A low temperature heat recovery system

Abstract

The present invention relates to the technical field of heat pump systems, and in particular to a low-temperature heat recovery system. A low-temperature heat recovery system includes a compressor, a first four-way valve, a second four-way valve, an air-side heat exchanger, an air conditioning water heat exchanger, a hot water heat exchanger, a liquid reservoir, an economizer, a first throttling element, a second throttling element, and a mainstream pipeline; the low-temperature heat recovery system includes a refrigeration cycle mode, a heating cycle mode, a hot water cycle mode, and a heat recovery cycle mode. In this technical solution, the four modes are all supercooled by the economizer, which can reduce the exhaust temperature and expand the operating range on the one hand; on the other hand, it increases the main circuit supercooling, so that it can operate normally in a low temperature environment, improving the system capacity and energy efficiency. There is only one liquid reservoir, and the refrigerant does not pass through the liquid reservoir in the refrigeration cycle mode, which helps to reduce the system supercooling loss, and also reduces the amount of refrigerant injected.

Description

Technical Field

[0001] The present invention relates to the technical field of heat pump systems, and in particular to a low-temperature heat recovery system. Background Art

[0002] Heat pump is a highly efficient energy-saving device that fully utilizes low-grade thermal energy. Heat can be transferred spontaneously from a high-temperature object to a low-temperature object, but not spontaneously in the opposite direction. The working principle of a heat pump is a mechanical device that forces heat to flow from a low-temperature object to a high-temperature object in a reverse cycle. It consumes only a small amount of reverse cycle net work to obtain a large amount of heat supply, and can effectively utilize the low-grade thermal energy that is difficult to use to achieve energy saving.

[0003] The application of air source heat pump technology in the fields of air conditioning, heating and hot water has greatly improved the quality of human life. For places where air conditioning, heating and hot water are required at the same time, the full heat recovery refrigeration system combines the refrigeration, heating and hot water systems into one, with more powerful functions. It can recover the waste heat during refrigeration and use it to heat domestic hot water, which not only saves the cost of heating water, but also reduces the "heat island effect" of the community. It is a more energy-saving and green system.

[0004] However, due to the limitations of climatic and environmental conditions, ordinary heat recovery air-cooled heat pump units can only operate above an ambient temperature of -15°C. In extremely cold areas, due to the low temperature, the refrigerant specific volume becomes larger, which will lead to insufficient compressor suction mass flow, insufficient motor cooling, and excessively high exhaust temperature, which will endanger the safety of the unit and prevent normal operation. The condensing temperature is related to the water temperature. For heating or hot water conditions, the water temperature remains unchanged, the condensing temperature remains basically unchanged, and the evaporation temperature decreases due to the decrease in ambient temperature. The lower the ambient temperature, the greater the compression ratio of the compressor, the higher the exhaust temperature, and the unit cannot operate safely. Summary of the invention

[0005] In order to solve the above problems, the purpose of the present invention is to provide a low-temperature heat recovery system that can operate stably and reliably at low ambient temperatures, while greatly improving the system's energy efficiency and meeting the needs of refrigeration, heating and hot water in extremely cold areas.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: including a compressor, a first four-way valve, a second four-way valve, an air-side heat exchanger, an air-conditioning water heat exchanger, a hot water heat exchanger, a liquid storage tank, an economizer, a first throttling element, a second throttling element, and a mainstream pipeline; the first four-way valve includes a control valve port C1, a control valve port D1, a control valve port E1 and a control valve port S1, the control valve port D1 is connected to the outlet of the compressor, the control valve port E1 is connected to the first port of the hot water heat exchanger, and the control valve port S1 is connected to the inlet of the compressor; the second four-way valve includes a control valve port C2, a control valve port D2, a control valve port E2 and a control valve port S2, the control valve port C2 is connected to the first port of the air-side heat exchanger, the control valve port D2 is connected to the control valve port C1, the control valve port E2 is connected to the first port of the air-conditioning water heat exchanger, and the control valve port S2 is connected to the inlet of the compressor; the mainstream pipeline includes a first pipeline, The first branch, the second branch and the third branch, the first pipeline is connected between the second port of the air-side heat exchanger and the first port of the economizer, the first port of the second branch is connected to the first port of the third branch and the first port of the first branch, the second port of the first branch is connected to the fourth port of the economizer, the second port of the second branch is connected to the second port of the air-side heat exchanger, the second port of the third branch is connected to the second port of the air-conditioning water heat exchanger, the second branch is provided with a first throttling element, and the third branch is provided with a second throttling element; the second port of the air-conditioning water heat exchanger is connected to the inlet of the liquid reservoir through a second pipeline, the second port of the hot water heat exchanger is connected to the inlet of the liquid reservoir through a third pipeline, the third pipeline is provided with a fourth branch in parallel, and the fourth branch is provided with a hot water defrosting solenoid valve and a throttling capillary; the low-temperature heat recovery system includes a refrigeration cycle mode, a heating cycle mode, a hot water cycle mode and a heat recovery cycle mode;

[0007] The low-temperature heat recovery system further includes a first one-way valve, which is disposed on the first pipeline to prevent the refrigerant in the liquid reservoir from flowing back into the air-side heat exchanger when the low-temperature heat recovery system is in a hot water defrost cycle mode;

[0008] The low-temperature heat recovery system also includes a second one-way valve, which is arranged on the second pipeline to prevent the refrigerant in the liquid storage device from flowing back into the air conditioning water heat exchanger when the low-temperature heat recovery system is in a heating cycle mode.

[0009] Preferably, when the low-temperature heat recovery system is in the refrigeration cycle mode, the control valve port C1 is connected to the control valve port D1, the control valve port C2 is connected to the control valve port D2, the control valve port E2 is connected to the control valve port S2, the second throttling element is opened, and the first throttling element is closed; at this time, the refrigerant in the low-temperature heat recovery system passes through the compressor, the control valve port D1, the control valve port C1, the control valve port D2, the control valve port C2, the air side heat exchanger, the economizer, the second throttling element, the air conditioning water heat exchanger, and the control valve port E2 in sequence. , control valve port S2, and finally flows back to the compressor; when the low-temperature heat recovery system is in the heating cycle mode, the control valve port C1 is connected to the control valve port D1, the control valve port E2 is connected to the control valve port D2, the control valve port C2 is connected to the control valve port S2, the first throttling element is opened, and the second throttling element is closed; at this time, the refrigerant in the low-temperature heat recovery system passes through the compressor, the control valve port D1, the control valve port C1, the control valve port D2, the control valve port E2, the air conditioning water heat exchanger, the liquid storage device, the economizer, the first throttling element element, air side heat exchanger, control valve port C2, control valve port S2, and finally flows back to the compressor; when the low-temperature heat recovery system is in hot water circulation mode, the control valve port E1 is connected with the control valve port D1, the control valve port C2 is connected with the control valve port S2, the first throttling element is opened, and the second throttling element is closed; at this time, the refrigerant in the low-temperature heat recovery system passes through the compressor, control valve port D1, control valve port E1, hot water heat exchanger, liquid storage tank, economizer, first throttling element, air side heat exchanger, control valve port C2, Control valve port S2, and finally return to the compressor; when the low-temperature heat recovery system is in the heat recovery cycle mode, the control valve port E1 is connected with the control valve port D1, the control valve port E2 is connected with the control valve port S2, the second throttling element is opened, and the first throttling element is closed; at this time, the refrigerant in the low-temperature heat recovery system passes through the compressor, control valve port D1, control valve port E1, hot water heat exchanger, liquid storage tank, economizer, second throttling element, air conditioning water heat exchanger, control valve port E2, control valve port S2 in sequence, and finally returns to the compressor.

[0010] Preferably, the low-temperature heat recovery system also includes a hot water defrost mode. When the low-temperature heat recovery system is in the hot water defrost mode, the control valve port C1 is connected to the control valve port D1, the control valve port E1 is connected to the control valve port S1, the control valve port C2 is connected to the control valve port D2, and the first throttling element and the second throttling element are closed; at this time, the refrigerant in the low-temperature heat recovery system passes through the compressor, the control valve port D1, the control valve port C1, the control valve port D2, the control valve port C2, the air side heat exchanger, the liquid storage tank, the hot water defrost solenoid valve, the capillary tube, the hot water heat exchanger, the control valve port E1, the control valve port S1, and finally flows back to the compressor.

[0011] Preferably, the low-temperature heat recovery system also includes a third one-way valve, which is arranged on the third pipe to prevent the refrigerant in the liquid storage tank from flowing back into the hot water heat exchanger when the low-temperature heat recovery system is in hot water circulation mode or heat recovery circulation mode.

[0012] Preferably, the low-temperature heat recovery system is further provided with a gas-liquid separator, which is arranged on the pipeline between the control valve port S2 and the compressor inlet.

[0013] Preferably, the low-temperature heat recovery system also includes a fourth pipeline, a fifth branch and a third throttling element arranged on the fifth branch, the fourth pipeline is arranged between the compressor and the third port of the economizer, the first port of the fifth branch is connected to the second port of the first branch, the second port of the fifth branch is connected to the second port of the economizer, the first port of the economizer is connected to the fourth port, and the second port is connected to the third port; when the low-temperature heat recovery system is in refrigeration cycle mode, heating cycle mode, hot water cycle mode and heat recovery cycle mode, the third throttling element is in an open state.

[0014] Preferably, the low-temperature heat recovery system further comprises a filter, and the filter is arranged on the first pipeline, close to the economizer.

[0015] Preferably, the low-temperature heat recovery system further comprises a high-pressure sensor and a low-pressure sensor, wherein the high-pressure sensor and the low-pressure sensor are respectively arranged at the outlet and the inlet of the compressor, and a high-pressure switch is also arranged between the high-pressure sensor and the compressor.

[0016] The present invention adopts the above technical solution. The system only has three throttling elements, one filter, three one-way valves and one liquid storage device to realize four modes of cooling, heating, hot water and heat recovery, which reduces the cost and is simple and reliable.

[0017] In addition, all four modes use economizer supercooling, which can reduce the exhaust temperature and expand the operating range on the one hand; on the other hand, it can increase the main circuit supercooling so that it can operate normally in a low temperature environment, improving system capacity and energy efficiency.

[0018] The liquid reservoir is set on the high-pressure side of all modes. In this arrangement, the liquid reservoir is not directly connected to the low-pressure side during defrosting and mode switching, preventing the stored refrigerant from returning to the compressor at the moment of mode switching, causing liquid return to the compressor. In addition, there is only one liquid reservoir. In the refrigeration cycle mode, the refrigerant does not pass through the liquid reservoir, which helps reduce the system's supercooling loss and also reduces the amount of refrigerant injected; in the heating, hot water and heat recovery modes, the refrigerant passes through the liquid reservoir to store the refrigerant that does not participate in the cycle, ensuring reliable operation of the system.

[0019] When the system is in cooling, heating, heat recovery and hot water modes, the refrigerant on the low-pressure side passes through the control valve port S2 of the second four-way valve and the gas-liquid separator to return to the compressor, passing through only one four-way valve, which helps to reduce the pressure loss on the low-pressure side and improve the system's energy efficiency.

[0020] Finally, in order to make the system operate more reliably and effectively in a low-temperature environment, an air supply channel is added to the compressor. The refrigerant diverted from the main circuit passes through the third throttling element and exchanges heat with the main circuit in the economizer, replenishing the medium-pressure gas into the compression intermediate chamber of the compressor, thereby increasing the exhaust volume, reducing the exhaust temperature, and improving the heating capacity. This allows the heat pump system to provide sufficient heating capacity even at low ambient temperatures, while increasing the main circuit supercooling and improving energy efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the connection relationship between various components in a low-temperature heat recovery system.

[0022] Figure 2 This is a refrigerant flow diagram when a low-temperature heat recovery system is in refrigeration cycle mode.

[0023] Figure 3 This is a refrigerant flow diagram when a low-temperature heat recovery system is in a heat recovery cycle mode.

[0024] Figure 4 This is a refrigerant flow diagram when a low-temperature heat recovery system is in a heating cycle mode.

[0025] Figure 5 This is a refrigerant flow diagram when a low-temperature heat recovery system is in hot water circulation mode.

[0026] Figure 6 This is a refrigerant flow diagram for a low-temperature heat recovery system in hot water defrosting mode. DETAILED DESCRIPTION

[0027] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0028] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0029] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more, unless otherwise clearly specified.

[0030] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0032] like Figure 1-6 A low-temperature heat recovery system shown includes a compressor 10, a first four-way valve 20, a second four-way valve 30, an air-side heat exchanger 40, an air-conditioning water heat exchanger 50, a hot water heat exchanger 60, a liquid storage tank 70, an economizer 80, a gas-liquid separator 90, a first throttling element 110, a second throttling element 120, a third throttling element 180, a mainstream pipeline 190, a first one-way valve 100, a second one-way valve 130, and a third one-way valve 160.

[0033] The first four-way valve 20 includes a control valve port C1, a control valve port D1, a control valve port E1 and a control valve port S1, the control valve port D1 is connected to the outlet of the compressor 10, the control valve port E1 is connected to the first port 63 of the hot water heat exchanger, and the control valve port S1 is connected to the inlet of the compressor 10;

[0034] The second four-way valve 30 includes a control valve port C2, a control valve port D2, a control valve port E2 and a control valve port S2, the control valve port C2 is connected to the first port 41 of the air side heat exchanger, the control valve port D2 is connected to the control valve port C1, the control valve port E2 is connected to the first port 53 of the air conditioning water heat exchanger, and the control valve port S2 is connected to the inlet of the compressor 10;

[0035] The mainstream pipeline 190 includes a first pipeline 101, a first branch 102, a second branch 103 and a third branch 104. The first pipeline 101 is connected between the second port 42 of the air side heat exchanger and the first port 81 of the economizer. The first port 151 of the second branch is connected to the first port 152 of the third branch and the first port 153 of the first branch. The second port 154 of the first branch is connected to the fourth port 84 of the economizer. The second port 155 of the second branch is connected to the second port 42 of the air side heat exchanger. The second port 156 of the third branch is connected to the second port 54 of the air conditioning water heat exchanger. The second branch 103 is provided with a first throttling element 110, and the third branch 104 is provided with a second throttling element 120.

[0036] The second port 54 of the air conditioning water heat exchanger is connected to the inlet of the liquid reservoir 70 via a second pipe 107, and the second port 64 of the hot water heat exchanger is connected to the inlet of the liquid reservoir 70 via a third pipe 105. A fourth branch 106 is provided in parallel on the third pipe 105, and a hot water defrost solenoid valve 150 and a throttling capillary 140 are provided on the fourth branch 106.

[0037] In this embodiment, the low temperature heat recovery system includes a refrigeration cycle mode, a heating cycle mode, a hot water cycle mode, a heat recovery cycle mode and a hot water defrosting mode when working. When the system is actually working, it switches between the refrigeration cycle mode, the heating cycle mode, the hot water cycle mode, the heat recovery cycle mode and the hot water defrosting mode by controlling the first four-way valve 20, the second four-way valve 30, the first throttling element 110 and the second throttling element 120.

[0038] The first one-way valve 100 is arranged on the first pipe 101 to prevent the refrigerant in the liquid reservoir 70 from flowing back into the air side heat exchanger 40 when the low-temperature heat recovery system is in the hot water defrost cycle mode; the second one-way valve 130 is arranged on the second pipe 107 to prevent the refrigerant in the liquid reservoir 70 from flowing back into the air-conditioning water heat exchanger 50 when the low-temperature heat recovery system is in the heating cycle mode; the third one-way valve 160 is arranged on the third pipe 105 to prevent the refrigerant in the liquid reservoir 70 from flowing back into the hot water heat exchanger 60 when the low-temperature heat recovery system is in the hot water circulation mode or the heat recovery cycle mode.

[0039] More specifically, if Figure 2 As shown, when the low-temperature heat recovery system is in the refrigeration cycle mode, the control valve port C1 is connected to the control valve port D1, the control valve port C2 is connected to the control valve port D2, the control valve port E2 is connected to the control valve port S2, the second throttling element 120 is opened, and the first throttling element 110 is closed; at this time, the refrigerant in the low-temperature heat recovery system passes through the compressor 10, the control valve port D1, the control valve port C1, the control valve port D2, the control valve port C2, the air side heat exchanger 40, the economizer 80, the second throttling element 120, the air conditioning water heat exchanger 50, the control valve port E2, the control valve port S2, and finally flows back to the compressor 10.

[0040] like Figure 4 As shown, when the low-temperature heat recovery system is in the heating cycle mode, the control valve port C1 is connected to the control valve port D1, the control valve port E2 is connected to the control valve port D2, the control valve port C2 is connected to the control valve port S2, the first throttling element 110 is opened, and the second throttling element 120 is closed; at this time, the refrigerant in the low-temperature heat recovery system passes through the compressor 10, the control valve port D1, the control valve port C1, the control valve port D2, the control valve port E2, the air conditioning water heat exchanger 50, the liquid storage tank 70, the economizer 80, the first throttling element 110, the air side heat exchanger 40, the control valve port C2, the control valve port S2, and finally flows back to the compressor 10.

[0041] like Figure 5 As shown, when the low-temperature heat recovery system is in the hot water circulation mode, the control valve port E1 is connected to the control valve port D1, the control valve port C2 is connected to the control valve port S2, the first throttling element 110 is opened, and the second throttling element 120 is closed; at this time, the refrigerant in the low-temperature heat recovery system passes through the compressor 10, the control valve port D1, the control valve port E1, the hot water heat exchanger 60, the liquid storage tank 70, the economizer 80, the first throttling element 110, the air side heat exchanger 40, the control valve port C2, the control valve port S2, and finally flows back to the compressor 10.

[0042] like Figure 3As shown, when the low-temperature heat recovery system is in the heat recovery cycle mode, the control valve port E1 is connected to the control valve port D1, the control valve port E2 is connected to the control valve port S2, the second throttling element 120 is opened, and the first throttling element 110 is closed; at this time, the refrigerant in the low-temperature heat recovery system passes through the compressor 10, the control valve port D1, the control valve port E1, the hot water heat exchanger 60, the liquid storage tank 70, the economizer 80, the second throttling element 120, the air-conditioning water heat exchanger 50, the control valve port E2, the control valve port S2, and finally flows back to the compressor 10.

[0043] like Figure 6 As shown, when the low-temperature heat recovery system is in the hot water defrost cycle mode, the control valve port C1 is connected to the control valve port D1, the control valve port E1 is connected to the control valve port S1, the control valve port C2 is connected to the control valve port D2, and the first throttling element 110 and the second throttling element 120 are closed; at this time, the refrigerant in the low-temperature heat recovery system passes through the compressor 10, the control valve port D1, the control valve port C1, the control valve port D2, the control valve port C2, the air side heat exchanger 40, the liquid storage tank 70, the hot water defrost solenoid valve 150, the capillary 140, the hot water heat exchanger 60, the control valve port E1, the control valve port S1, and finally flows back to the compressor 10.

[0044] It should be noted that a water flow path is formed between the water inlet end 51 and the water outlet end 52 of the air-conditioning water heat exchanger 50, and heat exchange is performed with the refrigerant flow path flowing through the air-conditioning water heat exchanger 50; a water flow path is formed between the water inlet end 61 and the water outlet end 62 of the hot water heat exchanger 60, and heat exchange is performed with the refrigerant flow path flowing through the hot water heat exchanger 60.

[0045] The gas-liquid separator 90 is disposed on the pipeline between the control valve port S2 and the inlet of the compressor 10 so as to separate the gas and liquid of the refrigerant entering the compressor 10 .

[0046] It should be further explained that the low-temperature heat recovery system also includes a fourth pipeline 108 and a fifth branch 109, a third throttling element 180 is arranged on the fifth branch 109, the fourth pipeline 108 is arranged as an air supply channel between the compressor 10 and the third port 83 of the economizer, the first port 157 of the fifth branch is connected to the second port 154 of the first branch, the second port 158 ​​of the fifth branch is connected to the second port 82 of the economizer, the first port 81 of the economizer is connected to the fourth port 84 of the economizer, and the second port 82 of the economizer is connected to the third port 83 of the economizer. Here, the refrigerant diversion of the main circuit is heat-exchanged with the main circuit in the economizer through the third throttling element.

[0047] When the low-temperature heat recovery system is in a refrigeration cycle mode, a heating cycle mode, a hot water cycle mode, and a heat recovery cycle mode, the third throttling element 180 is in an open state.

[0048] The low-temperature heat recovery system in this embodiment also includes a filter 170, which is arranged on the first pipe 101. When the low-temperature heat recovery system is in refrigeration cycle mode, heating cycle mode, hot water cycle mode, and heat recovery cycle mode, the filter 170 is used to filter impurities in the refrigerant.

[0049] In addition, the low-temperature heat recovery system also includes a high-pressure sensor 201 and a low-pressure sensor 202. The high-pressure sensor 201 and the low-pressure sensor 202 are respectively arranged at the outlet and the inlet of the compressor 10 for detecting the pressure at both ends of the compressor 10, and the high-pressure switch 203 arranged between the high-pressure sensor 201 and the compressor 10 is used for safe control of the pressure in the pipeline.

[0050] In this specific embodiment, the system has only three throttling elements, one filter, three one-way valves, and one liquid storage device to realize four modes: cooling, heating, hot water, and heat recovery, which reduces costs and is simple and reliable. In addition, the four modes are all supercooled by the economizer 80, which can reduce the exhaust temperature and expand the operating range on the one hand; on the other hand, it can increase the supercooling degree of the main circuit, so that it can operate normally in a low temperature environment, improving the system capacity and energy efficiency.

[0051] In the hot water defrost mode, the dedicated hot water defrost solenoid valve 150 and the capillary tube 140 are connected in series to ensure stable and reliable defrosting in the hot water mode.

[0052] The accumulator 70 is arranged on the high-pressure side of all modes. The arrangement of the accumulator 70 is such that the accumulator is not directly connected to the low-pressure side during defrosting and mode switching, preventing the stored refrigerant from returning to the compressor 10 at the moment of mode switching, causing liquid return to the compressor 10. In addition, there is only one accumulator, and the refrigerant does not pass through the accumulator in the refrigeration cycle mode, which helps reduce the system's supercooling loss and also reduces the amount of refrigerant injected; while in the heating, hot water and heat recovery modes, the refrigerant passes through the accumulator 70, storing the refrigerant that does not participate in the cycle, ensuring reliable operation of the system.

[0053] When the system is in cooling, heating, heat recovery and hot water modes, the refrigerant on the low-pressure side passes through the control valve port S2 of the second four-way valve 30 and the gas-liquid separator 90 and returns to the compressor 10. It only passes through one four-way valve, which helps to reduce the pressure loss on the low-pressure side and improve the system's energy efficiency.

[0054] In order to make the system operate more reliably and effectively in a low-temperature environment, the present invention also adds an air supply channel to the compressor. The refrigerant diverted from the main path passes through the third throttling element and exchanges heat with the main path in the economizer, and replenishes medium-pressure gas into the compression intermediate chamber of the compressor, thereby increasing the exhaust volume, reducing the exhaust temperature, and improving the heating capacity. The heat pump system can provide sufficient heating capacity even at low ambient temperatures, while increasing the main path supercooling and improving energy efficiency.

[0055] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0056] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. A low temperature heat recovery system, characterized in that: The invention comprises a compressor (10), a first four-way valve (20), a second four-way valve (30), an air-side heat exchanger (40), an air-conditioning water heat exchanger (50), a hot water heat exchanger (60), a liquid storage device (70), an economizer (80), a first throttling element (110), a second throttling element (120), and a mainstream pipeline (190); The first four-way valve (20) comprises a control valve port C1, a control valve port D1, a control valve port E1 and a control valve port S1, the control valve port D1 is connected to the outlet of the compressor (10), the control valve port E1 is connected to the first port (63) of the hot water heat exchanger, and the control valve port S1 is connected to the inlet of the compressor (10); The second four-way valve (30) comprises a control valve port C2, a control valve port D2, a control valve port E2 and a control valve port S2, the control valve port C2 being connected to the first port (41) of the air-side heat exchanger, the control valve port D2 being connected to the control valve port C1, the control valve port E2 being connected to the first port (53) of the air-conditioning water heat exchanger, and the control valve port S2 being in communication with the inlet of the compressor (10); The main flow pipeline (190) comprises a first pipeline (101), a first branch (102), a second branch (103) and a third branch (104); the first pipeline (101) is connected between the second port (42) of the air-side heat exchanger and the first port (81) of the economizer; the first port (151) of the second branch is connected to the first port (152) of the third branch and the first port (153) of the first branch; the second port (154) of the first branch is connected to the fourth port (84) of the economizer; the second port (155) of the second branch is connected to the second port (42) of the air-side heat exchanger; the second port (156) of the third branch is connected to the second port (54) of the air-conditioning water heat exchanger; the second branch (103) is provided with a first throttling element (110); and the third branch (104) is provided with a second throttling element (120); The second port (54) of the air-conditioning water heat exchanger is connected to the inlet of the liquid reservoir (70) via a second pipe (107), and the second port (64) of the hot water heat exchanger is connected to the inlet of the liquid reservoir (70) via a third pipe (105), a fourth branch (106) is provided in parallel with the third pipe (105), and a hot water defrosting solenoid valve (150) and a throttling capillary (140) are provided on the fourth branch (106); The low temperature heat recovery system includes a refrigeration cycle mode, a heating cycle mode, a hot water cycle mode and a heat recovery cycle mode; The low-temperature heat recovery system further comprises a first one-way valve (100), wherein the first one-way valve (100) is arranged on the first pipeline (101) to prevent the refrigerant in the liquid storage device (70) from flowing back into the air-side heat exchanger (40) when the low-temperature heat recovery system is in a hot water defrosting cycle mode; The low-temperature heat recovery system further comprises a second one-way valve (130), which is arranged on the second pipeline (107) to prevent the refrigerant in the liquid storage tank (70) from flowing back into the air conditioning water heat exchanger (50) when the low-temperature heat recovery system is in a heating cycle mode.

2. A low temperature heat recovery system according to claim 1, characterized in that: When the low-temperature heat recovery system is in a refrigeration cycle mode, the control valve port C1 is connected to the control valve port D1, the control valve port C2 is connected to the control valve port D2, the control valve port E2 is connected to the control valve port S2, the second throttling element (120) is opened, and the first throttling element (110) is closed; at this time, the refrigerant in the low-temperature heat recovery system passes through the compressor (10), the control valve port D1, the control valve port C1, the control valve port D2, the control valve port C2, the air side heat exchanger (40), the economizer (80), the second throttling element (120), the air conditioning water heat exchanger (50), the control valve port E2, the control valve port S2, and finally flows back to the compressor (10); When the low-temperature heat recovery system is in a heating cycle mode, the control valve port C1 is connected to the control valve port D1, the control valve port E2 is connected to the control valve port D2, the control valve port C2 is connected to the control valve port S2, the first throttling element (110) is opened, and the second throttling element (120) is closed; at this time, the refrigerant in the low-temperature heat recovery system passes through the compressor (10), the control valve port D1, the control valve port C1, the control valve port D2, the control valve port E2, the air conditioning water heat exchanger (50), the liquid storage tank (70), the economizer (80), the first throttling element (110), the air side heat exchanger (40), the control valve port C2, the control valve port S2, and finally flows back to the compressor (10); When the low-temperature heat recovery system is in the hot water circulation mode, the control valve port E1 is connected to the control valve port D1, the control valve port C2 is connected to the control valve port S2, the first throttling element (110) is opened, and the second throttling element (120) is closed; at this time, the refrigerant in the low-temperature heat recovery system passes through the compressor (10), the control valve port D1, the control valve port E1, the hot water heat exchanger (60), the liquid storage tank (70), the economizer (80), the first throttling element (110), the air side heat exchanger (40), the control valve port C2, the control valve port S2, and finally flows back to the compressor (10); When the low-temperature heat recovery system is in a heat recovery cycle mode, the control valve port E1 is connected to the control valve port D1, the control valve port E2 is connected to the control valve port S2, the second throttling element (120) is opened, and the first throttling element (110) is closed; at this time, the refrigerant in the low-temperature heat recovery system passes through the compressor (10), the control valve port D1, the control valve port E1, the hot water heat exchanger (60), the liquid storage tank (70), the economizer (80), the second throttling element (120), the air conditioning water heat exchanger (50), the control valve port E2, the control valve port S2, and finally flows back to the compressor (10).

3. A low temperature heat recovery system according to claim 1, characterized in that: The low-temperature heat recovery system also includes a hot water defrost circulation mode. When the low-temperature heat recovery system is in the hot water defrost circulation mode, the control valve port C1 is connected to the control valve port D1, the control valve port E1 is connected to the control valve port S1, the control valve port C2 is connected to the control valve port D2, and the first throttling element (110) and the second throttling element (120) are closed. At this time, the refrigerant in the low-temperature heat recovery system passes through the compressor (10), the control valve port D1, the control valve port C1, the control valve port D2, the control valve port C2, the air side heat exchanger (40), the liquid storage tank (70), the hot water defrost solenoid valve (150), the capillary tube (140), the hot water heat exchanger (60), the control valve port E1, and the control valve port S1 in sequence, and finally flows back to the compressor (10).

4. A low temperature heat recovery system according to claim 1, characterized in that: The low-temperature heat recovery system further comprises a third one-way valve (160), wherein the third one-way valve (160) is arranged on the third pipeline (105) to prevent the refrigerant in the liquid storage device (70) from flowing back into the hot water heat exchanger (60) when the low-temperature heat recovery system is in a hot water circulation mode or a heat recovery circulation mode.

5. The low temperature heat recovery system according to any one of claims 1 to 4, characterized in that: The low-temperature heat recovery system is further provided with a gas-liquid separator (90), and the gas-liquid separator (90) is arranged on the pipeline between the control valve port S2 and the inlet of the compressor (10).

6. A low temperature heat recovery system according to claim 5, characterized in that: The low-temperature heat recovery system further comprises a fourth pipeline (108), a fifth branch (109), and a third throttling element (180) arranged on the fifth branch (109); the fourth pipeline (108) is arranged between the compressor (10) and the third port (83) of the economizer; the first port (157) of the fifth branch is connected to the second port (154) of the first branch; the second port (158) of the fifth branch is connected to the second port (82) of the economizer; the first port (81) of the economizer is in communication with the fourth port (84) of the economizer; and the second port (82) of the economizer is in communication with the third port (83) of the economizer; When the low-temperature heat recovery system is in a refrigeration cycle mode, a heating cycle mode, a hot water cycle mode, and a heat recovery cycle mode, the third throttling element (180) is in an open state.

7. A low temperature heat recovery system according to claim 1, characterized in that: The low-temperature heat recovery system further comprises a filter (170), wherein the filter (170) is arranged on the first pipeline (101).

8. A low temperature heat recovery system according to claim 1, characterized in that: The low-temperature heat recovery system further comprises a high-pressure sensor (201) and a low-pressure sensor (202), wherein the high-pressure sensor (201) and the low-pressure sensor (202) are respectively arranged at the outlet and the inlet of the compressor (10), and a high-pressure switch (203) is also arranged between the high-pressure sensor (201) and the compressor (10).

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