A heat pump system with coupled double defrosting mode and a method for operating the same

Abstract

The application discloses a heat pump system with coupled double defrosting modes and a running method thereof. The system is characterized in that only under a single refrigerant circuit, multiple mode running methods are realized, including a conventional refrigeration running method, a conventional heating running method, an auxiliary heat discharge high-temperature hot water preparation running method, an environment temperature below-10 DEG C reverse cycle defrosting running method, and an environment temperature above-10 DEG C outdoor evaporation coil rotation defrosting continuous heating running method. The system comprises a compressor, a cold-heat four-way valve, a condenser (high-efficiency tank), a liquid accumulator, an electronic expansion valve, a gas-liquid separator, a one-way stop valve, a switching valve and three sets of outdoor evaporation coils. The system is characterized in that by switching the states of the switching valve and the cold-heat four-way valve, the corresponding outdoor evaporation coils are controlled individually or jointly. The application realizes multiple functions by flexible control according to requirements and belongs to the technical field of heat pump systems.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat pump systems, in particular to a heat pump system coupled with a double defrosting mode and an operation method thereof. BACKGROUND

[0002] Air source heat pumps are widely used for their energy-saving and high-efficiency performance. Air source heat pump systems use the principle of reverse Carnot cycle to absorb energy from low-temperature air to heat air or hot water, which is the trend of heating in today's era. The heat pump system only needs to consume 1kw of electric energy to absorb 2-6kw of heat from the air, and the efficiency of the air source heat pump system is 2-3 times that of the traditional boiler when preparing the same hot water. However, when the air source heat pump operates in a low-temperature and high-humidity environment, frosting is inevitable. Frosting gradually deteriorates the heat exchange effect of the air source outdoor heat exchanger, and seriously reduces the energy efficiency of the air source heat pump. The traditional reverse cycle defrosting can effectively solve the adverse effects of frosting on the air source heat pump, but at the same time, it also brings disadvantages, such as large system pressure fluctuation, reduced outdoor thermal comfort, and inability to continuously heat. In addition, the traditional air source heat pump has low working efficiency and poor heating capacity when working in an unfavorable environment, and it is difficult to continuously produce high-temperature hot water exceeding 55℃, which cannot meet people's heating needs. In cold and severe cold regions, a large amount of high-temperature hot water is needed for heating in the heating season, and the traditional air source heat pump cannot meet the heating demand. If electric heating is used, the energy consumption is large and the practicality is poor; coal or gas heating will waste energy and pollute the environment. Therefore, a multifunctional heat pump is urgently needed to overcome the shortcomings of traditional heat pumps, continuously produce cooling and heating, and produce high-temperature hot water in any environment, without being affected by defrosting when heating in a low-temperature and high-humidity environment.

[0003] At present, multifunctional air source heat pump systems have been further developed to meet different needs of people.

[0004] Jiang Xiaoyong, Jiang Qiyun, Liu Wei, Chen Min, Zhou Jun, Zhou Libo. A multifunctional air source heat pump water heater [P]. (Hunan Province: CN111365803A, 2020-07-03.) The present application discloses a multifunctional air source heat pump water heater, which is mainly used for providing domestic hot water and heating hot water, and can recover the cold wind generated during hot water production in summer. However, due to the lack of defrosting function, it is only suitable for use in southern regions, which is not conducive to large-scale promotion.

[0005] Yang, Yong'an, Du, Qihun, Zhu, Yiqun, Huang, Chengjun. A multifunctional heat pump module and an air source heat pump system composed of the same[P] (Tianjin: CN111306834A, 2020-06-19) provides a heat pump module capable of switching to different operating modes according to use needs and a heat pump system composed of the same. The invention uses a cascade cycle system in winter operation, a part of the multifunctional heat pump module as a high-temperature stage heating cycle, and another part of the multifunctional heat pump module as a low-temperature stage heating cycle. The second heat exchanger in the multifunctional heat pump module as a low-temperature stage heating cycle acts as a condenser to release heat into the first heat accumulator, and the second heat exchanger in the multifunctional heat pump module as a high-temperature stage heating cycle acts as an evaporator to absorb heat from the first heat accumulator. The heat pump system of the invention can meet the needs of winter heating and summer heating by controlling the number of low-temperature stages and high-temperature stages of the cascade heat pump system according to different outdoor working conditions, and is suitable for a wide range of areas; the air source heat pump system of the invention does not use condenser evaporators for heat exchange between high-temperature stages and low-temperature stages, but uses heat storage devices for heat exchange, which can achieve flexible control of the heat load according to the number of high-temperature stages and low-temperature stages. However, compared with traditional air source heat pumps, the introduction of heat storage devices increases the initial investment, and the air source system is relatively large in size.

[0006] Chen, Yongchang, Hou, Lingjun, Wu, Yuting, Du, Chunxu, Lei, Zhang. A non-stop defrosting air source heat pump heating system[P] (Beijing: CN113375207B, 2022-10-18). The invention discloses a non-stop defrosting air source heat pump. In heating mode, the refrigerant can absorb heat from the fin heat exchanger and also from the solar energy heat storage water tank, greatly improving the utilization of comprehensive energy. In defrosting mode, the invention uses air supplementing and enthalpy increasing technology, so that the air source heat pump system can still heat, overcoming the disadvantage of air source heat pumps not working at low temperatures, and can realize simultaneous heating and defrosting, achieving non-stop defrosting. However, the solar photovoltaic and photothermal system is easily affected by weather conditions, especially in winter in northern regions, where the intensity of sunlight is insufficient and there are often severe weather conditions, which seriously affect the operation and stability of the air source heat pump system.

[0007] Yang, Y., Li, Z., Yan, N., Wan, S., Jiang, X., Shi, Y., Shen, L., Zhang, X. An air conditioning heat pump system for producing high-temperature hot water at low ambient temperature [P]. (Jiangsu Province: CN114754430A, 2022-07-15) The invention discloses an air conditioning heat pump system for producing high-temperature hot water at low ambient temperature, which includes three cycles. The first cycle is a low-pressure stage compressor-driven refrigerant refrigeration cycle, the second cycle is a high-pressure stage compressor-driven refrigerant refrigeration cycle, and the low-pressure stage compressor and the high-pressure stage compressor exchange heat through an evaporative condenser. The third cycle is a water pump-driven hot water circulation and a refrigerant heat exchange in the high-pressure stage condenser. This dual-stage compression refrigeration cycle system can effectively improve the heating capacity at low ambient temperature, produce high-temperature hot water above 65°C at an ambient temperature below -40°C, and improve the economic efficiency of heat pump air conditioning operation. This system can be used in some specific environments, but is not suitable for general promotion, and still faces the problem of frosting on the outdoor heat exchanger after a certain period of operation.

[0008] The above air source heat pump system improves the traditional air source heat pump to some extent, but the function is still relatively single, the regional adaptability is poor, and it is easily affected by the environment. At present, the research and application of multifunctional air source heat pump are still relatively few.

[0009] The present application aims to invent a single circuit heat pump system with coupled double defrosting mode, which is characterized in that various heat pump functions are realized by combining electric control technology under a single refrigerant circuit. The system has strong adaptability, can realize daily heating and cooling, and can produce high-temperature hot water by auxiliary heat rejection. In a low-temperature and harsh environment, the system can use reverse cycle defrosting mode or outdoor evaporative coil rotation defrosting to continuously produce heat. The single circuit heat pump system with coupled double defrosting mode of the present application uses multiple sets of parallel outdoor evaporative coils (three sets of parallel outdoor evaporative coils are described in this paper, and more than three sets of parallel outdoor evaporative coils can also be adjusted according to the technical principle), one cold-heat four-way valve, two electronic expansion valves, nine one-way stop valves, and three switching valves to realize refrigerant flow direction and flow control of the multifunctional air source heat pump system. The switching valve is composed of three valve ports and a valve core. The connection of different valve ports is changed by controlling the valve core with electric signals. When the switching valve is in the power-on state: the valve core is in the lower part, and the first valve port and the second valve port of the switching valve are connected. When the switching valve is in the power-off state: the valve core is in the upper part, and the second valve port and the third valve port of the switching valve are connected. The refrigerant flow direction in the three sets of outdoor evaporative coils is controlled by the three switching valves to realize different functions: heating condition: all three switching valves are in the power-off state, and the three sets of parallel outdoor evaporative coils are evaporators; cooling condition: all three switching valves are in the power-on state, and the three sets of parallel outdoor evaporative coils are condensers; reverse cycle defrosting condition: all three switching valves are in the power-off state, and the three sets of parallel outdoor evaporative coils are evaporators; auxiliary heat rejection for producing high-temperature hot water: at least one of the three switching valves is in the power-on state, that is, at least one of the three sets of parallel outdoor evaporative coils is a condenser, and the other two sets of outdoor evaporative coils are evaporators; rotation defrosting for continuous heating: at least one of the three switching valves is in the power-off state, that is, at least one of the three sets of parallel outdoor evaporative coils is an evaporator, and the other two sets of outdoor evaporative coils are condensers. After the defrosting of this outdoor evaporative coil is completed, the same operation of switching another switching valve can realize rotation defrosting for continuous heating. In addition, the components of the single circuit heat pump system with coupled double defrosting mode of the present application are all traditional basic components. The reasonable operation method is realized by proper pipeline connection and component switching without introducing additional devices. Therefore, the multifunctional air source heat pump system has low initial investment, strong system function, convenient installation, high safety, high energy efficiency, and is suitable for promotion. SUMMARY

[0010] In view of the problems in the prior art, the first invention of the present application provides a single circuit heat pump system with coupled double defrosting mode, which can control flexibly and realize multiple functions. According to the demand, multiple functions can be realized, including refrigeration, heating, auxiliary heat rejection for high-temperature hot water, reverse cycle defrosting, and rotation defrosting for continuous heating. The control is relatively flexible.

[0011] The second object of the present application is to provide a method for operating the single-circuit heat pump system with the first coupled double-defrosting mode, which can independently produce refrigeration.

[0012] The third object of the present application is to provide a method for operating the single-circuit heat pump system with the second coupled double-defrosting mode, which can independently produce heating.

[0013] The fourth object of the present application is to provide a method for operating the single-circuit heat pump system with the third coupled double-defrosting mode, which can produce high-temperature hot water with auxiliary heat rejection.

[0014] The fifth object of the present application is to provide a method for operating the single-circuit heat pump system with the fourth coupled double-defrosting mode, which can adopt reverse-cycle defrosting when the outdoor ambient temperature is below -10℃.

[0015] The sixth object of the present application is to provide a method for operating the single-circuit heat pump system with the fourth coupled double-defrosting mode, which can adopt rotating defrosting for continuous heating when the outdoor ambient temperature is above -10℃ (including -10℃).

[0016] In order to achieve the above objects, the present application adopts the following technical solutions:

[0017] A single-loop heat pump system with coupled dual defrosting methods and its operation method include a compressor, a four-way hot and cold valve, a condenser (high-efficiency tank), a liquid receiver, an electronic expansion valve, a gas-liquid separator, a one-way shut-off valve, a switching valve, and three sets of outdoor evaporator coils. The switching valve consists of three valve ports and a valve core. The connection of different valve ports is changed by controlling the valve core with an electrical signal. When the switching valve is energized: the valve core is in the lower position, and the first and second valve ports of the switching valve are connected; when the switching valve is de-energized: the valve core is in the upper position, and the second and third valve ports of the switching valve are connected. The compressor outlet is connected to the first valve port of the four-way hot and cold valve, the third valve port of the four-way hot and cold valve is connected to the condenser inlet, and the second valve port of the four-way hot and cold valve is connected to... The gas-liquid separator inlet is connected, the fourth port of the hot and cold four-way valve is connected to the storage tank, and the condenser (high-efficiency tank) outlet is connected to the storage tank inlet. The first, second, and third switching valves have their first ports connected to each other and to the fourth port of the hot and cold four-way valve. The first switching valve's first port is connected to the fourth port of the hot and cold four-way valve, its second port is connected to the first outdoor heat exchanger, and its third port is connected to the gas-liquid separator inlet. The second switching valve's second port is connected to the second outdoor heat exchanger, and its second port is connected to the third outdoor heat exchanger. The third switching valve's third port is connected to the gas-liquid separator inlet. The three switching valves are connected in series with their respective outdoor evaporator coils, and the three sets of outdoor evaporator coils are connected in parallel. Individual control of a single switching valve allows for individual control of the corresponding outdoor evaporator coil, or multiple switching valves can be controlled simultaneously to jointly control the three parallel outdoor evaporator coils.

[0018] Furthermore: the third valve port of the hot and cold four-way valve is connected to the inlet of the gas-liquid separator; the fourth valve port of the hot and cold four-way valve and the first branch pipe of the liquid receiver are connected to the first valve port of the first switching valve; the second branch pipe of the liquid receiver is connected to the manifold of the first branch pipe of the outdoor heat exchanger; the second branch pipe of the liquid receiver is connected to the manifold of the second branch pipe of the outdoor heat exchanger; and the manifold of the first branch pipe of the outdoor heat exchanger is connected to the manifold of the second branch pipe of the outdoor heat exchanger.

[0019] Furthermore, the fourth valve port of the hot and cold four-way valve is equipped with a one-way shut-off valve, the first and third branch pipes of the liquid receiver are equipped with one-way shut-off valves, the second branch pipe of the liquid receiver is equipped with an electronic expansion valve A, the first branch pipe and the second branch pipe of the outdoor heat exchanger are both equipped with one-way shut-off valves, and the manifold of the second branch pipe of the outdoor heat exchanger is equipped with an electronic expansion valve B.

[0020] This makes the flow of refrigerant within the unit more controllable, ensuring that the direction of refrigerant flow is unique.

[0021] The cold-heat four-way valve has two working states: A working state: the first valve port and the second valve port of the cold-heat four-way valve are connected, and the third valve port and the fourth valve port are connected; B working state: the first valve port and the fourth valve port of the cold-heat four-way valve are connected, and the second valve port and the third valve port are connected.

[0022] The switching valve is composed of three valve ports and a valve core, and the connection of different valve ports is changed by controlling the valve core through an electric signal; the switching valve is in an energized state: the first valve port and the second valve port are connected; the switching valve is in a de-energized state: the second valve port and the third valve port are connected.

[0023] The first coupling double-defrosting mode single-loop heat pump system and its operation method, including the following single refrigeration operation method: the first valve port and the fourth valve port of the cold-heat four-way valve are connected, the first switching valve, the second switching valve and the third switching valve are in the energized state, the one-way stop valve 11(1), 11(2), 11(3), 12 and 14 are in the connected state, the one-way stop valve 13, 10(1), 10(2) and 10(3) are in the disconnected state, and the electronic expansion valves A and B are in the open state. Realize the single refrigeration of the multifunctional heat pump system.

[0024] The second coupling double-defrosting mode single-loop heat pump system and its operation method, including the following single heating operation method: the first valve port and the second valve port of the cold-heat four-way valve are connected, the one-way stop valve 11(1), 11(2), 11(3), 12, 13 and 14 are in the disconnected state, the one-way stop valve 10(1), 10(2) and 10(3) are in the connected state, the first switching valve, the second switching valve and the third switching valve are in the de-energized state, the electronic expansion valve A is open, and the electronic expansion valve B is closed. Realize the single heating of the coupling double-defrosting mode single-loop heat pump system.

[0025] The third coupling double-defrosting mode single-loop heat pump system and its operation method, including the following auxiliary heat removal high-temperature hot water production operation method:

[0026] At least three outdoor heat exchangers are provided, at least one outdoor heat exchanger switching valve is in the energized state, and at least two outdoor heat exchanger switching valves are in the de-energized state. The present application takes outdoor heat exchanger A as a condenser for illustration, and actual arrangement can be made according to specific conditions and requirements: the first valve port and the second valve port of the cold-heat four-way valve are connected, the first switching valve is in the energized state, the second switching valve and the third switching valve are in the de-energized state, the one-way stop valve 12, 11(1), 10(2), 10(3) and 18 are in the connected state, the one-way stop valve 13, 14, 10(1), 11(2) and 11(3) are in the disconnected state, and the electronic expansion valves A and B are in the open state. Realize the auxiliary heat removal hot water production of the coupling double-defrosting mode single-loop heat pump system.

[0027] The fourth coupling double defrosting mode single loop heat pump system and its operation method, including the operation method of reverse defrosting when the ambient temperature is below-10 DEG C: the first valve port and the fourth valve port of the cold and hot four-way valve are connected, the first switch valve, the second switch valve and the third switch valve are in the power-on state, the one-way stop valve 11(1), 11(2), 11(3), 12 and 14 are in the connected state, the one-way stop valve 13, 10(1), 10(2) and 10(3) are in the disconnected state, and the electronic expansion valves A and B are in the open state. The reverse cycle defrosting of the coupling double defrosting mode single loop heat pump system is realized.

[0028] The fifth coupling double defrosting mode single loop heat pump system and its operation method, including the operation method of continuous heating by rotation defrosting when the ambient temperature is above-10 DEG C:

[0029] At least three outdoor heat exchangers are arranged, at least one switch valve of the outdoor heat exchanger is in the power-on state, and at least two switch valves of the outdoor heat exchanger are in the power-off state. The operation mode for defrosting and continuous heating of the first outdoor heat exchanger is that the first valve port and the second valve port of the cold and hot four-way valve are connected, the first switch valve is in the power-on state, the second switch valve and the third switch valve are in the power-off state, the one-way stop valve 12, 11(1), 10(2), 10(3) and 18 are in the connected state, the one-way stop valve 13, 14, 10(1), 11(2) and 11(3) are in the disconnected state, and the electronic expansion valves A and B are in the open state. The rotation defrosting and continuous heating of the coupling double defrosting mode single loop heat pump system are realized.

[0030] The operation method for defrosting and continuous heating of the second outdoor heat exchanger is that the first valve port and the second valve port of the cold and hot four-way valve are connected, the first switch valve and the third switch valve are in the power-off state, the second switch valve is in the power-on state, the one-way stop valve 12, 10(1), 11(2), 10(3) are in the connected state, the one-way stop valve 13, 14, 10(2), 11(1) and 11(3) are in the disconnected state, and the electronic expansion valves A and B are in the open state. The rotation defrosting and continuous heating of the coupling double defrosting mode single loop heat pump system are realized.

[0031] The operation method for defrosting and continuous heating of the third outdoor heat exchanger is that the first valve port and the second valve port of the cold and hot four-way valve are connected, the first switch valve and the second switch valve are in the power-off state, the third switch valve is in the power-on state, the one-way stop valve 12, 10(1), 10(2), 11(3) are in the connected state, the one-way stop valve 13, 14, 11(1) and 11(2) are in the disconnected state, and the electronic expansion valves A and B are in the open state. The rotation defrosting and continuous heating of the coupling double defrosting mode single loop heat pump system are realized.

[0032] In general, the present application has the following advantages:

[0033] The single-circuit heat pump system coupled with the double defrosting mode can realize different operation modes by changing the circulation path of the refrigerant through the opening and closing of the cold-heat four-way valve, the first switching valve, the second switching valve, the third switching valve, the one-way stop valve, the electronic expansion valve A and the electronic expansion valve B. The system can realize the single heating mode, the single cooling mode, the auxiliary heat rejection mode for obtaining high-temperature hot water, the reverse cycle defrosting mode and the rotating defrosting continuous heating mode.

[0034] The application has the functions of single heating and single cooling of the traditional heat pump, but the traditional heat pump has many limitations, such as: frost makes the traditional heat pump have to stop heating and remove frost; the system cannot continuously obtain high-temperature hot water in an adverse environment, etc. In order to overcome the shortcomings of the traditional heat pump, three sets of parallel outdoor evaporating coils are arranged, which can individually or jointly play the role of heat rejection and cold rejection, and are connected with other components to realize different functions. For example: when the system is in a high-temperature environment, continuous heating makes the exhaust pressure gradually rise, at this time, one outdoor heat exchanger is used as a condenser to assist heat rejection, so that the exhaust pressure of the system is reduced, the operating condition is stable, and high-temperature hot water is obtained; when the system is in a low-temperature environment, frost makes the heating energy efficiency of the system gradually decrease, the switching valve corresponding to the outdoor heat exchanger can be switched to rotate defrosting, at this time, the other outdoor heat exchanger normally evaporates and absorbs heat, realizing continuous heating of the system rotating defrosting. The application can flexibly change the flow direction of the refrigerant according to the needs, realize different functions of the outdoor evaporating coil, and realize the needs of life heating and cooling in all climates. At the same time, the problem that the traditional air source heat pump cannot continuously heat during defrosting and affects heating is solved. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a structural connection diagram of the single-circuit heat pump system coupled with the double defrosting mode.

[0036] Figure 2 is a structural diagram of the cold-heat four-way valve A state.

[0037] Figure 3 is a structural diagram of the cold-heat four-way valve B state.

[0038] Figure 4 is a structural diagram of the switching valve in the power-on state.

[0039] Figure 5 is a structural diagram of the switching valve in the power-off state.

[0040] Figure 6 is a refrigerant circulation path diagram of the single-circuit heat pump system coupled with the double defrosting mode in the single heating mode.

[0041] Figure 7is the circulating path of refrigerant of the single circuit heat pump system of coupled double defrosting mode when the single refrigeration is carried out.

[0042] Figure 8 is the circulating path of refrigerant of the single circuit heat pump system of coupled double defrosting mode when the high temperature hot water is prepared by auxiliary heat rejection.

[0043] Figure 9 is the circulating path of refrigerant of the single circuit heat pump system of coupled double defrosting mode when the reverse cycle defrosting is carried out.

[0044] Figure 10 is the circulating path of refrigerant of the single circuit heat pump system of coupled double defrosting mode when the rotation defrosting is carried out. DETAILED DESCRIPTION

[0045] In order to facilitate the unified viewing of various reference signs in the drawings of the specification, the reference signs appearing in the drawings of the specification are uniformly explained as follows:

[0046] 1 is a gas-liquid separator, 2 is a compressor, 3 is a cold-hot four-way valve, 4 is a high-efficiency tank (condenser), 5 is a liquid accumulator, 6 is an electronic expansion valve A, 7 is an electronic expansion valve B, 8(1) is a first outdoor heat exchanger, 8(2) is a second outdoor heat exchanger, 8(3) is a third outdoor heat exchanger, 9(1) is a first switching valve, 9(2) is a second switching valve, 9(3) is a third switching valve, 10(1), 10(2), 10(3), 11(1), 11(2), 12(3), 13, 14 are all one-way stop valves, 15 is a first valve port of the cold-hot four-way valve, 16 is a second valve port of the cold-hot four-way valve, 17 is a third valve port of the cold-hot four-way valve, 18 is a fourth valve port of the cold-hot four-way valve, 19 is a first valve port of the switching valve, 20 is a second valve port of the switching valve, 21 is a third valve port of the switching valve, 22 is a liquid accumulator main pipe, 23 is a liquid accumulator first branch pipe, 24 is a liquid accumulator second branch pipe, 25 is a liquid accumulator third branch pipe, 26 is a junction point 1, 27 is a junction point 2, 28 is a junction point 3, 29(1), 29(2), 29(3) are return pipes, and 30 is a delivery return pipe.

[0047] For the convenience of description, the following embodiment is explained as follows: in all the following embodiments, the total number of outdoor heat exchangers in the single circuit heat pump system of coupled double defrosting mode is three, and one outdoor heat exchanger is taken as a condenser in the high temperature hot water preparation mode by auxiliary heat rejection or in the rotation defrosting continuous heating mode, but the actual situation is not limited to this, and different numbers of outdoor evaporators and auxiliary heat rejection condensers can be set according to specific needs.

[0048] Embodiment 1

[0049] In combination with Figure 1 , Figure 2 ,Figure 3 、 Figure 4 、 Figure 5 、 One The single-circuit heat pump system with coupled double defrosting mode comprises a compressor, a cold-heat four-way valve, a condenser (high-efficiency tank), a liquid accumulator, an electronic expansion valve, a gas-liquid separator, a one-way stop valve, and a switching valve. The gas-liquid separator, the compressor, and the cold-heat four-way valve are connected in series, the condenser is connected in series with the liquid accumulator, the outdoor heat exchanger has a plurality of outdoor heat exchangers, and in the present embodiment, three outdoor heat exchangers are provided. The condenser and the three outdoor heat exchangers are connected in parallel with each other, and they work independently without interfering with each other.

[0050] The outlet of the gas-liquid separator is in communication with the inlet of the compressor, the outlet of the compressor is in communication with the first valve port of the cold-heat four-way valve, and the refrigerant flows out of the compressor, then flows to the cold-heat four-way valve, and then flows to the condenser, the liquid accumulator, the outdoor heat exchanger, and finally flows to the gas-liquid separator and returns to the compressor.

[0051] The first switching valve, the second switching valve, and the third switching valve are each provided with a first valve port, a second valve port, and a third valve port. When the first switching valve, the second switching valve, and the third switching valve are in an energized state, only the first valve port and the second valve port are connected. When the first switching valve, the second switching valve, and the third switching valve are in a de-energized state, only the second valve port and the third valve port are connected.

[0052] The first valve port of the cold-heat four-way valve is in communication with the outlet of the compressor, the second valve port of the cold-heat four-way valve is in communication with the condenser, the third valve port of the cold-heat four-way valve is connected to the inlet of the gas-liquid separator, and the fourth valve port of the cold-heat four-way valve is in communication with the first valve port of the switching valve. When the cold-heat four-way valve is in state A, the refrigerant flowing out of the compressor flows into the first valve port, then flows out of the second valve port of the cold-heat four-way valve to the condenser (high-efficiency tank), and then flows to the liquid accumulator.

[0053] The outlet of the liquid accumulator is provided with a dry pipe in communication with the tank body, the dry pipe is divided into a first sub-pipe, a second sub-pipe, and a third sub-pipe, a part of the dry pipe is located inside the liquid accumulator, and the first sub-pipe, the second sub-pipe, and the third sub-pipe are located outside the liquid accumulator. The second sub-pipe is in communication with the fourth valve port of the cold-heat four-way valve and the first valve port of the switching valve. The second sub-pipe is in communication with the first sub-pipe convergence pipe of the outdoor heat exchanger, and the third sub-pipe is in communication with the second sub-pipe convergence pipe of the outdoor heat exchanger.

[0054] The outdoor heat exchanger inlet is bifurcated into a first outdoor branch pipe and a second outdoor branch pipe, one end of the first outdoor branch pipe and the second outdoor branch pipe is communicated with the outdoor heat exchanger through the same pipeline. The other end of the first outdoor branch pipe of the heat exchanger is connected with the first converging pipe of the outdoor heat exchanger through a pipeline, and the other end of the second outdoor branch pipe of the outdoor heat exchanger is connected with the second converging pipe of the outdoor heat exchanger through a pipeline. When flowing from the liquid accumulator to the outdoor heat exchanger, the refrigerant flows through the liquid accumulator main pipe, the second branch pipe of the liquid accumulator, the first branch pipe of the outdoor heat exchanger, the converging pipe of the outdoor heat exchanger, and then flows into the outdoor heat exchanger.

[0055] The first switch valve port is connected with the fourth valve port of the cold and hot four-way valve, and the first valve port of the first switch valve is connected with the liquid accumulator through the first branch pipe of the liquid accumulator and the liquid accumulator main pipe. The third valve port of the switch valve is connected with the return pipe, and all the return pipes are connected with the return pipe.

[0056] After the refrigerant flows out of the liquid accumulator, different flow states are realized according to the opening and closing of the one-way stop valve and the power-on and power-off state of the switch valve. When the switch valve is in the power-on state, the first valve port of the switch valve and the second valve port of the switch valve are connected, the refrigerant flows into the first valve port from the second valve port of the switch valve. When the switch valve is in the power-off state, the second valve port and the third valve port are connected, the refrigerant flows into the second valve port, and the refrigerant flowing out of the third valve port to the return pipe is gathered into the return pipe, then flows back to the gas-liquid separator from the return pipe, and finally flows back to the compressor to complete the cycle.

[0057] The second branch pipe of the liquid accumulator and the second branch pipe of the outdoor heat exchanger are respectively provided with electronic expansion valves A and B, and the first branch pipe of the liquid accumulator, the second branch pipe of the liquid accumulator and the first branch pipe of the outdoor heat exchanger are respectively provided with one-way stop valves,

[0058] The one-way stop valve 12 is connected with the third valve port of the cold and hot four-way valve and the first branch pipe of the liquid accumulator. The refrigerant can flow from the third valve port of the cold and hot four-way valve to the condenser, then flow to the liquid accumulator through the pipeline, or flow from the liquid accumulator to the condenser through the pipeline.

[0059] The one-way stop valve 13 is connected with the intersection point 1 and the intersection point 2, when the electronic expansion valve A is closed, the refrigerant can only flow from the first branch pipe of the liquid accumulator to the switch valve and then to the outdoor heat exchanger. When it is needed to flow the refrigerant from the liquid accumulator to the gas-liquid separator through the outdoor heat exchanger, the electronic expansion valve A is in the open state, and the first, second and third switch valves are in the power-off state. At this time, the refrigerant flowing out of the liquid accumulator flows through the second branch pipe of the liquid accumulator, then enters the electronic expansion valve A, then flows through the outdoor heat exchanger, and finally flows back to the gas-liquid separator. Because the second branch pipe of the outdoor heat exchanger is provided with a one-way stop valve, the refrigerant of the liquid accumulator cannot flow into the outdoor heat exchanger from the second branch pipe of the outdoor heat exchanger.

[0060] One-way shut-off valve 14 is connected to junction point 3 and junction point 1. One-way shut-off valves 13 on the first branch pipe of the liquid receiver and one-way shut-off valve 14 on the second branch pipe of the liquid receiver have the same flow direction. When the refrigerant flows from the outdoor heat exchanger into the liquid receiver, it passes through the second branch pipe of the outdoor heat exchanger, the junction pipe of the second branch pipe of the outdoor heat exchanger, the third branch pipe of the liquid receiver, and the main pipe of the liquid receiver in sequence. When the refrigerant flows from the liquid receiver into the outdoor heat exchanger, it passes through the main pipe of the liquid receiver, the second branch pipe of the liquid receiver, the junction pipe of the first branch pipe of the outdoor heat exchanger, and the first branch pipe of the outdoor heat exchanger in sequence, or it passes through the main pipe of the liquid receiver, the first branch pipe of the liquid receiver, and the switching valve in sequence.

[0061] Example 2:

[0062] Except for the following technical features, the other unmentioned technical features are the same as in Example 1.

[0063] Combination Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 7 As shown, when using the above-described coupled dual-defrost method in a single-loop heat pump system, the following methods for generating cooling are included:

[0064] The first and fourth ports of the hot and cold four-way valve are connected. The first, second, and third switching valves are energized. Electronic expansion valve A is closed, and electronic expansion valve B is open. After flowing out of the compressor, the refrigerant passes sequentially through the hot and cold four-way valve and the one-way shut-off valve 12 into the first port of the switching valve. Then, it passes sequentially through the outdoor heat exchanger, the one-way shut-off valve 11, the second branch pipe of the outdoor heat exchanger, electronic expansion valve B, the third branch pipe of the liquid receiver, the one-way shut-off valve 14, the liquid receiver main pipe, the liquid receiver, the condenser (high-efficiency tank), the hot and cold four-way valve, and the return pipe before returning to the compressor, completing the independent refrigeration cycle. During this process, all three outdoor heat exchangers can work together, or one or two of them can work simultaneously.

[0065] Example 3

[0066] Except for the following technical features, the other unmentioned technical features are the same as in Example 1.

[0067] Combination Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 As shown, when using the above-described coupled dual-defrost method in a single-loop heat pump system, the following individual heating methods are included:

[0068] The first valve port and the second valve port of the cold-hot four-way valve are connected, the first switching valve, the second switching valve and the third switching valve are in the power-off state, the electronic expansion valve A is opened, the electronic expansion valve B is closed, and the refrigerant flows out from the compressor and then passes through the cold-hot four-way valve 3, the condenser 4, the liquid accumulator 5, the liquid accumulator dry pipe 22, the liquid accumulator second branch pipe 24, the electronic expansion valve A 6, the outdoor heat exchanger first branch pipe 10, the one-way stop valve 10, the outdoor heat exchanger 8, the switching valve second valve port, the switching valve third valve port, the gas return pipe and the return pipe in sequence, and then returns to the compressor, and the separate heating cycle is completed. In this process, the three outdoor heat exchangers can work together or one or two of them can work.

[0069] Embodiment 3

[0070] Except for the following technical features, the rest of the technical features not mentioned are the same as those in Embodiment 1.

[0071] In combination with Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 8 , when the single-loop heat pump system using the above-mentioned coupling double-defrosting mode is used, the following method for preparing high-temperature hot water by auxiliary heat rejection is included (taking the first outdoor heat exchanger as an example)

[0072] The first valve port and the second valve port of the cold-hot four-way valve are connected, the first switching valve is in the power-on state, the second switching valve and the third switching valve are in the power-off state, the electronic expansion valve A and the electronic expansion valve B are both opened, the refrigerant flows out from the compressor and then passes through the cold-hot four-way valve, the condenser and the liquid accumulator, and then part of the refrigerant passes through the electronic expansion valve A, and the other part of the refrigerant passes through the liquid accumulator first branch pipe, the first switching valve, the first outdoor heat exchanger, the first outdoor heat exchanger second branch pipe, the electronic expansion valve B, and then merges with the refrigerant flowing through the electronic expansion valve A to flow into the other two outdoor heat exchangers through the outdoor heat exchanger first branch pipe, and then passes through the second switching valve, the third switching valve second valve port, the second switching valve and the third switching valve third valve port, the gas return pipe and the return pipe, and then returns to the compressor through the gas-liquid separator after auxiliary heat rejection, and the cycle for preparing hot water is completed. In this process, the three outdoor heat exchangers work together, and the present application takes the first outdoor heat exchanger for auxiliary heat rejection, the second outdoor heat exchanger and the third outdoor heat exchanger for normal evaporation and heat absorption as an example.

[0073] Embodiment 4

[0074] Except for the following technical features, the rest of the technical features not mentioned are the same as those in Embodiment 1.

[0075] In combination with Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5、 Figure 9 As shown in the single-circuit heat pump system using the above-mentioned coupled double-defrosting mode, the method includes the following reverse cycle defrosting:

[0076] The first valve port and the fourth valve port of the cold-heat four-way valve are connected, the first switch valve, the second switch valve, and the third switch valve are in the energized state, the electronic expansion valve A is closed, and the electronic expansion valve B is opened. The refrigerant flows out from the compressor, sequentially passes through the cold-heat four-way valve and the one-way stop valve 12, enters the first valve port of the switch valve, and then sequentially passes through the outdoor heat exchanger, the one-way stop valve 11, the second branch pipe of the outdoor heat exchanger, the electronic expansion valve B, the third branch pipe of the liquid accumulator, the one-way stop valve 14, the dry pipe of the liquid accumulator, the liquid accumulator, the condenser (high-efficiency tank), the cold-heat four-way valve, and the gas return pipe to return to the compressor. The cold cycle is completed. In this process, the three outdoor heat exchangers can work together or one or two of them can work.

[0077] Embodiment 5:

[0078] In addition to the following technical features, the remaining unmentioned technical features are the same as those in Embodiment 1.

[0079] In combination with Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 、 Figure 10 As shown in the single-circuit heat pump system using the above-mentioned coupled double-defrosting mode, the method includes the following reverse cycle defrosting:

[0080] The first valve port and the second valve port of the cold-heat four-way valve are connected, the first switch valve is in the energized state, the second switch valve and the third switch valve are in the de-energized state, the electronic expansion valve A and the electronic expansion valve B are both opened. The refrigerant flows out from the compressor, sequentially passes through the cold-heat four-way valve, the condenser, and the liquid accumulator, and then part of the refrigerant passes through the electronic expansion valve A, and the other part passes through the first branch pipe of the liquid accumulator, the first switch valve, the first outdoor heat exchanger, the second branch pipe of the first outdoor heat exchanger, the electronic expansion valve B, and then merges with the refrigerant flowing through the electronic expansion valve A to flow into the other two outdoor heat exchangers through the first branch pipe of the outdoor heat exchanger, and then passes through the second valve port of the second switch valve and the third valve port of the third switch valve, the gas return pipe, and the return pipe to return to the compressor after passing through the gas-liquid separator. The hot water cycle is completed by auxiliary heat rejection. In this process, the three outdoor heat exchangers work together, and after the first outdoor heat exchanger completes defrosting, the corresponding switch valve can be controlled to defrost the next heat exchanger. The present application takes the first outdoor heat exchanger defrosting for continuous heating as an example.

[0081] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above embodiments, and any changes, modifications, substitutions, combinations, simplifications, etc. made without departing from the spirit and principles of the present application should be equivalent replacement manners and should be included in the protection scope of the present application.

Claims

1. A single-circuit heat pump system with coupled dual-defrosting mode, comprising a compressor, a cold-heat four-way valve, a high-efficiency tank, a liquid accumulator, an electronic expansion valve, a gas-liquid separator, first to third one-way stop valves, first to third switching valves, and first to third outdoor heat exchangers; the compressor outlet is connected to the first valve port of the cold-heat four-way valve, the second valve port of the cold-heat four-way valve is connected to the inlet of the high-efficiency tank, the third valve port of the cold-heat four-way valve is connected to the inlet of the gas-liquid separator, the fourth valve port of the cold-heat four-way valve is connected to the first valve port of the first to third switching valves through a second shunt pipe, and the outlet of the high-efficiency tank is connected to the inlet of the liquid accumulator; the first valve port of the first to third switching valves is connected, and the fourth valve port of the cold-heat four-way valve is connected through the second shunt pipe; the second valve port of the first switching valve is connected to the first outdoor heat exchanger, the second valve port of the second switching valve is connected to the second outdoor heat exchanger, and the second valve port of the third switching valve is connected to the third outdoor heat exchanger; the third valve ports of the first to third switching valves are connected to the inlet of the gas-liquid separator through a first manifold pipe; The first to third outdoor heat exchangers are respectively provided with a first branch pipe and a second branch pipe on the side away from the corresponding switching valve, all the first branch pipes are connected to an outdoor heat exchanger first branch pipe manifold, and all the second branch pipes are connected to a second branch pipe manifold; the first to third outdoor heat exchangers are respectively provided with first to third one-way stop valves on the first branch pipes, and fourth to sixth one-way stop valves on the second branch pipes; The outlet of the liquid accumulator is provided with a first to third branch pipe of the liquid accumulator, the fourth valve port of the cold-heat four-way valve is provided with a seventh one-way stop valve, the first branch pipe of the liquid accumulator is provided with an eighth one-way stop valve, the third branch pipe of the liquid accumulator is provided with a ninth one-way stop valve, and the second branch pipe of the liquid accumulator is provided with an electronic expansion valve A; the second branch pipe manifold of the outdoor heat exchanger is provided with an electronic expansion valve B; The fourth valve port of the cold-heat four-way valve, the first branch pipe of the liquid accumulator, and the first valve port of the first switching valve are connected, the second branch pipe of the liquid accumulator is connected to the outdoor heat exchanger first branch pipe manifold, and the first branch pipe manifold is connected to the second branch pipe manifold.

2. A method of operating a single loop heat pump system coupled with a dual defrost mode as defined in claim 1, characterized in that: The following single refrigeration operation method is included: The cold-heat four-way valve is in state B, the first to third switching valves are in the power-on state, the seventh, ninth, fourth to sixth one-way stop valves are opened, the eighth, first to third one-way stop valves are closed, the electronic expansion valve A is closed, and the electronic expansion valve B is opened.

3. A method of operating a single loop heat pump system coupled with a dual defrost mode as defined in claim 1, wherein: The following single heating operation method is included: The cold-heat four-way valve is in state A, the first to third switching valves are in the power-off state, the first to third one-way stop valves are opened, the fourth to ninth one-way stop valves are closed, the electronic expansion valve A is opened, and the electronic expansion valve B is closed.

4. A method of operating a single loop heat pump system coupled with a dual defrost mode as defined in claim 1, wherein: The following operation method for obtaining high-temperature hot water by auxiliary heat rejection is included, when the first outdoor heat exchanger is used for auxiliary heat rejection: The first outdoor heat exchanger is set as a condenser, the cold-heat four-way valve is in state A, the first switching valve is in the power-on state, the second to third switching valves are in the power-off state, the eighth, second to fourth one-way stop valves are opened, the first, fifth, sixth, seventh, and ninth one-way stop valves are closed, and the electronic expansion valve A and the electronic expansion valve B are both opened.

5. A method of operating a single loop heat pump system coupled with a dual defrost mode as defined in claim 1, wherein: Simultaneously including two stable defrosting modes, namely the operation method of reverse cycle defrosting and the operation method of alternate defrosting and continuous heating, the operation method of reverse cycle defrosting: the cold and hot four-way valve is in B state, the first to third switching valves are in the energized state, the fourth to seventh and ninth one-way stop valves are opened, the eighth and first to third one-way stop valves are closed, the electronic expansion valve A is closed, and the electronic expansion valve B is opened; The operation method of alternate defrosting and continuous heating: the first outdoor heat exchanger is set as a condenser, the cold and hot four-way valve is in A state, the first switching valve is in the energized state, the second to third switching valves are in the de-energized state, the eighth, second to fourth one-way stop valves are all opened, the first, fifth, sixth, seventh, ninth one-way stop valves are closed, and the electronic expansion valve A and the electronic expansion valve B are both opened.

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