A heat recovery heat pump system and a control method thereof

Abstract

The present application relates to the field of air conditioners, and in particular, provides a heat recovery heat pump system and a control method thereof. The heat recovery heat pump system comprises a compressor, a liquid accumulator circuit, a first branch circuit, a second branch circuit, a third switch valve, a fourth switch valve and an outdoor air branch circuit. The liquid accumulator circuit comprises a liquid inlet side and a liquid outlet side, and the liquid inlet side is connected in parallel with a first gas port and a first branch circuit gas outlet. The compressor comprises a discharge side and a return side, the discharge side is connected in parallel with a first branch circuit gas inlet, a second branch circuit gas inlet and a second gas port, the discharge side is further provided with a first switch valve, the first switch valve controls the flow rate of refrigerant flowing to the second branch circuit gas inlet and the second gas port, and the return side is connected in parallel with the liquid outlet side, the first switch valve and a second branch circuit gas outlet. The present application ensures that the amount of refrigerant in the system is always appropriate, thereby improving the working efficiency of the heat recovery heat pump system, and at the same time, the use of a large gas-liquid separator is reduced, thereby effectively saving costs.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, and more specifically, to a heat recovery heat pump system and its control method. Background Technology

[0002] With the increasing prominence of energy issues and the ever-increasing demands for energy efficiency, heat pump technology, as a highly efficient energy utilization device, has been widely used in many fields.

[0003] To adapt to the diverse needs of modern users, existing heat recovery heat pumps are multifunctional. A single heat recovery heat pump system can provide cooling in summer and heating in winter, with some systems also providing domestic hot water year-round. This integration of multiple functions meets user requirements in different seasons and under different needs, while reducing equipment investment and installation space requirements.

[0004] However, one shortcoming of the relevant technology is that the existing heat recovery refrigeration main mode system uses the maximum amount of refrigerant. After filling the device with this amount of refrigerant, in other modes such as refrigeration, heating, and main heating mode, excess refrigerant will remain in the condenser. In refrigeration mode, excess refrigerant will remain in the outdoor air heat exchanger; in main refrigeration mode, it will remain in both the hot water heat exchanger and the outdoor air heat exchanger; and in heating mode and main heating mode, it will remain in the hot water heat exchanger. This results in excessive high-pressure liquid subcooling and an increase in condensing temperature. Therefore, the efficiency of the refrigeration system deteriorates. Summary of the Invention

[0005] The present invention aims to provide a heat recovery heat pump system and its control method to solve the technical problem of low efficiency of refrigeration systems in related technologies.

[0006] To solve the above problems, the present invention adopts the following technical solution:

[0007] A heat recovery heat pump system includes a compressor, a liquid receiver circuit, a first branch circuit, a second branch circuit, and an external gas branch circuit. The liquid receiver circuit includes a liquid inlet side and a liquid outlet side, with the liquid inlet side connected in parallel with the first gas port and the first branch circuit outlet. The compressor includes a discharge side and a return side, with the discharge side connected in parallel with the first branch circuit inlet, the second branch circuit inlet, and the second gas port. The discharge side is also equipped with a first switching valve, which controls the refrigerant flow rate to the second branch circuit inlet and the second gas port. The return side is connected in parallel with the liquid outlet side, the first switching valve, and the second branch circuit outlet.

[0008] Compared with existing technologies, the technical effects achieved by this solution are as follows: This application connects the liquid inlet side of the receiver circuit in parallel with the first gas port and the first branch gas outlet, and connects the compressor discharge side in parallel with the first branch gas inlet, the second branch gas inlet, and the second gas port, thus achieving flexible switching between different branches and reasonable distribution of refrigerant. Simultaneously, by controlling the opening and closing of the liquid inlet and outlet sides of the receiver circuit, the refrigerant flow between the circulation pipeline and the receiver is controlled, thereby ensuring that the amount of refrigerant in the circulation pipeline is always appropriate. Therefore, excess refrigerant will not remain in the circulation pipeline, preventing excessive high-pressure liquid subcooling, rising condensing temperature, and decreased refrigeration system efficiency.

[0009] Furthermore, the liquid storage circuit includes a liquid storage tank, a third switching valve, and a fourth switching valve. The third switching valve is located on the liquid inlet side, and the fourth switching valve is located on the liquid outlet side.

[0010] Compared with existing technologies, the technical effects achieved by adopting this technical solution are as follows: Specifically, the inflow and outflow of refrigerant in the liquid receiver circuit can be precisely controlled through these two switching valves. At the same time, when the system malfunctions, the status of the liquid receiver, the third switching valve, and the fourth switching valve can be checked to carry out corresponding maintenance and adjustments.

[0011] Furthermore, the external gas branch includes an external gas heat exchanger, a second switching valve, and an external gas expansion valve. The first end of the second switching valve and the first end of the external gas expansion valve are connected in parallel with the outlet end of the external gas heat exchanger, and the second end of the second switching valve and the second end of the external gas expansion valve are connected in parallel with the third switching valve. The second branch includes a cold water expansion valve and a cold water heat exchanger. One side of the cold water expansion valve is connected to the third switching valve, and the other side of the cold water expansion valve is connected to the liquid outlet side of the cold water heat exchanger. The first branch includes a hot water heat exchanger and a fifth switching valve. The inlet end of the hot water heat exchanger is connected to the exhaust end, and the fifth switching valve controls the refrigerant flow rate of the first branch.

[0012] Compared with existing technologies, the technical effects achieved by this solution are as follows: By adjusting the opening of the external gas expansion valve and the cold water expansion valve, the superheat of the refrigerant on the compressor return side reaches the set value, ensuring the system's refrigeration efficiency. In cooling mode, while handling the cooling load by absorbing heat from the cold water through the cold water heat exchanger, the combined heat absorbed from the cold water and the compression workload are released to the outside air through the external gas heat exchanger. In main cooling mode, while handling the cooling load by absorbing heat from the cold water through the cold water heat exchanger, a portion of the combined heat absorbed from the cold water and the compression workload is released to the outside air through the external gas heat exchanger. The heat exchanger releases heat to the outside air, and the remaining heat is released to hot water through the hot water heat exchanger to handle the heating load. In heating mode, heat is absorbed from the outside air through the outside air heat exchanger, and the combined heat absorbed from the outside air and the compressor's workload are released to hot water through the hot water heat exchanger to handle the heating load. In main heating mode, heat is absorbed from the cold water through the cold water heat exchanger to handle the cooling load, and simultaneously, while absorbing heat from the outside air through the outside air heat exchanger, the combined heat absorbed from the cold water and the outside air, along with the compressor's workload, are released to hot water through the hot water heat exchanger to handle the heating load. Through reasonable connections and coordinated operation with the liquid receiver circuit and the compressor's exhaust and return sides, the entire heat recovery heat pump system can operate stably under various operating conditions. Different branches can be switched and coordinated according to actual needs to achieve effective heat recovery and utilization.

[0013] Furthermore, the fifth switching valve is located between the outlet of the hot water heat exchanger and the third switching valve.

[0014] Compared with existing technologies, the technical effects achieved by adopting this technical solution are as follows: placing the fifth switching valve between the outlet of the hot water heat exchanger and the third switching valve is conducive to accurately controlling the discharge path and flow rate of the refrigerant in the first branch. At the same time, the amount of refrigerant leading to the outside gas branch and the second branch is controlled by the first switching valve.

[0015] Furthermore, the fifth switching valve is located between the air inlet and exhaust sides of the hot water heat exchanger.

[0016] Compared with existing technologies, the technical effects achieved by adopting this technical solution are as follows: the fifth switching valve is set between the gas inlet of the hot water heat exchanger and the exhaust side of the compressor. The fifth switching valve directly controls the flow of refrigerant in the first branch. At the same time, when the first branch malfunctions, the status of the fifth switching valve can be checked, which facilitates maintenance.

[0017] Furthermore, the first switching valve includes: a sixth switching valve and a seventh switching valve. One side of the sixth switching valve is connected to the exhaust side, and the other side of the sixth switching valve is connected to the inlet end of the external gas heat exchanger. One side of the seventh switching valve is connected to the sixth switching valve, and the other side of the seventh switching valve is connected to the return gas side.

[0018] Compared with existing technologies, the technical advantages of this solution are as follows: the refrigerant flow to the external gas branch is precisely controlled by the sixth switching valve, and the refrigerant flow to the second branch is precisely controlled by the seventh switching valve, with flexible switching capabilities to suit different operating conditions. Simultaneously, in the system's thermal bypass defrosting mode, the refrigerant on the compressor's exhaust side circulates to the external gas heat exchanger, where it condenses into high-pressure liquid refrigerant while dissolving frost. The high-pressure liquid refrigerant is depressurized through the external gas expansion valve and stored in the receiver in a gas-liquid two-phase separated state. The compressor only draws in the gaseous phase refrigerant from the top of the receiver, thus preventing the liquid refrigerant from being directly drawn into the compressor.

[0019] In the hot bypass defrosting mode, the liquid receiver also functions as a gas-liquid separator, so there is no need to install a gas-liquid separator on the compressor inlet side, or a small gas-liquid separator can be installed, saving costs and space.

[0020] Furthermore, the heat recovery heat pump system is also equipped with an eighth switching valve, one end of which is located at the gas inlet of the hot water heat exchanger, and the other end of which is connected to the return gas side.

[0021] Compared with existing technologies, the technical effects achieved by adopting this technical solution are as follows: by setting an eighth switching valve, the system can select a reverse defrosting mode. The system can use the heat absorbed from the hot water and the heat generated by the compression work from the hot water heat exchanger for external defrosting, which improves the efficiency of the defrosting mode and significantly reduces the defrosting time.

[0022] Furthermore, the heat recovery heat pump system is equipped with a detection module, which includes a pressure detector and a temperature detector. The pressure detector is located on the exhaust side and the return side; the temperature detector is located on the hot water heat exchanger, the outdoor air heat exchanger, the cold water heat exchanger, and the compressor.

[0023] Compared with existing technologies, the technical effects achieved by this solution are as follows: the system calculates the subcooling or superheat of the circulating refrigerant based on the information from the detection module, and directs the circulating refrigerant into the receiver or from the receiver into the circulation path according to the system settings, ensuring that the amount of refrigerant in the system is appropriate and improving the system's working efficiency.

[0024] Furthermore, another objective of the present invention is to provide a heat pump system control method, implemented through the aforementioned heat recovery heat pump system, the control method comprising the following steps:

[0025] Adjust the opening and closing of the first branch, the second branch, and the outside air branch according to the heat pump system operating mode; obtain the compressor pressure value; obtain the temperature value of the operating components of the heat pump system; calculate the high-pressure liquid subcooling degree or high-pressure liquid superheat degree based on the compressor pressure value and the temperature value of the operating components of the heat pump system; adjust the refrigerant amount in the receiver circuit according to the high-pressure liquid subcooling degree or high-pressure liquid superheat degree.

[0026] Compared with existing technologies, the technical effects achieved by this solution are as follows: When the original heat pump system inputs refrigerant into the system based on the main cooling mode with the largest refrigerant liquid holding capacity, regardless of the system's operating mode, excess refrigerant will remain in the heat exchanger, resulting in excessive refrigerant subcooling and thus affecting system efficiency. Therefore, this system improves system efficiency by detecting the pressure values ​​and subcooling of each component within the system and adjusting the system to ensure that the amount of circulating refrigerant is always appropriate.

[0027] Furthermore, adjusting the refrigerant quantity in the receiver circuit based on the high-pressure liquid subcooling or high-pressure liquid superheat includes the following steps: determining the heat pump system operating mode; determining whether the high-pressure liquid subcooling or high-pressure liquid superheat is within the set value range; if yes, closing the receiver circuit inlet side and receiver circuit outlet side; if no, proceeding to step A; step A includes: determining whether the high-pressure liquid subcooling or high-pressure liquid superheat is higher than the set value; if yes, opening the receiver circuit inlet side and closing the receiver circuit outlet side; determining whether the high-pressure liquid subcooling or high-pressure liquid superheat is lower than the set value; if yes, opening the receiver circuit outlet side and closing the receiver circuit inlet side.

[0028] Compared with existing technologies, the technical effects achieved by adopting this technical solution are as follows: The system works by switching valve circuits according to different operating modes of the heat pump system. At the same time, when the refrigerant in the system circulation circuit is insufficient, refrigerant is output from the liquid receiver, and when the refrigerant in the system circulation circuit is excessive, excess refrigerant is input into the liquid receiver, thereby ensuring that the amount of refrigerant in the circulation circuit is always appropriate. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of a heat recovery heat pump system according to an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of another heat recovery heat pump system according to an embodiment of the present invention;

[0031] Figure 3 This is a circuit diagram of the cooling mode of a heat recovery heat pump system according to an embodiment of the present invention;

[0032] Figure 4 This is a circuit diagram of the refrigeration main body mode of the heat recovery heat pump system according to an embodiment of the present invention;

[0033] Figure 5 This is a circuit diagram of the heating mode of the heat recovery heat pump system according to an embodiment of the present invention;

[0034] Figure 6 This is a circuit diagram of the heating main mode of the heat recovery heat pump system according to an embodiment of the present invention;

[0035] Figure 7 This is a schematic diagram of the circuit of the heat recovery heat pump system in the heat bypass defrosting mode according to an embodiment of the present invention.

[0036] Figure 8 This is a circuit diagram of the reverse defrosting mode of the heat recovery heat pump system according to an embodiment of the present invention.

[0037] Explanation of reference numerals in the attached figures:

[0038] 1-Heat recovery heat pump system; 10-Compressor; 20-Hot water heat exchanger; 21-Fifth switching valve; 22-First gas port; 23-Second gas port; 30-Outdoor gas heat exchanger; 31-Outdoor gas expansion valve; 32-Second switching valve; 40-Cold water heat exchanger; 41-Cold water expansion valve; 50-Liquid receiver; 51-Third switching valve; 52-Fourth switching valve; 60-First switching valve; 61-Sixth switching valve; 62-Seventh switching valve; 80-Eighth switching valve. Detailed Implementation

[0039] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0040] See Figures 1-8 The heat recovery heat pump system 1 provided in this embodiment of the invention includes: a compressor 10, a liquid receiver circuit, a first branch circuit, a second branch circuit, and an external gas branch circuit. The liquid receiver circuit includes a liquid inlet side and a liquid outlet side. The compressor 10 includes an exhaust side and a return gas side. The liquid inlet side is connected in parallel with the first gas port 22 and the gas outlet of the first branch circuit. The exhaust side is connected in parallel with the gas inlet of the first branch circuit, the gas inlet of the second branch circuit, and the gas outlet 23. The exhaust side is also provided with a first switching valve 60, which controls the flow rate of refrigerant to the gas inlet of the second branch circuit and the gas outlet 23. The return gas side is connected in parallel with the liquid outlet side, the first switching valve 60, and the gas outlet of the second branch circuit.

[0041] For example, the first switching valve 60 can be a three-way switching valve, which controls the flow of refrigerant from the compressor 10 to the outside air branch and the second branch.

[0042] This application connects the liquid inlet side of the receiver circuit in parallel with the first gas port 22 and the first branch gas outlet, and connects the discharge side of the compressor 10 in parallel with the first branch gas inlet, the second branch gas inlet, and the second gas port 23, thus achieving flexible switching between different branches and reasonable distribution of refrigerant. Simultaneously, by controlling the opening and closing of the liquid inlet and outlet sides of the receiver circuit, the refrigerant flow between the circulation pipeline and the receiver 50 is controlled, thereby ensuring that the amount of refrigerant in the circulation pipeline is always appropriate. Therefore, excess refrigerant will not remain in the circulation pipeline, preventing excessive high-pressure liquid subcooling, rising condensing temperature, and decreased refrigeration system efficiency.

[0043] Furthermore, such as Figure 1 As shown, the liquid storage circuit includes a liquid storage tank 50, a third switching valve 51 and a fourth switching valve 52. The third switching valve 51 is located on the liquid inlet side and the fourth switching valve 52 is located on the liquid outlet side.

[0044] Specifically, these two switching valves can precisely control the inflow and outflow of refrigerant in the receiver circuit. At the same time, when the system malfunctions, the status of the receiver 50, the third switching valve 51, and the fourth switching valve 52 can be checked to carry out corresponding maintenance and adjustments.

[0045] Furthermore, the external gas branch includes an external gas heat exchanger 30, a second switching valve 32, and an external gas expansion valve 31. The first end of the second switching valve 32 and the first end of the external gas expansion valve 31 are connected in parallel with the outlet end of the external gas heat exchanger 30, and the second end of the second switching valve 32 and the second end of the external gas expansion valve 31 are connected in parallel with the third switching valve 51. The second branch includes a cold water expansion valve 41 and a cold water heat exchanger 40. One side of the cold water expansion valve 41 is connected to the third switching valve 51, and the other side of the cold water expansion valve 41 is connected to the liquid outlet side of the cold water heat exchanger 40. The first branch includes a hot water heat exchanger 20 and a fifth switching valve 21. The inlet end of the hot water heat exchanger 20 is connected to the exhaust side, and the fifth switching valve 21 controls the refrigerant flow rate of the first branch.

[0046] See Figures 4-6 By adjusting the opening of the external gas expansion valve 31 and the cold water expansion valve 41, the superheat of the refrigerant on the return gas side of the compressor 10 is made to reach the set value, ensuring the refrigeration efficiency of the system. In cooling mode, while absorbing heat from the cold water through the cold water heat exchanger 40 to handle the cooling load, the heat absorbed from the cold water and the total compression workload are released to the outside air through the external gas heat exchanger 30. In main cooling mode, while absorbing heat from the cold water through the cold water heat exchanger 40 to handle the cooling load, a portion of the heat absorbed from the cold water and the total compression workload is released to the outside air through the external gas heat exchanger 30, and the remaining heat is released to the outside air. Partially, heat is released to the hot water through the hot water heat exchanger 20 to handle the heating load. In heating mode, heat is absorbed from the outside air through the outside air heat exchanger 30, and the heat absorbed from the outside air, combined with the workload of the compressor 10, is released to the hot water through the hot water heat exchanger 20 to handle the heating load. In the main heating mode, heat is absorbed from the cold water through the cold water heat exchanger 40 to handle the cooling load. Simultaneously, while absorbing heat from the outside air through the outside air heat exchanger 30, the heat absorbed from the cold water, the heat absorbed from the outside air, and the workload of the compressor 10 are combined and released to the hot water through the hot water heat exchanger 20 to handle the heating load. Through reasonable connection and coordinated operation with the liquid receiver circuit and the exhaust and return sides of the compressor 10, the entire heat recovery heat pump system 1 can operate stably under various operating conditions. Different branches can be switched and coordinated according to actual needs to achieve effective heat recovery and utilization.

[0047] Furthermore, the fifth switching valve 21 is located between the air outlet of the hot water heat exchanger 20 and the third switching valve 51.

[0048] Placing the fifth switching valve 21 between the outlet of the hot water heat exchanger 20 and the third switching valve 51 facilitates precise control of the refrigerant discharge path and flow rate in the first branch. At the same time, the amount of refrigerant flowing to the outside gas branch and the second branch is controlled by the first switching valve 60.

[0049] Furthermore, such as Figure 2 As shown, the fifth switching valve 21 is located between the air inlet and the exhaust side of the hot water heat exchanger 20.

[0050] The fifth switching valve 21 is set between the inlet end of the hot water heat exchanger 20 and the exhaust side of the compressor 10. The fifth switching valve 21 directly controls the flow of refrigerant in the first branch. At the same time, when the first branch malfunctions, the status of the fifth switching valve 21 can be checked, which facilitates maintenance.

[0051] Further, see Figure 1 and Figure 7 The first switching valve 60 includes: a sixth switching valve 61 and a seventh switching valve 62. One side of the sixth switching valve 61 is connected to the exhaust side, and the other side of the sixth switching valve 61 is connected to the inlet end of the external gas heat exchanger 30. One side of the seventh switching valve 62 is connected to the sixth switching valve 61, and the other side of the seventh switching valve 62 is connected to the return gas side.

[0052] The system switches loops by closing the cold water expansion valve 41, the second switching valve 32, the fifth switching valve 21, the seventh switching valve 62, and the eighth switching valve 80, and opening the third switching valve 51, the fourth switching valve 52, and the external gas expansion valve 31, thus adjusting the system to the heat bypass defrosting mode. Furthermore, the opening degree of the external gas expansion valve 31 is adjusted to keep the refrigerant pressure values ​​of each component within the set range, and defrosting ends when the refrigerant pressure reaches the set upper limit.

[0053] The amount of refrigerant flowing to the outside air branch is precisely controlled by the sixth switching valve 61, and the amount of refrigerant flowing to the second branch is precisely controlled by the seventh switching valve 62, which can be flexibly switched according to different operating conditions. Simultaneously, in the system's thermal bypass defrosting mode, the refrigerant on the compressor 10's discharge side circulates to the outside air heat exchanger 30, where it condenses into high-pressure liquid refrigerant while dissolving frost. The high-pressure liquid refrigerant is depressurized through the outside air expansion valve 31 and stored in the receiver 50 in a gas-liquid two-phase separated state. The compressor 10 only draws in the gas phase refrigerant from the top of the receiver 50, thus preventing the liquid refrigerant from being directly drawn into the compressor 10. In this thermal bypass defrosting mode, the receiver 50 also functions as a gas-liquid separator, so a gas-liquid separator is not required on the compressor 10's inlet side, or only a small gas-liquid separator is needed, saving cost and space.

[0054] Furthermore, the heat recovery heat pump system 1 is also equipped with an eighth switching valve 80, one end of which is located at the gas inlet of the hot water heat exchanger 20, and the other end of which is connected to the return gas side.

[0055] With the eighth switching valve 80 installed, the system can select the reverse defrosting mode. The system can use the heat absorbed by the hot water and the heat generated by the compression work from the hot water heat exchanger 20 to defrost the outside air, which improves the efficiency of the defrosting mode and significantly reduces the defrosting time.

[0056] The system switches the loop by closing the fifth switching valve 21, the seventh switching valve 62, the second switching valve 32, the third switching valve 51, the fourth switching valve 52 and the cold water expansion valve 41, and adjusts the system to reverse defrost mode.

[0057] Furthermore, the heat recovery heat pump system 1 is equipped with a detection module, which includes a pressure detector and a temperature detector. The pressure detector is located on the exhaust side and the return side; the temperature detector is located on the hot water heat exchanger 20, the outdoor air heat exchanger 30, the cold water heat exchanger 40, and the compressor 10.

[0058] In this invention, in cooling mode, the subcooling of the high-pressure refrigerant is calculated based on the measurements from the high-pressure sensor and the refrigerant temperature sensor on the outside air heat exchanger 30. In cooling main mode, heating mode, and heating main mode, the subcooling of the high-pressure refrigerant is calculated based on the measurements from the high-pressure sensor and the refrigerant temperature sensor on the hot water heat exchanger 20. When the calculated subcooling value is higher than the set upper limit, the refrigerant flows from the circulation pipeline to the receiver 50. When the calculated subcooling value is lower than the set lower limit, the refrigerant flows from the receiver 50 back to the circulation pipeline. When the calculated subcooling value is within the set range, the refrigerant flow between the circulation pipeline and the receiver 50 is shut off, thereby ensuring that the amount of refrigerant in the circulation pipeline is always appropriate. Therefore, excess refrigerant in the circulation pipeline will not remain in the system heat exchanger, resulting in excessive subcooling of the high-pressure refrigerant, increased condensation temperature, and decreased system efficiency.

[0059] Furthermore, another objective of the present invention is to provide a heat pump system control method, implemented through the aforementioned heat recovery heat pump system 1, the control method comprising the following steps:

[0060] Adjust the opening and closing of the first branch, the second branch, and the outside air branch according to the heat pump system operating mode; obtain the pressure value of compressor 10; obtain the temperature value of the operating components of the heat pump system; calculate the high-pressure liquid subcooling degree or high-pressure liquid superheat degree according to the pressure value of compressor 10 and the temperature value of the operating components of the heat pump system; adjust the refrigerant amount in the receiver circuit according to the high-pressure liquid subcooling degree or high-pressure liquid superheat degree.

[0061] When the original heat pump system inputs refrigerant based on the main cooling mode with the largest refrigerant liquid holding capacity, regardless of the system's operating mode, excess refrigerant will remain in the heat exchanger, resulting in excessive refrigerant subcooling and affecting system efficiency. Therefore, this system improves system efficiency by detecting the pressure values ​​and subcooling of each component within the system and adjusting the system to ensure that the amount of circulating refrigerant is always appropriate.

[0062] Furthermore, adjusting the refrigerant quantity of the 50-channel receiver based on the high-pressure liquid subcooling or high-pressure liquid superheat includes the following steps: determining the heat pump system operating mode; determining whether the high-pressure liquid subcooling or high-pressure liquid superheat is within the set value range; if yes, closing the receiver inlet side and receiver outlet side; if no, proceeding to step A; step A includes: determining whether the high-pressure liquid subcooling or high-pressure liquid superheat is higher than the set value; if yes, opening the receiver inlet side and closing the receiver outlet side; determining whether the high-pressure liquid subcooling or high-pressure liquid superheat is lower than the set value; if yes, opening the receiver outlet side and closing the receiver inlet side.

[0063] The system operates by switching valve circuits according to different operating modes of the heat pump system. At the same time, when the refrigerant in the system circulation circuit is insufficient, refrigerant is output from the liquid receiver 50, and when the refrigerant in the system circulation circuit is excessive, excess refrigerant is input into the liquid receiver 50, thereby ensuring that the amount of refrigerant in the circulation circuit is always appropriate.

[0064] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A heat recovery heat pump system, characterized in that, include: The compressor (10), the liquid receiver circuit, the first branch circuit, the second branch circuit, and the external air branch circuit, among which, The liquid storage circuit includes an inlet side and an outlet side, and the external gas branch includes a first gas port (22) and a second gas port (23). The inlet side is connected to the gas side of the first gas port (22), and the outlet of the first branch is connected in parallel. The compressor (10) includes an exhaust side and a return side. The first branch is connected in parallel with the first branch inlet, the second branch inlet, and the second port (23). The exhaust side is also provided with a first switching valve (60). The first switching valve (60) controls the flow rate of refrigerant to the second branch inlet and the second port (23). The return side is connected in parallel with the liquid outlet side, the first switching valve (60), and the second branch outlet. The external gas branch includes an external gas heat exchanger (30), a second switching valve (32) and an external gas expansion valve (31). The first end of the second switching valve (32) and the first end of the external gas expansion valve (31) are connected in parallel with the outlet end of the external gas heat exchanger (30). The second end of the second switching valve (32) and the second end of the external gas expansion valve (31) are connected in parallel with the third switching valve (51). The second branch includes a cold water expansion valve (41) and a cold water heat exchanger (40). One side of the cold water expansion valve (41) is connected to the third switching valve (51), and the other side of the cold water expansion valve (41) is connected to the liquid outlet side of the cold water heat exchanger (40). The first branch includes a hot water heat exchanger (20) and a fifth switching valve (21). The inlet end of the hot water heat exchanger (20) is connected to the exhaust side, and the fifth switching valve (21) controls the refrigerant flow rate of the first branch. The first switching valve (60) includes: a sixth switching valve (61) and a seventh switching valve (62). One side of the sixth switching valve (61) is connected to the exhaust side, and the other side of the sixth switching valve (61) is connected to the inlet end of the external gas heat exchanger (30). The seventh switching valve (62) is connected to the sixth switching valve (61) on one side and to the return gas side on the other side.

2. The heat recovery heat pump system according to claim 1, characterized in that, The liquid storage circuit includes a liquid storage tank (50), a third switching valve (51) and a fourth switching valve (52), wherein the third switching valve (51) is located on the liquid inlet side and the fourth switching valve (52) is located on the liquid outlet side.

3. The heat recovery heat pump system according to claim 1, characterized in that, The fifth switching valve (21) is located between the outlet of the hot water heat exchanger (20) and the third switching valve (51).

4. The heat recovery heat pump system according to claim 1, characterized in that, The fifth switching valve (21) is located between the air inlet end and the exhaust end of the hot water heat exchanger (20).

5. The heat recovery heat pump system according to claim 1 or 3, characterized in that, The heat recovery heat pump system is also provided with an eighth switching valve (80), one end of which is located at the air inlet of the hot water heat exchanger (20), and the other end of which is connected to the return air side.

6. The heat recovery heat pump system according to claim 5, characterized in that, The heat recovery heat pump system is equipped with a detection module, which includes a pressure detector and a temperature detector. The pressure detector is located on the exhaust side and the return side; the temperature detector is located on the hot water heat exchanger (20), the outside air heat exchanger (30), the cold water heat exchanger (40), and the compressor (10).

7. A heat pump system control method, implemented using a heat recovery heat pump system as described in any one of claims 1 to 6, characterized in that, The heat pump system control method includes the following steps: Adjust the opening and closing of the first branch, the second branch, and the outside air branch according to the heat pump system operating mode; Obtain the pressure value of the compressor (10); Obtain the temperature values ​​of the operating components of the heat pump system; The high-pressure liquid subcooling or high-pressure liquid superheat is calculated based on the pressure value of the compressor (10) and the temperature value of the operating components of the heat pump system. Adjust the amount of refrigerant in the reservoir according to the degree of supercooling or superheat of the high-pressure liquid.

8. The heat pump system control method as described in claim 7, characterized in that, Adjusting the refrigerant quantity in the reservoir circuit based on the high-pressure liquid subcooling degree or the high-pressure liquid superheat includes the following steps: Determine the operating mode of the heat pump system; Determine whether the high-pressure liquid supercooling degree or high-pressure liquid superheating degree is within the set value range. If yes, close the liquid inlet side and the liquid outlet side of the liquid reservoir. If no, proceed to step A. Step A includes: determining whether the high-pressure liquid supercooling degree or high-pressure liquid superheat degree is higher than the set value; if so, opening the liquid inlet side of the reservoir and closing the liquid outlet side of the reservoir; determining whether the high-pressure liquid supercooling degree or high-pressure liquid superheat degree is lower than the set value; if so, opening the liquid outlet side of the reservoir and closing the liquid inlet side of the reservoir.

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