be considered that the heat pump system needs to add air to increase enthalpy. For example, when the ambient temperature is ≤2°C and the compressor frequency-set frequency is ≤5Hz and the condensing temperature is ≤38°C.

[0106] In this embodiment, the air replenishment and enthalpy increase conditions are set according to the above conditions, which is conducive to ensuring that the insufficient output capacity of the heat pump system is discovered in time during the heating operation, and that air replenishment and enthalpy increase are performed in time to improve the output capacity of the system, thereby realizing timely and effective improvement of the energy efficiency of the heat pump system.

[0107] Further, 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 condition includes at least one of the following conditions:

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

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

[0110] The condensing temperature is determined according to the current exhaust pressure of the compression device. Specifically, the exhaust pressure is detected by the above-mentioned pressure sensor, and the saturation temperature corresponding to the exhaust pressure is determined as the condensing temperature here.

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

[0112] The first condensing temperature is specifically the minimum temperature that the condensing temperature is allowed to reach when the compression device operates reliably.

[0113] The preset superheat is specifically the maximum superheat that the exhaust gas superheat is allowed to reach when the compression device operates reliably.

[0114] In this embodiment, when the second state parameter satisfies the above conditions at the same time, 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 condensing temperature is ≤40°C and the exhaust superheat is ≥15°C.

[0115] In this embodiment, the liquid injection conditions are set according to the above conditions, which is conducive to ensuring that the reliability risk of the compression device is discovered in time during the process of replenishing air and increasing enthalpy in the heat pump system, and the air replenishment branch is sprayed with liquid in time to cool the gaseous refrigerant therein. The cooled gaseous refrigerant enters the compression device to replenish air and increase enthalpy, and the exhaust temperature of the compression device can be quickly reduced, thereby realizing the energy efficiency of the heat pump system and timely and effectively improving the operating reliability of the compression device.

[0116] In order to better understand the technical effect of improving energy efficiency and improving the operating reliability of the compression device after the liquid injection branch of the embodiment of the present invention is sprayed to the gas injection branch, the following is combined with Figure 4 The pressure-enthalpy diagram is used to illustrate:

[0117] In this embodiment, the gaseous refrigerant flowing into the air supply branch is the saturated gaseous refrigerant coming out of the air outlet of the flash evaporator. When the air supply valve is opened alone, the state point of the air supply port of the compressor is the saturated gaseous point B. After entering the middle cavity of the compression device through the air supply port, it is mixed with the exhaust gas H that has undergone the first-stage compression to state point A. State point A is the suction state point of the second-stage compression. After the second-stage compression, it reaches state point D. The AD section is the compression process of the second-stage cylinder.

[0118] In this state, the liquid injection valve is opened to increase the amount of supplementary air entering the compressor. From the pressure-enthalpy diagram, it can be seen that after the liquid injection valve is opened, the refrigerant passes through the throttling of the liquid injection valve and the throttling component, and changes from state point F to state point G of gas-liquid two-phase. State point G and saturated gas point B are first mixed to supersaturated state point C, and enter the middle cavity of the compressor together to mix with the first-stage exhaust H, further reducing the exhaust temperature of the mixing point, making its state point shift to the left. In order to take into account both compression reliability (preventing liquid compression) and high energy efficiency, the theoretical optimal point is state point B. After being compressed by the secondary cylinder, it reaches state point E, and the BE section is the compression process of the secondary cylinder.

[0119] Further, based on any of the above embodiments, another embodiment of the control method of the heat pump system of the present application is proposed. In this embodiment, referring to Figure 5 , after the step of controlling the liquid injection valve to open, the method further comprises:

[0120] Step S40, obtaining a change value of the exhaust gas superheat corresponding to the compression device;

[0121] The exhaust superheat is detected periodically, and the difference between the currently detected exhaust superheat and the previously detected exhaust superheat is determined as the change value here. Alternatively, the change value here can also be determined based on the difference between the maximum value and the minimum value of multiple exhaust superheats detected within a preset time period.

[0122] Step S50, controlling the liquid injection valve to adjust the opening according to the change value.

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

[0124] In one implementation, the interval of the change value can be determined, the opening adjustment parameter can be determined according to the interval, and the opening of the spray valve can be controlled according to the opening adjustment parameter. In another implementation, the opening adjustment parameter can be determined according to the size relationship or quantity relationship between the change value and the preset change threshold, and the opening of the spray valve can be controlled according to the opening adjustment parameter.

[0125] In this embodiment, the change in the exhaust superheat value can accurately reflect the reliability risk of the compression device. Therefore, the opening of the liquid injection valve is adjusted according to the change in value, which is beneficial to ensure that the liquid injection branch can provide an accurate amount of liquid replenishment for the air supply branch, and ensure that the gas entering the compression device from the air supply port after mixing can reach a supersaturated state, so as to achieve air supply and enthalpy increase while the exhaust temperature of the compressor can be quickly reduced, thereby achieving energy efficiency improvement and effectively improving the operating reliability of the compression device.

[0126] Furthermore, in the present embodiment, 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 spray valve is controlled to decrease its opening. The preset change threshold is specifically the target value that the change value of the exhaust superheat needs to reach for reliable operation of the compression device during the process of replenishing enthalpy. In the process of increasing or decreasing the opening, the spray valve can be adjusted according to a preset fixed opening adjustment value, or the opening adjustment value can be determined according to the actual operating state parameters of the heat pump system, and the opening of the spray valve can be increased or decreased according to the opening adjustment value. For example, the refrigerant outflow temperature of the first-stage compression can be predicted according to the compression frequency and return air temperature of the compression device, and the opening adjustment value can be determined according to the refrigerant outflow temperature to ensure that the refrigerant discharged from the first-stage compression can reach a saturated gas state after mixing with the refrigerant entering the air replenishment port, thereby effectively improving the energy efficiency and operating reliability of the compression device at the same time.

[0127] In this embodiment, the injection valve is controlled to increase or decrease its opening based on the relationship between the change value and the preset change threshold, which can ensure that the change value of the exhaust superheat can reach the preset change value, thereby achieving an effective improvement in the operating reliability while improving the energy efficiency of the compressor.

[0128] Further, based on any of the above embodiments, another embodiment of the control method of the heat pump system of the present application is proposed. In this embodiment, the air supplement subcooling unit includes a flash evaporator, and the heat pump system also includes a throttle valve, which is arranged between the outdoor heat exchanger and the flash evaporator or between the indoor heat exchanger and the flash evaporator, and the air supplement branch is connected to the air outlet of the flash evaporator. Figure 6 , after the step of controlling the air supply valve to open, the method further includes:

[0129] Step S60, obtaining 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 to dry saturated gas.

[0131] When the air supply valve is in the open state, the intermediate pressure of the compression device here is detected.

[0132] Step S70: controlling the throttle valve to adjust its opening according to the intermediate pressure.

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

[0134] In one implementation, the pressure range in which the intermediate pressure is located can be determined, the opening adjustment parameter can be determined according to the pressure range, and the throttle valve can be controlled to adjust the opening according to the opening adjustment parameter. In another implementation, the opening adjustment parameter can be determined according to the magnitude relationship or quantitative relationship between the intermediate pressure and the target pressure, and the throttle valve can be controlled to adjust the opening according to the opening adjustment parameter.

[0135] In this embodiment, the size of the intermediate pressure can accurately reflect the current energy efficiency of the compression device. Based on this, the opening of the throttle valve is regulated according to the intermediate pressure, which is beneficial to replenishing air and increasing enthalpy while effectively improving the energy efficiency of the heat pump system.

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

[0137] The target pressure is specifically the target value that the intermediate pressure needs to reach when the heat pump system achieves optimal energy efficiency. The target pressure can be a preset fixed value, or a value determined according to the actual operation of the heat pump system. In this embodiment, in order to ensure that the system energy efficiency is accurately and effectively improved, before adjusting the throttle valve opening, the exhaust pressure of the compression device and the compression frequency of the compression device are obtained; the target pressure is determined according to the exhaust pressure and the compression frequency. Different exhaust pressures and different compression frequencies correspond to different target pressures.

[0138] When the throttle valve increases or decreases its opening, it can be adjusted according to a preset fixed opening adjustment value, or the opening adjustment value can be determined according to the actual operating state parameters of the heat pump system, and the opening of the throttle valve can be increased or decreased according to the opening adjustment value. For example, the opening adjustment value can be determined according to the current opening of the control valve, the current opening of the injection valve, the temperature of the air supply port, and the exhaust temperature, thereby improving the energy efficiency of the heat pump system while improving the operating reliability of the compression device.

[0139] In this embodiment, the throttle valve is controlled to increase or decrease its opening 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 energy efficiency of the compressor.

[0140] Further, based on any of the above embodiments, another embodiment of the control method of the heat pump system of the present application is proposed. In this embodiment, the heat pump system further includes a throttle valve and a control valve, the air supplement subcooling unit includes a flash evaporator, the throttle valve is arranged between the outdoor heat exchanger and the flash evaporator, and the control valve is arranged between the indoor heat exchanger and the flash evaporator. Figure 7 , the control method of the heat pump system further includes:

[0141] Step S101, controlling the heat pump system to perform heating operation and obtaining the exhaust gas superheat of the compression device;

[0142] The exhaust superheat detection process is as follows: the exhaust temperature and exhaust pressure of the compression device are detected by the above-mentioned pressure sensor and temperature sensor, the saturation temperature corresponding to the exhaust pressure is determined, and the exhaust superheat here is determined according to the difference between the exhaust temperature and the saturation temperature.

[0143] Step S102, controlling the throttle valve and / or the control valve to adjust the opening according to the exhaust gas superheat, and executing the step of obtaining the first state parameter 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 the control valve according to the exhaust gas superheat.

[0145] In one implementation of this embodiment, the throttle valve is first controlled to adjust the opening according to the exhaust superheat, and when the throttle valve adjustment opening reaches a certain condition, the control valve is controlled to adjust the opening according to the exhaust superheat. In this embodiment, the throttle valve opening is adjusted according to the exhaust superheat until the throttle valve opening exceeds the preset opening range or triggers the protection condition of the heat pump system; the control valve is adjusted to adjust the opening according to the exhaust superheat. Here, the throttle valve opening is adjusted preferentially within the preset opening range or when the system protection condition is not triggered, and the control valve is adjusted when it exceeds the range or the system protection condition is triggered, which is conducive to ensuring the stability of the pressure in the flash evaporator and ensuring that saturated steam can be quickly input to the air supply port after the air supply enthalpy increase condition is triggered, so as to achieve a rapid improvement in the energy efficiency of the heat pump system.

[0146] In another implementation of the present embodiment, the opening of one of the throttle valve and the control valve can also be adjusted according to the exhaust superheat control, wherein the valve body whose opening 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 of one of the throttle valve and the control valve can be selected to be adjusted according to the interval of the flash pressure in the flash evaporator.

[0147] In another implementation of this embodiment, the throttle valve and the control valve can also be controlled to adjust the openings simultaneously according to the exhaust gas superheat. Specifically, the target adjustment value and the adjustment ratio of the throttle valve and the control valve can be determined according to the exhaust gas superheat, the first adjustment value of the throttle valve and the second adjustment value of the control valve can be determined according to the target adjustment value and the adjustment ratio, and the throttle valve opening can be adjusted according to the first adjustment value while the control valve opening can be adjusted according to the second adjustment value.

[0148] In this embodiment, when the exhaust gas superheat is less than the target superheat, the throttle valve is controlled to reduce the opening; when the exhaust gas superheat is greater than the target superheat, the throttle valve is controlled to increase the opening. Based on this, it can be ensured that the exhaust gas 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 reduce the opening; when the exhaust superheat is greater than the target superheat, the control valve is controlled to increase the 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. Adjusting the opening of the throttle valve and / or the control valve according to the exhaust superheat can ensure that the heating capacity of the current system can meet the actual demand.

[0151] In addition, an embodiment of the present invention further proposes a storage medium, on which a control program of a heat pump system is stored. When the control program of the heat pump system is executed by a processor, the relevant steps of any embodiment of the control method of the heat pump system are implemented.

[0152] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or system. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0153] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0154] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, including a number of instructions for a terminal device (which can be a mobile phone, computer, server, heat pump system, or network device, etc.) to execute the methods described in each embodiment of the present invention.

[0155] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A control method for a heat pump system, characterized in that: The heat pump system comprises a compression device, a four-way valve, an outdoor heat exchanger, an air-supplement subcooling unit, an indoor heat exchanger, an air-supplement branch and a liquid injection branch. The compression device, the four-way valve, the outdoor heat exchanger, the air-supplement subcooling unit and the indoor heat exchanger are connected in sequence. The air-supplement subcooling unit is communicated with the air-supplement port or the secondary compression air suction port of the compression device through the air-supplement branch. One end of the liquid injection branch is connected between the indoor heat exchanger and the air-supplement subcooling unit or between the outdoor heat exchanger and the air-supplement subcooling unit. The other end of the liquid injection branch is communicated with the air-supplement branch. The air-supplement branch is provided with an air-supplement valve, and the liquid injection branch is provided with a liquid injection valve. The control method of the heat pump system comprises the following steps: Controlling the heating operation of the heat pump system and obtaining a first state parameter of the heat pump system; When the first state parameter satisfies the air supply enthalpy increase condition, controlling the air supply valve to open and obtaining the second state parameter of the heat pump system; When the second state parameter meets the liquid injection condition, the liquid injection valve is controlled to open.

2. The control method of the heat pump system according to claim 1, characterized in that: 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 condition includes at least one of the following conditions: The condensation temperature of the heat pump system is not greater than a first preset condensation temperature; The exhaust superheat of the compression device is not less than a preset superheat.

3. The control method of the heat pump system according to claim 1, characterized in that: After the step of controlling the liquid injection valve to open, the method further comprises: Obtaining a change value of exhaust superheat corresponding to the compression device; The opening of the liquid injection valve is controlled to be adjusted according to the change value.

4. The control method of the heat pump system according to claim 3, characterized in that: The step of controlling the liquid injection valve to adjust the opening according to the change value comprises: When the change value is greater than a preset change threshold, controlling the liquid injection valve to increase its opening; When the change value is less than the preset change threshold, the liquid injection valve is controlled to reduce the opening degree.

5. The control method of the heat pump system according to claim 1, characterized in that: The air-supplementing subcooling unit includes a flash evaporator, the heat pump system also includes a throttle valve, the throttle valve is arranged between the outdoor heat exchanger and the flash evaporator or between the indoor heat exchanger and the flash evaporator, the air-supplementing branch is connected to the air outlet of the flash evaporator, and after the step of controlling the opening of the air-supplementing valve, the method further includes: obtaining an intermediate pressure of the compression device; The throttle valve is controlled to adjust its opening according to the intermediate pressure.

6. The control method of the heat pump system according to claim 5, characterized in that: The step of controlling the throttle valve to adjust the opening according to the intermediate pressure comprises: When the intermediate pressure is greater than the target pressure, controlling the throttle valve to increase its opening; When the intermediate pressure is lower than the target pressure, the throttle valve is controlled to reduce its opening degree.

7. The control method of the heat pump system according to claim 6, characterized in that: Before the step of controlling the throttle valve to adjust the opening according to the intermediate pressure, the method further includes: Acquire the exhaust pressure of the compression device and the compression frequency of the compression device; The target pressure is determined according to the exhaust pressure and the compression frequency.

8. The control method of the heat pump system according to claim 1, characterized in that: The first state parameter includes 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 air supplement enthalpy increase condition includes 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 a second preset condensing temperature.

9. The control method of a heat pump system according to any one of claims 1 to 8, characterized in that: The heat pump system further includes a throttle valve and a control valve, the air supplement subcooling unit includes a flash evaporator, the throttle valve is arranged between the outdoor heat exchanger and the flash evaporator, the control valve is arranged between the indoor heat exchanger and the flash evaporator, and the control method of the heat pump system further includes: Controlling the heating operation of the heat pump system and obtaining the exhaust superheat of the compression device; The throttle valve and / or the control valve are controlled to adjust the opening according to the exhaust gas superheat, and the step of obtaining the first state parameter of the heat pump system is performed.

10. The control method of the heat pump system according to claim 9, characterized in that: The step of controlling the throttle valve and / or the control valve to adjust the opening according to the exhaust gas superheat comprises: adjusting the opening of the throttle valve according to the exhaust gas superheat until the opening of the throttle valve exceeds a preset opening range or triggers a protection condition of the heat pump system; The control valve opening is adjusted according to the exhaust gas superheat.

11. The control method of the heat pump system according to claim 10, characterized in that: The step of adjusting the opening of the throttle valve according to the exhaust gas superheat comprises: When the exhaust gas superheat is less than the target superheat, controlling the throttle valve to reduce the opening; When the exhaust gas superheat is greater than the target superheat, the throttle valve is controlled to increase its opening.

12. The control method of the heat pump system according to claim 10, characterized in that: The step of adjusting the opening of the control valve according to the exhaust superheat comprises: When the exhaust gas superheat is less than the target superheat, controlling the control valve to reduce the opening; When the exhaust gas superheat is greater than the target superheat, the control valve is controlled to increase its opening.

13. A heat pump system, characterized in that: The heat pump system comprises a control device, a compression device, a four-way valve, an outdoor heat exchanger, an air-supplement subcooling unit, an indoor heat exchanger, an air-supplement branch and a liquid injection branch. The compression device, the four-way valve, the outdoor heat exchanger, the air-supplement subcooling unit and the indoor heat exchanger are connected in sequence. The air-supplement subcooling unit is connected with the air-supplement port or the secondary compression air suction port of the compression device through the air-supplement branch. One end of the liquid injection branch is connected between the indoor heat exchanger and the air-supplement subcooling unit or between the outdoor heat exchanger and the air-supplement subcooling unit. The other end of the liquid injection branch is connected with the air-supplement branch. The air-supplement branch is provided with an air-supplement valve, and the liquid injection branch is provided with a liquid injection valve. The air supply valve and the liquid injection valve are both 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, the steps of the control method for the heat pump system as described in any one of claims 1 to 12 are implemented.

14. The heat pump system according to claim 13, characterized in that: The heat pump system also includes a throttle valve and a control valve. The air supplement subcooling unit includes a flash evaporator. The throttle valve is arranged between the outdoor heat exchanger and the flash evaporator or between the indoor heat exchanger and the flash evaporator. The control valve is arranged between the indoor heat exchanger and the flash evaporator. The control valve is connected to the control device.

15. A storage medium, characterized in that: The storage medium stores a control program of the heat pump system, and when the control program of the heat pump system is executed by the processor, the steps of the control method of the heat pump system according to any one of claims 1 to 12 are implemented.

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