A data center liquid cooling system with waste heat recovery and phase change energy storage functions

Abstract

This invention provides a data center liquid cooling system with waste heat recovery and phase change energy storage functions. The system includes a cooling system, an integrated cooling and heat recovery system, and a waste heat utilization system. The integrated cooling and heat recovery system includes an integrated cooling module and a waste heat recovery module. The system has three modes: full waste heat recovery mode, partial waste heat recovery mode, and no waste heat recovery mode. In the full and partial waste heat recovery modes, the waste heat recovery module and waste heat utilization system prevent waste of heat in the data center. In the partial and no waste heat recovery modes, the integrated cooling and heat recovery system can switch between mechanical refrigeration loops, fully natural refrigeration loops, and partially natural refrigeration loops, allowing the system to maximize the use of natural cold sources for cooling, thus helping to reduce the energy consumption of the data center.

Description

Technical Field

[0001] This invention relates to the field of server technology, and more specifically to a data center liquid cooling system with waste heat recovery and phase change energy storage functions. Background Technology

[0002] The rapidly developing next-generation network technologies are generating ever-increasing volumes of data, data interactions, and data computations. Data center energy consumption primarily originates from IT equipment, air conditioning systems, lighting systems, and power distribution systems. Air conditioning systems account for approximately 40% of the total energy consumption of a data center. Therefore, utilizing natural cooling sources can significantly reduce data center cooling energy consumption and PUE (Power Usage Effectiveness). Furthermore, almost all the electrical energy consumed by data center equipment is converted into heat energy. This waste heat is easily extracted and readily available. If this waste heat can be collected and used for heating and hot water supply to surrounding buildings, it can alleviate heating pressure on those buildings and cooling pressure on the data center's cooling system.

[0003] Compared to air cooling technology, liquid cooling systems show greater development potential and significantly lower PUE values. Immersion liquid cooling systems and direct-plate liquid cooling systems have been implemented, but they still face many problems in actual operation. For example, immersion liquid cooling systems require large amounts of coolant, greatly limiting the scale of data centers and making operation and maintenance difficult. Spray liquid cooling technology, on the other hand, offers advantages such as precise localized heat dissipation, low contact thermal resistance, small temperature difference in heat transfer, high temperature control accuracy, and fast response speed. Currently proposed spray liquid cooling systems mainly use direct dripping of coolant, which is closer to a locally immersed immersion liquid cooling system. However, this results in heat transfer deterioration due to coolant stagnation on the heat exchange surface.

[0004] Data center cooling loads fluctuate, while data centers require extremely high reliability. Adding energy storage modules can serve as an emergency buffer, meeting the high reliability requirements of data centers. Currently, commonly used energy storage technologies include chemical energy storage and sensible thermal energy storage, but both technologies have certain drawbacks. For example, chemical thermal energy storage suffers from complex reaction processes, high equipment performance requirements, and low cost-effectiveness. Sensible thermal energy storage materials generally have low thermal density, large temperature variations, and require a large system space, making them difficult to use in compact spaces. Summary of the Invention

[0005] Purpose of the invention: The technical problem to be solved by the present invention is to address at least one deficiency of the existing technology by providing a data center liquid cooling system with waste heat recovery and phase change energy storage functions, which can recover waste heat and help the data center operate with low energy consumption, safety and reliability.

[0006] To address the aforementioned technical problems, this invention provides a data center liquid cooling system with waste heat recovery and phase change energy storage functions. This system includes a cooling system, a comprehensive refrigeration and heat recovery system, and a waste heat utilization system. The cooling system includes a server spray liquid cooling system, a first heat exchanger, and a honeycomb-shell phase change energy storage heat exchanger. The cooling system can switch between different refrigerant circulation loops. These different refrigerant circulation loops include a first refrigerant circulation loop formed by connecting the server spray liquid cooling system and the first heat exchanger through pipelines, and a second refrigerant circulation loop formed by connecting the server spray liquid cooling system, the first heat exchanger, and the honeycomb-shell phase change energy storage heat exchanger through pipelines. The server spray liquid cooling system is used to transfer server heat to the first refrigerant in the refrigerant circulation loop.

[0007] The integrated refrigeration and heat recovery system includes an integrated refrigeration module and a waste heat recovery module. The integrated refrigeration module includes a second heat exchanger, a chiller unit, an evaporator, and a natural cold source. The integrated refrigeration and heat recovery system can switch between different cooling water circulation loops. These different circulation loops include a fully natural refrigeration loop formed by connecting the honeycomb-tube phase change energy storage heat exchanger and the second heat exchanger; a mechanical refrigeration loop formed by connecting the honeycomb-tube phase change energy storage heat exchanger and the chiller unit; and a partially natural refrigeration loop formed by connecting the honeycomb-tube phase change energy storage heat exchanger, the second heat exchanger, and the chiller unit. The second heat exchanger is used to exchange heat between the cooling water in the cooling water circulation loop and the cooling water from the natural cold source.

[0008] The waste heat recovery module includes an evaporator, a compressor, and a condenser. The evaporator and the first heat exchanger are optionally connected to form a waste heat recovery loop. The evaporator, compressor, and condenser are optionally connected to form a heat pump loop. The waste heat recovery loop and the heat pump loop exchange heat through the evaporator, and the heat from the heat pump loop is transferred to the waste heat utilization system through the condenser.

[0009] Specifically, the waste heat utilization system includes a hot water storage tank with a first channel and a second channel, and a heating terminal. The condenser, the inlet and outlet of the second channel of the hot water storage tank, and the heating terminal can be selectively connected to form a hot water circulation loop. Cold water absorbs heat from the high-temperature refrigerant in the condenser and becomes hot water, which then enters the hot water storage tank. The first channel of the hot water storage tank is used to connect to the domestic hot water pipe network.

[0010] Specifically, the server enclosure is inclined and includes a spray surface, and the atomizing nozzles of the server spray liquid cooling system are positioned directly opposite the spray surface.

[0011] Specifically, the honeycomb-tube phase change energy storage heat exchanger includes a shell, a cylindrical cavity is provided inside the shell, a plurality of tubes are provided inside the cylindrical cavity, a refrigerant channel is provided inside the tubes, a phase change material layer is provided on the outer wall of the tubes, and a cooling water channel is provided between the side wall of the cylindrical cavity and the phase change material layer.

[0012] Optionally, the phase change material layer is selected from materials with a phase change temperature of 35℃~40℃. Preferably, the phase change material layer is Zn(NO3)2•6H2O, with a phase change temperature of 36~36.4℃, a phase change heat storage capacity of 134~258 kJ / kg, and a specific heat capacity of 1.34 kJ / (kg•m³). 3 Its density is 1937–2065 kg / m³. 3 Its thermal conductivity is 0.464–0.469 W / (m•K).

[0013] Specifically, the cooling system includes a first valve and a second valve. The second valve is connected to the pipeline between the first heat exchanger and the honeycomb-shell phase change energy storage heat exchanger. One end of the first valve is connected to the pipeline between the first heat exchanger and the second valve, and the other end is connected to the pipeline between the honeycomb-shell phase change energy storage heat exchanger and the server spray liquid cooling system.

[0014] Specifically, the integrated refrigeration and heat recovery system includes a third valve, a fourth valve, a fifth valve, and a sixth valve. The honeycomb-shell phase change energy storage heat exchanger, the third valve, the second heat exchanger, and the fifth valve are sequentially connected to form the natural refrigeration cycle. The honeycomb-shell phase change energy storage heat exchanger, the fourth valve, and the sixth valve are sequentially connected to the chiller unit to form the mechanical refrigeration cycle. The honeycomb-shell phase change energy storage heat exchanger, the third valve, the second heat exchanger, and the sixth valve are sequentially connected to the chiller unit to form a partial natural refrigeration cycle.

[0015] Specifically, the waste heat recovery module further includes a throttling element and an eighth valve. The evaporator, compressor, condenser, throttling element, and eighth valve are sequentially connected to form a heat pump circulation loop. The waste heat utilization system includes a ninth valve. The condenser, the inlet and outlet of the second channel of the hot water storage tank, the ninth valve, and the heating terminal are sequentially connected to form a hot water circulation loop. The hot water circulation loop is equipped with a water inlet for supplying chilled water, which is located on the pipeline between the heating terminal and the condenser.

[0016] Specifically, the system has three modes: a full waste heat recovery mode, a partial waste heat recovery mode, and a no waste heat recovery mode. When surrounding buildings have heat demand and the refrigerant temperature flowing out of the first channel of the first heat exchanger is between 18 and 27°C, the system operates in full waste heat recovery mode. When surrounding buildings have heat demand and the refrigerant temperature flowing out of the first channel of the first heat exchanger is above 27°C, the system operates in partial waste heat recovery mode. When surrounding buildings have no heat demand, the system operates in no waste heat recovery mode.

[0017] When the system is in waste heat recovery mode, the first valve 16 is open, the second valve is closed, the third, fourth, fifth and sixth valves are all closed, the honeycomb tube phase change energy storage heat exchanger, the second heat exchanger and the chiller are all closed, the seventh to eighth valves are all open, and the heat pump circulation loop is in working condition.

[0018] When the system is in waste heat recovery mode and waste heat non-recovery mode, if the temperature of the cooling water flowing out of the channel outlet of the honeycomb tube phase change energy storage heat exchanger connected to the second heat exchanger is higher than the temperature of the cooling water flowing into the channel inlet of the second heat exchanger connected to the natural cold source, then the first valve is closed, the second valve is opened, the fourth and sixth valves are opened, and the third and fifth valves are closed, and both the chiller and the honeycomb tube phase change energy storage heat exchanger are in working condition.

[0019] If the cooling water temperature flowing out of the outlet of the channel connected to the second heat exchanger is lower than the cooling water temperature flowing into the inlet of the channel connected to the natural cold source, and the cooling water temperature flowing out of the outlet of the channel connected to the second heat exchanger reaches a set value, then the first valve is closed, the second valve is opened, the third and fifth valves are opened, the fourth and sixth valves are closed, the chiller unit is shut down, and both the second heat exchanger and the honeycomb-shell phase change heat exchanger are in working condition.

[0020] If the cooling water temperature flowing out of the outlet of the channel connected to the second heat exchanger is lower than the cooling water temperature flowing into the inlet of the channel connected to the natural cold source, and the cooling water temperature flowing out of the outlet of the channel connected to the second heat exchanger does not reach the set value, then the first valve is closed, the second valve is opened, the third and sixth valves are opened, and the fourth and fifth valves are closed. The chiller, the second heat exchanger, and the honeycomb tube phase change heat exchanger are all in working condition.

[0021] When the system is in waste heat non-recovery mode, valves seven through eight are closed, the heat pump circulation loop is inactive, valve nine is closed, and the hot water storage tank, heating terminal, and water inlet are all inactive.

[0022] Beneficial effects:

[0023] (1) The data center liquid cooling system with waste heat recovery and phase change energy storage functions proposed in this invention has three modes, including full waste heat recovery mode, partial waste heat recovery mode, and no waste heat recovery mode. In the full waste heat recovery mode and the partial waste heat recovery mode, the setting of waste heat recovery module and waste heat utilization system avoids the waste of heat consumption in the data center. At the same time, in the partial waste heat recovery mode and the no waste heat recovery mode, because the integrated cooling heat recovery system in the system can switch between mechanical cooling cycle loop, completely natural cooling cycle loop and partially natural cooling cycle loop, the system can maximize the use of natural cold source for cooling, which helps to reduce the energy consumption of the data center.

[0024] (2) The server spray liquid cooling system of the present invention adopts the cooling method of direct spraying of atomized liquid. Compared with the direct dripping of coolant used in the existing spray liquid cooling system, its heat exchange efficiency is higher. The server box is placed at an angle, so that the coolant cannot remain on the heat exchange surface, avoiding the heat transfer deterioration caused by the retention of coolant, and greatly improving the cooling efficiency.

[0025] (3) As a phase change energy storage device, the honeycomb tube-type phase change energy storage heat exchanger of the present invention can buffer the impact caused by changes in server load, and ensure a certain emergency transition time during shutdown maintenance or air conditioning failure, so as to ensure the normal, reliable and continuous operation of the server. Compared with the chemical energy storage technology and sensible heat energy storage technology used in the prior art, the energy storage density of phase change energy storage is 5 to 10 times that of sensible heat energy storage. The phase change material has small temperature and volume changes during the phase change process. At the same time, the cost of phase change energy storage is lower than that of sensible heat energy storage and chemical energy storage.

[0026] (4) The waste heat utilization system set up in this invention will recover waste heat from the data center for domestic hot water and winter heating in the surrounding buildings throughout the year, which helps to save heating costs for the surrounding buildings. Attached Figure Description

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0028] Figure 1 A schematic diagram of a data center liquid cooling system with waste heat recovery and phase change energy storage functions is provided as an embodiment of this application;

[0029] Figure 2A schematic diagram of the refrigerant circulation of a server spray liquid cooling system provided in one embodiment of this application;

[0030] Figure 3 A schematic cross-sectional view of a honeycomb-tube phase change energy storage heat exchanger provided in one embodiment of this application;

[0031] Figure 4 A schematic diagram of the system structure when the integrated refrigeration module is in mechanical refrigeration mode, as provided in one embodiment of this application;

[0032] Figure 5 A schematic diagram of the system structure of the integrated refrigeration module provided in one embodiment of this application when it is in a completely natural refrigeration mode.

[0033] Figure 6 This is a schematic diagram of the system structure when the integrated cooling module provided in one embodiment of this application is in partial natural cooling mode.

[0034] The reference numerals in the accompanying drawings of this application are as follows:

[0035] Server Spray Liquid Cooling System: 1. First Heat Exchanger; 2. Honeycomb Tube Phase Change Energy Storage Heat Exchanger; 3. Natural Cold Source; 4. Second Heat Exchanger; 5. Chiller Unit; 6. Evaporator; 7. Compressor; 8. Condenser; 9. Hot Water Storage Tank; 10. Heating Terminal; 11. Refrigerant Enrichment Unit; 12. Server Cabinet; 13. Refrigerant Pump; 14. Water Inlet; 15. First Valve; 16. Second Valve; 17. Third Valve; 18. Fourth Valve; 19. Fifth Valve; 20. Sixth Valve; 21. Seventh Valve; 22. Throttling Element; 23. Eighth Valve; 24. Ninth Valve; 25. Cooling System; 100. First Channel; 1001. Second Channel; 1002. Integrated Cooling and Heating System. The system includes a heat recovery system 200, a first heat exchanger first channel 201, a first heat exchanger second channel 202, a honeycomb tube phase change energy storage heat exchanger first channel 301, a honeycomb tube phase change energy storage heat exchanger second channel 302, a chiller unit first channel 601, a chiller unit second channel 602, a shell 303, a refrigerant channel 304, a phase change material layer 305, a cooling water channel 306, a waste heat utilization system 300, a second heat exchanger first channel 501, a second heat exchanger second channel 502, an evaporator first channel 701, an evaporator second channel 702, a condenser first channel 901, and a condenser second channel 902. Detailed Implementation

[0036] The technical solution of this application will now be described in detail with reference to the accompanying drawings.

[0037] like Figure 1As shown, this invention provides a data center liquid cooling system with waste heat recovery and phase change energy storage functions. The system includes a cooling system 100, a comprehensive cooling and heat recovery system 200, and a waste heat utilization system 300. The cooling system 100 includes a server spray liquid cooling system 1, a first heat exchanger 2, and a honeycomb-tube phase change energy storage heat exchanger 3. The cooling system 100 can switch between different refrigerant circulation loops. These different refrigerant circulation loops include a first refrigerant circulation loop formed by connecting the server spray liquid cooling system 1 and the first heat exchanger 2 through pipelines, and a second refrigerant circulation loop formed by connecting the server spray liquid cooling system 1, the first heat exchanger 2, and the honeycomb-tube phase change energy storage heat exchanger 3 through pipelines. The server spray liquid cooling system 1 is used to transfer server heat to the first refrigerant in the refrigerant circulation loop.

[0038] like Figure 1 As shown, the integrated refrigeration and heat recovery system 200 includes an integrated refrigeration module and a waste heat recovery module. The integrated refrigeration module includes a second heat exchanger 5, a chiller unit 6, an evaporator 7, and a natural cold source 4. The integrated refrigeration and heat recovery system 200 can switch between different cooling water circulation loops. These different circulation loops include a mechanical refrigeration loop formed by connecting the honeycomb-tube phase change energy storage heat exchanger 3 and the chiller unit 6; a completely natural refrigeration loop formed by connecting the honeycomb-tube phase change energy storage heat exchanger 3 and the second heat exchanger 5; and a partially natural refrigeration loop formed by connecting the honeycomb-tube phase change energy storage heat exchanger 3, the second heat exchanger 5, and the chiller unit 6. The second heat exchanger 5 is used to exchange heat between the cooling water in the cooling water circulation loop and the cooling water from the natural cold source 4.

[0039] like Figure 1 As shown, the waste heat recovery module includes an evaporator 7, a compressor 8, and a condenser 9. The evaporator 7 is optionally connected to the first heat exchanger 2 to form a waste heat recovery loop. The evaporator 7, compressor 8, and condenser 9 are optionally connected to form a heat pump loop. The waste heat recovery loop and the heat pump loop exchange heat through the evaporator 7, and the heat from the heat pump loop is transferred to the waste heat utilization system 300 through the condenser 9.

[0040] Specifically, such as Figure 1As shown, the waste heat utilization system 300 includes a hot water storage tank 10 with a first channel 1001 and a second channel 1002 and a heating terminal 11. The condenser 9, the inlet and outlet of the second channel 1002 of the hot water storage tank 10, and the heating terminal 11 can be selectively connected to form a hot water circulation loop. Cold water absorbs heat from the high-temperature refrigerant in the condenser 9 and becomes hot water, which then enters the hot water storage tank 10. The first channel 1001 of the hot water storage tank 10 is used to connect to the domestic hot water pipe network.

[0041] In one embodiment, such as Figure 2 As shown, the server enclosure 13 is tilted. The server enclosure 13 includes a spray surface, and the atomizing nozzles of the server spray liquid cooling system 1 are positioned directly opposite the spray surface, but are not shown in the figure.

[0042] Specifically, such as Figure 3 As shown, the honeycomb-tube phase change energy storage heat exchanger 3 includes a shell 303, a cylindrical cavity is provided inside the shell 303, a plurality of tubes are provided inside the cylindrical cavity, a refrigerant channel 304 is provided inside the tubes, a phase change material layer 305 is provided on the outer wall of the tubes, and a cooling water channel 306 is provided between the side wall of the cylindrical cavity and the phase change material layer 305.

[0043] Optionally, the phase change material layer 305 is selected from materials with a phase change temperature of 35℃~40℃. Preferably, the phase change material layer 305 is Zn(NO3)2•6H2O, with a phase change temperature of 36~36.4℃, a phase change heat storage of 134~258kJ / kg, and a specific heat capacity of 1.34kJ / (kg•m³). 3 Its density is 1937–2065 kg / m³. 3 Its thermal conductivity is 0.464–0.469 W / (m•K).

[0044] Specifically, such as Figure 1 As shown, the cooling system 100 includes a first valve 16 and a second valve 17. The second valve 17 is connected to the pipeline between the first heat exchanger 2 and the honeycomb-shell phase change energy storage heat exchanger 3. One end of the first valve 16 is connected to the pipeline between the first heat exchanger 2 and the second valve 17, and the other end is connected to the pipeline between the honeycomb-shell phase change energy storage heat exchanger 3 and the server spray liquid cooling system 1.

[0045] Specifically, such as Figure 1 As shown, the integrated refrigeration and heat recovery system 200 includes a third valve 18, a fourth valve 19, a fifth valve 20, and a sixth valve 21. (As indicated...) Figure 4 As shown, the honeycomb-tube phase change energy storage heat exchanger 3, the fourth valve 19, and the sixth valve 21 are sequentially connected to the chiller unit 6 to form the mechanical refrigeration cycle loop. Figure 5As shown, the honeycomb-tube phase change energy storage heat exchanger 3, the third valve 18, the second heat exchanger 5, and the fifth valve 20 are sequentially connected to form the natural refrigeration cycle loop. Figure 6 As shown, the honeycomb tube phase change energy storage heat exchanger 3, the third valve 18, the second heat exchanger 5, the sixth valve 21 and the chiller unit 6 are sequentially connected to form the partial natural refrigeration cycle loop.

[0046] Specifically, such as Figure 1 As shown, the waste heat recovery module also includes a throttling element 23 and an eighth valve 24. The evaporator 7, compressor 8, condenser 9, throttling element 23 and eighth valve 24 are connected in sequence to form a heat pump circulation loop.

[0047] Specifically, such as Figure 1 As shown, the waste heat utilization system 300 includes a ninth valve 25. The inlet and outlet of the second channel 1002 of the condenser 9 and the hot water storage tank 10, the ninth valve 25 and the heating terminal 11 are sequentially connected to form a hot water circulation loop.

[0048] Furthermore, such as Figure 1 As shown, the hot water circulation loop is provided with a water inlet 15 for replenishing chilled water, and the water inlet 15 is located on the pipeline between the heating terminal 11 and the condenser 9.

[0049] Specifically, the system has three modes: a full waste heat recovery mode, a partial waste heat recovery mode, and a no waste heat recovery mode. When surrounding buildings have heat demand and the refrigerant temperature flowing out of the first channel 201 of the first heat exchanger is between 18 and 27°C, the system operates in full waste heat recovery mode. When surrounding buildings have heat demand and the refrigerant temperature flowing out of the first channel 201 of the first heat exchanger is above 27°C, the system operates in partial waste heat recovery mode. When surrounding buildings have no heat demand, the system operates in no waste heat recovery mode.

[0050] When the system is in waste heat recovery mode, the first valve 16 is open, the second valve 17 is closed, the third valve 18, the fourth valve 19, the fifth valve 20 and the sixth valve 21 are all closed, the honeycomb tube phase change energy storage heat exchanger 3, the second heat exchanger 5 and the chiller unit 6 are all closed, the seventh valve 22 to the eighth valve 24 are all open, the evaporator 7, the compressor 8, the condenser 9 and the throttling element 23 are all in the active state, the ninth valve 25 is open, and the hot water storage tank 10, the heating terminal 11 and the water inlet 15 are all in the active state.

[0051] When the system is in waste heat recovery mode and waste heat non-recovery mode, if the cooling water temperature flowing out of the outlet of the channel connecting the honeycomb tube phase change energy storage heat exchanger 3 and the second heat exchanger 5 is higher than the cooling water temperature flowing into the inlet of the channel connecting the second heat exchanger 5 and the natural cold source 4, then... Figure 4 As shown, the first valve 16 is closed, the second valve 17 is open, the fourth valve 19 and the sixth valve 21 are open, and the third valve 18 and the fifth valve 20 are closed. Both the chiller unit 6 and the honeycomb-coated phase change energy storage heat exchanger 3 are in operation. At this time, the system's integrated refrigeration module is in mechanical refrigeration mode.

[0052] If the temperature of the cooling water flowing out of the outlet of the channel connecting the honeycomb tube phase change heat exchanger 3 and the second heat exchanger 5 is lower than the temperature of the cooling water flowing into the inlet of the channel connecting the second heat exchanger 5 and the natural cold source 4, and the temperature of the cooling water flowing out of the outlet of the channel connecting the second heat exchanger 5 and the honeycomb tube phase change heat exchanger 3 reaches a set value, then... Figure 5 As shown, the first valve 16 is closed, the second valve 17 is open, the third valve 18 and the fifth valve 20 are open, the fourth valve 19 and the sixth valve 21 are closed, the chiller unit 6 is shut down, and the second heat exchanger 5 and the honeycomb tube phase change energy storage heat exchanger 3 are both in operation. At this time, the integrated refrigeration module of the system is in a completely natural refrigeration mode.

[0053] If the cooling water temperature flowing out of the outlet of the channel connecting the honeycomb tube phase change heat exchanger 3 and the second heat exchanger 5 is lower than the cooling water temperature flowing into the inlet of the channel connecting the second heat exchanger 5 and the natural cold source 4, and the cooling water temperature flowing out of the outlet of the channel connecting the second heat exchanger 5 and the honeycomb tube phase change heat exchanger 3 does not reach the set value, then... Figure 6 As shown, the first valve 16 is closed, the second valve 17 is open, the third valve 18 and the sixth valve 21 are open, and the fourth valve 19 and the fifth valve 20 are closed. The chiller unit 6, the second heat exchanger 5, and the honeycomb tube phase change energy storage heat exchanger 3 are all in operation. At this time, the integrated refrigeration module of the system is in a partial natural cooling mode.

[0054] When the system is in waste heat recovery mode, valves 22 to 24 are all open, and the evaporator 7, compressor 8, condenser 9 and throttling element 23 are all in the active state. Valve 25 is open, and the hot water storage tank 10, heating terminal 11 and water inlet 15 are all in the active state.

[0055] When the system is in the waste heat non-recovery mode, valves 22 to 24 are all closed, evaporator 7, compressor 8, condenser 9 and throttling element 23 are all inactive, valve 25 is closed, and hot water storage tank 10, heating terminal 11 and water inlet 15 are all inactive.

[0056] Example 1

[0057] like Figure 1 As shown, this embodiment provides a data center liquid cooling system with waste heat recovery and phase change energy storage functions. The system includes a cooling system 100, an integrated cooling and heat recovery system 200, and a waste heat utilization system 300.

[0058] like Figure 1 As shown, the cooling system 100 includes a server spray liquid cooling system 1, a first heat exchanger 2, a first valve 16, a second valve 17, and a honeycomb-tube phase change energy storage heat exchanger 3. The first heat exchanger 2 has a first heat exchanger first channel 201 and a first heat exchanger second channel 202 capable of exchanging heat with each other. The honeycomb-tube phase change energy storage heat exchanger 3 includes a honeycomb-tube phase change energy storage heat exchanger first channel 301 and a honeycomb-tube phase change energy storage heat exchanger second channel 302, which exchange heat with each other. The server spray liquid cooling system 1 is connected to the first heat exchanger first channel 201, and the second valve 17 is connected in series with the honeycomb-tube phase change energy storage heat exchanger first channel 301 and then in parallel with the first valve 16. The server spray liquid cooling system 1 includes a refrigerant enrichment unit 12, a refrigerant pump 14, and a server enclosure 13, as shown below. Figure 2As shown. The coolant in the server spray liquid cooling system 1 is insulated and has good cooling properties, including but not limited to fluorinated liquid and pure water, which can be selected according to the operating conditions. In the server spray liquid cooling system 1, the refrigerant after heat exchange enters the server enclosure 13 after passing through the refrigerant pump 14. The spray nozzle array inside the enclosure includes multiple spray nozzles, which are directed at the main heat-generating components such as the motherboard chip and GPU. After absorbing the heat of the equipment, the refrigerant is introduced into the refrigerant enrichment unit 12 through the coolant outlet pipe. Then, the refrigerant can re-enter the circulation as refrigerant after passing through the second channel 202 of the first heat exchanger 2 and the first channel 201 of the honeycomb tube phase change energy storage heat exchanger 3. The cooling water from the integrated cooling heat recovery system 200 flows through the second channel 202 of the first heat exchanger 2 to recover the heat of the refrigerant for utilization. To ensure that the heat-carrying refrigerant in the server enclosure 13 enters the refrigerant enrichment unit 12 in a timely manner, the server enclosure 13 is placed at an angle inside the rack. The advantages of tilting the server chassis 13 are twofold: First, with the chassis tilted, the distance between the nozzle center and the cooling components increases, avoiding insufficient atomization distance. Second, this method allows the spray cone—the cone-shaped area formed by a large number of spray droplets—to extend more fully in the spray direction, resulting in a larger coverage area within the chassis.

[0059] The integrated refrigeration and heat recovery system 200 includes a honeycomb-tube phase change energy storage heat exchanger 3, a third valve 18, a fourth valve 19, a fifth valve 20, a sixth valve 21, a second heat exchanger 5, a chiller unit 6, an evaporator 7, a compressor 8, a condenser 9, and a natural cold source 4. The second heat exchanger 5 and the chiller unit 6 are connected in series, and then connected in series with the second channel 302 of the honeycomb-tube phase change energy storage heat exchanger. The natural cold source 4, the second channel 502 of the second heat exchanger, and the first channel 701 of the evaporator are connected in sequence. Based on the temperature of the working fluid in the natural cold source and the second channel 302 of the honeycomb-tube phase change energy storage heat exchanger, the opening and closing of the third valve 18, the fourth valve 19, the fifth valve 20, and the sixth valve 21 are controlled, allowing the heat exchanger 5 and the chiller unit 6 to operate individually or simultaneously, switching between three refrigeration modes: fully natural refrigeration mode, partially natural refrigeration mode, and mechanical refrigeration mode. Because the recovered waste heat has a low quality and is difficult to utilize directly, the system introduces a heat pump circulation loop to improve its quality. This heat pump circulation loop includes an evaporator second channel 702, a compressor 8, and a condenser first channel 901. The heat is then delivered to the waste heat utilization system through the condenser second channel 902. Based on the heating terminal 11 and hot water demand of the waste heat utilization system, the system recovers heat from the refrigerant in the cooling system's machine room. By controlling the opening and closing of valves, three waste heat recovery modes are switched: full waste heat recovery mode, partial waste heat recovery mode, and no waste heat recovery mode. The working fluid of the natural cold source 4 always serves as the cold source for the chiller unit 6.

[0060] The cooling system and the integrated refrigeration and heat recovery system are connected by a honeycomb-shell phase change energy storage heat exchanger 3. The shell 303 of the honeycomb-shell phase change energy storage heat exchanger 3 is cylindrical and contains numerous shells, significantly improving the heat exchange efficiency of the shell structure. For example... Figure 3 As shown, the outer wall of the sleeve is provided with a phase change material layer 305, and the inside of the sleeve is provided with a refrigerant channel 304. The refrigerant enters the first heat exchanger 2 through the first channel 201 of the honeycomb sleeve-type phase change energy storage heat exchanger 3 to transfer heat from the server refrigerant. Between the phase change material layer 305 and the sleeve is a cooling water channel 306. The cooling water carries away the heat from the refrigerant in the inner layer of the sleeve and then enters a new cooling cycle through the second channel 202 of the honeycomb 3. The phase change material filled in the phase change module has a phase change temperature of 35℃~40℃. Specifically, the material selected for the phase change material layer 305 is Zn(NO3)2•6H2O, with a phase change temperature of 36~36.4℃, a phase change heat storage capacity of 134~258kJ / kg, and a specific heat capacity of 1.34kJ / (kg•m³). 3 Its density is 1937–2065 kg / m³. 3 Its thermal conductivity is 0.464–0.469 W / (m•K).

[0061] The waste heat utilization system 300 includes a condenser 9, a hot water storage tank 10, a heating terminal 11, a ninth valve 25, and a water inlet 15. After the water absorbs heat and heats up by flowing through the second channel 902 of the condenser, it enters the hot water storage tank. Part of it enters the hot water supply pipe, and part of it enters the heating terminal 11. The water that has released heat and cooled down, together with the water in the inlet, re-enters the second channel 902 of the condenser for heat exchange.

[0062] The system in this embodiment can operate in different modes depending on different working conditions. The specific process is as follows:

[0063] I. Waste heat recovery mode.

[0064] If surrounding buildings have heat demand, and the refrigerant temperature flowing out of the first channel 201 of the first heat exchanger is within 18~27℃, then all the heat from the refrigerant in the computer room is recovered by the waste heat recovery system 300, which is in full waste heat recovery mode. In the cooling system 100, the first valve 16 is open and the second valve 17 is closed. The refrigerant from the server spray liquid cooling system 1 enters the first channel 201 of the first heat exchanger and exchanges heat with the cooling water in the second channel 202, then flows through the first valve 16 and re-enters the server spray liquid cooling system 1.

[0065] In the integrated refrigeration and heat recovery system 200, since all the heat of the refrigerant in the computer room is carried away in the first heat exchanger 2, the third valve 18, the fourth valve 19, the fifth valve 20, and the sixth valve 21 are all closed, as are the honeycomb tube phase change energy storage heat exchanger 3, the second heat exchanger 5, and the chiller unit 6. The seventh valve 22, the throttling element 23, and the eighth valve 24 are all opened, starting the heat pump circulation loop. The compressor 8 starts to do work on the low-temperature refrigerant. After the refrigerant is heated, it enters the first channel 901 of the condenser. The refrigerant releases heat in the condenser 9 and becomes a low-temperature, low-pressure refrigerant through the throttling element 23. It then enters the second channel 702 of the evaporator through the eighth valve 24 to exchange heat with the cooling water from the first heat exchanger 2. After the heat exchange is completed, the refrigerant flows back to the compressor 8.

[0066] In the waste heat recovery system 300, cold water absorbs heat from the high-temperature refrigerant in the condenser 9 and becomes hot water, which then enters the hot water storage tank 10. The first channel 1001 of the hot water storage tank 10 connects to the domestic hot water network, providing hot water to the surrounding buildings throughout the year. The outlet of the second channel 1002 of the hot water storage tank connects to the heating terminal 11, providing heating to the surrounding buildings in winter. Since domestic hot water cannot be recovered, the water inlet 15 needs to be opened to replenish cold water. The cold water mixes with the return water from the heating terminal 11 and then enters the second channel 902 of the condenser.

[0067] II. Waste heat recovery mode.

[0068] If surrounding buildings have heat demand, and the refrigerant temperature flowing out of the first channel 201 outlet of the first heat exchanger 2 is higher than 27°C, then part of the heat from the refrigerant in the computer room is recovered by the waste heat recovery system 300, which is the waste heat recovery mode. In the cooling system 100, the first valve 16 is closed and the second valve 17 is open. The refrigerant from the server spray liquid cooling system 1 enters the first channel 201 of the first heat exchanger and exchanges heat with the water in the second channel 202. Then it flows through the second valve 17 into the first channel 201 of the honeycomb tube phase change energy storage heat exchanger 3 to exchange heat with the phase change material for further cooling, and then enters the server spray liquid cooling system 1 again.

[0069] In the integrated cooling and heat recovery system 200, some of the heat from the refrigerant in the computer room is carried away in the first heat exchanger 2, while the remaining heat needs to be transferred by the cooling system. First, it is determined whether the cooling water temperature at the outlet of the second channel 302 of the honeycomb-coated phase change energy storage heat exchanger is lower than the inlet temperature of the second channel 502 of the second heat exchanger. If not, it is in mechanical cooling mode. Figure 4As shown, open the fourth valve 19 and the sixth valve 21, and close the third valve 18 and the fifth valve 20. Cooling water enters the first channel of the chiller unit 6, cools down to 22℃, and then returns to the second channel 302 of the honeycomb tube phase change energy storage heat exchanger. If so, open the third valve 18 and close the fourth valve 19. Cooling water enters the first channel 501 of the second heat exchanger to exchange heat with the natural cold source working fluid. Then, determine whether the outlet temperature of the first channel 501 of the second heat exchanger reaches 22℃. If the outlet temperature of the first channel 501 of the second heat exchanger reaches 22℃, it is in natural cooling mode. Figure 5 As shown, the fifth valve 20 is opened and the fourth valve 21 is closed. The cooling water returns to the second channel 302 of the honeycomb-coated phase change energy storage heat exchanger via the fifth valve 20. If the outlet temperature of the first channel 501 of the second heat exchanger does not reach 22℃, it is in partial natural cooling mode, such as... Figure 6 As shown, the fourth valve 21 is opened and the fifth valve 20 is closed. Cooling water enters the first channel 601 of the chiller unit 6 through the fourth valve 21 for further cooling. After cooling to 22°C, it returns to the second channel 302 of the honeycomb tube phase change energy storage heat exchanger. The seventh valve 22 to the eighth valve 24 are all opened, starting the heat pump cycle. The compressor 8 starts to do work on the low-temperature refrigerant. After the refrigerant is heated, it enters the first channel 901 of the condenser. The refrigerant releases heat in the condenser 9 and becomes a low-temperature, low-pressure refrigerant through the throttling element 23. It then enters the second channel 702 of the evaporator through the eighth valve 24 to exchange heat with the water from the first heat exchanger 2. After the heat exchange is completed, the refrigerant flows back to the compressor 8.

[0070] The implementation method in the waste heat utilization system 300 is the same as that in the waste heat full recovery mode.

[0071] III. Waste heat not recovered mode.

[0072] If the surrounding buildings have no heat demand, the waste heat is not recovered. In the cooling system 100, the first valve 16 is closed and the second valve 17 is open. The refrigerant from the server spray liquid cooling system 1 enters the first heat exchanger, first channel 201, and exchanges heat with the water in the second channel 202. Then, it flows through the second valve 17 into the honeycomb tube phase change energy storage heat exchanger, first channel 301, where it exchanges heat with the phase change material for further cooling. Finally, it re-enters the server spray liquid cooling system 1.

[0073] In the integrated cooling and heat recovery system 200, all the heat from the refrigerant in the computer room needs to be transferred by the cooling system. First, it is determined whether the cooling water temperature at the outlet of the second channel 302 of the honeycomb-tube phase change energy storage heat exchanger is lower than the inlet temperature of the second channel 502 of the second heat exchanger. If not, it is in mechanical cooling mode. The fourth valve 19 and the sixth valve 21 are opened, and the third valve 18 and the fifth valve 20 are closed. The cooling water enters the first channel 601 of the chiller unit, cools down to 22°C, and then returns to the second channel 302 of the honeycomb-tube phase change energy storage heat exchanger. If so, the third valve 18 is opened, and the fourth valve 19 is closed. The cooling water enters the first channel 501 of the second heat exchanger to exchange heat with the natural cold source working fluid. Then, it is determined whether the outlet temperature of the first channel 501 of the second heat exchanger reaches 22°C. If the outlet temperature of the first channel 501 of the second heat exchanger reaches 22°C, it is in natural cooling mode. The fifth valve 20 is opened, and the fourth valve 21 is closed. The cooling water returns to the second channel 302 of the honeycomb-tube phase change energy storage heat exchanger via the fifth valve 20. If the outlet temperature of the first channel 501 of the second heat exchanger does not reach 22℃, it enters partial natural cooling mode. The fourth valve 21 is opened, and the fifth valve 20 is closed. Cooling water enters the first channel 201 of the chiller unit 6 via the fourth valve 21 for further cooling. After cooling to 22℃, it returns to the second channel 302 of the honeycomb tube phase change energy storage heat exchanger. The seventh valve 22 through the eighth valve 24 are all closed, and the heat pump circulation is not started.

[0074] In the waste heat utilization system 300, the ninth valve 25 is closed, and the hot water storage tank 10, heating terminal 11 and water inlet 15 are not activated.

[0075] IV. Emergency Mode.

[0076] If equipment in the integrated cooling and heat recovery system 200, such as the honeycomb tube phase change energy storage heat exchanger 3, the second heat exchanger 5, and the chiller unit 6, malfunctions, and the waste heat utilization system 300 does not or does not completely transfer the heat from the refrigerant in the computer room, then it enters emergency mode. In the cooling system 100, the first valve 16 is closed, and the second valve 17 is open. The refrigerant from the server spray liquid cooling system 1 enters the first channel 201 of the first heat exchanger, the second valve 17, and the first channel 301 of the honeycomb tube phase change energy storage heat exchanger in sequence, where it exchanges heat with the phase change material and cools down to the required temperature before re-entering the server spray liquid cooling system 1.

[0077] The operation of the waste heat utilization system 300 is controlled according to demand.

[0078] This invention provides a concept and method for a data center liquid cooling system with waste heat recovery and phase change energy storage functions. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A data center liquid cooling system with waste heat recovery and phase change energy storage functions, characterized in that, The system includes a cooling system (100), an integrated refrigeration and heat recovery system (200), and a waste heat utilization system (300). The cooling system (100) includes a server spray liquid cooling system (1), a first heat exchanger (2), and a honeycomb tube phase change energy storage heat exchanger (3); the cooling system (100) can switch between different refrigerant circulation loops, the different refrigerant circulation loops include a first refrigerant circulation loop formed by connecting the server spray liquid cooling system (1) and the first heat exchanger (2) through pipelines, and a second refrigerant circulation loop formed by connecting the server spray liquid cooling system (1), the first heat exchanger (2), and the honeycomb tube phase change energy storage heat exchanger (3) through pipelines; the server spray liquid cooling system (1) is used to transfer heat from the server enclosure (13) to the first refrigerant in the refrigerant circulation loop; The integrated refrigeration and heat recovery system (200) includes an integrated refrigeration module and a waste heat recovery module; the integrated refrigeration module includes a second heat exchanger (5), a chiller unit (6), an evaporator (7), and a natural cold source (4); the integrated refrigeration and heat recovery system (200) can switch between different cooling water circulation loops; the different cooling water circulation loops include a completely natural refrigeration circulation loop formed by connecting the honeycomb tube phase change energy storage heat exchanger (3) and the second heat exchanger (5), a mechanical refrigeration circulation loop formed by connecting the honeycomb tube phase change energy storage heat exchanger (3) and the chiller unit (6), and a partially natural refrigeration circulation loop formed by connecting the honeycomb tube phase change energy storage heat exchanger (3), the second heat exchanger (5), and the chiller unit (6); the second heat exchanger (5) is used to exchange heat between the cooling water in the cooling water circulation loop and the cooling water from the natural cold source (4); The waste heat recovery module includes an evaporator (7), a compressor (8), and a condenser (9). The evaporator (7) and the first heat exchanger (2) are selectively connected through a seventh valve (22) to form a waste heat recovery loop. The evaporator (7), the compressor (8), and the condenser (9) are selectively connected to form a heat pump loop. The waste heat recovery loop and the heat pump loop exchange heat through the evaporator (7), and the heat from the heat pump loop is transferred to the waste heat utilization system (300) through the condenser (9). The cooling system (100) includes a first valve (16) and a second valve (17). The second valve (17) is connected to the pipeline between the first heat exchanger (2) and the honeycomb tube phase change energy storage heat exchanger (3). One end of the first valve (16) is connected to the pipeline between the first heat exchanger (2) and the second valve (17), and the other end is connected to the pipeline between the honeycomb tube phase change energy storage heat exchanger (3) and the server spray liquid cooling system (1).

2. The data center liquid cooling system with waste heat recovery and phase change energy storage functions according to claim 1, characterized in that, The waste heat utilization system (300) includes a hot water storage tank (10) with a first channel (1001) and a second channel (1002) and a heating terminal (11). The inlet and outlet of the condenser (9), the second channel (1002) of the hot water storage tank (10), and the heating terminal (11) can be selectively connected to form a hot water circulation loop. After the cold water absorbs the heat of the high-temperature refrigerant through the condenser (9), it becomes hot water and enters the hot water storage tank (10). The first channel (1001) of the hot water storage tank (10) is used to connect to the domestic hot water pipe network.

3. A data center liquid cooling system with waste heat recovery and phase change energy storage functions according to claim 1, characterized in that, The server enclosure (13) is inclined and includes a spray surface, and the atomizing nozzle of the server spray liquid cooling system (1) is positioned directly opposite the spray surface.

4. A data center liquid cooling system with waste heat recovery and phase change energy storage functions according to claim 1, 2, or 3, characterized in that, The honeycomb-tube phase change energy storage heat exchanger (3) includes a shell (303), a cylindrical cavity is provided inside the shell (303), a plurality of tubes are provided inside the cylindrical cavity, a refrigerant channel (304) is provided inside the tubes, a phase change material layer (305) is provided on the outer wall of the tubes, and a cooling water channel (306) is provided between the side wall of the cylindrical cavity and the phase change material layer (305).

5. A data center liquid cooling system with waste heat recovery and phase change energy storage functions according to claim 4, characterized in that, The phase change material layer (305) is selected from materials with a phase change temperature of 35℃~40℃.

6. A data center liquid cooling system with waste heat recovery and phase change energy storage functions according to claim 5, characterized in that, The phase change material layer (305) is made of Zn(NO3)2•6H2O, with a phase change temperature of 36~36.4℃, a phase change heat storage capacity of 134~258kJ / kg, and a specific heat capacity of 1.34kJ / (kg•m³). 3 Its density is 1937–2065 kg / m³. 3 Its thermal conductivity is 0.464–0.469 W / (m•K).

7. A data center liquid cooling system with waste heat recovery and phase change energy storage functions according to claim 1, characterized in that, The integrated refrigeration and heat recovery system (200) includes a third valve (18), a fourth valve (19), a fifth valve (20), and a sixth valve (21); the honeycomb tube phase change energy storage heat exchanger (3), the third valve (18), the second heat exchanger (5), and the fifth valve (20) are sequentially connected to form the natural refrigeration loop; the honeycomb tube phase change energy storage heat exchanger (3), the fourth valve (19), and the sixth valve (21) are sequentially connected to the chiller unit (6) to form the mechanical refrigeration loop; the honeycomb tube phase change energy storage heat exchanger (3), the third valve (18), the second heat exchanger (5), and the sixth valve (21) are sequentially connected to the chiller unit (6) to form the partial natural refrigeration loop.

8. A data center liquid cooling system with waste heat recovery and phase change energy storage functions according to claim 7, characterized in that, The waste heat recovery module also includes a throttling element (23) and an eighth valve (24). The evaporator (7), compressor (8), condenser (9), throttling element (23) and eighth valve (24) are connected in sequence to form a heat pump circulation loop. The waste heat utilization system (300) includes a ninth valve (25), the condenser (9), the inlet and outlet of the second channel (1002) of the hot water storage tank (10), and the ninth valve (25) and heating terminal (11) are connected in sequence to form a hot water circulation loop. The hot water circulation loop is provided with a water inlet (15) for replenishing chilled water. The water inlet (15) is located on the pipeline between the heating terminal (11) and the condenser (9).

9. A data center liquid cooling system with waste heat recovery and phase change energy storage functions according to claim 8, characterized in that, The system has three modes, namely, a full waste heat recovery mode, a partial waste heat recovery mode, and a no waste heat recovery mode. When the surrounding buildings have heat demand and the temperature of the refrigerant flowing out of the first channel (201) of the first heat exchanger (2) is within 18~27℃, the system is in the full waste heat recovery mode. When the surrounding buildings have heat demand and the temperature of the refrigerant flowing out of the first channel (201) of the first heat exchanger (2) is higher than 27℃, the system is in the partial waste heat recovery mode. When the surrounding buildings have no heat demand, the system is in the no waste heat recovery mode. When the system is in waste heat recovery mode, the first valve 16 is open, the second valve (17) is closed, the third valve (18), the fourth valve (19), the fifth valve (20) and the sixth valve (21) are all closed, the honeycomb tube phase change energy storage heat exchanger (3), the second heat exchanger (5) and the chiller (6) are all closed, the seventh valve (22) to the eighth valve (24) are all open, the evaporator (7), the compressor (8), the condenser (9) and the throttling element (23) are all in the active state, the ninth valve (25) is open, and the hot water storage tank (10), the heating terminal (11) and the water inlet (15) are all in the active state; When the system is in waste heat recovery mode and waste heat non-recovery mode, if the temperature of the cooling water flowing out of the channel outlet of the honeycomb tube phase change energy storage heat exchanger (3) connected to the second heat exchanger (5) is higher than the temperature of the cooling water flowing in of the channel inlet of the second heat exchanger (5) connected to the natural cold source (4), then the first valve (16) is closed, the second valve (17) is opened, the fourth valve (19) and the sixth valve (21) are opened, and the third valve (18) and the fifth valve (20) are closed. The chiller unit (6) and the honeycomb tube phase change energy storage heat exchanger (3) are both in the active state. If the temperature of the cooling water flowing out of the outlet of the channel connecting the honeycomb tube phase change energy storage heat exchanger (3) and the second heat exchanger (5) is lower than the temperature of the cooling water flowing into the inlet of the channel connecting the second heat exchanger (5) and the natural cold source (4), and the temperature of the cooling water flowing out of the outlet of the channel connecting the second heat exchanger (5) and the honeycomb tube phase change energy storage heat exchanger (3) reaches the set value, then the first valve (16) is closed, the second valve (17) is opened, the third valve (18) and the fifth valve (20) are opened, the fourth valve (19) and the sixth valve (21) are closed, the chiller unit (6) is shut down, and the second heat exchanger (5) and the honeycomb tube phase change energy storage heat exchanger (3) are both in the active state; If the temperature of the cooling water flowing out of the outlet of the channel connecting the honeycomb tube phase change energy storage heat exchanger (3) and the second heat exchanger (5) is lower than the temperature of the cooling water flowing into the inlet of the channel connecting the second heat exchanger (5) and the natural cold source (4), and the temperature of the cooling water flowing out of the outlet of the channel connecting the second heat exchanger (5) and the honeycomb tube phase change energy storage heat exchanger (3) does not reach the set value, then the first valve (16) is closed, the second valve (17) is opened, the third valve (18) and the sixth valve (21) are opened, and the fourth valve (19) and the fifth valve (20) are closed. The chiller unit (6), the second heat exchanger (5) and the honeycomb tube phase change energy storage heat exchanger (3) are all in the active state. When the system is in waste heat recovery mode, valves 7 (22) to 8 (24) are all open, and the evaporator (7), compressor (8), condenser (9) and throttling element (23) are all in the active state. Valve 9 (25) is open, and the hot water storage tank (10), heating terminal (11) and water inlet (15) are all in the active state. When the system is in the waste heat non-recovery mode, valves 7 (22) to 8 (24) are all closed, and the evaporator (7), compressor (8), condenser (9) and throttling element (23) are all inactive. Valve 9 (25) is closed, and the hot water storage tank (10), heating terminal (11) and water inlet (15) are all inactive.

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