Heat recovery type heat pump system and control method thereof

Abstract

The invention relates to the field of air conditioners, and particularly provides a heat recovery type heat pump system and a control method thereof. The heat recovery type heat pump system comprises a compressor, a liquid storage device circuit, a first branch circuit, a second branch circuit, a third switching valve, a fourth switching valve and an external air branch circuit, the liquid storage device circuit comprises a liquid inlet side and a liquid outlet side, and the liquid inlet side is connected with a first air port and an air outlet of the first branch circuit in parallel; the compressor comprises an exhaust side and an air return side, the exhaust side is connected with the first branch air inlet, the second branch air inlet and the second air port in parallel, the exhaust side is further provided with a first switching valve, the first switching valve controls the flow of refrigerants flowing to the second branch air inlet and the second air port, and the air return side is connected with the liquid outlet side, the first switching valve and the second branch air outlet in parallel. According to the heat recovery type heat pump system, it is guaranteed that the amount of refrigerants in the system is appropriate all the time, then the working efficiency of the heat recovery type heat pump system is improved, meanwhile, use of a large gas-liquid separator is reduced, and cost is effectively saved.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioning, and in particular to a heat recovery heat pump system and a control method thereof. Background Art

[0002] As energy issues become increasingly prominent and people's requirements for energy efficiency continue to increase, heat pump technology has been widely used in many fields as a highly efficient energy utilization equipment.

[0003] In order to adapt to the various needs of current user scenarios, the existing heat recovery heat pump has the characteristics of multi-function. A heat recovery heat pump system can provide cooling function in summer and heating function in winter. Some systems can also provide domestic hot water throughout the year. It realizes the integration of multiple functions, meets the user's use requirements in different seasons and different needs, and reduces equipment investment and installation space.

[0004] However, one of the shortcomings of the related art is that the existing heat recovery refrigeration main mode system has the maximum refrigerant volume. After the refrigerant volume is filled into the device, the excess refrigerant liquid will be retained in the condenser in other refrigeration modes, heating modes, and heating main modes. In the refrigeration mode, the excess refrigerant is retained in the external air heat exchanger, in the refrigeration main mode, in the warm water heat exchanger and the external air heat exchanger, and in the heating mode and heating main mode, in the warm water heat exchanger, resulting in too much supercooling of the high-pressure liquid and an increase in the condensation 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 a control method thereof to solve the technical problem of low efficiency of a refrigeration system in the related art.

[0006] In order to solve the above problems, the present invention adopts the following technical solutions: A heat recovery heat pump system includes: a compressor, a liquid storage circuit, a first branch, a second branch and an external air branch, wherein the liquid storage circuit includes a liquid inlet side and a liquid outlet side, and the liquid inlet side is connected in parallel with a first air port and a first branch air outlet; the compressor includes an exhaust side and an air return side, and the exhaust side is connected in parallel with a first branch air inlet, a second branch air inlet and a second air port, and the exhaust side is also provided with a first switching valve, and the first switching valve controls the refrigerant flow to the second branch air inlet and the second air port, and the air return side is connected in parallel with the liquid outlet side, the first switching valve and the second branch air outlet.

[0007] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: the present application connects the liquid inlet side of the liquid reservoir circuit in parallel with the first air port and the first branch air outlet, and connects the exhaust side of the compressor in parallel with the first branch air inlet, the second branch air inlet, and the second air port, thereby achieving flexible switching between different branches and reasonable distribution of refrigerants. At the same time, by controlling the opening and closing of the liquid inlet and liquid outlet sides of the liquid reservoir circuit, the flow of refrigerant between the circulation pipeline and the liquid reservoir is controlled, so that the amount of refrigerant in the circulation pipeline is always appropriate. Therefore, there will be no excess refrigerant retained in the circulation pipeline, resulting in excessive supercooling of the high-pressure liquid, an increase in the condensation temperature, and a decrease in the efficiency of the refrigeration system.

[0008] Furthermore, the liquid reservoir circuit includes a liquid reservoir, a third switching valve and a fourth switching valve, the third switching valve is arranged at the liquid inlet side, and the fourth switching valve is arranged at the liquid outlet side.

[0009] Compared with the prior art, the technical effect achieved by adopting this technical solution is: specifically, the inflow and outflow of the refrigerant in the liquid storage circuit can be accurately controlled through these two switching valves. At the same time, when a system failure occurs, corresponding repairs and adjustments can be carried out by checking the status of the liquid storage, the third switching valve and the fourth switching valve.

[0010] Furthermore, the external air branch includes an external air heat exchanger, a second switching valve and an external air expansion valve. The first end of the second switching valve and the first end of the external air expansion valve are connected in parallel with the air outlet of the external air heat exchanger, and the second end of the second switching valve and the second end of the external air 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 air inlet end of the hot water heat exchanger is connected to the exhaust side, and the fifth switching valve controls the refrigerant flow of the first branch.

[0011] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: by adjusting the opening of the external air expansion valve and the opening of the cold water expansion valve, the superheat of the refrigerant on the return air side of the compressor reaches the set value, thereby ensuring the refrigeration efficiency of the system. In the refrigeration mode, while the cold water heat exchanger absorbs heat from the cold water to process the refrigeration load, the heat absorbed from the cold water and the compression workload are combined to release heat to the external air through the external air heat exchanger; in the refrigeration main mode, while the cold water heat exchanger absorbs heat from the cold water to process the refrigeration load, the part of the heat absorbed from the cold water and the compression workload are combined to release heat to the external air through the external air heat exchanger. The heat exchanger releases heat to the outside air, and the remaining part releases heat to hot water through the hot water heat exchanger to process the heating load; in the heating mode, heat is absorbed from the outside air through the outside air heat exchanger, and the heat absorbed from the outside air and the compressor workload are combined to release heat to the hot water through the hot water heat exchanger to process the heating load; in the main heating mode, heat is absorbed from cold water through the cold water heat exchanger to process the cooling load, and while absorbing heat from the outside air through the outside air heat exchanger, the heat absorbed from the cold water and the heat absorbed from the outside air and the compressor workload are combined to release heat to the hot water through the hot water heat exchanger to process the heating load. Each branch is reasonably connected and coordinated with the liquid storage circuit and the exhaust and return air sides of the compressor, so that the entire heat recovery heat pump system can operate smoothly under various working conditions. Different branches can be switched and coordinated according to actual needs to achieve effective recovery and utilization of heat.

[0012] Furthermore, the fifth switching valve is arranged between the air outlet end of the hot water heat exchanger and the third switching valve.

[0013] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: placing the fifth switching valve between the outlet end 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 external air branch and the second branch is controlled by the first switching valve.

[0014] Furthermore, the fifth switching valve is arranged between the air inlet end and the exhaust side of the hot water heat exchanger.

[0015] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: the fifth switching valve is set between the air inlet end of the hot water heat exchanger and the exhaust side of the compressor, and the fifth switching valve directly controls the circulation of the refrigerant in the first branch. At the same time, when a fault occurs in the first branch, the status of the fifth switching valve can be checked, which facilitates maintenance.

[0016] 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 air inlet end of the external air 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 air side.

[0017] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: the amount of refrigerant flowing to the external air branch is accurately controlled by the sixth switching valve, and the amount of refrigerant flowing to the second branch is accurately controlled by the seventh switching valve, and can be flexibly switched according to different working conditions. At the same time, in the system thermal bypass defrost mode, the refrigerant on the exhaust side of the compressor circulates to the external air heat exchanger, and condenses into high-pressure liquid refrigerant while dissolving the frost. The high-pressure liquid refrigerant is decompressed by the external air expansion valve and stored in the liquid reservoir in a state of gas-liquid separation. The compressor only inhales gas-phase refrigerant from the upper part of the liquid reservoir, thereby preventing the liquid refrigerant from being directly inhaled by the compressor.

[0018] At this time, in the hot bypass defrost mode, the liquid receiver also serves as a gas-liquid separator, so there is no need to set up a gas-liquid separator on the air inlet side of the compressor, or a small gas-liquid separator can be set up, saving cost and space.

[0019] Furthermore, the heat recovery heat pump system is also provided with an eighth switching valve, one end of the eighth switching valve is arranged at the air inlet end of the hot water heat exchanger, and the other end of the eighth switching valve is connected to the return air side.

[0020] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: by setting the eighth switching valve, the system can select the reverse defrost mode, and the system can use the heat absorbed by the hot water and the heat generated by the compression work through the hot water heat exchanger for external air defrosting, thereby improving the efficiency of the defrost mode and greatly reducing the defrost time.

[0021] Furthermore, the heat recovery heat pump system is provided with a detection module, which includes: a pressure detector and a temperature detector, the pressure detector is arranged on the exhaust side and the return air side; the temperature detector is arranged on the hot water heat exchanger, the outside air heat exchanger, the cold water heat exchanger and the compressor.

[0022] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: the system calculates the subcooling or superheating of the circulating refrigerant according to the information of the detection module, and flows the circulating refrigerant into the liquid storage tank or from the liquid storage tank into the circulation circuit according to the system setting, thereby ensuring the appropriate amount of refrigerant in the system and improving the system working efficiency.

[0023] Furthermore, another object of the present invention is to provide a heat pump system control method, which is implemented by the above-mentioned heat recovery heat pump system, and the control method comprises the steps of: The first branch, the second branch and the external air branch are opened and closed according to the operation mode of the heat pump system; the pressure value of the compressor is obtained; the temperature values ​​of the operating components of the heat pump system are obtained; the high-pressure liquid subcooling degree or the high-pressure liquid superheating degree is calculated according to the pressure value of the compressor and the temperature values ​​of the operating components of the heat pump system; the amount of refrigerant in the liquid storage circuit is adjusted according to the high-pressure liquid subcooling degree or the high-pressure liquid superheating degree.

[0024] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: when the original heat pump system inputs refrigerant into the system based on the main refrigeration mode with the largest refrigerant liquid holding amount, no matter what mode the system works in, there will be excess refrigerant retained in the heat exchanger, resulting in excessive refrigerant supercooling, thereby affecting the system's working efficiency. Therefore, this system detects the pressure value and supercooling of each component in the system, and ensures that the amount of circulating refrigerant in the system is always appropriate through system allocation, thereby improving the system's working efficiency.

[0025] Furthermore, adjusting the amount of refrigerant in the reservoir circuit according to the degree of subcooling or superheating of the high-pressure liquid includes the following steps: determining the operating mode of the heat pump system; determining whether the degree of subcooling or superheating of the high-pressure liquid is within a set value range, if so, closing the liquid inlet side of the reservoir circuit and the liquid outlet side of the reservoir circuit, if not, entering step A; step A includes: determining whether the degree of subcooling or superheating of the high-pressure liquid is higher than a set value, if so, opening the liquid inlet side of the reservoir circuit and closing the liquid outlet side of the reservoir circuit; determining whether the degree of subcooling or superheating of the high-pressure liquid is lower than a set value, if so, opening the liquid outlet side of the reservoir circuit and closing the liquid inlet side of the reservoir circuit.

[0026] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: the working mode of this system is to switch the valve circuit according to the different operating modes of the heat pump system. At the same time, when the refrigerant in the system circulation circuit is insufficient, the refrigerant is output from the liquid reservoir. When the refrigerant in the system circulation circuit is excessive, the excess refrigerant is input into the liquid reservoir, thereby ensuring that the amount of refrigerant in the circulation circuit is always appropriate. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic structural diagram of a heat recovery heat pump system according to an embodiment of the present invention; Figure 2 A schematic structural diagram of another heat recovery heat pump system according to an embodiment of the present invention; Figure 3 A circuit diagram of a heat recovery heat pump system in a refrigeration mode according to an embodiment of the present invention; Figure 4 A circuit diagram of a heat recovery heat pump system in a cooling main mode according to an embodiment of the present invention; Figure 5 A circuit diagram of a heating mode of a heat recovery heat pump system according to an embodiment of the present invention; Figure 6 A circuit diagram of a main heating mode of a heat recovery heat pump system according to an embodiment of the present invention; Figure 7 A circuit diagram of a heat bypass defrost mode of a heat recovery heat pump system according to an embodiment of the present invention; Figure 8 Schematic diagram of a circuit of a reverse defrost mode of a heat recovery heat pump system according to an embodiment of the present invention.

[0028] Description of reference numerals: 1-heat recovery heat pump system; 10-compressor; 20-hot water heat exchanger; 21-fifth switching valve; 22-first air port, 23-second air port; 30-external air heat exchanger; 31-external air expansion valve; 32-second switching valve; 40-cold water heat exchanger; 41-cold water expansion valve; 50-liquid storage tank; 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 DESCRIPTION

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0030] See also Figure 1-Figure 8 , which is a heat recovery heat pump system 1 provided by an embodiment of the present invention, includes: a compressor 10, a liquid reservoir circuit, a first branch, a second branch and an external air branch, wherein the liquid reservoir circuit includes a liquid inlet side and a liquid outlet side, the compressor 10 includes an exhaust side and an air return side, the liquid inlet side is connected in parallel with the first air port 22 and the first branch air outlet; the exhaust side is connected in parallel with the first branch air inlet, the second branch air inlet, and the second air port 23, the exhaust side is also provided with a first switching valve 60, the first switching valve 60 controls the refrigerant flow to the second branch air inlet and the second air port 23, and the air return side is connected in parallel with the liquid outlet side, the first switching valve 60, and the second branch air outlet.

[0031] For example, the first switching valve 60 may be a three-way switching valve, and the three-way switching valve is used to control the refrigerant flowing from the compressor 10 to the external air branch and the second branch.

[0032] The present application connects the liquid inlet side of the liquid reservoir circuit in parallel with the first air port 22 and the first branch air outlet, and connects the exhaust side of the compressor 10 in parallel with the first branch air inlet, the second branch air inlet, and the second air port 23, thereby achieving flexible switching between different branches and reasonable distribution of refrigerants. At the same time, by controlling the opening and closing of the liquid inlet and liquid outlet sides of the liquid reservoir circuit, the flow of refrigerant between the circulation pipeline and the liquid reservoir 50 is controlled, so that the amount of refrigerant in the circulation pipeline is always appropriate. Therefore, there will be no excess refrigerant retained in the circulation pipeline, resulting in excessive supercooling of the high-pressure liquid, an increase in the condensation temperature, and a decrease in the efficiency of the refrigeration system.

[0033] Further, such as Figure 1 As shown, the liquid reservoir circuit includes a liquid reservoir 50, a third switching valve 51 and a fourth switching valve 52, the third switching valve 51 is arranged at the liquid inlet side, and the fourth switching valve 52 is arranged at the liquid outlet side.

[0034] Specifically, the inflow and outflow of the refrigerant in the liquid storage circuit can be accurately controlled by these two switching valves. At the same time, when a system failure occurs, corresponding maintenance and adjustments can be carried out by checking the status of the liquid storage 50, the third switching valve 51 and the fourth switching valve 52.

[0035] Furthermore, the external air branch includes an external air heat exchanger 30, a second switching valve 32 and an external air expansion valve 31. The first end of the second switching valve 32 and the first end of the external air expansion valve 31 are connected in parallel with the air outlet end of the external air heat exchanger 30, and the second end of the second switching valve 32 and the second end of the external air 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 air 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 of the first branch.

[0036] See also Figure 4-Figure 6 , by adjusting the opening of the outside air expansion valve 31 and the opening of the cold water expansion valve 41 so that the refrigerant superheat on the return air side of the compressor 10 reaches the set value, the refrigeration efficiency of the system is guaranteed. In the cooling mode, while the cold water heat exchanger 40 absorbs heat from the cold water to process the cooling load, the heat absorbed from the cold water and the compression workload are combined to release heat to the outside air through the outside air heat exchanger 30; in the cooling main mode, while the cold water heat exchanger 40 absorbs heat from the cold water to process the cooling load, the part of the heat absorbed from the cold water and the compression workload is combined to release heat to the outside air through the outside air heat exchanger 30, and the remaining Part of it releases heat to hot water through the hot water heat exchanger 20 to process the heating load; in the heating mode, it absorbs heat from the outside air through the outside air heat exchanger 30, and the heat absorbed from the outside air and the workload of the compressor 10 are combined to release heat to the hot water through the hot water heat exchanger 20 to process the heating load; in the main heating mode, it absorbs heat from the cold water through the cold water heat exchanger 40 to process the cooling load, and while absorbing heat from the outside air through the outside air heat exchanger 30, the heat absorbed from the cold water and the heat absorbed from the outside air and the workload of the compressor 10 are combined to release heat to the hot water through the hot water heat exchanger 20 to process the heating load. Each branch is reasonably connected and coordinated with the liquid storage circuit and the exhaust side and return air side of the compressor 10, so that the entire heat recovery heat pump system 1 can operate smoothly under various working conditions. Different branches can be switched and coordinated according to actual needs to achieve effective recovery and utilization of heat.

[0037] Furthermore, the fifth switching valve 21 is disposed between the air outlet end of the hot water heat exchanger 20 and the third switching valve 51 .

[0038] Placing the fifth switching valve 21 between the outlet end of the hot water heat exchanger 20 and the third switching valve 51 is beneficial for 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 external air branch and the second branch is controlled by the first switching valve 60.

[0039] Further, such as Figure 2 As shown, the fifth switching valve 21 is disposed between the air inlet end and the exhaust side of the hot water heat exchanger 20 .

[0040] The fifth switching valve 21 is arranged between the air 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 the refrigerant in the first branch. At the same time, when a fault occurs in the first branch, the state of the fifth switching valve 21 can be checked, which facilitates maintenance.

[0041] For further information, 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 air inlet end of the external air 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 air side.

[0042] The system switches the circuit 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 air expansion valve 31 to adjust the system to the thermal bypass defrosting mode. The opening of the external air expansion valve 31 is adjusted to make the refrigerant pressure values ​​of each component of the system within the set range, and when the refrigerant pressure value reaches the set upper limit, the defrosting ends.

[0043] The amount of refrigerant flowing to the external 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, and can be flexibly switched according to different working conditions. At the same time, in the system thermal bypass defrost mode, the refrigerant on the exhaust side of the compressor 10 circulates to the external air heat exchanger 30, and condenses into high-pressure liquid refrigerant while dissolving the frost. The high-pressure liquid refrigerant is decompressed by the external air expansion valve 31 and stored in the liquid reservoir 50 in a state of gas-liquid separation. The compressor 10 only inhales the gas phase refrigerant from the upper part of the liquid reservoir 50, thereby preventing the liquid refrigerant from being directly inhaled by the compressor 10. At this time, in the thermal bypass defrost mode, the liquid reservoir 50 also serves as a gas-liquid separator, so there is no need to set a gas-liquid separator on the air inlet side of the compressor 10, or a small gas-liquid separator can be set, saving cost and space.

[0044] Furthermore, the heat recovery heat pump system 1 is further provided with an eighth switching valve 80 , one end of the eighth switching valve 80 is provided at the air inlet end of the hot water heat exchanger 20 , and the other end of the eighth switching valve 80 is connected to the return air side.

[0045] By setting the eighth switching valve 80, the system can select the reverse defrost mode. The system can use the heat absorbed by the hot water and the heat generated by the compression work through the hot water heat exchanger 20 to defrost the external air, thereby improving the efficiency of the defrost mode and greatly reducing the defrost time.

[0046] The system switches the circuit 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 the reverse defrost mode.

[0047] Furthermore, the heat recovery heat pump system 1 is provided with a detection module, which includes: a pressure detector and a temperature detector, the pressure detector is arranged on the exhaust side and the return air side; the temperature detector is arranged on the hot water heat exchanger 20, the outdoor air heat exchanger 30, the cold water heat exchanger 40 and the compressor 10.

[0048] In the present invention, the high-pressure refrigerant subcooling is calculated based on the measured values ​​of the high-pressure sensor and the refrigerant temperature sensor on the side of the outside air heat exchanger 30 in the cooling mode, and the high-pressure refrigerant subcooling is calculated based on the measured values ​​of the high-pressure sensor and the refrigerant temperature sensor on the hot water heat exchanger 20 in the cooling main mode, heating mode and heating main mode. When the calculated value of the subcooling is higher than the set upper limit, the refrigerant flows from the circulation pipeline to the liquid reservoir 50. When the calculated value of the subcooling is lower than the set lower limit, the refrigerant flows from the liquid reservoir 50 to the circulation pipeline. When the calculated value of the subcooling is within the set range, the refrigerant flow between the circulation pipeline and the liquid reservoir 50 is shut off, thereby ensuring that the amount of refrigerant in the circulation pipeline is always appropriate. Therefore, there will be no excess circulation pipeline refrigerant trapped in the system heat exchanger, resulting in too much high-pressure refrigerant subcooling, an increase in condensation temperature, and a decrease in system efficiency.

[0049] Furthermore, another object of the present invention is to provide a heat pump system control method, which is implemented by the above-mentioned heat recovery heat pump system 1, and the control method comprises the steps of: Adjust the opening and closing of the first branch, the second branch and the external air branch according to the operating mode of the heat pump system; obtain the pressure value of the compressor 10; obtain the temperature values ​​of the operating components of the heat pump system; calculate the high-pressure liquid subcooling or high-pressure liquid superheating according to the pressure value of the compressor 10 and the temperature values ​​of the operating components of the heat pump system; adjust the refrigerant amount in the liquid storage circuit according to the high-pressure liquid subcooling or high-pressure liquid superheating.

[0050] When the original heat pump system inputs refrigerant into the system based on the main refrigeration mode with the largest refrigerant liquid holding amount, no matter which mode the system works in, there will be excess refrigerant retained in the heat exchanger, resulting in excessive refrigerant supercooling, which in turn affects the system's working efficiency. Therefore, this system detects the pressure value and supercooling of each component in the system, and ensures that the amount of circulating refrigerant in the system is always appropriate through system allocation, thereby improving the system's working efficiency.

[0051] Furthermore, adjusting the refrigerant amount in the reservoir 50 according to the high-pressure liquid supercooling degree or the high-pressure liquid superheating degree includes the steps of: judging the operation mode of the heat pump system; judging whether the high-pressure liquid supercooling degree or the high-pressure liquid superheating degree is within the set value range, if so, closing the liquid inlet side of the reservoir road and the liquid outlet side of the reservoir road, if not, entering step A; step A includes: judging whether the high-pressure liquid supercooling degree or the high-pressure liquid superheating degree is higher than the set value, if so, opening the liquid inlet side of the reservoir road and closing the liquid outlet side of the reservoir road; judging whether the high-pressure liquid supercooling degree or the high-pressure liquid superheating degree is lower than the set value, if so, opening the liquid outlet side of the reservoir road and closing the liquid inlet side of the reservoir road.

[0052] The system works by switching the valve circuit according to the different operating modes of the heat pump system. At the same time, when the refrigerant in the system circulation circuit is insufficient, the refrigerant is output from the liquid reservoir 50. When the refrigerant in the system circulation circuit is excessive, the excess refrigerant is input into the liquid reservoir 50, thereby ensuring that the amount of refrigerant in the circulation circuit is always appropriate.

[0053] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A heat recovery heat pump system, characterized in that: include: A compressor (10), a liquid storage circuit, a first branch circuit, a second branch circuit, and an external air branch circuit, wherein: The liquid reservoir circuit comprises a liquid inlet side and a liquid outlet side, the external air branch circuit comprises a first air port (22) and a second air port (23), the liquid inlet side is connected in parallel with the first air port (22) and the first branch air outlet; The compressor (10) includes an exhaust side and a return side, the exhaust side is connected in parallel with the first branch air inlet, the second branch air inlet, and the second air port (23), the exhaust side is also provided with a first switching valve (60), the first switching valve (60) controls the refrigerant flow to the second branch air inlet and the second air port (23), and the return side is connected in parallel with the liquid outlet side, the first switching valve (60), and the second branch air outlet.

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

3. The heat recovery heat pump system according to claim 2, characterized in that: The external air branch comprises an external air heat exchanger (30), a second switching valve (32) and an external air expansion valve (31); a first end of the second switching valve (32) and a first end of the external air expansion valve (31) are connected in parallel to an air outlet end of the external air heat exchanger (30); a second end of the second switching valve (32) and a second end of the external air expansion valve (31) are connected in parallel to the third switching valve (51); The second branch comprises 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 a third switching valve (51), and the other side of the cold water expansion valve (41) is connected to a liquid outlet side of the cold water heat exchanger (40); The first branch comprises a hot water heat exchanger (20) and a fifth switching valve (21); the air 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.

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

5. The heat recovery heat pump system according to claim 3, characterized in that: The fifth switching valve (21) is arranged between the air inlet end and the exhaust side of the hot water heat exchanger (20).

6. The heat recovery heat pump system according to claim 5, characterized in that: The first switching valve (60) comprises: 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 air inlet end of the external air 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 air side.

7. The heat recovery heat pump system according to claim 4 or 6, characterized in that: The heat recovery heat pump system is further provided with an eighth switching valve (80), one end of the eighth switching valve (80) being arranged at the air inlet end of the hot water heat exchanger (20), and the other end of the eighth switching valve (80) being connected to the air return side.

8. The heat recovery heat pump system according to claim 7, characterized in that: The heat recovery heat pump system is provided with a detection module, the detection module comprising: a pressure detector and a temperature detector, the pressure detector being provided on the exhaust side and the return air side; the temperature detector being provided on the hot water heat exchanger (20), the outside air heat exchanger (30), the cold water heat exchanger (40) and the compressor (10).

9. A heat pump system control method, implemented by the heat recovery heat pump system according to any one of claims 1 to 8, characterized in that: The control method comprises the steps of: Regulating the opening and closing of the first branch, the second branch and the external air branch according to the operation mode of the heat pump system; Obtaining a pressure value of the compressor (10); Obtaining temperature values ​​of operating components of the heat pump system; Calculating the degree of subcooling or superheating of the high-pressure liquid according to the pressure value of the compressor (10) and the temperature values ​​of the operating components of the heat pump system; The amount of refrigerant in the accumulator circuit is adjusted according to the degree of subcooling of the high-pressure liquid or the degree of superheating of the high-pressure liquid.

10. The heat pump system control method according to claim 9, characterized in that: Adjusting the amount of refrigerant in the liquid storage circuit according to the high-pressure liquid subcooling degree or the high-pressure liquid superheating degree comprises the following steps: Determining an operating mode of the heat pump system; Determine whether the high-pressure liquid subcooling degree or the high-pressure liquid superheating degree is within the set value range, if so, close the liquid inlet side of the liquid reservoir path and the liquid outlet side of the liquid reservoir path, if not, enter step A; The step A comprises: determining whether the high-pressure liquid subcooling degree or the high-pressure liquid superheating degree is higher than the set value, and if so, opening the liquid inlet side of the reservoir road and closing the liquid outlet side of the reservoir road; determining whether the high-pressure liquid subcooling degree or the high-pressure liquid superheating degree is lower than the set value, and if so, opening the liquid outlet side of the reservoir road and closing the liquid inlet side of the reservoir road.

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