Solar energy heat storage based heat pump active air injection enthalpy-increasing defrosting system and method

Abstract

The present application relates to the technical fields of solar heat pump energy storage, and discloses a heat pump active jet enhanced heat pump defrosting method based on solar heat storage. The active jet enhanced heat pump based on solar heat storage is designed, and a heat storage defrosting module is additionally arranged in the system, which comprises an electronic expansion valve and an electromagnetic valve. A defrosting coil is designed in the heat storage water tank as a refrigerant passage for heat storage defrosting. During defrosting, the switching of the refrigerant flow path is realized by controlling the electronic expansion valve of the terminal indoor unit and the electronic expansion valve and the electromagnetic valve of the heat storage defrosting module. During defrosting, the refrigerant passes through the coil of the heat storage water tank to absorb heat, thereby enhancing the defrosting effect and effectively preventing the liquid-carrying operation of the compressor. At the same time, during the defrosting process, the opening degree of the jet enhanced electronic expansion valve is controlled, so that the exhaust superheat degree of the compressor can be controlled, the refrigerant circulation amount during defrosting can be improved, the low pressure can be increased, and the defrosting time can be shortened. The defrosting technology does not reduce the water temperature during the defrosting process, and does not affect the heating comfort.

Description

Technical Field

[0001] This invention relates to the field of solar heat pump energy storage system technology, and in particular to a heat pump active jet enthalpy-increasing defrosting system and method based on solar thermal storage. Background Technology

[0002] When a heat pump unit operates in winter, the outdoor heat exchanger absorbs heat from the outside air. The temperature around the outdoor heat exchanger is low, causing water vapor in the air to condense and form frost on its surface. As the frost layer thickens, the heat exchanger's heat exchange capacity decreases significantly, fan power consumption increases, and operating conditions deteriorate, thus affecting the air conditioner's heating performance. Therefore, defrosting is necessary to remove the frost layer from the heat exchanger surface.

[0003] Currently, there are many methods for rapid defrosting and protection control of air conditioners. Among them, the reverse circulation defrosting method is the most mature and widely used method in the air conditioning (heat pump) industry. The specific control method is as follows: when the unit meets the defrosting conditions, the four-way reversing valve reverses, changes the direction of refrigerant flow, and the unit operates in cooling mode. The high-temperature gaseous refrigerant discharged by the inverter compressor enters the outdoor heat exchanger and releases heat, thereby melting the frost layer on the surface of the outdoor heat exchanger.

[0004] However, the above defrosting methods have the following problems: First, when the air conditioner enters defrosting mode, the four-way reversing valve reverses, and a large amount of liquid refrigerant in the outdoor heat exchanger will quickly return to the low-pressure side of the inverter compressor under the action of pressure difference. This will cause the inverter compressor to operate with liquid, and the large amount of liquid refrigerant will dilute the lubricating oil of the inverter compressor, which may damage the inverter compressor in severe cases. Second, when the frost layer on the surface of the outdoor heat exchanger is thick, the defrosting time of the air conditioner will be long, sometimes even up to 10 minutes, which seriously affects the heating effect and the comfort of using the air conditioner. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a solar-powered heat pump active vapor injection enthalpy-increasing defrosting system and method. This system adds a heat storage defrosting module to the solar-powered active vapor injection enthalpy-increasing heat pump, including an electronic expansion valve and a solenoid valve. A defrosting coil is designed in the hot water storage tank, serving as the refrigerant path and heat source for heat storage defrosting. During defrosting, the refrigerant flow path is switched by controlling the electronic expansion valve of the terminal indoor unit and the electronic expansion valve and solenoid valve of the heat storage defrosting module. During defrosting, the refrigerant absorbs heat through the coil in the hot water storage tank, enhancing the defrosting effect and effectively preventing the compressor from operating with liquid. Simultaneously, by controlling the opening of the vapor injection enthalpy-increasing electronic expansion valve, the defrosting process can control the compressor exhaust superheat and increase the refrigerant circulation volume during defrosting, raising the low pressure and shortening the defrosting time. This defrosting technology does not lower the hot water temperature during the defrosting process and does not affect heating comfort.

[0006] To achieve the first objective of this invention, the present invention provides the following technical solution:

[0007] The solar-powered heat pump active vapor injection defrosting system includes:

[0008] The system comprises an outdoor unit module, an indoor unit module, a solar thermal storage module, and a thermal storage defrosting module. The outdoor unit module includes a variable frequency compressor, an oil separator, a four-way valve, an outdoor heat exchanger, a gas-liquid separator, an active vapor injection enthalpy-increasing economizer, and a second subcooling electronic expansion valve. The solar thermal storage module includes solar collector tubes and a hot water storage tank.

[0009] The discharge pipe of the variable frequency compressor is connected to the d-pipe of the four-way valve via an oil separator. The e-pipe of the four-way valve is connected to one end of the outdoor heat exchanger. The c-pipe of the four-way valve is connected to the gas pipe of the indoor unit module. The s-pipe of the four-way valve is connected to the inlet pipe of the gas-liquid separator. The c-pipe is connected to the main gas pipe. The outlet pipe of the gas-liquid separator is connected to the return gas pipe of the variable frequency compressor. The other end of the outdoor heat exchanger is connected to the main liquid pipe.

[0010] The indoor unit module includes an indoor unit gas pipe, an indoor unit liquid pipe, an indoor unit electronic expansion valve, and a fan coil unit or capillary tube assembly. The indoor unit gas pipe is connected to the main gas pipe, and the indoor unit liquid pipe is connected to the main liquid pipe.

[0011] The heat storage defrosting module includes an energy-saving electronic expansion valve, a solenoid valve, and a heat exchange and defrosting coil. The heat exchange and defrosting coil is installed inside the hot water storage tank. One end of the energy-saving electronic expansion valve is connected to the liquid pipe of the indoor unit, and the other end of the energy-saving electronic expansion valve is connected to the heat exchange and defrosting coil. One end of the solenoid valve is connected to the heat exchange and defrosting coil, and the other end of the solenoid valve is connected to the gas pipe of the indoor unit.

[0012] Furthermore, the economizer for active vapor injection enthalpy enhancement is connected to an active vapor injection enthalpy enhancement branch pipe inlet pipe, an active vapor injection enthalpy enhancement branch pipe outlet pipe, an active vapor injection enthalpy enhancement water inlet pipe, and an active vapor injection enthalpy enhancement water outlet pipe. The active vapor injection enthalpy enhancement branch pipe inlet pipe is connected to the main liquid pipe, and the active vapor injection enthalpy enhancement branch pipe outlet pipe is connected to the variable frequency compressor. The active vapor injection enthalpy enhancement water inlet pipe and the active vapor injection enthalpy enhancement water outlet pipe are respectively connected to the outlet and return water inlet of the hot water storage tank. A main electronic expansion valve is installed on the main liquid pipe between the economizer for active vapor injection enthalpy enhancement and the outdoor heat exchanger. The electronic expansion valve is connected to the main liquid pipe and the evaporator inlet pipe.

[0013] Furthermore, the active vapor injection enthalpy-enhancing heat pump system includes a temperature detection module, which comprises an outdoor ambient temperature sensor, an exhaust temperature sensor, an intake temperature sensor, a coil temperature sensor on the outdoor heat exchanger, a liquid pipe temperature sensor, a water tank temperature sensor, and a secondary active vapor injection enthalpy-enhancing temperature detection component. The secondary active vapor injection enthalpy-enhancing temperature detection component includes a vapor injection enthalpy-enhancing water inlet temperature sensor, a vapor injection enthalpy-enhancing water outlet temperature sensor, a refrigerant injection inlet pipe temperature sensor, and a refrigerant injection outlet pipe temperature sensor.

[0014] The outdoor ambient temperature sensor is used to detect the outdoor ambient temperature T. ao The exhaust temperature sensor is used to detect the exhaust temperature T. d The inhalation temperature sensor is used to detect the inhalation temperature T. s The coil temperature sensor on the outdoor heat exchanger is used to detect the coil temperature T. def The liquid pipe temperature sensor is used to detect the temperature T of the main liquid pipe. liq The water tank temperature sensor is used to detect the temperature T of the hot water storage tank. tank ,

[0015] The refrigerant injection inlet temperature sensor is used to detect the inlet temperature T of the active vapor injection enthalpy-enhancing refrigerant. inj,in The refrigerant injection outlet temperature sensor is used to detect the outlet temperature T of the active vapor injection enthalpy-enhancing refrigerant. inj,out The jet enthalpy inlet water temperature sensor is used to detect the inlet water temperature T on the active jet enthalpy heat source side. w-inj,in The jet enthalpy-enhancing water temperature sensor is used to detect the outlet water temperature T on the side of the active jet enthalpy-enhancing heat source. w-inj,out .

[0016] Furthermore, the outdoor unit module also includes a conventional vapor injection enthalpy enhancement module, including a first-stage vapor injection enthalpy enhancement economizer and a first subcooled electronic expansion valve. The first-stage vapor injection enthalpy enhancement economizer is connected to the main liquid pipe, the liquid storage tank outlet pipe, the first-stage vapor injection enthalpy enhancement branch pipe inlet pipe, and the first-stage vapor injection enthalpy enhancement branch pipe outlet pipe. The main liquid pipe and the first-stage vapor injection enthalpy enhancement branch pipe inlet pipe are connected to the outlet end of the liquid storage tank. The inlet end of the liquid storage tank is connected to the liquid pipe of the indoor unit module. The first-stage vapor injection enthalpy enhancement branch pipe outlet pipe is connected to the variable frequency compressor.

[0017] To achieve the second objective of this invention, the present invention provides the following technical solution:

[0018] The solar-based heat pump active vapor injection enthalpy-increasing defrosting method, configured in any of the above-described solar-based active vapor injection enthalpy-increasing heat pump systems, is characterized by:

[0019] Step S1: Defrosting entry judgment conditions are configured. When the defrosting entry judgment conditions are met, the defrosting preparation stage is entered, and the operating frequency of the variable frequency compressor is adjusted.

[0020] Step S2: Defrosting start conditions are configured. When the defrosting start conditions are met, the defrosting stage begins. The exhaust superheat is defined as the compressor exhaust temperature minus the saturation temperature corresponding to the exhaust pressure. The second subcooled electronic expansion valve is controlled according to the exhaust superheat. The heat storage defrosting electronic expansion valve and the solenoid valve are opened to perform defrosting.

[0021] Step S3: Defrost exit conditions are configured. When the defrost exit conditions are met, the defrost exit preparation stage is entered, and the operating frequency of the variable frequency compressor is adjusted.

[0022] Step S4: The defrost exit end condition is configured. When the defrost exit end condition is met, the drying operation stage after defrost is completed is entered. The second subcooled electronic expansion valve is controlled according to its normal operation control logic, and the heat storage defrost electronic expansion valve and solenoid valve are closed.

[0023] Step S5: The drying operation exit conditions after defrosting are configured. When the drying operation exit conditions after defrosting are met, the drying operation phase after defrosting ends.

[0024] Furthermore, in step S2, the defrosting start condition is configured with a defrosting preparation time. When the defrosting start condition is met and the time for entering the defrosting preparation stage reaches the preset defrosting preparation time, it is considered that the defrosting start condition is met.

[0025] Furthermore, in step S3, the defrost exit condition is configured with a defrost coil temperature threshold. When the actual defrost coil temperature is detected to be greater than the preset defrost coil temperature threshold within a preset continuous defrost duration, it is considered that the defrost exit condition is met.

[0026] The defrost exit condition is also configured with a condensation temperature threshold. When the actual detected condensation temperature is greater than the preset condensation temperature threshold, it is considered that the defrost exit condition is met.

[0027] The defrost exit condition is also configured with a defrost time threshold. When the actual defrost time reaches the preset defrost time threshold, it is considered that the defrost exit condition is met.

[0028] Furthermore, in step S4, the defrost exit end condition is configured with a defrost exit preparation time. When the defrost exit condition is met and the time spent in the defrost exit preparation stage reaches the preset defrost exit preparation time, it is considered that the defrost exit end condition is met.

[0029] Furthermore, in step S5, the drying operation exit condition after defrosting is configured with a refrigerant drying operation duration. When the duration of entering the drying operation stage after defrosting reaches the preset refrigerant drying operation duration after defrosting, it is considered that the drying operation exit condition after defrosting is met.

[0030] Furthermore, in step S2, the second subcooled electronic expansion valve is configured with an opening adjustment strategy, which is configured with a hysteresis threshold to calculate the exhaust superheat ΔT. d When the exhaust superheat is greater than the preset first superheat value ΔT d,set1 When the hysteresis threshold is reached, the second subcooled electronic expansion valve opens to the preset initial opening degree, and then operates according to the preset superheat ΔT. d,set1 Control; when the current actual exhaust superheat ΔT d Less than the preset first superheat ΔT d,set1 - Hysteresis threshold, the second subcooled electronic expansion valve reduces its opening; when the current actual exhaust superheat ΔT d Given the preset first superheat ΔT d,set1 + Hysteresis threshold and preset first superheat ΔT d,set1 Between the hysteresis threshold, the second subcooled electronic expansion valve maintains its current opening degree when the exhaust superheat is less than the preset second superheat value ΔT. d,set2 The second subcooled electronic expansion valve is closed.

[0031] The beneficial effects of this invention are:

[0032] This invention utilizes a heating assembly for heat storage defrosting. A solar collector absorbs solar energy to produce hot water, which is then stored in a hot water storage tank. When the heat pump system is operating normally, the stored hot water serves as the external heat source required for active vapor injection enthalpy enhancement, thereby increasing the heating capacity of the heat pump system. During defrosting, the refrigerant flows through the heat storage defrosting coil in the hot water storage tank, absorbing the stored heat. The gaseous refrigerant, after absorbing heat, returns to the inverter compressor, effectively preventing the inverter compressor from operating with liquid, avoiding damage to the inverter compressor, and shortening the defrosting time. This also improves the comfort of using the air conditioning (heat pump) unit during defrosting. Attached Figure Description

[0033] Figure 1 This is a system schematic diagram of the direct expansion active jet enthalpy-increasing heat pump based on solar thermal energy in Example 1;

[0034] Figure 2 This is a circulation flow diagram when both the active vapor injection enthalpy enhancement and the first-stage vapor injection enthalpy enhancement are turned off during the heating operation of a heat pump system;

[0035] Figure 3This is a circulation flow diagram of a heat pump system during heating operation when the active vapor injection enthalpy enhancement is off and the first-stage vapor injection enthalpy enhancement is on.

[0036] Figure 4 This is a circulation flow diagram of a heat pump system during heating operation when the active vapor injection enthalpy enhancement is off and both primary vapor injection enthalpy enhancements are on.

[0037] Figure 5 This is a flow diagram of the circulation path during defrosting in a heat pump system;

[0038] Figure 6 This is a defrosting sequence diagram of various components in a heat pump system during defrosting.

[0039] Figure 7 This is a system schematic diagram of the active jet enthalpy-enhancing heat pump based on solar thermal energy in Example 2.

[0040] Figure label:

[0041] 1. Variable frequency compressor; 2. High pressure sensor; 3. Oil separator; 4. Four-way valve; 5. Outdoor heat exchanger; 6. Main electronic expansion valve; 7. Liquid receiver; 8. Liquid pipe shut-off valve; 9. Gas pipe shut-off valve; 10. Gas-liquid separator; 11. Oil return capillary tube; 21. First-stage vapor injection enthalpy booster economizer; 22. First subcooling electronic expansion valve; 32. Active vapor injection enthalpy booster economizer; 32. Second subcooling electronic expansion valve; 41. Solar collector tube; 42. Hot water storage tank; 43. Hot water storage pump; 44. Jet pump; 45. Heat storage defrost coil; 51. Indoor unit electronic expansion valve; 52. Capillary tube assembly; 53. Fan coil; 54. Heat storage defrost module; 55. Heat storage defrost electronic expansion valve; 56. Solenoid valve; 61. Condenser; 62. Buffer tank; 63. Heating water pump. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0044] Example 1:

[0045] The heat pump active vapor injection enthalpy-increasing defrosting system based on solar thermal storage includes an outdoor unit module, an indoor unit module, a solar thermal storage module, and a thermal storage defrosting module. The outdoor unit module includes a variable frequency compressor 1, an oil separator 3, a four-way valve 4, an outdoor heat exchanger 5, a gas-liquid separator 10, an active vapor injection enthalpy-increasing economizer 31, and a second subcooled electronic expansion valve 32. The solar thermal storage module includes a solar collector tube 41 and a hot water storage tank 42.

[0046] The exhaust pipe of the variable frequency compressor 1 is connected to the d pipe of the four-way valve 4 via the oil separator 3. The e pipe of the four-way valve 4 is connected to one end of the outdoor heat exchanger 5. The c pipe of the four-way valve 4 is connected to the gas pipe of the indoor unit module. The s pipe of the four-way valve 4 is connected to the inlet pipe of the gas-liquid separator 10. The c pipe is connected to the main gas pipe. The outlet pipe of the gas-liquid separator 10 is connected to the return gas pipe of the variable frequency compressor 1. The other end of the outdoor heat exchanger 5 is connected to the main liquid pipe.

[0047] The indoor unit module includes an indoor unit gas pipe and an indoor unit liquid pipe. The indoor unit gas pipe is connected to the main gas pipe, and the indoor unit liquid pipe is connected to the main liquid pipe. In this embodiment, the indoor unit module includes multiple sets of capillary tube groups 52 connected in parallel and one or more fan coil units 53. Figure 1 Only one set of fan coil unit 53 is provided in the document, but in practice, multiple sets of fan coil units 53 can be freely matched. Figure 1 The diagram shows two sets of capillary tube assemblies 52 and one set of fan coil unit 53. In reality, multiple sets of capillary tube assemblies 52 and fan coil unit 53 can be freely matched. Each capillary tube assembly 52 or fan coil unit 53 is equipped with an electronic expansion valve 51 at the end of the indoor unit.

[0048] The heat storage defrosting module includes a heat storage defrosting electronic expansion valve 55, a solenoid valve 56, and a heat storage defrosting coil 45. The heat storage defrosting coil 45 is disposed in the heat storage tank 42. One end of the heat storage defrosting electronic expansion valve 55 is connected to the liquid pipe of the indoor unit, and the other end of the heat storage defrosting electronic expansion valve 55 is connected to the heat storage defrosting coil 45. One end of the solenoid valve 56 is connected to the heat storage defrosting coil 45, and the other end of the solenoid valve 56 is connected to the gas pipe of the indoor unit.

[0049] The active vapor injection enthalpy enhancer economizer 31 is connected to an active vapor injection enthalpy enhancer branch pipe inlet, an active vapor injection enthalpy enhancer branch pipe outlet, an active vapor injection enthalpy enhancer water inlet pipe, and an active vapor injection enthalpy enhancer water outlet pipe. The active vapor injection enthalpy enhancer branch pipe inlet is connected to the main liquid pipe, and the active vapor injection enthalpy enhancer branch pipe outlet is connected to the variable frequency compressor 1. The active vapor injection enthalpy enhancer water inlet pipe and the active vapor injection enthalpy enhancer water outlet pipe are respectively connected to the outlet and return water inlet of the hot water storage tank 42. The hot water storage tank 42 and the solar collector tube 41 are connected by a hot water storage inlet pipe and a hot water storage return water pipe. A main electronic expansion valve 6 is installed on the main liquid pipe between the active vapor injection enthalpy enhancer economizer 31 and the outdoor heat exchanger 5. The electronic expansion valve is connected to the main liquid pipe and the evaporator inlet pipe.

[0050] The active vapor injection enthalpy-enhancing heat pump system includes a temperature detection module, which includes an outdoor ambient temperature sensor, an exhaust temperature sensor, an intake temperature sensor, a coil temperature sensor on the outdoor heat exchanger 5, a liquid pipe temperature sensor, a water tank temperature sensor, and a secondary active vapor injection enthalpy-enhancing temperature detection component. The secondary active vapor injection enthalpy-enhancing temperature detection component includes a vapor injection enthalpy-enhancing water inlet temperature sensor, a vapor injection enthalpy-enhancing water outlet temperature sensor, a refrigerant injection inlet pipe temperature sensor, and a refrigerant injection outlet pipe temperature sensor.

[0051] The outdoor ambient temperature sensor is used to detect the outdoor ambient temperature T. ao The exhaust temperature sensor is used to detect the exhaust temperature T. d The inhalation temperature sensor is used to detect the inhalation temperature T. s The coil temperature sensor on the outdoor heat exchanger 5 is used to detect the coil temperature T. def The liquid pipe temperature sensor is used to detect the temperature T of the main liquid pipe. liq The water tank temperature sensor is used to detect the temperature T of the hot water storage tank. tank ;

[0052] The refrigerant injection inlet temperature sensor is used to detect the inlet temperature T of the active vapor injection enthalpy-enhancing refrigerant. inj,in The refrigerant injection outlet temperature sensor is used to detect the outlet temperature T of the active vapor injection enthalpy-enhancing refrigerant. inj,out The jet enthalpy inlet water temperature sensor is used to detect the inlet water temperature T on the active jet enthalpy heat source side. w-inj,in The jet enthalpy-enhancing water temperature sensor is used to detect the outlet water temperature T on the side of the active jet enthalpy-enhancing heat source. w-inj,out .

[0053] The outdoor unit module also includes a first-stage vapor injection enthalpy booster economizer 21 and a first subcooled electronic expansion valve 22. The first-stage vapor injection enthalpy booster economizer 21 is connected to the main liquid pipe 23, the outlet pipe of the liquid storage tank 7, the inlet pipe 24 of the first-stage vapor injection enthalpy booster branch pipe, and the outlet pipe 25 of the first-stage vapor injection enthalpy booster branch pipe. The main liquid pipe 23 and the inlet pipe 24 of the first-stage vapor injection enthalpy booster branch pipe are connected to the outlet end of the liquid storage tank 7. The inlet end of the liquid storage tank 7 is connected to the liquid pipe of the indoor unit module. The outlet pipe 25 of the first-stage vapor injection enthalpy booster branch pipe is connected to the variable frequency compressor 1.

[0054] When the heat pump system is in heating mode, the system circulation path is as follows: Figure 2 As shown, the high-temperature gaseous refrigerant discharged from the variable frequency compressor 1 enters the indoor unit module for heat exchange after passing through the oil separator 3, the d-pipe of the four-way valve 4, the c-pipe of the four-way valve 4, and the gas pipe shut-off valve 9. After releasing heat, the refrigerant passes through the liquid pipe shut-off valve 8 and the liquid receiver 7, then through the main electronic expansion valve 6, the outdoor heat exchanger 5, the e-pipe of the four-way valve 4, the s-pipe of the four-way valve 4, and the gas-liquid separator 10 before returning to the variable frequency compressor 1.

[0055] When the first-stage vapor injection enthalpy booster is activated, the injected refrigerant passes through the first subcooled electronic expansion valve 22 and enters the economizer 21 of the first-stage vapor injection enthalpy booster. The injected refrigerant and the refrigerant in the main liquid line exchange heat in the economizer 21. The injected refrigerant is then injected into the intermediate pressure chamber of the variable frequency compressor 1, causing the liquid line temperature Tliq to decrease and the subcooling (the difference between the saturation temperature corresponding to the high-pressure pressure Pd and the liquid line temperature Tliq) to increase, thereby absorbing more air energy. Simultaneously, because the injected refrigerant is injected into the intermediate pressure chamber of the variable frequency compressor 1, the compression work increases, thus increasing the heating capacity.

[0056] The system loop flow diagram is as follows Figure 3 As shown, the high-temperature gaseous refrigerant discharged from the variable frequency compressor 1 enters the indoor unit module for heat exchange after passing through the oil separator 3, the d-pipe of the four-way valve 4, the c-pipe of the four-way valve 4, and the gas pipe shut-off valve 9. After releasing heat, the refrigerant passes through the liquid pipe shut-off valve 8 and the liquid receiver 7. Part of the refrigerant flows through the main liquid pipe: through the first-stage vapor injection enthalpy booster economizer 21, the main electronic expansion valve 6, the outdoor heat exchanger 5, the e-pipe of the four-way valve 4, the s-pipe of the four-way valve 4, and the gas-liquid separator 10 before returning to the variable frequency compressor 1. The other part of the refrigerant is throttled by the first subcooled electronic expansion valve 22 and enters the first-stage vapor injection enthalpy booster economizer 21 to exchange heat with the refrigerant in the main liquid pipe, and then returns to the variable frequency compressor 1 through the first-stage vapor injection enthalpy booster branch pipe outlet 25.

[0057] When both the primary and secondary active vapor injection enthalpy enhancers are activated, during heat pump heating operation, the hot water in the storage tank 42 is pumped by the jet pump 44 to the economizer 31 of the secondary active vapor injection enthalpy enhancer. The injected refrigerant passes through the second subcooled electronic expansion valve 32 and enters the economizer 31, where it exchanges heat with the hot water. The refrigerant that has absorbed heat is then injected into the intermediate pressure chamber of the variable frequency compressor 1, converting the heat from the external hot water into heating capacity, significantly improving the performance of the heat pump unit. The flow rate of the vapor injection enthalpy enhancer hot water can be adjusted, thus achieving on-demand quantitative supply of stored heat, which is then converted into heating capacity.

[0058] The system loop flow diagram is as follows Figure 4 As shown, the high-temperature gaseous refrigerant discharged from the variable frequency compressor 1 passes through the oil separator 3, the d-pipe of the four-way valve 4, the c-pipe of the four-way valve 4, and the gas pipe shut-off valve 9 before reaching the indoor unit module for heat exchange. After releasing heat, the refrigerant passes through the liquid pipe shut-off valve 8 and the liquid receiver 7. Part of the refrigerant then flows through the main liquid pipe: through the first-stage vapor injection enthalpy enhancer 21, the main electronic expansion valve 6, the outdoor heat exchanger 5, the e-pipe of the four-way valve 4, the S-pipe of the four-way valve 4, and the gas-liquid separator 10 before returning to the variable frequency compressor 1; a portion of the refrigerant... After being throttled by the first subcooled electronic expansion valve 22, the refrigerant enters the first-stage vapor injection enthalpy enhancer 21 to exchange heat with the refrigerant in the main liquid pipe, and then returns to the variable frequency compressor 1 through the outlet pipe of the first-stage vapor injection enthalpy enhancer branch pipe; another part of the refrigerant is throttled by the second subcooled electronic expansion valve 32 and enters the second-stage active vapor injection enthalpy enhancer 31 to exchange heat with the external heat source. After evaporating and absorbing heat, it flows out through the active vapor injection pipe outlet pipe and merges with the refrigerant flowing out of the first-stage vapor injection enthalpy enhancer branch pipe outlet pipe, entering the intermediate pressure chamber of the variable frequency compressor 1. In this embodiment, the external heat source is specifically supplied by the hot water storage tank 42. The hot water in the hot water storage tank 42 is pumped by the jet water pump 44 through the second-stage active vapor injection enthalpy enhancer 31 to exchange heat with the refrigerant flowing through the second-stage active vapor injection enthalpy enhancer 31.

[0059] When the heat pump system involved in this application requires defrosting, a reverse defrosting method is adopted, that is, after the defrosting conditions are met, the unit is stopped for 30 seconds and then started, the four-way valve 4 is reversed, and the refrigerant circulation direction is as follows. Figure 5As shown, the high-temperature gaseous refrigerant discharged from the variable frequency compressor 1 passes through the oil separator 3, the d-pipe of the four-way valve 4, the e-pipe of the four-way valve 4, the outdoor heat exchanger 5, and the main electronic expansion valve 6. Part of the refrigerant flows through the active vapor injection enthalpy enhancer 32 to exchange heat with the external heat source. After evaporation and heat absorption, it flows out through the active vapor injection pipe and merges with the refrigerant flowing out of the first-stage vapor injection enthalpy enhancer branch pipe, entering the intermediate pressure chamber of the variable frequency compressor 1. The other part flows through the liquid receiver 7, the liquid pipe shut-off valve 8, the heat storage defrost electronic expansion valve 55, the heat storage defrost coil 45, and the solenoid valve 56, then through the gas pipe shut-off valve 9, the c-pipe of the four-way valve 4, the s-pipe of the four-way valve 4, and the gas-liquid separator 10 before returning to the variable frequency compressor 1.

[0060] The defrosting process of a heat pump system consists of four phases: defrosting preparation, defrosting, defrosting exit preparation, and drying operation after defrosting. The following provides a detailed description of the operating status of each component within the heat pump system during each phase.

[0061] The solar-based heat pump active vapor injection enthalpy-increasing defrosting method is configured in the solar-based active vapor injection enthalpy-increasing heat pump system described above:

[0062] Step S1: Defrosting entry judgment conditions are configured. When the defrosting entry judgment conditions are met, the defrosting preparation stage is entered, and the operating frequency of the variable frequency compressor 1 is adjusted.

[0063] Step S2: Defrosting start conditions are configured. When the defrosting start conditions are met, the defrosting stage is entered. The exhaust superheat is defined as the compressor exhaust temperature minus the saturation temperature corresponding to the exhaust pressure. The second subcooled electronic expansion valve 32 is controlled according to the exhaust superheat. The heat storage defrosting electronic expansion valve 55 and the solenoid valve 56 are opened to perform defrosting.

[0064] Step S3: Defrost exit conditions are configured. When the defrost exit conditions are met, the defrost exit preparation stage is entered, and the operating frequency of the variable frequency compressor 1 is adjusted.

[0065] Step S4: The defrost exit end condition is configured. When the defrost exit end condition is met, the drying operation stage after the defrost is completed is entered. The second subcooled electronic expansion valve 32 is controlled according to its normal operation control logic, and the heat storage defrost electronic expansion valve 55 and solenoid valve 56 are closed.

[0066] Step S5: The drying operation exit conditions after defrosting are configured. When the drying operation exit conditions after defrosting are met, the drying operation phase after defrosting ends, which means the refrigerant drying operation process ends.

[0067] The patent “A control method for air conditioner defrosting mode, computer-readable storage medium and air conditioner (patent number CN110017569B)” provides a model for determining the defrosting entry condition: a precise determination model based on machine self-learning time-coil temperature-condensing temperature-defrosting accumulation coefficient, which eliminates the phenomenon of entering defrosting too early or too late, false defrosting or even no defrosting, which will not be elaborated here.

[0068] Defrosting sequence diagram as follows Figure 6 As shown, the following is an introduction based on the operating stages of the heat pump system:

[0069] 1) Normal operation phase of heat pump system

[0070] The variable frequency compressor 1 is automatically controlled, the outdoor fan is automatically controlled for heating, the four-way valve 4 is de-energized (the flow is specifically in pipe d into pipe c and out, and in pipe e into pipe s and out), the heating water pump 63 is turned on, and the opening of the main electronic expansion valve 6, the first subcooling electronic expansion valve 22, the second subcooling electronic expansion valve 32, the indoor unit electronic expansion valve 51, the jet water pump 44, and the hot water storage pump 43 are all automatically adjusted. The heat storage defrost electronic expansion valve 55 and the solenoid valve 56 are both closed, and the heat pump system operates in normal heating mode. The automatic control in this invention means normal operation control according to their respective control logics. The system circulation path is as follows: Figure 2-4 Any one of them is shown;

[0071] 2) Defrosting preparation stage

[0072] The defrosting preparation stage is determined by the defrosting entry conditions. When the defrosting entry conditions are met, the defrosting preparation stage begins. At this time, the operating frequency of the variable frequency compressor 1 is reduced to the defrosting preparation frequency, such as 20 rpm. The fan speed on the outdoor heat exchanger 5, the opening of the main electronic expansion valve 6, the opening of the first subcooling electronic expansion valve 22, the opening of the second subcooling electronic expansion valve 32, the opening of the indoor unit electronic expansion valve 51, the jet water pump 44, and the hot water storage pump 43 are automatically adjusted according to normal control. The four-way valve 4 is de-energized (the specific flow is inflow from pipe d to pipe c and outflow from pipe e to pipe s). The heat storage defrosting electronic expansion valve 55 and the solenoid valve 56 are both closed. During the normal heating operation of the heat pump system, except for the change in the operating frequency of the variable frequency compressor 1, the system circulation path remains the same. Figure 2-4 Any one of them is shown;

[0073] 3) Defrosting stage

[0074] The defrosting start condition determines whether to enter the defrosting stage. The defrosting start condition is configured with a defrosting preparation time. When the time for entering the defrosting preparation stage reaches the preset defrosting preparation time, for example, the defrosting preparation time is set to 30 seconds, it is considered that the defrosting start condition is met.

[0075] When the pre-set defrost preparation time is reached, the defrost phase begins; that is, after 30 seconds of pre-defrost preparation, the defrost phase commences. The control is as follows:

[0076] The variable frequency compressor 1 operates at the set defrosting frequency, such as 75-85 rpm. The outdoor fan stops for a period of time, such as 2-3 minutes, and the fan speed is controlled according to the cooling operation mode. The four-way valve 4 is energized (the flow is specifically: d-pipe inflow to e-pipe outflow, c-pipe inflow to S-pipe outflow). The main electronic expansion valve 6 is maintained at a certain defrosting opening. The indoor unit electronic expansion valve 51 on the main liquid pipe is closed, the first subcooling electronic expansion valve 22 is closed, and the heat storage defrosting electronic expansion valve 55 in the heat storage defrosting module 54 is opened and maintained at the defrosting opening, such as 300-450 rpm. The solenoid valve 56 is open, and the heating water pump 63 remains running. The second subcooling electronic expansion valve 32 enters the vapor injection enthalpy enhancement mode, controlled according to the exhaust superheat. The system circulation path is as follows: Figure 5 As shown. The second subcooled electronic expansion valve 32 is controlled as follows:

[0077] During the heat storage defrosting process, the exhaust temperature and high-pressure are simultaneously monitored to obtain the saturation temperature corresponding to the high-pressure pressure, and the exhaust superheat ΔT is calculated. d When the exhaust superheat is greater than the preset first superheat value ΔT d,set1 When the hysteresis threshold is reached, the second subcooled electronic expansion valve opens to the preset initial opening degree, and then operates according to the preset superheat ΔT. d,set1 Control; when the current actual exhaust superheat ΔT d Less than the preset first superheat ΔT d,set1 - Hysteresis threshold, the second subcooled electronic expansion valve reduces its opening; when the current actual exhaust superheat ΔT d Given the preset first superheat ΔT d,set1 + Hysteresis threshold and preset first superheat ΔT d,set1 Between the hysteresis threshold, the second subcooled electronic expansion valve maintains its current opening degree when the exhaust superheat is less than the preset second superheat value ΔT. d,set2 The second subcooling electronic expansion valve is closed. The control of the jet pump 44 and the control of the second subcooling electronic expansion valve 32 are synchronized. When the second subcooling electronic expansion valve 32 is open, the jet pump 44 starts running; when the second subcooling electronic expansion valve 32 is closed, the jet pump 44 stops running.

[0078] 4) Defrosting preparation stage

[0079] The defrost exit conditions are used to determine whether to enter the defrost exit preparation stage. When the defrost exit conditions are met, the defrost exit preparation stage begins.

[0080] The defrosting process is completed according to the following conditions:

[0081] Once the defrosting stage is entered, if any of conditions ①, ②, or ③ are met, the defrosting process will exit and the defrosting exit action will be executed.

[0082] ① The defrost exit condition is configured with a defrost coil temperature threshold. When the actual defrost coil temperature is detected to be greater than the preset defrost ambient temperature threshold within a preset continuous defrost duration, the defrost exit condition is considered met; for example: when the actual defrost coil temperature is detected to be greater than the preset defrost ambient temperature threshold for 1 minute, the defrost exit condition is considered met. def Temperature > 10℃ or T detected for 15 consecutive seconds def If the temperature is above 15℃ for 10 seconds, the defrosting exit condition is considered met.

[0083] ② The defrost exit condition is also configured with a condensation temperature threshold. When the actual detected condensation temperature is greater than the preset condensation temperature threshold, it is considered to meet the defrost exit condition. For example, when the actual detected condensation temperature is greater than the preset condensation temperature threshold, such as 48-52℃, it is considered to meet the defrost exit condition.

[0084] ③ The defrost exit condition is also configured with a maximum defrost time threshold. When the actual defrost time reaches the preset maximum defrost time threshold, it is considered to meet the defrost exit condition. For example, when the actual defrost time reaches 10 minutes, it is considered to meet the defrost exit condition.

[0085] The defrosting preparation and exit phase is controlled as follows:

[0086] The operating frequency of the variable frequency compressor 1 is reduced to the defrost exit frequency, such as 20 rpm. The machine remains in a stopped state, and the fan speed is controlled according to the refrigeration operation mode. The main electronic expansion valve 6 is maintained at a certain defrost opening. The indoor unit electronic expansion valve 51 on the main liquid pipe is closed. The opening of the heat storage defrost electronic expansion valve 55 in the heat storage defrost module 54 is maintained at a defrost opening of 300-450 rpm. The solenoid valve 56 remains open, and the heating water pump 63 remains running. Except for the change in the operating frequency of the variable frequency compressor 1, the operating states of the other components are the same as in the defrost stage, and the system circulation path remains the same. Figure 5 As shown (in order to in) Figure 5 The image clearly shows the refrigerant circulation path during defrosting. Figure 5 (The heat pump terminal that does not participate in defrosting is not shown);

[0087] 5) Drying operation phase after defrosting

[0088] The decision to enter the drying operation phase after defrosting is determined by the defrosting exit termination condition. The defrosting exit termination condition is configured with a defrosting exit preparation time. When the duration of the defrosting exit preparation phase reaches the preset defrosting exit preparation time, the defrosting exit termination condition is considered met; for example, the defrosting exit preparation time is set to 30 seconds.

[0089] When the defrosting termination conditions are met, the system enters the drying operation phase after defrosting. The operating frequency of the variable frequency compressor 1 is adjusted to the starting frequency, the outdoor fan of the outdoor heat exchanger is automatically controlled for heating, the four-way valve 4 is de-energized, the heating water pump 63 remains open, the main electronic expansion valve 6 reduces its opening to the basic opening for 120 seconds, and then automatically adjusts its opening. The openings of the first subcooling electronic expansion valve 22 and the second subcooling electronic expansion valve 32 are automatically adjusted. The indoor unit electronic expansion valve 51 and the jet water pump 44 are turned on, the hot water storage pump 43 is automatically controlled, and the heat storage defrosting electronic expansion valve 55 and the solenoid valve 56 are closed. The system circulation path remains as before. Figure 2-4 As shown.

[0090] 6) Normal operation phase of heat pump system

[0091] The decision to enter the normal operation phase of the heat pump system is determined by the exit conditions for the drying operation phase after defrosting. These exit conditions are configured with a refrigerant drying operation duration. When the duration of the drying operation phase after defrosting reaches a preset refrigerant drying operation duration, the exit conditions are considered met; for example, the refrigerant drying operation duration is set to 180 seconds. After the drying operation phase after defrosting lasts for 180 seconds, the system enters the normal operation phase.

[0092] Example 2:

[0093] like Figure 6 As shown, Embodiment 2 provides a solar-powered heat pump active vapor injection defrosting system based on solar thermal storage, using water as the heat exchange medium. Unlike Embodiment 1, the indoor unit module in Embodiment 2 is specifically a heat pump unit using water as the heat exchange medium. The indoor unit is a hydraulic module, which consists of a condenser 61, a heating water pump 63, and a buffer tank 62. It can be used to heat other home facilities, such as underfloor heating. The control method is the same as in Embodiment 1.

[0094] Working principle:

[0095] This application relates to a solar-powered heat pump active vapor injection enthalpy-increasing defrosting method. Through the installation of a hot water storage tank 42 and solar collector tubes 41, hot water is generated using solar energy and stored in the hot water storage tank 42. The hot water storage tank in this application has a dual function: firstly, it exchanges heat with the refrigerant entering the heat storage defrosting module 54 during the defrosting stage, improving defrosting capacity and speed; secondly, it serves as an external heat source for the heat pump's active vapor injection enthalpy-increasing function. During normal operation of the heat pump, it exchanges heat with the injected refrigerant entering the economizer. After absorbing heat, the injected refrigerant is injected into the intermediate pressure chamber of the compressor, converting the external heat source heat into heating capacity in the form of injection enthalpy difference. This allows the heat pump system to be applied to lower temperature environments. During defrosting, the indoor unit's fan is turned off, and the refrigerant flows through the coils in the hot water storage tank 42, absorbing the stored heat. The gaseous refrigerant, after absorbing heat, returns to the inverter compressor 1, effectively preventing the inverter compressor 1 from operating with liquid. Furthermore, it shortens the defrosting time without affecting the comfort of the terminal indoor units.

[0096] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A heat pump-based active vapor injection defrosting system with solar thermal storage, characterized in that: The system includes an outdoor unit module, an indoor unit module, a solar thermal storage module, and a thermal storage defrosting module. The outdoor unit module includes a variable frequency compressor (1), an oil separator (3), a four-way valve (4), an outdoor heat exchanger (5), a gas-liquid separator (10), an active vapor injection enthalpy booster (31), and a second subcooled electronic expansion valve (32). The solar thermal storage module includes a solar collector tube (41) and a hot water storage tank (42). The exhaust pipe of the variable frequency compressor (1) is connected to the d pipe of the four-way valve (4) via the oil separator (3). The e pipe of the four-way valve (4) is connected to one end of the outdoor heat exchanger (5). The c pipe of the four-way valve (4) is connected to the gas pipe of the indoor unit module. The s pipe of the four-way valve (4) is connected to the inlet pipe of the gas-liquid separator (10). The c pipe is connected to the main gas pipe. The outlet pipe of the gas-liquid separator (10) is connected to the return gas pipe of the variable frequency compressor (1). The other end of the outdoor heat exchanger (5) is connected to the main liquid pipe. The indoor unit module includes an indoor unit gas pipe, an indoor unit liquid pipe, an indoor unit electronic expansion valve (51), and a fan coil unit (53) or a capillary tube assembly (52). The indoor unit gas pipe is connected to the main gas pipe, and the indoor unit liquid pipe is connected to the main liquid pipe. The heat storage defrosting module includes a heat storage defrosting electronic expansion valve (55), a solenoid valve (56), and a heat storage defrosting coil (45). The heat storage defrosting coil (45) is installed inside the heat storage tank (42). One end of the heat storage defrosting electronic expansion valve (55) is connected to the liquid pipe of the indoor unit, and the other end of the heat storage defrosting electronic expansion valve (55) is connected to the heat storage defrosting coil (45). One end of the solenoid valve (56) is connected to the heat storage defrosting coil (45), and the other end of the solenoid valve (56) is connected to the gas pipe of the indoor unit. The active vapor injection enthalpy booster economizer (31) is connected to an active vapor injection enthalpy booster branch pipe inlet, an active vapor injection enthalpy booster branch pipe outlet, an active vapor injection enthalpy booster water inlet pipe, and an active vapor injection enthalpy booster water outlet pipe. The active vapor injection enthalpy booster branch pipe inlet is connected to the main liquid pipe, and the active vapor injection enthalpy booster branch pipe outlet is connected to the variable frequency compressor (1). The active vapor injection enthalpy booster water inlet pipe and the active vapor injection enthalpy booster water outlet pipe are respectively connected to the outlet and return water inlet of the hot water storage tank (42). The hot water storage tank (42) and the solar collector tube (41) are connected by a hot water storage inlet pipe and a hot water storage outlet pipe. A main electronic expansion valve (6) is installed on the main liquid pipe between the active vapor injection enthalpy booster economizer (31) and the outdoor heat exchanger (5). The electronic expansion valve is connected to the main liquid pipe and the evaporator inlet pipe.

2. The heat pump active jet enthalpy-increasing defrosting system based on solar thermal storage according to claim 1, characterized in that: The active vapor injection enthalpy-enhancing heat pump system includes a temperature detection module, which comprises an outdoor ambient temperature sensor, an exhaust temperature sensor, an intake temperature sensor, a coil temperature sensor on the outdoor heat exchanger (5), a liquid pipe temperature sensor, a water tank temperature sensor, and a secondary active vapor injection enthalpy-enhancing temperature detection component. The secondary active vapor injection enthalpy-enhancing temperature detection component includes a vapor injection enthalpy-enhancing water inlet temperature sensor, a vapor injection enthalpy-enhancing water outlet temperature sensor, a refrigerant injection inlet pipe temperature sensor, and a refrigerant injection outlet pipe temperature sensor. The outdoor ambient temperature sensor is used to detect the outdoor ambient temperature T. ao The exhaust temperature sensor is used to detect the exhaust temperature T. d The inhalation temperature sensor is used to detect the inhalation temperature T. s The coil temperature sensor on the outdoor heat exchanger (5) is used to detect the coil temperature T. def The liquid pipe temperature sensor is used to detect the temperature T of the main liquid pipe. liq The water tank temperature sensor is used to detect the temperature T of the hot water storage tank. tank , The refrigerant injection inlet temperature sensor is used to detect the inlet temperature T of the active vapor injection enthalpy-enhancing refrigerant. inj,in The refrigerant injection outlet temperature sensor is used to detect the outlet temperature T of the active vapor injection enthalpy-enhancing refrigerant. inj,out The jet enthalpy inlet water temperature sensor is used to detect the inlet water temperature T on the active jet enthalpy heat source side. w-inj,in The jet enthalpy-enhancing water temperature sensor is used to detect the outlet water temperature T on the side of the active jet enthalpy-enhancing heat source. w-inj,out .

3. The heat pump active jet enthalpy-increasing defrosting system based on solar thermal storage according to claim 1, characterized in that: The outdoor unit module also includes a first-stage vapor injection enthalpy booster (21) and a first subcooled electronic expansion valve (22). The first-stage vapor injection enthalpy booster (21) is connected to the main liquid pipe (23), the outlet pipe of the liquid storage tank (7), the inlet pipe (24) of the first-stage vapor injection enthalpy booster branch pipe, and the outlet pipe (25) of the first-stage vapor injection enthalpy booster branch pipe. The main liquid pipe (23) and the inlet pipe (24) of the first-stage vapor injection enthalpy booster branch pipe are connected to the outlet end of the liquid storage tank (7). The inlet end of the liquid storage tank (7) is connected to the liquid pipe of the indoor unit module. The outlet pipe (25) of the first-stage vapor injection enthalpy booster branch pipe is connected to the variable frequency compressor (1).

4. A solar-powered heat pump active vapor injection enthalpy-increasing defrosting method, configured in any one of the solar-powered active vapor injection enthalpy-increasing heat pump systems as described in any one of claims 1-3, characterized in that: Step S1: Defrosting entry judgment conditions are configured. When the defrosting entry judgment conditions are met, the defrosting preparation stage is entered, and the operating frequency of the variable frequency compressor (1) is adjusted. Step S2: Defrosting start conditions are configured. When the defrosting start conditions are met, the defrosting stage is entered. The exhaust superheat is defined as the compressor exhaust temperature minus the saturation temperature corresponding to the exhaust pressure. The second subcooled electronic expansion valve (32) is controlled according to the exhaust superheat. The heat storage defrosting electronic expansion valve (55) and the solenoid valve (56) are opened to perform defrosting. Step S3: Defrost exit conditions are configured. When the defrost exit conditions are met, the defrost exit preparation stage is entered, and the operating frequency of the variable frequency compressor (1) is adjusted. Step S4: The defrost exit end condition is configured. When the defrost exit end condition is met, the drying operation stage after the defrost is completed is entered. The second subcooled electronic expansion valve (32) is controlled according to its normal operation control logic, and the heat storage defrost electronic expansion valve (55) and solenoid valve (56) are closed. Step S5: The drying operation exit conditions after defrosting are configured. When the drying operation exit conditions after defrosting are met, the drying operation phase after defrosting ends.

5. The heat pump active jet defrosting method based on solar thermal storage according to claim 4, characterized in that: In step S2, the defrosting start condition is configured with a defrosting preparation time. When the defrosting entry determination condition is met and the time for entering the defrosting preparation stage reaches the preset defrosting preparation time, it is considered that the defrosting start condition is met and the defrosting control is entered.

6. The heat pump active jet defrosting method based on solar thermal storage according to claim 4, characterized in that: In step S3, the defrost exit condition is configured with a defrost coil temperature threshold. When the actual defrost coil temperature is detected to be greater than the preset defrost coil temperature threshold within a preset continuous defrost duration, it is considered that the defrost exit condition is met. The defrost exit condition is also configured with a condensation temperature threshold. When the actual detected condensation temperature is greater than the preset condensation temperature threshold, it is considered that the defrost exit condition is met. The defrost exit condition is also configured with a maximum defrost time threshold. When the actual defrost time reaches the preset maximum defrost time threshold, it is considered that the defrost exit condition is met.

7. The heat pump active jet defrosting method based on solar thermal storage according to claim 4, characterized in that: In step S4, the defrost exit end condition is configured with a defrost exit preparation time. When the defrost exit condition is met and the time spent in the defrost exit preparation stage reaches the preset defrost exit preparation time, it is considered that the defrost exit end condition is met.

8. The heat pump active jet defrosting method based on solar thermal storage according to claim 4, characterized in that: In step S5, the drying operation exit condition after defrosting is configured with a refrigerant drying operation duration. When the duration of entering the drying operation stage after defrosting reaches the preset refrigerant drying operation duration after defrosting, it is considered that the drying operation exit condition after defrosting is met.

9. The heat pump active jet defrosting method based on solar thermal storage according to claim 4, characterized in that: In step S2, the second subcooled electronic expansion valve is configured with an opening adjustment strategy, which is configured with a hysteresis threshold to calculate the exhaust superheat ΔT. d When the exhaust superheat is greater than the preset first superheat value ΔT d,set1 When the hysteresis threshold is reached, the second subcooled electronic expansion valve opens to the preset initial opening degree, and then operates according to the preset superheat ΔT. d,set1 control; When the current actual exhaust superheat ΔT d Less than the preset first superheat ΔT d,set1 - Hysteresis threshold, the second subcooled electronic expansion valve reduces its opening; when the current actual exhaust superheat ΔT d Given the preset first superheat ΔT d,set1 + Hysteresis threshold and preset first superheat ΔT d,set1 Between the hysteresis threshold, the second subcooled electronic expansion valve maintains its current opening degree when the exhaust superheat is less than the preset second superheat value ΔT. d,set2 The second subcooled electronic expansion valve is closed.

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