Backboard air conditioning system with multiple cold source supply modes

Abstract

The utility model relates to a back plate air-conditioning system with a multi-cold-source supply mode, which comprises an outdoor multi-cold-source integrated cooling-water machine, an environment temperature sensor, an indoor back plate air-conditioning unit, an indoor temperature sensor and a controller, a liquid outlet of the outdoor multi-cold-source integrated cooling-water machine is communicated with a liquid inlet of the indoor back plate air-conditioning unit, and a liquid outlet of the outdoor multi-cold-source integrated cooling-water machine is communicated with a liquid outlet of the indoor back plate air-conditioning unit. A liquid outlet of the indoor backboard air conditioning unit is communicated with a liquid inlet of the outdoor multi-cold-source integrated cooling-water machine; the outdoor multi-cold-source integrated cooling-water machine comprises a fan, a variable-frequency compressor, a first bypass valve, a finned condenser, a variable-frequency fluorine pump, a second bypass valve, a throttling device, a double-coil heat exchanger, a natural cooling coil, a first three-way valve and a second three-way valve. And the fan, the variable-frequency compressor, the first bypass valve, the variable-frequency fluorine pump, the second bypass valve, the first three-way valve, the second three-way valve, the environment temperature sensor and the indoor temperature sensor are electrically connected with the controller. Corresponding modes can be switched according to seasonal temperature changes, and the energy-saving and consumption-reducing effects are achieved.

Description

Technical Field

[0001] This utility model relates to the field of evaporative cooling and heat exchange products and control, specifically to a back panel air conditioning system with multiple cold source supply modes. Background Technology

[0002] To maintain a constant indoor temperature, refrigeration units need to operate year-round to cool the computer room equipment and ensure its normal operation. In areas with scarce water resources, traditional water-cooling systems are limited due to their high water consumption, making air-cooled cooling sources an alternative. Therefore, improving the energy efficiency of air-cooled cooling sources and reducing power consumption is crucial. Under the dual pressure of energy conservation, emission reduction, and lower operating costs, a new energy-saving technology and product are needed to fully utilize abundant natural cooling resources and combine multiple technologies to achieve high efficiency and low energy consumption in the unit. Utility Model Content

[0003] In order to overcome the shortcomings of existing products and technologies, this utility model provides a back panel air conditioning system with multiple cold source supply modes, which can adopt different operating modes according to different ambient temperatures, making full use of natural cooling, refrigerant pump refrigeration and mechanical refrigeration, thus greatly reducing energy consumption.

[0004] The technical solution of this utility model embodiment is as follows:

[0005] A back-panel air conditioning system with a multi-cold source supply mode includes an outdoor multi-cold source integrated chiller, an ambient temperature sensor, an indoor back-panel air conditioning unit, an indoor temperature sensor, and a controller. The liquid outlet of the outdoor multi-cold source integrated chiller is connected to the liquid inlet of the indoor back-panel air conditioning unit through a pipe, and the liquid outlet of the indoor back-panel air conditioning unit is connected to the liquid inlet of the outdoor multi-cold source integrated chiller through a pipe.

[0006] The outdoor multi-source integrated chiller includes a fan, a variable frequency compressor, a first bypass valve, a finned condenser, a variable frequency refrigerant pump, a second bypass valve, a throttling device, a dual-coil heat exchanger, a natural cooling coil, a first three-way valve, and a second three-way valve. The liquid outlet of the indoor back panel air conditioning unit is connected to the inlet of the first three-way valve via a pipe. The first outlet of the first three-way valve is connected to the liquid inlet of the natural cooling coil via a pipe. The second outlet of the first three-way valve is connected to the hot end inlet of the dual-coil heat exchanger via a pipe. The hot end outlet of the dual-coil heat exchanger is connected to the first inlet of the second three-way valve via a pipe. The second inlet of the second three-way valve is connected to the liquid outlet of the natural cooling coil via a pipe. The outlet of the second three-way valve is connected to the liquid inlet of the indoor back panel air conditioning unit via a pipe.

[0007] The cold end outlet of the dual-coil heat exchanger is connected to the inlet of the variable frequency compressor via a pipe. The outlet of the variable frequency compressor is connected to the inlet of the finned condenser via a pipe. The liquid outlet of the finned condenser is connected to the liquid inlet of the variable frequency refrigerant pump via a pipe. The liquid outlet of the variable frequency refrigerant pump is connected to one end of the throttling device via a pipe. The other end of the throttling device is connected to the cold end inlet of the dual-coil heat exchanger via a pipe. The two ends of the first bypass valve are connected to the outlet and inlet of the variable frequency compressor via pipes, respectively. The two ends of the second bypass valve are connected to the outlet and inlet of the variable frequency refrigerant pump via pipes, respectively.

[0008] The finned condenser and natural cooling coil are located on the side of the fan's air delivery direction. The fan, the variable frequency compressor, the first bypass valve, the variable frequency refrigerant pump, the second bypass valve, the first three-way valve, the second three-way valve, the ambient temperature sensor, and the indoor temperature sensor are electrically connected to the controller.

[0009] Preferably, the indoor back panel air conditioning unit includes multiple back panel air conditioners, the liquid inlets of the multiple back panel air conditioners are connected to the outlet of the second three-way valve through pipes, and the liquid outlets of the multiple back panel air conditioners are connected to the inlet of the first three-way valve through pipes. The back panel air conditioner is a gravity heat pipe back panel air conditioner.

[0010] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0011] This system employs air cooling and is suitable for small to medium-sized new data centers and the renovation of existing data centers, serving as a cooling source for server rooms. Air-cooled systems primarily rely on air as the heat exchange medium and do not directly consume water resources, thus offering significant advantages in water-scarce regions. The system combines natural cooling coils with refrigerant pump refrigeration and compressor refrigeration, sharing a fan with the condenser to reduce energy waste. By utilizing refrigerant pump refrigeration and natural cooling instead of compressor refrigeration, the system can operate in partial or full free cooling mode during transitional seasons and winter, fully utilizing natural cooling sources, improving unit energy efficiency, and reducing energy consumption. The refrigerant in the heat pipe section and the chiller section is completely isolated and does not mix, avoiding flow regulation issues and reduced heat pipe circulation efficiency problems caused by shared refrigerant, resulting in more stable and efficient unit operation. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of a back panel air conditioning system with multiple cooling source supply modes according to the present invention.

[0013] Figure 2 This is a schematic diagram illustrating the principle of a back-panel air conditioning system with multiple cooling source supply modes operating in the first mode according to this utility model.

[0014] Figure 3 This is a schematic diagram illustrating the principle of a back panel air conditioning system with multiple cooling source supply modes operating in the second mode according to this utility model.

[0015] Figure 4 This is a schematic diagram illustrating the principle of a back panel air conditioning system with multiple cooling source supply modes operating in the third mode according to this utility model.

[0016] Figure 5 This is a schematic diagram illustrating the principle of a back panel air conditioning system with multiple cooling source supply modes operating in the fourth mode according to this utility model.

[0017] 100. Outdoor multi-source integrated chiller; 101. Fan; 102. Variable frequency compressor; 103. First bypass valve; 104. Finned condenser; 105. Variable frequency refrigerant pump; 106. Second bypass valve; 107. Throttling device; 108. Dual-coil heat exchanger; 109. Natural cooling coil; 110. First three-way valve; 111. Second three-way valve; 200. Indoor rear panel air conditioning unit; 201. Rear panel air conditioner. Detailed Implementation

[0018] To facilitate understanding of this utility model, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of this utility model are shown in the drawings. However, this utility model can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this utility model.

[0019] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0021] like Figure 1 As shown, a back-panel air conditioning system with multiple cooling source supply modes is described. Figure 1This is a schematic diagram of a back-panel air conditioning system with a multi-cold source supply mode according to the present invention; it includes an outdoor multi-cold source integrated chiller 100, an ambient temperature sensor, an indoor back-panel air conditioning unit 200, an indoor temperature sensor, and a controller. The liquid outlet of the outdoor multi-cold source integrated chiller 100 is connected to the liquid inlet of the indoor back-panel air conditioning unit 200 via a pipe, and the liquid outlet of the indoor back-panel air conditioning unit 200 is connected to the liquid inlet of the outdoor multi-cold source integrated chiller 100 via a pipe. The outdoor multi-cold source integrated chiller 100 includes a fan 101, a variable frequency compressor 102, a first bypass valve 103, a finned condenser 104, and a variable frequency refrigerant pump 105. The system includes a second bypass valve 106, a throttling device 107, a dual-coil heat exchanger 108, a natural cooling coil 109, a first three-way valve 110, and a second three-way valve 111. The outlet of the indoor rear panel air conditioning unit 200 is connected to the inlet of the first three-way valve 110 via a pipe. The first outlet of the first three-way valve 110 is connected to the inlet of the natural cooling coil 109 via a pipe. The second outlet of the first three-way valve 110 is connected to the hot-end inlet of the dual-coil heat exchanger 108 via a pipe. The hot-end outlet of the dual-coil heat exchanger 108 is connected to the first inlet of the second three-way valve 111 via a pipe. The second inlet of the second three-way valve 111 is connected to the second outlet of the second three-way valve 111 via a pipe. The outlet of the second three-way valve 111 is connected to the liquid outlet of the indoor back panel air conditioning unit 200 via a pipe, and the outlet of the second three-way valve 111 is connected to the liquid inlet of the second three-way valve 111 via a pipe. The cold end outlet of the dual-coil heat exchanger 108 is connected to the inlet of the variable frequency compressor 102 via a pipe. The outlet of the variable frequency compressor 102 is connected to the inlet of the finned condenser 104 via a pipe. The liquid outlet of the finned condenser 104 is connected to the inlet of the variable frequency refrigerant pump 105 via a pipe. The liquid outlet of the variable frequency refrigerant pump 105 is connected to one end of the throttling device 107 via a pipe. The other end of the throttling device 107 is connected to the dual-coil heat exchanger 108 via a pipe. The cold end liquid inlet is connected, and the two ends of the first bypass valve 103 are connected to the outlet and inlet of the variable frequency compressor 102 respectively through pipes. The two ends of the second bypass valve 106 are connected to the outlet and inlet of the variable frequency refrigerant pump 105 respectively through pipes. The finned condenser 104 and the natural cooling coil 109 are located on the side of the air delivery direction of the fan 101. The fan 101, the variable frequency compressor 102, the first bypass valve 103, the variable frequency refrigerant pump 105, the second bypass valve 106, the first three-way valve 110, the second three-way valve 111, the ambient temperature sensor, the indoor temperature sensor and the controller are electrically connected.

[0022] The rear-panel air conditioning system of this utility model combines four refrigeration technologies: compressor refrigeration, completely natural cooling refrigeration, compressor refrigeration plus natural cooling refrigeration, and variable frequency refrigerant pump plus natural cooling refrigeration. The refrigeration unit adopts air cooling, and its main components include a variable frequency compressor, a variable frequency refrigerant pump, a throttling device, a fan, a dual-coil heat exchanger, a finned condenser, and a natural cooling coil. The natural cooling coil and the finned condenser share a fan. Several control devices are also commonly used, including a first bypass valve, a second bypass valve, a first three-way valve, and a second three-way valve. When the first bypass valve is open, the inverter compressor is shut down, and the refrigerant liquid passes through the first bypass valve. When the second bypass valve is open, the inverter refrigerant pump is shut down, and the refrigerant liquid passes through the second bypass valve. The first and second three-way valves are selective flow devices. When their first channel is open and their second channel is closed, the liquid in the back panel air conditioner is transported to the natural cooling coil for cooling circulation. When their first channel is closed and their second channel is open, the liquid in the back panel air conditioner is transported to the dual-coil heat exchanger to exchange heat and provide a refrigerant cold source for cooling circulation with the refrigerant pump and compressor. These control devices are all electrically connected to the controller, which controls the operation in a certain mode based on the temperature monitored by the ambient temperature sensor and the indoor temperature sensor.

[0023] The structural difference between this system and ordinary air-cooled chillers lies in its use of a low-pressure-ratio inverter compressor, connected in series with an inverter refrigerant pump, and the addition of a natural cooling module. The entire system utilizes low-temperature outdoor air to supply cooling to the data center terminals. When the outdoor temperature is sufficiently low, the system automatically switches to a fully natural cooling mode to achieve energy savings.

[0024] The dual-coil heat exchanger consists of two independent heat exchange coils. One heat exchange coil is connected to the back panel air conditioner, and the other is connected to the chiller. The refrigerants charged in the two parts are completely isolated and exchange heat only through the dual-coil heat exchanger. The dual-coil heat exchanger and the heat pipe back panel air conditioner form a heat pipe system. The compressor, dual-coil heat exchanger, condenser, and throttling device form a refrigeration system.

[0025] For the specific arrangement of the indoor back panel air conditioning unit, preferably, the indoor back panel air conditioning unit 200 includes multiple back panel air conditioners 201, the liquid inlets of the multiple back panel air conditioners 201 are connected to the outlet of the second three-way valve 111 through pipes, and the liquid outlets of the multiple back panel air conditioners 201 are connected to the inlet of the first three-way valve 110 through pipes. The back panel air conditioner 201 is a gravity heat pipe back panel air conditioner.

[0026] Multiple backplane air conditioners can be evenly distributed in one or more computer rooms. The heat exchange coils inside the backplane air conditioners are gravity heat pipe backplane air conditioners, which can transport heat exchange liquid by gravity, saving the energy consumption of power pumps.

[0027] The rear-panel air conditioning system of this utility model has multiple cooling source supply modes, and it operates in four different modes under the control of the controller. For example... Figure 2 As shown, Figure 2 This is a schematic diagram illustrating the principle of a back-panel air conditioning system with multiple cooling source supply modes operating in the first mode of this utility model. The first mode is completely natural cooling: During periods of very low winter temperatures, the unit automatically detects the difference between the ambient temperature and the water temperature, performs calculations and analyses, and enters the completely natural cooling mode when the outdoor atmospheric temperature can provide 100% of the terminal cooling capacity demand. At this time, the compressor stops running, and only the fan is running. The refrigerant absorbs heat and evaporates into a gaseous state in the evaporator of the back-panel air conditioning heat pipe, then returns to the natural cooling coil to exchange heat with the low-temperature air and condenses into a liquid state. It then returns to the back-panel air conditioning unit along the connecting pipe for gravity-type separation heat pipe circulation, achieving cooling and allowing the unit to reach its highest energy-saving operating state.

[0028] When the ambient temperature is less than or equal to the first set value, the controller sends a shutdown signal to the variable frequency compressor, the first bypass valve, the variable frequency refrigerant pump, and the second bypass valve. The controller also sends an opening signal to the fan and a first conduction signal to the first three-way valve and the second three-way valve. The variable frequency compressor, the first bypass valve, the variable frequency refrigerant pump, and the second bypass valve are closed, while the first channels of the first three-way valve and the second three-way valve are open. The fan is turned on, and the natural cooling coil provides the cold source, and the system operates in the first mode. When the system is operating in the first mode, the controller monitors the indoor temperature in real time. When the indoor temperature is less than or equal to the fourth set value, the system remains in the first mode. When the liquid refrigerant temperature is greater than the fourth set value, the system switches to the second mode.

[0029] like Figure 3 As shown, Figure 3 This is a schematic diagram illustrating the principle of a back-panel air conditioning system with multiple cooling source supply modes operating in the second mode. The second mode is a combination of inverter refrigerant pump refrigeration and natural cooling: this mode is activated during periods of low temperature in transitional seasons when the outdoor atmospheric temperature cannot fully meet the cooling demand of the terminal units. The refrigerant pump starts, the compressor stops, and the bypass valve on the compressor side opens. The system still primarily uses natural cooling, and the refrigerant pump refrigeration system, consisting of a condenser, refrigerant pump, throttling device, evaporator, and bypass valve, completely replaces the compressor refrigeration mode.

[0030] When the temperature value is greater than the first set value and less than or equal to the second set value, the controller sends a shut-off signal to the variable frequency compressor and the second bypass valve, and an open signal to the first bypass valve, the variable frequency refrigerant pump, and the fan. The controller sends a third conduction signal to the first three-way valve and the second three-way valve. The first bypass valve, the variable frequency refrigerant pump, and the fan open, while the variable frequency compressor and the second bypass valve close. The first and second channels of the first and second three-way valves are both open, and the variable frequency refrigerant pump and the natural cooling coil provide the cold source. The system operates in the second mode. When the system is operating in the second mode, the system monitors the indoor temperature value in real time. When the indoor temperature value is less than or equal to the fourth set value, the system continues to operate in the second mode. When the liquid refrigerant temperature value is greater than the fourth set value, the system switches to the third mode.

[0031] like Figure 4 As shown, Figure 4 This is a schematic diagram illustrating the principle of a back-panel air conditioning system with multiple cooling source supply modes operating in the third mode of this utility model. The third mode is compressor refrigeration plus natural cooling: this mode is operated during periods of higher temperatures in the transitional season. The refrigerant pump is turned off, the compressor is started, and the bypass valve on the refrigerant pump side is opened. The system mainly uses compression refrigeration, consisting of a condenser, compressor, throttling device, dual-coil heat exchanger, and bypass valve, forming a compressor mechanical refrigeration system. At the same time, natural cooling is also activated as an auxiliary function. Since the ambient temperature is not yet very high, natural cooling can handle part of the heat exchange load. At this time, the compressor provides the remaining cooling capacity, resulting in lower energy consumption compared to high-load compressor operation.

[0032] When the temperature value is greater than the second set value and less than or equal to the third set value, the controller sends a shut-off signal to the first bypass valve and the variable frequency refrigerant pump. The controller sends an open signal to the variable frequency compressor, the second bypass valve, and the fan. The controller sends a third conduction signal to the first three-way valve and the second three-way valve. The variable frequency compressor, the second bypass valve, and the fan open, while the first bypass valve and the variable frequency refrigerant pump close. The first and second channels of the first and second three-way valves are both open, and the variable frequency compressor and the natural cooling coil provide the cold source. The system operates in the third mode. When the system is operating in the third mode, the system monitors the indoor temperature value in real time. When the indoor temperature value is less than or equal to the fourth set value, the system continues to operate in the third mode. When the liquid refrigerant temperature value is greater than the fourth set value, the system switches to the fourth mode.

[0033] like Figure 5 As shown, Figure 5This is a schematic diagram illustrating the principle of a back-panel air conditioning system with multiple cooling source supply modes operating in the fourth mode of this utility model. The fourth mode is compressor refrigeration: this mode is operated during the high-temperature period in summer. The refrigerant pump is turned off, the compressor is started, the bypass valve on the refrigerant pump side is opened, and the system mainly uses compression refrigeration. The compressor mechanical refrigeration system consists of a condenser, compressor, throttling device, dual-coil heat exchanger, and bypass valve. At this time, the compressor operates at high load, providing sufficient cooling capacity to meet the temperature requirements of the computer room.

[0034] When the temperature value exceeds the third set value, the controller sends a shut-off signal to the first bypass valve and the variable frequency refrigerant pump, and sends an open signal to the variable frequency compressor, the second bypass valve, and the fan. The controller sends a second conduction signal to the first three-way valve and the second three-way valve. The variable frequency compressor, the second bypass valve, and the fan are turned on, the first bypass valve and the variable frequency refrigerant pump are turned off, and the second channels of the first three-way valve and the second three-way valve are opened. The variable frequency compressor provides a cold source independently, and the system operates in the fourth mode.

[0035] The system first monitors the ambient temperature to determine which mode to start and run in, and then monitors the computer room temperature to intelligently switch to the appropriate mode, so that it runs in the most energy-efficient mode while meeting the computer room temperature requirements.

[0036] The first, second, third, and fourth settings are system preset values. Typically, the first setting is 5℃, the second is 15℃, the third is 25℃, and the fourth is 26℃. The cooling capacity provided increases from the first mode to the fourth mode. If the room temperature exceeds the preset value under the current operating mode, it needs to switch to the next mode with greater cooling capacity until the room temperature reaches the preset value.

[0037] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0038] This system employs air cooling and is suitable for small to medium-sized new data centers and the renovation of existing data centers, serving as a cooling source for server rooms. Air-cooled systems primarily rely on air as the heat exchange medium and do not directly consume water resources, thus offering significant advantages in water-scarce regions. The system combines natural cooling coils with refrigerant pump refrigeration and compressor refrigeration, sharing a fan with the condenser to reduce energy waste. By utilizing refrigerant pump refrigeration and natural cooling instead of compressor refrigeration, the system can operate in partial or full free cooling mode during transitional seasons and winter, fully utilizing natural cooling sources, improving unit energy efficiency, and reducing energy consumption. The refrigerant in the heat pipe section and the chiller section is completely isolated and does not mix, avoiding flow regulation issues and reduced heat pipe circulation efficiency problems caused by shared refrigerant, resulting in more stable and efficient unit operation.

[0039] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0040] The above embodiments only illustrate preferred implementations of this utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A backboard air conditioning system with multiple cold source supply mode, characterized in that, comprising an outdoor multi-cold source integrated water cooler, an ambient temperature sensor, an indoor backboard air conditioning unit, an indoor temperature sensor and a controller, the liquid outlet of the outdoor multi-cold source integrated water cooler is communicated with the liquid inlet of the indoor backboard air conditioning unit through a pipeline, and the liquid outlet of the indoor backboard air conditioning unit is communicated with the liquid inlet of the outdoor multi-cold source integrated water cooler through a pipeline; the outdoor multi-cold source integrated water cooler comprises a fan, a variable frequency compressor, a first bypass valve, a finned condenser, a variable frequency fluorine pump, a second bypass valve, a throttling device, a double-coil heat exchanger, a natural cooling coil, a first three-way valve and a second three-way valve, the liquid outlet of the indoor backboard air conditioning unit is communicated with the inlet of the first three-way valve through a pipeline, the first outlet of the first three-way valve is communicated with the liquid inlet end of the natural cooling coil through a pipeline, the second outlet of the first three-way valve is communicated with the hot end liquid inlet of the double-coil heat exchanger through a pipeline, the hot end liquid outlet of the double-coil heat exchanger is communicated with the first inlet of the second three-way valve through a pipeline, the second inlet of the second three-way valve is communicated with the liquid outlet end of the natural cooling coil through a pipeline, and the outlet of the second three-way valve is communicated with the liquid inlet of the indoor backboard air conditioning unit through a pipeline; the cold end gas outlet of the double-coil heat exchanger is communicated with the gas inlet of the variable frequency compressor through a pipeline, the gas outlet of the variable frequency compressor is communicated with the gas inlet of the finned condenser through a pipeline, the liquid outlet of the finned condenser is communicated with the liquid inlet of the variable frequency fluorine pump through a pipeline, the liquid outlet of the variable frequency fluorine pump is communicated with one end of the throttling device through a pipeline, the other end of the throttling device is communicated with the cold end liquid inlet of the double-coil heat exchanger through a pipeline, and the two ends of the first bypass valve are respectively communicated with the gas outlet and the gas inlet of the variable frequency compressor through pipelines, and the two ends of the second bypass valve are respectively communicated with the liquid outlet and the liquid inlet of the variable frequency fluorine pump through pipelines; the finned condenser and the natural cooling coil are on the side of the conveying wind of the fan, and the fan, the variable frequency compressor, the first bypass valve, the variable frequency fluorine pump, the second bypass valve, the first three-way valve, the second three-way valve, the ambient temperature sensor, the indoor temperature sensor and the controller are electrically connected.

2. The backboard air conditioning system according to claim 1, characterized in that, the indoor backboard air conditioning unit comprises a plurality of backboard air conditioners, the liquid inlets of the plurality of backboard air conditioners are communicated with the outlet of the second three-way valve through pipelines, the liquid outlets of the plurality of backboard air conditioners are communicated with the inlet of the first three-way valve through pipelines, and the backboard air conditioner is a gravity heat pipe backboard air conditioner.

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