Heat pump system with self-adaptive evaporation capacity

Abstract

According to the heat pump system with the self-adaptive evaporation capacity, the evaporation area and the refrigerant flow are dynamically adjusted by monitoring the heat load requirement of an evaporator in real time so as to adapt to different heat load requirements, and therefore a compressor is protected against overheating or liquid impact damage. The method specifically comprises the steps that an electronic expansion valve connected with a heat pump system is determined according to the heat load requirement, the initial opening degree is set, and the opening degree of the electronic expansion valve is adjusted through parameters such as the return air superheat degree so as to control the refrigerant flow; the system continuously monitors the return water temperature of the circulating water so as to re-determine the required electronic expansion valve, and the change of the thermal load requirement is adapted by dynamically adjusting the evaporation area and the refrigerant flow, so that the safe operation of the compressor is ensured; and meanwhile, the exhaust superheat degree delta Tp is synchronously monitored in real time, a series of negative effects on the heat pump system due to the fact that the exhaust superheat degree delta Tp is too high are prevented, and safe operation of the system is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of heat pumps, and in particular to a heat pump system with adaptive evaporation capacity. Background Art

[0002] Water source heat pump water heaters can be used for hot water supply in residential and commercial buildings. They can provide stable temperature, and because the temperature of the water source is relatively stable, the heat pump operation is more reliable and efficient. Its working principle is that the refrigerant absorbs the heat of the water flowing through the evaporator, and releases the heat to the hot water storage tank after the compressor raises the temperature.

[0003] At present, during operation, the evaporator can absorb heat from a variety of low-temperature media. For example, WO2022267814A1 proposes a temperature control system coupled to a heat pump water heater. By coupling the evaporator to the return pipe of the indoor heating system, the refrigerant in the evaporator absorbs the heat of the circulating water flowing through it. The refrigerant absorbs heat and changes from liquid to gas, and then changes to a high-temperature and high-pressure gas after the compressor. It then flows through the water tank heat exchanger to heat the water in the water tank, thereby providing domestic hot water. However, with this temperature control system, due to the large differences in user application terminals in the indoor heating system, including different house areas and different numbers and types of user terminal heat exchanger groups (such as floor heating, radiators, fan coils, etc.), the circulating water temperature and flow in the return pipe of the indoor heating system will change dramatically.

[0004] In the prior art, in a traditional water source heat pump water heater system, a single expansion valve is usually used to control the flow of refrigerant into the evaporator based on a fixed volume evaporator. This system is simple in design, but has certain limitations. A single expansion valve and a fixed volume evaporator may not be sufficient to dynamically adjust the capacity of the evaporator according to the actual heat load, affecting the stability and life of the compressor. Therefore, it is urgent to optimize the evaporator and propose a corresponding control method for it. Summary of the invention

[0005] Based on this, the purpose of the present invention is to overcome the defects or shortcomings of the prior art and provide a heat pump system with adaptive evaporation capacity.

[0006] A heat pump system with adaptive evaporation capacity comprises a compressor connected by a refrigerant circulation pipeline, a condenser, a first electronic expansion valve and a second electronic expansion valve arranged in parallel, and an evaporator with adjustable evaporation area, wherein the first electronic expansion valve controls the flow of refrigerant flowing through a larger evaporation area, and the second electronic expansion valve controls the flow of refrigerant with a smaller evaporation area, and further comprises a pressure detection module, a temperature detection module, a switch module, and a controller connected to the compressor, the first electronic expansion valve, the second electronic expansion valve, the pressure detection module, the temperature detection module, and the switch module in communication, characterized in that the controller performs adaptive control of the evaporation capacity of the heat pump system in the following manner:

[0007] Get the current circulating water return temperature T i :If the current circulating water return temperature T i Greater than the evaporation temperature T z ,, then start the second electronic expansion valve; in other cases, start the first electronic expansion valve;

[0008] After the system has been running for a period of time, according to the current return air temperature T s and evaporation temperature T z Calculate return gas superheat ΔT s , and based on the return gas superheat ΔT s Adjust the opening of the activated electronic expansion valve to continuously obtain the circulating water return temperature T at the next moment i .

[0009] Compared with the prior art, the heat pump system with adaptive evaporation capacity proposed in the present invention can dynamically adjust the capacity of the evaporator according to the actual heat load, thereby solving the problems of accelerated wear of compressor parts due to superheated steam entering the compressor and liquid hammer caused by liquid or wet steam entering the compressor, thereby protecting the compressor, improving the energy efficiency of the heat pump system, and extending the service life of the equipment.

[0010] Specifically, according to the current return air temperature T s and evaporation temperature T z Calculate return gas superheat ΔT s , determine the return air superheat ΔT at the current moment s and target superheat ΔT s-set Relationship:

[0011] For example, the return air superheat ΔT at the current moment s Greater than target superheat ΔT s-set , then increase the opening of the electronic expansion valve;

[0012] For example, the return air superheat ΔT at the current moment s Equal to the target superheat ΔT s-set , the opening of the electronic expansion valve remains unchanged;

[0013] For example, the return air superheat ΔT at the current moment s Less than target superheat ΔT s-set , then reduce the opening of the electronic expansion valve.

[0014] Further, when the second electronic expansion valve is started, the opening of the second electronic expansion valve is obtained. If the opening is less than or equal to the minimum allowable opening and is maintained for more than 10 seconds, the second electronic expansion valve is closed and the first electronic expansion valve is started.

[0015] Further, when the first electronic expansion valve is started, the opening of the first electronic expansion valve is obtained. If the opening is greater than or equal to the maximum allowable opening and is maintained for more than 10 seconds, the first electronic expansion valve is closed and the second electronic expansion valve is started.

[0016] Furthermore, the system startup control method is also included: obtaining the actual temperature T of the water tank at the current moment t , the state of the target water flow switch, the current circulating water return temperature T i , the downtime of the compressor, if it satisfies: the actual temperature of the water tank at the current moment T t Less than or equal to the water tank set temperature T t-set Start-stop temperature difference ΔT qt The difference between the target water flow switch and the current circulating water return temperature T i Greater than the minimum return water temperature T i-low , and the compressor downtime is greater than 3 minutes, start the system.

[0017] Furthermore, the method further includes controlling the opening of the electronic expansion valve based on the exhaust gas superheat: according to the actual exhaust gas temperature T at the current moment p and condensation temperature T l Calculate the exhaust superheat ΔT p , determine the exhaust superheat ΔT at the current moment p Is it greater than the allowable valve opening temperature difference ΔT? k , if the exhaust superheat ΔT at the current moment is satisfied p Greater than the allowable valve opening temperature difference ΔT k , obtain the current opening of the electronic expansion valve, and determine whether the current opening of the electronic expansion valve is greater than the maximum allowable opening:

[0018] If the current opening of the electronic expansion valve = the maximum allowable opening, the electronic expansion valve maintains the current opening unchanged;

[0019] If the opening of the electronic expansion valve at the current moment is less than the maximum allowable opening, the electronic expansion valve increases its opening according to a specific cycle and a specific increase;

[0020] In other cases, the opening of the electronic expansion valve remains unchanged.

[0021] Specifically, the water tank setting temperature T t-set is 55℃; start-stop temperature difference ΔT qt 5℃; minimum return water temperature T i-low 7℃; allowable valve opening temperature difference ΔT k is 25℃; target superheat ΔT s-set is 3℃.

[0022] Specifically, the evaporator includes a refrigerant pipeline through which the refrigerant flows and a circulating water pipeline through which the circulating water in the return pipe of the indoor heating system flows. The evaporator is coupled to the return pipe in the indoor heating system that flows through the user's terminal heat exchanger. The circulating water in the return pipe exchanges heat with the refrigerant in the refrigerant pipeline through the circulating water pipeline.

[0023] Furthermore, a first inlet and a first outlet are provided at both ends of the refrigerant pipeline, a second inlet is provided in the middle of the refrigerant pipeline, and a third inlet and a second outlet are provided at both ends of the circulating water pipeline; the first electronic expansion valve is connected to the refrigerant pipeline through the first inlet, and the second electronic expansion valve is connected to the refrigerant pipeline through the second inlet; the compressor is connected to the refrigerant pipeline through the first outlet.

[0024] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the structure of a heat pump system according to an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the structure of an evaporator in a heat pump system according to an embodiment of the present invention;

[0027] Figure 3 This is a flow chart of a control method for evaporator capacity adaptation according to an embodiment of the present invention;

[0028] Figure 4 A flow chart of a control method for system startup according to an embodiment of the present invention;

[0029] Figure 5 The present invention is a flow chart of a control method for controlling the opening of an electronic expansion valve based on exhaust gas superheat according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] When using a fixed-volume evaporator, if the temperature of the return pipe of the indoor heating system is too high and the flow is too high, it means that the heat it provides for exchanging with the refrigerant in the evaporator is excessive, causing the refrigerant to overheat, which in turn causes the temperature of the steam inhaled by the compressor to increase, reducing the heating coefficient of the heat pump system and increasing the energy consumption of the compressor. Long-term superheated steam entering the compressor will also accelerate the wear of the compressor components and shorten its life. When the temperature of the return pipe of the indoor heating system is too low and the flow is too low, it means that the heat it provides for exchanging with the refrigerant in the evaporator is low, resulting in incomplete evaporation of the refrigerant. Liquid or wet steam may be inhaled by the compressor, causing liquid hammer and causing serious damage to the compressor.

[0031] Therefore, the control method and device provided by the present invention change the evaporation area of ​​the evaporator according to the actual heat load, and adjust the refrigerant flow rate in combination with the opening of the electronic expansion valve, thereby dynamically and accurately adjusting the capacity of the evaporator to avoid negative impacts on the compressor caused by overheating or insufficient evaporation of the refrigerant.

[0032] The scheme of the present invention is described in detail below with reference to the accompanying drawings.

[0033] like Figure 1 As shown, the heat pump system with adaptive evaporation capacity of an embodiment of the present invention, the heat pump system 100 includes a compressor 110, a condenser 120, a filter 130, an electronic expansion valve group 140, an evaporator 150, and a temperature detection module 160, a pressure detection module 170, a switch module 180, a control module 190, and other auxiliary pipes connected by a refrigerant circulation pipeline.

[0034] Specifically, the condenser 120 is composed of a condensing coil 122 wound around the outer wall of a water tank 121 .

[0035] Specifically, the electronic expansion valve group 140 includes a first electronic expansion valve 141 and a second electronic expansion valve 142 , wherein the first electronic expansion valve 141 and the second electronic expansion valve 142 are connected in parallel, one end of each of which is connected to the filter 130 , and the other end of each of which is connected to the evaporator 150 .

[0036] Specifically, Figure 2 As shown, the evaporator 150 includes a refrigerant pipeline 151 through which the refrigerant flows and a circulating water pipeline 152 through which the circulating water in the return pipe of the indoor heating system flows, wherein a first inlet A and a first outlet C are provided at both ends of the refrigerant pipeline 151, a second inlet B is provided in the middle of the refrigerant pipeline 151, and a third inlet E and a second outlet F are provided at both ends of the circulating water pipeline 152.

[0037] The first electronic expansion valve 141 is connected to the refrigerant pipeline 151 through the first inlet A, and the second electronic expansion valve 142 is connected to the refrigerant pipeline 151 through the second inlet B; the compressor 110 is connected to the refrigerant pipeline 151 through the first outlet C.

[0038] The evaporator 150 is coupled to the return water pipe in the indoor heating system that flows through the user terminal heat exchanger. The circulating water in the return water pipe flows through the circulating water pipeline 152 in the evaporator 150 through the third inlet E and the second outlet F. The evaporator 150 absorbs the heat of the circulating water therein, thereby increasing the temperature of the refrigerant in the evaporator 150 and reducing the temperature of the circulating water. Subsequently, the water in the water tank is heated by the compressor 110 and the condenser 120, thereby providing domestic hot water.

[0039] Specifically, the temperature detection module 160 includes a first temperature sensor 161 , a second temperature sensor 162 , a third temperature sensor 163 and a fourth temperature sensor 164 .

[0040] The first temperature sensor 161 is disposed at the exhaust end of the compressor and is used to collect the actual exhaust temperature T of the compressor 110. p , and the actual exhaust temperature T p transmitted to the controller.

[0041] The second temperature sensor 162 is disposed on the water tank 121 and is used to collect the actual temperature T of the water tank 121. t , and the actual temperature T t transmitted to the controller.

[0042] The third temperature sensor 163 is disposed on the return air end of the compressor and is used to collect the actual return air temperature T of the compressor 110. s , and the actual return air temperature T s transmitted to the controller.

[0043] The fourth temperature sensor 164 is disposed at the third inlet E of the circulating water pipeline 152 and is used to collect the circulating water return temperature T i , and the circulating water return temperature T i transmitted to the controller.

[0044] Specifically, the pressure detection module 170 includes a high pressure sensor 171 and a low pressure sensor 172 .

[0045] The high-pressure sensor 171 is disposed at the exhaust end of the compressor and is used to collect the pressure signal P of the high-temperature and high-pressure gaseous refrigerant discharged from the compressor 110. h , combined with the temperature and pressure comparison table, the condensation temperature T of the refrigerant under this pressure can be accurately obtained l , and transmit it to the controller.

[0046] The low pressure sensor 172 is disposed on the return air end of the compressor and is used to collect the pressure signal P of the low temperature and low pressure gaseous refrigerant sucked by the compressor 110. d , combined with the temperature and pressure comparison table, the evaporation temperature T of the refrigerant under this pressure can be accurately obtained z , and transmit it to the controller.

[0047] Among them, the exhaust superheat ΔT p is the actual exhaust temperature T p and condensation temperature T l The difference between return gas superheat ΔT s is the actual return air temperature T s and evaporation temperature T z The difference between .

[0048] Specifically, the switch module 180 includes a first switch 181 and a second switch 182 .

[0049] The first switch 181 is a high-pressure switch, which is arranged at the exhaust end of the compressor and is used to protect the refrigeration system and the compressor from damage or failure of system components caused by excessive condensing pressure.

[0050] The second switch 182 is a target-type water flow switch, which is disposed at the third inlet E of the circulating water pipeline 152 and is used to detect the flow of circulating water.

[0051] Specifically, the control module 190 includes a controller (not shown), wherein the controller is electrically connected or communicatively connected to the compressor 110 , the electronic expansion valve group 140 , the temperature detection module 160 , the pressure detection module 170 and the switch module 180 .

[0052] For details, please refer to Figure 3 to Figure 4 The controller of the heat pump system of the present invention performs adaptive control of evaporation capacity through the following method.

[0053] S10 obtains the actual temperature T of the water tank at the current moment t , the state of the target water flow switch, the current circulating water return temperature T i , the downtime of the compressor, if it satisfies: the actual temperature of the water tank at the current moment T t Less than or equal to the water tank set temperature T t-set Start-stop temperature difference ΔT qt The difference between the target water flow switch and the current circulating water return temperature T i Greater than the minimum return water temperature T i-low , and the compressor downtime is greater than 3 minutes, start the system.

[0054] S20 determines the current circulating water return temperature T i Is it greater than the evaporation temperature Tz :

[0055] If the current circulating water return temperature T i >Evaporation temperature T z , control the second electronic expansion valve to open to the initial opening, close the first electronic expansion valve, start the compressor, and after the compressor runs for more than 5 minutes, execute step S30;

[0056] If the current circulating water return temperature T i ≤Evaporation temperature T z , control the first electronic expansion valve to open to an initial opening, close the second electronic expansion valve, start the compressor, and after the compressor runs for more than 5 minutes, execute step S40.

[0057] S30 obtains the return air superheat ΔT at the current moment s , determine the return air superheat ΔT at the current moment s Is it greater than the target superheat ΔT? s-set :

[0058] For example, the return air superheat ΔT at the current moment s > Target superheat ΔT s-set , then increase the opening of the second electronic expansion valve;

[0059] For example, the return air superheat ΔT at the current moment s = Target superheat ΔT s-set , the opening of the second electronic expansion valve remains unchanged;

[0060] For example, the return air superheat ΔT at the current moment s <Target superheat ΔT s-set , then reduce the opening of the second electronic expansion valve;

[0061] In this process, the opening degree of the second electronic expansion valve is continuously obtained. If the opening degree satisfies the condition that the opening degree is less than or equal to the minimum allowable opening degree and is maintained for more than 10 seconds, step S20 is executed.

[0062] S40 obtains the return air superheat ΔT at the current moment s , determine the return air superheat ΔT at the current moment s Is it greater than the target superheat ΔT? s-set :

[0063] For example, the return air superheat ΔT at the current moment s > Target superheat ΔT s-set , then increase the opening of the first electronic expansion valve;

[0064] For example, the return air superheat ΔT at the current moment s = Target superheat ΔT s-set, the opening of the first electronic expansion valve remains unchanged;

[0065] For example, the return air superheat ΔT at the current moment s <Target superheat ΔT s-set , then reduce the opening of the first electronic expansion valve.

[0066] In this process, the opening of the first electronic expansion valve is continuously obtained. If the opening is greater than or equal to the maximum allowable opening and is maintained for more than 10 seconds, step S20 is executed.

[0067] Specifically, the values ​​of each parameter are shown in Table 1.

[0068]

[0069] See also Figure 5 Furthermore, the controller of the heat pump system of the present invention further includes controlling the opening of the electronic expansion valve based on the exhaust gas superheat:

[0070] Get the exhaust superheat ΔT at the current moment p , determine the exhaust superheat ΔT at the current moment p Is it greater than the allowable valve opening temperature difference ΔT? k , if the exhaust superheat ΔT at the current moment is satisfied p Greater than the allowable valve opening temperature difference ΔT k , obtain the current opening of the electronic expansion valve, and determine whether the current opening of the electronic expansion valve is greater than the maximum allowable opening:

[0071] If the current opening of the electronic expansion valve = the maximum allowable opening, the electronic expansion valve maintains the current opening unchanged;

[0072] If the opening of the electronic expansion valve at the current moment is less than the maximum allowable opening, the electronic expansion valve increases its opening according to a specific cycle and a specific increase;

[0073] In other cases, the opening of the electronic expansion valve remains unchanged.

[0074] Specifically, the exhaust gas superheat ΔT at the current moment p Less than or equal to the allowable valve opening temperature difference ΔT k , do not adjust the opening of the electronic expansion valve.

[0075] Specifically, the allowable valve opening temperature difference ΔT k The value is 25℃.

[0076] Specifically, when the evaporation capacity adaptive control method is performed, the exhaust gas superheat ΔT is monitored in real time. p , based on the exhaust superheat ΔT pThe control method of the exhaust gas superheat ΔT is used to control the opening of the electronic expansion valve. When the two control methods need to control the opening of the electronic expansion valve at the same time, the control method based on the exhaust gas superheat ΔT is preferred. p Control the opening of the electronic expansion valve.

[0077] The heat pump system with adaptive evaporation capacity proposed in this application dynamically adjusts the evaporation area and refrigerant flow rate by real-time monitoring the heat load demand of the evaporator to adapt to different heat load demands, thereby protecting the compressor from overheating or liquid hammer damage. Specifically, it includes determining the electronic expansion valve connected to the heat pump system according to the heat load demand, setting the initial opening, and using parameters such as the return air superheat to adjust the opening of the electronic expansion valve to control the refrigerant flow rate; the system continuously monitors the circulating water return temperature to re-determine the required electronic expansion valve, and dynamically adjusts the evaporation area and refrigerant flow rate to adapt to changes in heat load demand to ensure the safe operation of the compressor; at the same time, it simultaneously monitors the exhaust superheat ΔT in real time. p , to prevent exhaust gas overheating ΔT p Too high will have a series of negative effects on the heat pump system, ensuring the safe operation of the system.

[0078] This method not only improves the energy efficiency of the heat pump system, but also protects the compressor and extends the service life of the equipment through precise control of the electronic expansion valve.

[0079] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the embodiments of the present application. The singular forms of "a", "said" and "the" used in the embodiments of the present application and the claims are also intended to include plural forms, unless the context clearly indicates other meanings. It should also be understood that, unless otherwise specified, "first", "second", "third", etc. are only used to distinguish, rather than to describe a specific order or sequence, and cannot be understood to indicate or imply relative importance. When the above description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. In the description of the present application, for those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0080] The above-mentioned embodiments only express the implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, and the present invention is also intended to include these modifications and modifications.

Claims

1. A heat pump system with adaptive evaporation capacity, comprising a compressor connected by a refrigerant circulation pipeline, a condenser, a first electronic expansion valve and a second electronic expansion valve arranged in parallel, and an evaporator with adjustable evaporation area, wherein the first electronic expansion valve controls the flow of refrigerant flowing through a larger evaporation area, and the second electronic expansion valve controls the flow of refrigerant with a smaller evaporation area, and also comprises a pressure detection module, a temperature detection module, a switch module, and a controller connected to the compressor, the first electronic expansion valve, the second electronic expansion valve, the pressure detection module, the temperature detection module, and the switch module, characterized in that: The controller performs adaptive control of the evaporation capacity of the heat pump system in the following way: Get the current circulating water return temperature T i :If the current circulating water return temperature T i Greater than the evaporation temperature T z , the second electronic expansion valve is started; in other cases, the first electronic expansion valve is started; After the system has been running for a period of time, according to the current return air temperature T s and evaporation temperature T z Calculate return gas superheat ΔT s , and based on the return gas superheat ΔT s Adjust the opening of the activated electronic expansion valve and continuously obtain the next moment circulating water return temperature T i .

2. The heat pump system with adaptive evaporation capacity according to claim 1, characterized in that: According to the current return air temperature T s and evaporation temperature T z Calculate return gas superheat ΔT s , determine the return air superheat ΔT at the current moment s and target superheat ΔT s-set Relationship: For example, the return air superheat ΔT at the current moment s Greater than target superheat ΔT s-set , then increase the opening of the electronic expansion valve; For example, the return air superheat ΔT at the current moment s Equal to the target superheat ΔT s-set , the opening of the electronic expansion valve remains unchanged; For example, the return air superheat ΔT at the current moment s Less than target superheat ΔT s-set , then reduce the opening of the electronic expansion valve.

3. The heat pump system with adaptive evaporation capacity according to claim 2, characterized in that: The method also includes obtaining the opening of the second electronic expansion valve when starting the second electronic expansion valve, and if the opening is less than or equal to the minimum allowable opening and is maintained for more than 10 seconds, closing the second electronic expansion valve and starting the first electronic expansion valve.

4. The heat pump system with adaptive evaporation capacity according to claim 2, characterized in that: The method also includes obtaining the opening of the first electronic expansion valve when starting the first electronic expansion valve, and if the opening is greater than or equal to the maximum allowable opening and is maintained for more than 10 seconds, closing the first electronic expansion valve and starting the second electronic expansion valve.

5. The heat pump system with adaptive evaporation capacity according to claims 3 and 4, characterized in that: Also included is a system startup control method: obtaining the actual temperature T of the water tank at the current moment t , the state of the target water flow switch, the current circulating water return temperature T i And the downtime of the compressor, if it satisfies: the actual temperature of the water tank at the current moment T t Less than or equal to the water tank set temperature T t-set Start-stop temperature difference ΔT qt The difference between the target water flow switch and the current circulating water return temperature T i Greater than the minimum return water temperature T i-low , and the compressor downtime is greater than 3 minutes, start the system.

6. The heat pump system with adaptive evaporation capacity according to claim 5, characterized in that: It also includes controlling the opening of the electronic expansion valve based on the exhaust gas superheat: according to the actual exhaust gas temperature T at the current moment p and condensation temperature T l Calculate the exhaust superheat ΔT p , determine the exhaust superheat ΔT at the current moment p Is it greater than the allowable valve opening temperature difference ΔT? k , if the exhaust superheat ΔT at the current moment is satisfied p Greater than the allowable valve opening temperature difference ΔT k , obtain the current opening of the electronic expansion valve, and determine whether the current opening of the electronic expansion valve is greater than the maximum allowable opening: If the current opening of the electronic expansion valve = the maximum allowable opening, the electronic expansion valve maintains the current opening unchanged; If the opening of the electronic expansion valve at the current moment is less than the maximum allowable opening, the electronic expansion valve increases its opening according to a specific cycle and a specific increase; In other cases, the opening of the electronic expansion valve remains unchanged.

7. The heat pump system with adaptive evaporation capacity according to claim 6, characterized in that: Water tank set temperature T t-set is 55℃; start-stop temperature difference ΔT qt 5℃; minimum return water temperature T i-low 7℃; allowable valve opening temperature difference ΔT k is 25℃; target superheat ΔT s-set is 3℃.

8. The heat pump system with adaptive evaporation capacity according to claim 1, characterized in that: The evaporator includes a refrigerant pipeline through which the refrigerant flows and a circulating water pipeline through which the circulating water in the return pipe of the indoor heating system flows. The evaporator is coupled to the return pipe in the indoor heating system that flows through the user's terminal heat exchanger. The circulating water in the return pipe exchanges heat with the refrigerant in the refrigerant pipeline through the circulating water pipeline.

9. The heat pump system with adaptive evaporation capacity according to claim 8, characterized in that: It also includes that the first inlet and the first outlet are arranged at both ends of the refrigerant pipeline, the second inlet is arranged in the middle of the refrigerant pipeline, and the third inlet and the second outlet are arranged at both ends of the circulating water pipeline.

10. The heat pump system with adaptive evaporation capacity according to claim 9, characterized in that: The first electronic expansion valve is connected to the refrigerant pipeline through the first inlet, and the second electronic expansion valve is connected to the refrigerant pipeline through the second inlet; the compressor is connected to the refrigerant pipeline through the first outlet, and the circulating water of the return pipe flows through the circulating water pipeline in the evaporator through the third inlet and the second outlet.

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