Liquid cooling heat dissipation system

Abstract

The present application relates to the technical field of liquid cooling, and in particular to a liquid cooling heat dissipation system. The liquid cooling heat dissipation system comprises a primary side cooling unit, a secondary side cooling unit and a heat exchange unit, wherein an outlet of the primary side cooling unit is in communication with a primary side inlet of the heat exchange unit, and a primary side outlet of the heat exchange unit is in communication with an inlet of the primary side cooling unit; and the secondary side cooling unit comprises a pump drive unit, a static pressure water tank and a load unit, wherein an inlet of the pump drive unit is in communication with an outlet of the load unit, an outlet of the pump drive unit is in communication with the static pressure water tank, the static pressure water tank is in communication with the atmosphere and is also in communication with a secondary side inlet of the heat exchange unit, a secondary side outlet of the heat exchange unit is in communication with an inlet of the load unit, and the pump drive unit is a water pump for pumping water to an inlet side of the pump drive unit, thereby improving the safety of the liquid cooling heat dissipation system.

Description

Liquid cooling system

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to a Chinese patent application filed with the Patent Office of China on August 8, 2023, with application number 202310991519.X, entitled “LIQUID COOLING SYSTEM,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of liquid cooling technology, and in particular to a liquid cooling heat dissipation system. Background Art

[0004] With the rapid development of information and data technology and their applications, the performance of core server components such as CPUs and GPUs is significantly improving, and their power consumption and heat generation are also increasing exponentially. Consequently, traditional air cooling technology is no longer able to meet the cooling needs of servers and data center computer rooms. To further improve the cooling capacity of servers and data center computer rooms, more advanced liquid cooling technologies are currently being used to dissipate heat. Currently, there are two main types of server liquid cooling technologies: immersion cooling and cold plate cooling. Immersion cooling directly immerses the server in a specialized coolant to dissipate heat. However, due to its high overall cost and difficult maintenance, its application is relatively small. Cold plate cooling utilizes a liquid-cooled cold plate in direct contact with the server's heat-generating components (such as the CPU and GPU) to dissipate heat. Its cooling principle is that a coolant pump drives a heat exchange system, driving a coolant (such as water or ethylene glycol) through channels within the cold plate. Within these channels, the coolant passes through the cold plate walls, exchanging heat with the server's heat-generating components, thereby removing heat generated by the server's operation and achieving heat dissipation.

[0005] The coolant circulation pipeline in the current server liquid cooling technology is a positive pressure system. When the pipeline is damaged or the joint is loose, the pipeline leakage can only be detected by relying on the leakage detection line when the coolant has leaked to the specified location inside the server. At this time, the leakage has already occurred and has caused damage to the server, resulting in low safety of the liquid cooling system.

[0006] Summary of the Invention

[0007] Based on this, the present application provides a liquid cooling and heat dissipation system to improve the safety of the liquid cooling and heat dissipation system.

[0008] On the one hand, a liquid cooling heat dissipation system is provided, which includes a primary-side cooling unit, a secondary-side cooling unit and a heat exchange unit, the outlet of the primary-side cooling unit is connected to the primary-side inlet of the heat exchange unit, and the primary-side outlet of the heat exchange unit is connected to the inlet of the primary-side cooling unit; the secondary-side cooling unit includes a pump drive unit, a static pressure water tank and a load unit, the inlet of the pump drive unit is connected to the outlet of the load unit, the outlet of the pump drive unit is connected to the static pressure water tank, the static pressure water tank is connected to the atmosphere, the static pressure water tank is connected to the secondary-side inlet of the heat exchange unit, and the secondary-side outlet of the heat exchange unit is connected to the inlet of the load unit, wherein the pump drive unit is a water pump for pumping water from its inlet side.

[0009] In some embodiments, the secondary side cooling unit includes a secondary side liquid return unit, and the secondary side liquid return unit includes an exhaust tank. The bottom outlet of the static pressure water tank and the outlet of the load unit are both connected to the top inlet of the exhaust tank. The bottom outlet of the exhaust tank is connected to the inlet of the pump drive unit. A pressure-stabilizing exhaust valve is provided on the top of the exhaust tank.

[0010] In some embodiments, an exhaust stabilizing pressure sensor is also provided on the top of the exhaust tank, and the exhaust stabilizing pressure sensor is connected to the interior of the exhaust tank. The bottom outlet of the static pressure water tank and the top inlet of the exhaust tank are connected through a secondary side bypass return liquid pipeline, and a secondary side bypass regulating unit and a secondary side bypass check valve are provided on the secondary side bypass return liquid pipeline.

[0011] In some embodiments, a system fluid replenishment pipeline is provided between the bottom of the static pressure water tank and the top inlet of the exhaust tank, and a secondary side system fluid replenishment pump and a secondary side system fluid replenishment one-way valve are provided on the system fluid replenishment pipeline.

[0012] In some embodiments, the top of the static pressure water tank is connected to an automatic water tank refill pipeline and a manual water tank refill pipeline. The manual water tank refill pipeline includes a secondary side manual refill on-off valve, a secondary side refill filter and a secondary side water tank refill pump that are connected in sequence. The secondary side manual refill on-off valve is connected to the top of the static pressure water tank, and the secondary side water tank refill pump is connected to the refill water tank; one end of the automatic water tank refill pipeline is connected to the top of the static pressure water tank, and the other end is connected to the pressurized coolant delivery pipeline.

[0013] In some embodiments, the bottom of the static pressure water tank is connected to a drain pipe, a solenoid valve is provided on the drain pipe, and the top of the static pressure water tank is connected to an overflow pipe, the overflow pipe is in communication with the drain pipe.

[0014] In some embodiments, a secondary side water quality automatic detection and monitoring unit is connected to the bottom of the static pressure water tank, and the secondary side water quality automatic detection and monitoring unit is used to detect the water quality status of the secondary side coolant.

[0015] In some embodiments, the pump drive unit includes a first pump drive unit and a second pump drive unit arranged in parallel, and the first pump drive unit and the second pump drive unit both include a secondary side return liquid inlet on-off valve, a secondary side drive pump inlet shock absorber pipe, a secondary side drive pump, a secondary side drive pump outlet shock absorber pipe, a secondary side return liquid one-way valve and a secondary side return liquid outlet on-off valve that are connected in sequence, the secondary side return liquid inlet on-off valve is connected to the bottom outlet of the exhaust tank, and the secondary side return liquid outlet on-off valve is connected to the top of the static pressure water tank.

[0016] In some embodiments, a secondary side liquid return main circuit on-off valve, a secondary side ultraviolet sterilization device, a secondary side liquid return pressure sensor, a secondary side liquid return temperature sensor and a secondary side liquid return flow sensor are sequentially connected between the load unit and the top of the exhaust tank. The secondary side liquid return flow sensor is connected to the top of the exhaust tank, and the secondary side liquid return main circuit on-off valve is connected to the load unit.

[0017] In some embodiments, a secondary side liquid leakage detection device is connected in parallel between the secondary side liquid return pressure sensor and the secondary side liquid return flow sensor, and the secondary side liquid leakage detection device is a liquid bubble detector.

[0018] In some embodiments, the secondary side cooling unit includes a secondary side liquid supply unit, which includes a secondary side liquid supply pressure sensor, three secondary side liquid supply temperature sensors, a secondary side coolant visualization monitoring device and a secondary side liquid supply main on-off valve connected in sequence. The secondary side liquid supply pressure sensor is connected to the secondary side outlet of the heat exchange unit, and the secondary side liquid supply main on-off valve is connected to the load unit.

[0019] In some embodiments, the secondary side liquid supply pressure sensor includes a secondary side liquid supply inlet pressure sensor and a secondary side liquid supply outlet pressure sensor, and a secondary side first liquid supply module and a secondary side second liquid supply module arranged in parallel are connected between the secondary side liquid supply inlet pressure sensor and the secondary side liquid supply outlet pressure sensor. The secondary side first liquid supply module and the secondary side second liquid supply module both include a secondary side inlet on-off valve, a secondary side drain and water quality sampling valve, a secondary side filter, and a secondary side outlet on-off valve connected in sequence. The secondary side inlet on-off valve is connected to the secondary side liquid supply inlet pressure sensor, and the secondary side outlet on-off valve is connected to the secondary side liquid supply outlet pressure sensor.

[0020] In some embodiments, the primary side cooling unit includes a primary side liquid supply unit and a primary side refrigeration pump drive device, the primary side liquid supply unit includes a primary side liquid supply main line on-off valve, a primary side ultraviolet sterilization device, a primary side liquid supply temperature sensor, a primary side liquid supply pressure sensor, and a primary side liquid supply automatic exhaust valve connected in sequence, the primary side liquid supply main line on-off valve is connected to the outlet of the primary side refrigeration pump drive device, and the primary side liquid supply automatic exhaust valve is connected to the primary side inlet of the heat exchange unit.

[0021] In some embodiments, the primary side liquid supply pressure sensor includes a primary side inlet pressure sensor and a primary side outlet pressure sensor, and a primary side first liquid supply module and a primary side second liquid supply module arranged in parallel are connected between the primary side inlet pressure sensor and the primary side outlet pressure sensor. The primary side first liquid supply module and the primary side second liquid supply module both include a primary side inlet on-off valve, a primary side drain and water quality sampling valve, a primary side filter and a primary side outlet on-off valve connected in sequence, the primary side inlet on-off valve is communicated with the primary side inlet pressure sensor, and the primary side outlet on-off valve is communicated with the primary side outlet pressure sensor.

[0022] In some embodiments, the primary side cooling unit includes a primary side return liquid unit, and the primary side return liquid unit includes a primary side return liquid main line on-off valve, a primary side coolant visualization monitoring device, a primary side coolant flow sensor, a primary side return liquid temperature sensor, a primary side return liquid pressure sensor and a primary side coolant regulating device connected in sequence, the primary side return liquid main line on-off valve is connected to the inlet of the primary side refrigeration machine pump drive device, and the primary side coolant regulating device is connected to the primary side outlet of the heat exchange unit.

[0023] In some embodiments, the liquid cooling system further includes an external tube leakage detection device, and the external tube leakage detection device includes a resistance sensor.

[0024] In some embodiments, the primary-side chiller pump drive device includes an outdoor chiller, a primary-side coolant drive pump, a constant-pressure water replenishment device, and an automatic dosing device.

[0025] In another aspect, a liquid cooling and heat dissipation system is provided, comprising:

[0026] A pump drive unit, configured to pump water from a pipeline on an inlet side of the pump drive unit so that the pipeline in the secondary cooling unit flowing from the static water tank to the pump drive unit is in a negative pressure state, thereby forming a negative pressure pipeline;

[0027] a static pressure water tank, connected to the external atmospheric pressure, for establishing a pressure difference between the external atmospheric pressure and the negative pressure in the negative pressure pipeline, so as to establish a circulating flow power of the coolant in the secondary cooling unit through the pressure difference;

[0028] The load unit is used to transport the low-temperature coolant to the load under the circulating flow power and to form high-temperature coolant after performing heat exchange with the load.

[0029] In some embodiments, the system further comprises:

[0030] A secondary side return liquid temperature sensor is used for the temperature value of the secondary side return liquid unit, and a temperature feedback mechanism is established through the collected temperature value, the preset temperature value and the pump drive unit; in response to the temperature value of the secondary side return liquid temperature sensor being higher than the preset temperature value, the pumping power of the pump drive unit is increased to reduce the negative pressure of the negative pressure pipeline; and the circulating flow power is increased by increasing the pressure difference to further increase the flow rate in the secondary side cooling unit pipeline, so that the temperature value of the secondary side return liquid temperature sensor is lower than the preset temperature value.

[0031] In some embodiments, the system further comprises:

[0032] The secondary side bypass regulating unit is used to adjust the valve opening of the secondary side bypass regulating unit in response to the coolant demand of the load unit being lower than the minimum flow rate on the outlet side of the pump drive unit so that the flow rate on the outlet side of the pump drive unit exceeding the coolant demand of the load unit flows to the exhaust tank and returns to the inlet side of the pump drive unit.

[0033] The above technical solution of the present application has the following advantages over the related art:

[0034] In the above-mentioned liquid cooling and heat dissipation system, the pump drive unit pumps water on the pipeline on its inlet side, so that the pipeline between the bottom outlet of the static pressure water tank and the inlet of the pump drive unit is in a negative pressure state, forming a negative pressure pipeline; the static pressure water tank stores coolant, and the static pressure water tank is connected to the outside atmosphere; the pressure difference between the outside atmospheric pressure and the negative pressure of the load pipeline establishes the circulation flow power of the coolant in the secondary side cooling unit, and the secondary side negative pressure pipeline is always in a negative pressure state. The negative pressure pipeline in a negative pressure state can effectively reduce the leakage of coolant in the secondary side cooling unit pipeline, and effectively improve the safety of the liquid cooling and heat dissipation system and the data center. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0036] FIG1 is a system structure diagram of a liquid cooling and heat dissipation system provided in an embodiment of the present application;

[0037] FIG2 is a structural diagram of a primary-side cooling unit (a primary-side liquid supply unit and a primary-side liquid return unit) of a liquid cooling and heat dissipation system provided in an embodiment of the present application;

[0038] FIG3 is a structural diagram of a secondary side liquid supply unit of a liquid cooling and heat dissipation system provided in an embodiment of the present application;

[0039] FIG4 is a structural diagram of a secondary side liquid return unit of a liquid cooling and heat dissipation system provided in an embodiment of the present application;

[0040] FIG5 is a structural diagram of a static pressure water tank of a liquid cooling and heat dissipation system provided in an embodiment of the present application;

[0041] FIG6 is a structural diagram of an exhaust tank of a liquid cooling and heat dissipation system provided in an embodiment of the present application;

[0042] FIG7 is a structural diagram of a pump drive unit of a liquid cooling and heat dissipation system provided in an embodiment of the present application;

[0043] FIG8 is a flow chart of a liquid cooling method according to an embodiment of the present application.

[0044] Explanation of the accompanying symbols: 1. Primary side cooling unit; 101. Primary side liquid supply unit; 102. Primary side chiller pump drive device; 103. Primary side liquid return unit; 104. Primary side liquid supply main line on-off valve; 105. Primary side ultraviolet sterilization device; 106. Primary side liquid supply temperature sensor; 107. Primary side liquid supply automatic exhaust valve; 108. Primary side inlet pressure sensor; 109. Primary side outlet pressure sensor; 110. Primary side first liquid supply module; 111. Secondary side second liquid supply module; 112, primary side inlet on-off valve; 113, primary side drain and water quality sampling valve; 114, primary side filter; 115, primary side outlet on-off valve; 116, primary side return liquid main on-off valve; 117, primary side coolant visual monitoring device; 118, primary side coolant flow sensor; 119, primary side return liquid temperature sensor; 120, primary side return liquid pressure sensor; 121, primary side coolant regulating device; 2. Secondary cooling unit; 201. Secondary liquid supply unit; 202. Load unit; 203. Secondary liquid return unit; 204. Pump drive unit; 205. Static pressure tank; 206. Exhaust tank; 207. Pressure stabilizing exhaust valve; 208. Exhaust pressure stabilizing pressure sensor; 209. Secondary bypass liquid return line; 210. Secondary bypass regulating unit; 211. Secondary bypass check valve; 212. System liquid replenishment line; 213. Secondary system liquid replenishment pump; 214. Secondary system 215, automatic tank refill line; 216, manual tank refill line; 217, secondary side manual refill on-off valve; 218, secondary side refill filter; 219, secondary side tank refill pump; 220, drain line; 221, solenoid valve; 222, overflow line; 223, secondary side water quality automatic detection and monitoring unit; 224, first pump drive unit; 225, second pump drive unit; 226, secondary side return liquid inlet on-off valve; 227, secondary side drive pump inlet Shock absorber pipe; 228, secondary side drive pump; 229, secondary side drive pump outlet shock absorber pipe; 230, secondary side return liquid one-way valve; 231, secondary side return liquid outlet on-off valve; 232, secondary side return liquid main on-off valve; 233, secondary side UV sterilizer; 234, secondary side return liquid pressure sensor; 235, secondary side return liquid temperature sensor; 236, secondary side return liquid flow sensor; 237, secondary side leakage detection device; 238, secondary side supply liquid temperature sensor; 239, secondary Secondary side coolant visual monitoring device; 240, secondary side liquid supply main line on-off valve; 241, secondary side liquid supply inlet pressure sensor; 242, secondary side liquid supply outlet pressure sensor; 243, secondary side first liquid supply module; 244, secondary side second liquid supply module; 245, secondary side inlet on-off valve; 246, secondary side drain and water quality sampling valve; 247, secondary side filter; 248, secondary side outlet on-off valve; 249, secondary side main line one-way valve; 250, atmosphere connecting pipe; 3. Heat exchange unit. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0046] The conventional cold plate liquid cooling pump drive heat exchange system currently has the following disadvantages:

[0047] (1) The existing coolant circulation pipeline is a positive pressure system, which uses positive pressure to drive the coolant to circulate the coolant. That is, the pressure in the coolant circulation pipeline is greater than the external atmospheric pressure. It relies on the pressure generated by the continuous rotation of the water pump in the pump-driven heat exchange system to drive the coolant to circulate continuously in the coolant circulation pipeline. When the pipeline is damaged or the joint is loose, the coolant leaks and conducts electricity, causing damage to the server. In addition, the existing coolant leakage detection and remedial measures are not ideal. The pipeline leakage can only be detected by relying on the leakage detection line when the coolant has leaked to the specified location inside the server. At this time, the leakage has already occurred and has caused damage to the server. The pump-driven heat exchange system has no effective measures to block the pipeline leakage.

[0048] (2) There are no active disinfection measures for microorganisms and bacteria. After the system has been running for a long time, the biological mud and acidic substances produced by microorganisms will cause coolant pollution, corrosion damage to the coolant circulation pipes and liquid-cooled servers. At the same time, when the number of microorganisms and bacteria reaches a certain level, the normal operation of the system can only be ensured by thoroughly cleaning the cooling pipes and replacing all the coolant, resulting in a large amount of manpower and material resources.

[0049] (3) Without online monitoring and alarm measures for coolant water quality, it is easy for coolant that does not meet water quality requirements to circulate in the server, causing blockage and corrosion of the server cold plate pipes.

[0050] (4) The entire system lacks coolant shut-off devices before and after the vulnerable parts and parts that require frequent cleaning. When performing system maintenance, the system coolant must be completely drained before it can be carried out, making maintenance difficult and causing a certain degree of coolant waste.

[0051] (5) There is no closed-loop adaptive function. The pump-driven heat exchange system can only operate according to the set operating parameters. There is no self-sensing device, and it is impossible to obtain the actual operating status of the system in a timely manner. It is impossible to automatically adjust the equipment operating status according to the system usage requirements, including but not limited to the filter status sensing and judgment function, the heat exchanger status sensing and judgment function, the system automatic fluid replenishment function and active overflow functions.

[0052] In some embodiments, refer to Figure 1, which is a system structure diagram of a liquid cooling and heat dissipation system provided in an embodiment of the present application.

[0053] As shown in Figure 1, the liquid cooling system includes a primary-side cooling unit 1, a secondary-side cooling unit 2 and a heat exchange unit 3. The outlet of the primary-side cooling unit 1 is connected to the primary-side inlet of the heat exchange unit 3, and the primary-side outlet of the heat exchange unit 3 is connected to the inlet of the primary-side cooling unit 1; the outlet of the secondary-side cooling unit 2 is connected to the secondary-side inlet of the heat exchange unit 3, and the inlet of the secondary-side cooling unit 2 is connected to the secondary-side outlet of the heat exchange unit 3. The working principle of the liquid cooling heat dissipation system is as follows: the coolant (low-temperature coolant) generated by the primary-side cooling unit 1 flows into the primary-side inlet of the heat exchange unit 3 through the outlet of the primary-side cooling unit 1, and the high-temperature coolant formed after the coolant (low-temperature coolant) of the secondary-side cooling unit 2 exchanges heat with the load enters the secondary-side inlet of the heat exchange unit 3 through the outlet of the secondary-side cooling unit 2. In the heat exchange unit 3, the primary-side coolant (low-temperature coolant) entering the heat exchange unit 3 exchanges heat with the secondary-side high-temperature coolant entering the heat exchange unit 3, so that the primary-side coolant entering the heat exchange unit 3 becomes high-temperature coolant, and the high-temperature coolant then passes through the primary-side cooling unit 1 and becomes coolant (low-temperature coolant); so that the secondary-side high-temperature coolant entering the heat exchange unit 3 becomes coolant (low-temperature coolant), and the coolant (low-temperature coolant) exchanges heat with the load to form high-temperature coolant, and the cycle is repeated to achieve cooling of the load by the liquid cooling heat dissipation system. The heat exchange unit 3 is composed of a brazed integrated plate heat exchanger, which is used for heat exchange between the primary side cooling unit 1 and the secondary side cooling unit 2. Through heat exchange fins and countercurrent heat exchange technology, the high-temperature coolant in the secondary side cooling unit 2 is converted into low-temperature coolant, and the low-temperature coolant in the primary side cooling unit 1 is converted into high-temperature coolant, ultimately realizing the transfer and conversion of the heat generated by the load unit 202 (secondary side server and other loads) to the primary side cooling unit 1.

[0054] In some embodiments, as shown in FIG2 , FIG2 is a structural diagram of a primary-side cooling unit (including a primary-side liquid supply unit) of a liquid-cooled heat dissipation system provided in an embodiment of the present application.

[0055] The primary cooling unit 1 includes a primary chiller pump drive 102, a primary liquid supply unit 101, and a primary liquid return unit 103. The primary chiller pump drive 102 utilizes an outdoor chiller to provide the cooling source (i.e., coolant) required for heat dissipation for the entire liquid-cooled heat dissipation system. The coolant, such as water or ethylene glycol, is delivered by the primary chiller pump drive 102 to the heat exchange unit 3 via the primary liquid supply unit 101. The primary coolant in the heat exchange unit 3 then exchanges heat with the secondary high-temperature coolant before returning to the primary chiller pump drive 102 via the primary liquid return unit 103. The primary chiller pump drive 102 includes a primary coolant drive pump, which provides flow power for the coolant in the primary liquid supply unit 101 and the primary liquid return unit 103, thereby achieving circulation within the primary coolant unit.

[0056] The primary side liquid supply unit 101 includes a primary side liquid supply main on-off valve 104, a primary side ultraviolet sterilization device 105, a primary side liquid supply temperature sensor 106, a primary side inlet pressure sensor 108, a primary side outlet pressure sensor 109, and a primary side liquid supply automatic exhaust valve 107 connected in sequence. The primary side liquid supply main on-off valve 104 is connected to the outlet of the primary side chiller pump drive device 102, and the primary side liquid supply automatic exhaust valve 107 is connected to the primary side inlet of the heat exchange unit 3.

[0057] The primary liquid supply main line on-off valve is used to achieve integrated on-off control between the primary liquid supply unit 101 and the primary chiller pump drive 102, allowing the main liquid supply line to be shut down when subsequent maintenance of pipeline-related components is required or when the primary chiller pump drive 102 is relocated. The primary UV sterilizer 105 utilizes ultraviolet sterilization technology to actively disinfect the coolant in the primary cooling unit 1, preventing problems such as contamination of the coolant circulation pipeline caused by excessive microbial content in the primary cooling unit 1, or corrosion damage to liquid-cooled servers caused by excessive microbial content, thereby improving the water quality of the liquid cooling system. The primary-side liquid supply temperature sensor 106 is used to read and output the temperature of the primary-side liquid supply unit 101 pipeline. The temperature of the primary-side liquid supply unit 101 pipeline is output to the primary-side chiller pump drive device 102, so that the control system (not shown in the drawings) can adjust the operating status of the primary-side system through the primary-side chiller pump drive device 102 according to specific usage requirements. For example, when the temperature value obtained by the primary-side liquid supply temperature sensor 106 is higher than a preset temperature value, the control system increases the power of the primary-side coolant drive pump in the primary-side chiller pump drive device 102 or increases the cooling capacity of the outdoor chiller in the primary-side chiller pump drive device 102 to reduce the temperature value obtained by the primary-side liquid supply temperature sensor 106 to within the preset temperature value. The primary-side liquid supply pressure sensor is used to detect the coolant pressure in the primary-side liquid supply unit 101 pipeline. The primary side liquid supply automatic exhaust valve 107 is used to automatically discharge the gas mixed in the pipeline of the primary side liquid supply unit 101, avoiding the occurrence of cavitation damage to the pipeline caused by the presence of gas in the pipeline, thereby improving the safety of the liquid cooling system.

[0058] In some embodiments, the primary side liquid supply pressure sensor includes a primary side inlet pressure sensor 108 (located on the inlet side of the primary side filter 114) and a primary side outlet pressure sensor 109 (located on the outlet side of the primary side filter 114). As shown in Figure 2, the primary side inlet pressure sensor 108 and the primary side outlet pressure sensor 109 are connected to the primary side first liquid supply module 110 and the primary side second liquid supply module 111 arranged in parallel. The primary side first liquid supply module 110 and the primary side second liquid supply module 111 both include a primary side inlet on-off valve 112, a primary side drain and water quality sampling valve 113, a primary side filter 114 and a primary side outlet on-off valve 115 connected in sequence. The primary side inlet on-off valve 112 is connected to the primary side inlet pressure sensor 108, and the primary side outlet on-off valve 115 is connected to the primary side outlet pressure sensor 109.

[0059] The primary side filter 114 is located between the primary side inlet pressure sensor 108 and the primary side outlet pressure sensor 109. The primary side inlet pressure sensor 108 and the primary side outlet pressure sensor 109 together constitute the filter element status monitoring unit of the primary side filter 114. The status monitoring operation of the primary side filter 114 is realized by the difference between the primary side inlet pressure and the primary side outlet pressure. When the pressure difference between the two is greater than the preset pressure difference, it indicates that the primary side filter 114 is in a blocked state, and the control system automatically reminds the relevant maintenance personnel to perform operations such as cleaning and replacing the filter element of the primary side filter 114. The primary side inlet shut-off valve 112, the primary side drain and water quality sampling valve 113, the primary side filter 114 and the primary side outlet shut-off valve 115 of the primary side first liquid supply module 110 and the primary side inlet shut-off valve 112, the primary side drain and water quality sampling valve 113, the primary side filter 114 and the primary side outlet shut-off valve 115 of the primary side second liquid supply module 111 together constitute the primary side coolant filter pipeline assembly, which adopts a dual filter pipeline design of one in use and one in reserve to ensure that when a problem occurs in one of the pipelines or the filter element is cleaned and replaced, it will not affect the normal operation of the system, that is, the primary side When a problem occurs with the first liquid supply module 110 or the filter element is replaced, the pipeline of the first liquid supply module 110 is cut off through the primary inlet on-off valve 112 and the primary outlet on-off valve 115 of the first liquid supply module 110, and normal operation is carried out through the primary second liquid supply module 111. When a problem occurs with the second liquid supply module 111 or the filter element is replaced, the pipeline of the second liquid supply module 111 is cut off through the primary inlet on-off valve 112 and the primary outlet on-off valve 115 of the second liquid supply module 111, and normal operation is carried out through the primary first liquid supply module 110. The primary drain valve and water sampling valve enable the discharge of coolant from the primary filter pipeline assembly. The first and second liquid supply modules 110, 111 cooperate to enable the cleaning and replacement of the filter element and pipeline maintenance without shutting down the primary chiller pump drive device 102, thereby improving maintenance efficiency and reducing maintenance costs. Furthermore, the primary-side drain valve and water sampling valve facilitate convenient sampling of the coolant in primary cooling unit 1, enabling continuous sampling and inspection of the coolant in primary cooling unit 1. The primary-side filter 114 utilizes a flushable stainless steel filter element to remove particulate matter from the coolant in primary cooling unit 1, ensuring that the coolant meets the requirements for use and further improving its quality.

[0060] In some embodiments, as shown in FIG2 , FIG2 is a structural diagram of a primary-side cooling unit (including a primary-side liquid return unit) of a liquid-cooled heat dissipation system provided in an embodiment of the present application.

[0061] The primary liquid return unit 103 is responsible for transporting the high-temperature primary coolant from the heat exchange unit 3 to the primary chiller pump drive unit 102 for cooling. The primary liquid return unit 103 includes a primary liquid return main line on-off valve 116, a primary coolant visual monitoring device 117, a primary coolant flow sensor 118, a primary liquid return temperature sensor 119, a primary liquid return pressure sensor 120, and a primary coolant regulator 121, all connected in sequence. The primary liquid return main line on-off valve 116 is connected to the inlet of the primary chiller pump drive unit 102, and the primary coolant regulator 121 is connected to the primary outlet of the heat exchange unit 3.

[0062] The primary liquid return main line on-off valve is used to connect and disconnect the primary liquid return unit 103 and the primary chiller pump drive 102. This allows the return main line to be shut down when maintenance is required on primary liquid return unit 103 components or when the primary chiller pump drive heat exchanger is relocated. The primary coolant visual monitoring device 117 is used to monitor the coolant circulation status of the primary cooling unit 1. Using transparent tempered glass, the primary coolant visual monitoring device 117 allows operators to clearly and directly view the coolant circulation status, including but not limited to water turbidity, impurities, and bubble levels, thus improving the water quality monitoring capabilities of the liquid cooling system. The primary coolant flow sensor 118 is used to monitor the coolant flow in the primary cooling unit 1. It outputs and uploads data about the coolant flow in the primary cooling unit 1 to the control system, enabling the control system to monitor the coolant flow in the primary cooling unit 1 in real time and make adjustments based on actual needs. Specifically, when the coolant flow rate measured by the primary coolant flow sensor 118 does not reach a preset value, the power of the primary coolant drive pump in the primary chiller pump-driven heat exchanger is increased. Alternatively, when the coolant flow rate measured by the primary coolant flow sensor 118 exceeds a preset value, the power of the primary coolant drive pump in the primary chiller pump-driven heat exchanger is reduced. The operating principle of the primary return liquid temperature sensor 119 can be found in the primary supply liquid temperature sensor 106. The primary return liquid pressure sensor 120 is used to collect the return liquid pressure of the primary return liquid unit 103 pipeline, which is equivalent to the primary outlet pressure value of the heat exchange unit 3. The primary supply liquid pressure sensor is used to collect the supply liquid pressure of the primary supply liquid unit 101, which is equivalent to the primary inlet pressure value of the heat exchange unit 3. The primary inlet pressure value of the heat exchange unit 3 is compared with the primary outlet pressure value to obtain the pressure difference between the primary inlet and outlet of the heat exchange unit 3. This pressure difference can be used to determine the working status of the heat exchange unit 3. If the pressure difference is too large, it indicates that the heat exchange unit 3 may be internally blocked, so that maintenance personnel can perform maintenance in a timely manner to improve maintenance efficiency. At the same time, the return liquid pressure collected by the primary return liquid pressure sensor 120 can be used by the control system to adjust the operating status of the primary cooling unit 1 according to specific usage requirements, such as adjusting the flow rate of the primary chiller pump driving the heat exchange device according to actual needs. The primary side coolant regulating device 121 adopts an electric proportional valve design, which can adjust the relevant parameters such as the coolant pressure, flow and temperature of the primary side cooling unit 1 by adjusting the valve opening to meet the specific usage requirements of the primary side cooling unit 1.

[0063] In some embodiments, as shown in FIG3 , FIG3 is a structural diagram of a secondary side liquid supply unit of a liquid cooling and heat dissipation system provided in an embodiment of the present application.

[0064] The secondary cooling unit 2 includes a secondary liquid supply unit 201, a secondary liquid return unit 203, and a load unit 202. The secondary cooling unit 2 utilizes a pump drive unit 204 to circulate coolant within the secondary cooling unit 2 pipeline, continuously transferring heat generated by load units 202, such as servers and switches, to the heat exchange unit 3, thereby completing heat exchange between the secondary cooling unit 2 and the primary cooling unit 1. The secondary liquid supply unit 201 includes a secondary liquid supply pressure sensor, three secondary liquid supply temperature sensors 238, a secondary coolant visualization monitoring device 239, and a secondary liquid supply main on-off valve 240, all connected in sequence. The secondary liquid supply inlet pressure sensor 241 is connected to the secondary outlet of the heat exchange unit 3, and the secondary liquid supply main on-off valve 240 is connected to the load unit 202.

[0065] The secondary-side liquid supply temperature sensor 238 adopts a one-in-one, two-backup design, and is used to read and output the temperature of the coolant (low-temperature coolant) in the secondary-side liquid supply unit 201 pipeline. The coolant temperature collected by the secondary-side liquid supply temperature sensor 238 is output to the control system so that the control system can adjust the operating status of the secondary-side liquid supply unit 201 according to specific usage requirements. For specific adjustment methods, see the primary-side liquid supply temperature sensor 106. Different data centers have different levels and their reliability varies. Therefore, the secondary-side liquid supply temperature sensor 238 solution needs to be designed based on the level and reliability of the data center, including a one-in-one-backup solution (low reliability) and a one-in-two-backup solution (high reliability). The function of the secondary-side coolant visual monitoring device 239 is described in the description of the primary-side coolant visual monitoring device 117. The secondary-side liquid supply main line on-off valve 240 is used to achieve integrated on-off control between the secondary-side liquid supply unit 201 and the load unit 202. This allows the main liquid supply line to be shut down when maintenance is required for the secondary-side liquid supply unit 201 components and when the primary-side chiller pump drive unit 102 is relocated, improving maintenance efficiency. The load unit 202 is composed of liquid-cooled servers, liquid-cooled cabinets, and other related liquid cooling products. During operation, the load unit 202 generates a large amount of heat. The cold plate assembly in the liquid cooling product heats the low-temperature coolant provided by the secondary-side liquid supply unit 201 to the high-temperature coolant supplied by the secondary-side return unit 203, thereby completing the heat transfer and heat dissipation operation of the liquid cooling product.

[0066] In some embodiments, the secondary side liquid supply pressure sensor includes a secondary side liquid supply inlet pressure sensor 241 and a secondary side liquid supply outlet pressure sensor 242, and the secondary side liquid supply inlet pressure sensor 241 and the secondary side liquid supply outlet pressure sensor 242 are connected with a secondary side first liquid supply module 243 and a secondary side second liquid supply module 244 arranged in parallel. The secondary side first liquid supply module 243 and the secondary side second liquid supply module 244 both include a secondary side inlet on-off valve 245, a secondary side drain and water quality sampling valve 246, a secondary side filter 247, and a secondary side outlet on-off valve 248 connected in sequence. The secondary side inlet on-off valve 245 is connected to the secondary side liquid supply inlet pressure sensor 241, and the secondary side outlet on-off valve 248 is connected to the secondary side liquid supply outlet pressure sensor 242. The working principles of the secondary side first liquid supply module 243 and the secondary side second liquid supply module 244 are consistent with those of the primary side first liquid supply module 110 and the primary side second liquid supply module 111. For specific working methods, please refer to the description of the primary side first liquid supply module 110 and the primary side second liquid supply module 111.

[0067] In some embodiments, as shown in FIG4 , FIG4 is a structural diagram of a secondary side liquid return unit of a liquid cooling and heat dissipation system provided in an embodiment of the present application.

[0068] The secondary side liquid return unit 203 includes a pump drive unit 204 and a static pressure water tank 205. The inlet of the pump drive unit 204 is connected to the outlet of the load unit 202, and the outlet of the pump drive unit 204 is connected to the top of the static pressure water tank 205. The top of the static pressure water tank 205 is connected to the atmosphere. A bottom outlet is provided at the bottom of the static pressure water tank 205. The bottom outlet of the static pressure water tank 205 is connected to the secondary side inlet of the heat exchange unit 3, and the secondary side outlet of the heat exchange unit 3 is connected to the inlet of the load unit 202. The pump drive unit 204 is a water pump for pumping water on its inlet side.

[0069] The secondary side return liquid unit 203 uses the pump drive unit 204 to continuously transport the secondary side high temperature coolant that has completed heat exchange with the load unit 202 to the heat exchange unit 3, so as to complete the cooling operation of the secondary side high temperature coolant through the heat exchange unit 3. The pump drive unit 204 provides driving force for the coolant in the pipeline of the secondary side cooling unit 2. The pump drive unit 204 includes a secondary side drive pump 228. The secondary side drive pump 228 is an ordinary water pump. The secondary side drive pump 228 reduces the pressure on its inlet side, so that The pipeline between the inlet of the secondary drive pump 228 and the bottom outlet of the static water tank 205 is in a negative pressure state, thereby forming a negative pressure pipeline. As shown in Figure 5, the static water tank 205 is connected to the outside atmosphere via the atmospheric communication pipeline 250. The pressure of the static water tank 205 is greater than the pressure of the negative pressure pipeline. The pressure difference between the atmospheric pressure and the negative pressure creates a pressure differential. This pressure differential establishes the coolant circulation flow dynamics of the secondary cooling unit 2. Therefore, under the action of the circulation flow dynamics, the coolant in the static water tank 205 is transported to the negative pressure pipeline. In addition, the atmospheric communication pipeline 250 at the top of the static water tank 205 is used for the pressure relief operation of the static water tank 205. It is equipped with a dustproof end cap to prevent foreign particles from entering the water tank and contaminating the secondary coolant in the static water tank 205. In addition, a secondary main line check valve 249 is provided between the bottom outlet of the static water tank 205 and the secondary inlet of the heat exchange unit 3 to prevent the backflow of high-temperature coolant. The load unit (202) is used to perform heat exchange between the low-temperature coolant and the load to form a high-temperature coolant. The pressure difference established between the external atmospheric pressure and the negative pressure in the negative pressure pipeline enables the negative pressure pipeline to always operate in a negative pressure state, which can effectively reduce the leakage of the coolant and improve the safety of the liquid cooling system and the data center.

[0070] In some embodiments, the secondary side cooling unit 2 includes a secondary side liquid return unit 203, the secondary side liquid return unit 203 includes an exhaust tank 206, the bottom outlet of the static pressure water tank 205 and the outlet of the load unit 202 are both connected to the top inlet of the exhaust tank 206, the bottom outlet of the exhaust tank 206 is connected to the inlet of the pump drive unit 204, and a pressure-stabilizing exhaust valve 207 is provided at the top of the exhaust tank 206.

[0071] As shown in Figure 6, the coolant in the secondary cooling unit 2 may be mixed with gas. When gas is mixed in the pipeline between the bottom outlet of the static water tank 205 and the top inlet of the exhaust tank 206, the coolant in the pipeline between the bottom outlet of the static water tank 205 and the top inlet of the exhaust tank 206 flows into the exhaust tank 206, and the mixed gas also enters the exhaust tank 206 and is discharged through the pressure-stabilizing exhaust valve 207. When gas is mixed in the secondary high-temperature coolant generated after heat exchange with the load cell 202, the secondary high-temperature coolant generated after heat exchange with the load cell 202 enters the exhaust tank 206, and the mixed gas also enters the exhaust tank 206 and is discharged through the pressure-stabilizing exhaust valve 207, thereby preventing problems such as excessive noise and vibration caused by gas in the pipeline, pipeline damage, and cavitation damage to the water pump blades. The secondary coolant (high-temperature coolant) that has been degassed in the exhaust tank will enter the liquid outlet pipeline connected to the bottom outlet of the exhaust tank under the action of the secondary drive pump 228 and circulate in the circulation pipeline of the secondary cooling unit 2.

[0072] In some embodiments, an exhaust stabilizing pressure sensor 208 is further provided at the top of the exhaust tank 206, and the exhaust stabilizing pressure sensor 208 is connected to the interior of the exhaust tank 206. The bottom outlet of the static pressure water tank 205 and the top inlet of the exhaust tank 206 are connected through a secondary side bypass return liquid pipeline 209, and a secondary side bypass regulating unit 210 and a secondary side bypass check valve 211 are provided on the secondary side bypass return liquid pipeline 209.

[0073] The secondary high-temperature coolant flowing through the load unit 202 and completing heat exchange and the secondary high-temperature coolant flowing through the secondary bypass return liquid pipeline 209 both enter the secondary exhaust tank from the top inlet of the exhaust tank. The exhaust stabilizing pressure sensor 208 is used to collect the air pressure inside the exhaust tank 206. When the air pressure inside the exhaust tank 206 is lower than the threshold value, it means that the coolant inside the exhaust tank 206 is less. At this time, the coolant flow entering the exhaust tank 206 can be adjusted, such as increasing the rotation speed of the secondary side drive pump 228, and / or increasing the coolant flow flowing into the exhaust tank 206 through the secondary side bypass return liquid pipeline 209 to increase the air pressure inside the exhaust tank 206; when the air pressure inside the exhaust tank 206 is higher than the threshold value, it means that the coolant inside the exhaust tank 206 is more. At this time, the coolant flow entering the exhaust tank 206 can be adjusted, such as reducing the rotation speed of the secondary side drive pump 228, and / or reducing the coolant flow flowing into the exhaust tank 206 through the secondary side bypass return liquid pipeline 209 to reduce the air pressure inside the exhaust tank 206. Therefore, the valve opening of the secondary side bypass regulating unit 210 can be automatically adjusted according to actual needs to adjust the bypass flow. Furthermore, the flow of coolant entering the exhaust tank 206 from the secondary bypass return line 209 is regulated by adjusting the valve opening of the secondary bypass regulating unit 210 on the secondary bypass return line 209. A secondary bypass check valve 211 is also provided on the secondary bypass return line 209 to prevent coolant backflow. In addition, when the coolant demand of the load unit 202 is lower than the minimum flow rate delivered by the pump drive unit 204, the opening of the secondary side bypass regulating unit 210 of the secondary side return liquid bypass pipeline is increased to allow the coolant flowing to the static pressure water tank 205 through the pump drive unit 204 to flow directly back to the inlet side of the pump drive unit 204 through the exhaust tank 206, which is equivalent to connecting the liquid outlet and the liquid inlet of the pump drive unit 204 to return the coolant exceeding the coolant demand of the load unit 202 to the pump drive unit 204, so as to avoid the coolant exceeding the coolant demand of the load unit 202 overflowing through the static pressure water tank 205 and causing coolant waste.

[0074] In some embodiments, a system fluid replenishment pipeline 212 is provided between the bottom of the static pressure water tank 205 and the top inlet of the exhaust tank 206 , and a secondary side system fluid replenishment pump 213 and a secondary side system fluid replenishment one-way valve 214 are provided on the system fluid replenishment pipeline 212 .

[0075] The system refill pipeline 212 consists of a secondary system refill pump 213, a secondary system refill check valve 214, and related piping. For example, if the total number of servers in a data center increases, and therefore the number of load units 202 increases, the required coolant will increase. In this case, the secondary system refill pump 213 can be used to replenish the coolant in the static pressure water tank 205 into the pipeline of the secondary cooling unit 2 to meet the coolant demand at the load end. The secondary system refill check valve 214 prevents the coolant from flowing back into the pipeline. In addition, a parallel coolant branch is established between the load unit 202 and the secondary side return liquid main line on-off valve 232, and on-off valves are set at both ends of the branch. The branch is used to realize the installation of coolant heat dissipation pipelines for the newly added server loads without stopping the liquid cooling system when the total number of servers increases. At this time, the coolant demand needs to be increased. The staff sets the number of newly added server loads in the control system. The control system receives the number of servers set by the user and automatically calculates the coolant demand required for the newly added servers. Then, the control system replenishment pipeline 212 replenishes the required amount of coolant into the exhaust tank 206, which can improve the work efficiency of the operators and can also add heat dissipation pipelines for new server loads without stopping the system.

[0076] In some embodiments, the top of the static pressure water tank 205 is connected to a water tank automatic refill pipeline 215 and a water tank manual refill pipeline 216. The water tank manual refill pipeline 216 includes a secondary side manual refill on-off valve 217, a secondary side refill filter 218 and a secondary side water tank refill pump 219 that are connected in sequence. The secondary side manual refill on-off valve 217 is connected to the top of the static pressure water tank 205, and the secondary side water tank refill pump 219 is connected to the refill water tank; one end of the water tank automatic refill pipeline 215 is connected to the top of the static pressure water tank 205, and the other end is connected to the pressurized coolant delivery pipeline.

[0077] After the liquid cooling and heating system has been running for a long time, the amount of coolant will decrease. Therefore, it is necessary to regularly replenish the coolant in the static pressure water tank 205. The replenishment of coolant includes two methods: automatic replenishment and manual replenishment. The manual replenishment method includes a water tank manual replenishment pipeline 216. The water tank manual replenishment pipeline 216 consists of a secondary side manual replenishment on-off valve 217, a secondary side replenishment filter 218, a secondary side water tank replenishment pump 219 and a replenishment water tank. One end of the water tank manual replenishment pipeline 216 is connected to the top of the static pressure water tank 205, and the other end is connected to the replenishment water tank. The replenishment water tank is a container for the external non-pressure secondary side coolant. When the static pressure water tank 205 needs to be manually replenished, the operator manually opens the secondary side manual replenishment on-off valve 217 and starts the secondary side water tank replenishment pump 219 to perform the replenishment operation. At the same time, the secondary side replenishment filter 218 can filter and clean the replenished coolant to prevent impurities in the coolant from entering the pump-driven heat exchange system. The automatic refilling method includes an automatic refilling pipe 215 for the water tank, one end of which is connected to the top of the static pressure water tank 205, and the other end is connected to the external pressurized secondary side coolant delivery pipe, on which a switch solenoid valve is installed; when the static pressure water tank 205 outputs a refilling demand, its solenoid valve automatically opens, and the secondary side coolant will be automatically delivered to the inside of the water tank using the external pressurized secondary side coolant delivery pipe. When the refilling is completed, the solenoid valve automatically closes.

[0078] In some embodiments, a drain line 220 is connected to the bottom of the static pressure water tank 205 , a solenoid valve 221 is provided on the drain line 220 , and an overflow line 222 is connected to the top of the static pressure water tank 205 , and the overflow line 222 is in communication with the drain line 220 .

[0079] When the liquid cooling system is severely clogged, causing the coolant in the static water tank 205 to exceed the capacity of the static water tank 205, it is necessary to drain the coolant that exceeds the capacity of the static water tank 205. Therefore, an overflow pipe 222 is required to be provided at the top of the static water tank 205 to drain the coolant that exceeds the capacity of the static water tank 205 through the overflow pipe 222. Furthermore, when the coolant in the static water tank 205 needs to be drained, the coolant in the pressure-reducing water tank needs to be drained through the bottom of the static water tank 205. Therefore, a drain pipe 220 is provided at the bottom of the static water tank 205, and a solenoid valve 221 is provided on the drain pipe 220 to drain the coolant in the static water tank 205 through the solenoid valve 221. At the same time, overflow line 222 can be directly connected to drain line 220, and overflow coolant is directly discharged through drain line 220. Overflow line 222 is connected to the outlet side of solenoid valve 221 on drain line 220. Overflow line 222 is used for safe overflow of static pressure water tank 205, avoiding system failure caused by excessive water, and improving the safety of the liquid cooling system.

[0080] In some embodiments, a secondary-side water quality automatic detection and monitoring unit 223 is connected to the bottom of the static pressure water tank 205 , and the secondary-side water quality automatic detection and monitoring unit 223 is used to detect the water quality status of the secondary-side coolant.

[0081] The bottom of the static pressure water tank 205 is connected to a secondary side water quality automatic detection and monitoring unit 223. The secondary side water quality automatic detection and monitoring unit 223 is used to detect the water quality conditions such as turbidity, conductivity, pH and particle size of the coolant in the secondary side cooling unit 2. It has built-in corresponding sensors to complete related water quality detection work to improve the water quality of the coolant.

[0082] In some embodiments, the pump drive unit 204 includes a first pump drive unit 224 and a second pump drive unit 225 arranged in parallel. The first pump drive unit 224 and the second pump drive unit 225 both include a secondary side return liquid inlet on-off valve 226, a secondary side drive pump inlet shock absorber pipe 227, a secondary side drive pump 228, a secondary side drive pump outlet shock absorber pipe 229, a secondary side return liquid one-way valve 230 and a secondary side return liquid outlet on-off valve 231 that are connected in sequence. The secondary side return liquid inlet on-off valve 226 is connected to the bottom outlet of the exhaust tank 206, and the secondary side return liquid outlet on-off valve 231 is connected to the top of the static pressure water tank 205.

[0083] As shown in Figure 7, the pump drive unit 204 includes a first pump drive unit 224 and a second pump drive unit 225, which are arranged in parallel. Each of the first and second pump drive units 224 and 225 consists of a secondary return liquid inlet shut-off valve 226, a secondary drive pump inlet shock absorber pipe 227, a secondary drive pump 228, a secondary drive pump outlet shock absorber pipe 229, a secondary return liquid check valve 230, and a secondary return liquid outlet shut-off valve 231. The first and second pump drive units 224 and 225 utilize the secondary drive pump 228 to provide driving force for the circulation of coolant in the secondary cooling unit 2. The pump drive unit 204 employs a dual-pump rotational operation design, with one pump in use and one in standby. This ensures that system operation is not impacted if one pump drive unit experiences a problem requiring downtime for maintenance. It also prevents motor overheating, thermal degradation, decreased efficiency, and reduced service life caused by prolonged operation of a single pump, effectively extending the service life and operating efficiency of the pump drive units 204. The secondary drive pump inlet and outlet shock absorbers 227 and 229 are used to eliminate installation errors when connecting the secondary drive pump 228 to the pipeline and reduce vibration and impact during the operation of the secondary drive pump 228. The secondary return check valve 230 prevents the backflow of secondary coolant output by the secondary drive pump 228, which could cause a decrease in the drive pump's driving force and coolant backdraft within the static pressure tank 205. The secondary coolant inlet and outlet check valves work together to fully open and close the pipelines of the pump drive unit 204. Together, they facilitate maintenance of the pump drive unit 204's related components without shutting down the liquid cooling system.

[0084] In some embodiments, a secondary side liquid return main line on-off valve 232, a secondary side ultraviolet sterilization device 233, a secondary side liquid return pressure sensor 234, a secondary side liquid return temperature sensor 235 and a secondary side liquid return flow sensor 236 are connected in sequence between the load unit 202 and the top of the exhaust tank 206. The secondary side liquid return flow sensor 236 is connected to the top of the exhaust tank 206, and the secondary side liquid return main line on-off valve 232 is connected to the load unit 202.

[0085] The secondary liquid return main line on-off valve 232 is used to establish a comprehensive on-off connection between the secondary liquid return unit 203 and the load unit 202. This allows the liquid return main line to be shut down when maintenance is required on the secondary liquid return unit 203 components and when the primary chiller pump drive unit 102 is relocated. The secondary ultraviolet sterilization device 233 uses ultraviolet sterilization technology to actively sterilize microorganisms and bacteria in the coolant of the secondary cooling unit 2, preventing problems such as coolant contamination, coolant circulation piping, and corrosion damage to liquid-cooled servers caused by excessive microbial content in the secondary cooling unit 2 coolant. The secondary side return liquid pressure sensor 234 is used to read and output the return liquid pressure of the secondary side return liquid unit 203 and the pressure on the outlet side of the load unit 202, and outputs the return liquid pressure of the secondary side return liquid unit 203 to the control system. The control system compares this pressure value with the inlet side pressure of the load unit 202 measured by the secondary side liquid supply outlet pressure sensor 242. If the pressure difference between the two is large, it means that there may be a blockage at the load unit 202; in addition, the control system determines the size of the return liquid pressure value of the secondary side return liquid unit 203. If the return liquid pressure value of the secondary side return liquid unit 203 is too large, it is necessary to increase the power of the secondary side drive pump 228 to further reduce the negative pressure of the negative pressure pipeline, that is, to further increase the pressure difference between atmospheric pressure and negative pressure. The increased pressure difference improves the driving ability of the coolant in the secondary side cooling unit 2.

[0086] In some embodiments, a secondary-side liquid leakage detection device 237 is connected in parallel between the secondary-side liquid return pressure sensor 234 and the secondary-side liquid return flow sensor 236 .

[0087] The secondary side liquid leakage detection device 237 uses a liquid bubble detector to realize the real-time detection function of liquid leakage and pipeline damage of the secondary side cooling unit 2. When the pipeline is damaged, since the pipeline of the secondary side cooling unit 2 is in a negative pressure state, a large amount of external gas will enter the pipeline through the damaged part of the pipeline. At this time, the liquid bubble detector in the secondary side liquid leakage detection device 237 will be able to quickly detect the pipeline damage information and output it to the control system. The control system will then perform relevant processing operations based on the actual situation. Since the secondary side liquid leakage detection device 237 requires a specified coolant pressure when performing leakage detection, the secondary side liquid leakage detection device 237 is connected in parallel to the return liquid pipeline to ensure that the coolant pressure of the pipeline where the secondary side liquid leakage detection device 237 is located is within the specified value.

[0088] In some embodiments, the liquid cooling system further includes an external tube leakage detection device, which includes a resistance sensor.

[0089] The primary cooling unit 1 of the liquid-cooling heat dissipation system is still a positive pressure system. Therefore, an external leakage detection device is arranged at a location on the outside of the primary cooling unit 1 where leakage is likely to occur, such as by using a resistance sensor to sense whether the pipeline is leaking. In addition, the secondary cooling unit 2 uses a negative pressure system. However, if the secondary cooling unit 2 experiences a more serious leakage, such as a large damage area, coolant leakage may occur. Therefore, an external leakage detection device is arranged at a location on the secondary cooling unit 2 that is prone to leakage. By combining the secondary leakage detection device 237 with the external leakage detection device, the leakage detection capability is improved, thereby further enhancing the safety of the liquid-cooling heat dissipation system.

[0090] In some embodiments, the primary-side chiller pump drive device 102 includes an outdoor chiller, a primary-side coolant drive pump, a constant-pressure water replenishment device, and an automatic drug-feeding device.

[0091] The primary-side chiller pump drive unit 102 consists of an outdoor chiller, a primary-side coolant drive pump, a constant-pressure water replenishment device, and an automatic dosing device. It is used to cool the coolant in the primary cooling unit 1 and circulate the coolant. The outdoor chiller utilizes a compressor and evaporative heat dissipation to cool the coolant in the primary cooling unit 1. The primary-side coolant drive pump provides flow power for the coolant in the primary cooling unit 1, thereby enabling the coolant to circulate within the primary cooling unit 1.

[0092] In some embodiments, referring to Figures 4 and 8, Figure 4 is a structural diagram of the secondary side liquid return unit of the liquid cooling and heat dissipation system provided in an embodiment of the present application, and Figure 8 is a method flow chart of the liquid cooling and heat dissipation method provided in an embodiment of the present application.

[0093] The liquid cooling method comprises:

[0094] S101, performing a water pumping operation on the pipeline on the inlet side of the pump drive unit 204 by the pump drive unit 204 so that the pipeline between the bottom outlet of the static water tank 205 in the secondary cooling unit 2 and the inlet of the pump drive unit 204 is in a negative pressure state, thereby forming a negative pressure pipeline;

[0095] S102, establishing a pressure difference between the external atmospheric pressure and the negative pressure in the negative pressure pipeline, so as to establish a circulating flow power of the coolant in the secondary cooling unit 2 through the pressure difference;

[0096] S103, the high-temperature coolant flowing through the static pressure water tank 205 flows into the heat exchange unit 3 under the circulation flow power and forms a low-temperature coolant after heat exchange in the heat exchange unit 3;

[0097] S104 , under the action of the circulating flow power, the low-temperature coolant is transported to the load unit 202 and performs heat exchange with the load.

[0098] The pump drive unit 204 of the present application performs a pumping operation on the pipeline on the inlet side of the pump drive unit 204, so that the pipeline between the bottom outlet of the static pressure water tank 205 and the inlet of the pump drive unit 204 is in a negative pressure state, so the pipeline between the bottom outlet of the static pressure water tank 205 and the inlet of the pump drive unit 204 forms a negative pressure pipeline; the static pressure water tank 205 stores coolant, and the static pressure water tank 205 is connected to the outside atmosphere, so the outside atmospheric pressure and the negative pressure of the negative pressure pipeline produce a pressure difference, and the outside atmospheric pressure is greater than the pressure of the negative pressure pipeline, so the pressure difference generated by the outside atmospheric pressure and the negative pressure of the negative pressure pipeline establishes the circulation flow power of the coolant in the secondary side cooling unit 2. Under the circulating flow power, the high-temperature coolant in the static pressure water tank 205 is transported to the heat exchange unit 3, and the high-temperature coolant undergoes heat exchange in the heat exchange unit 3 to form a low-temperature coolant. The low-temperature coolant is transported to the load unit 202 under the circulating flow power, and the low-temperature coolant undergoes heat exchange with the load in the load unit 202 to achieve cooling of the load.

[0099] The pressure difference established between the external atmospheric pressure and the negative pressure in the negative pressure pipeline enables the negative pressure pipeline to always operate in a negative pressure state, which can effectively reduce the leakage of coolant and improve the safety of the liquid cooling system and data center.

[0100] In some embodiments, the method further comprises:

[0101] The low-temperature coolant after heat exchange at the load unit 202 becomes a high-temperature coolant;

[0102] The high-temperature coolant is transported through the pump drive unit 204 and delivered to the static pressure water tank 205 by the circulating flow power.

[0103] The low-temperature coolant forms a high-temperature coolant after heat exchange with the load in the load unit 202, and then the high-temperature coolant is transported to the pump drive unit 204 under the circulating flow power. The high-temperature coolant on the outlet side of the pump drive unit 204 is a pressurized coolant. The pressure of the pressurized coolant is greater than the atmospheric pressure, so the pressurized coolant further flows to the static pressure water tank 205, and the pressurized coolant is depressurized in the static pressure water tank 205, realizing the reciprocating circulation of the coolant in the secondary side cooling unit 2.

[0104] In some embodiments, the method further comprises:

[0105] A temperature feedback mechanism is established by combining the temperature value of the secondary side return liquid temperature sensor 235 with the preset temperature value and the pump drive unit 204;

[0106] In response to the temperature value of the secondary side return liquid temperature sensor 235 being higher than the preset temperature value, increasing the pumping power of the pump drive unit 204 to reduce the negative pressure of the negative pressure pipeline;

[0107] The circulating flow power is increased by increasing the pressure difference to increase the flow rate in the pipeline of the secondary cooling unit 2, so that the temperature value of the secondary side return liquid temperature sensor 235 is lower than the preset temperature value.

[0108] The secondary side return liquid temperature sensor 235 can monitor the temperature of the high-temperature coolant in the secondary side return liquid unit 203 pipeline in real time. A temperature feedback mechanism is established through the secondary side return liquid temperature sensor 235, the preset temperature value and the pump drive unit 204 to improve the control ability and safety of the control system. The specific working principle is: real-time monitoring of the temperature of the high-temperature coolant in the secondary side return liquid unit 203 pipeline, comparing the temperature of the high-temperature coolant in the secondary side return liquid unit 203 pipeline with the preset temperature value. If the temperature of the high-temperature coolant in the secondary side return liquid unit 203 pipeline is higher than the preset temperature value (high threshold), the pumping power of the pump drive unit 204 is increased to further reduce the negative pressure of the negative pressure pipeline. At this time, the pressure difference formed by the external atmospheric pressure and the negative pressure of the negative pressure pipeline will increase. The increased pressure difference increases the circulation flow power to further increase the flow rate in the secondary side cooling unit 2 pipeline until the secondary side return liquid temperature sensor 235 reaches the preset temperature value. If the temperature value of the secondary return liquid temperature sensor 235 is lower than the preset temperature value, the power increase operation of the pump drive unit 204 is stopped; if the temperature of the high-temperature coolant in the secondary side return liquid unit 203 pipeline is lower than the preset temperature value (low threshold), the pumping power of the pump drive unit 204 is reduced to further increase the negative pressure of the negative pressure pipeline. At this time, the pressure difference formed by the external atmospheric pressure and the negative pressure of the negative pressure pipeline will decrease. The reduced pressure difference reduces the circulation flow dynamics, thereby further reducing the flow rate in the secondary side cooling unit 2 pipeline until the temperature value of the secondary side return liquid temperature sensor 235 is higher than the preset temperature value, and the power reduction operation of the pump drive unit 204 is stopped. Furthermore, flow rate, temperature, and pressure are in a chain reaction relationship. Increasing the power of the pump drive unit 204 will increase the flow rate in the pipeline, which will correspondingly increase the pressure and reduce the temperature. In addition, a feedback mechanism can also be established using the temperature data collected by the secondary side supply liquid temperature sensor 238, and the specific working principle is the same.

[0109] In some embodiments, the method further comprises:

[0110] In response to the coolant demand of the load unit 202 being lower than the minimum flow rate on the outlet side of the pump drive unit 204, the valve opening of the secondary side bypass regulating unit 210 is adjusted so that the flow rate on the outlet side of the pump drive unit 204 that exceeds the coolant demand of the load unit 202 flows to the exhaust tank 206 and returns to the inlet side of the pump drive unit 204.

[0111] If the coolant demand of the load unit 202 is lower than the minimum flow rate on the outlet side of the pump drive unit 204, it means that the load of the load unit 202 is reduced. For example, there were ten servers before, and there is only one server now, but the coolant demand of the load unit 202 is lower than the minimum flow rate on the outlet side of the pump drive unit 204. At this time, the valve opening of the secondary side bypass regulating unit 210 is adjusted, and the opening of the secondary side bypass regulating unit 210 of the secondary side return liquid bypass pipeline is increased to make the coolant flowing from the pump drive unit 204 to the static pressure water tank 205 directly flow back to the inlet side of the pump drive unit 204 through the exhaust tank 206, which is equivalent to connecting the liquid outlet and the liquid inlet of the pump drive unit 204 to return the coolant exceeding the coolant demand of the load unit 202 to the pump drive unit 204, so as to avoid the coolant exceeding the coolant demand of the load unit 202 overflowing through the static pressure water tank 205 and causing coolant waste.

[0112] It should be understood that although the various steps in the flowchart of Figure 8 are shown in sequence as indicated by the arrows, these steps are not necessarily performed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be performed in other orders. Moreover, at least a portion of the steps in Figure 8 may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily performed at the same time, but can be performed at different times. The execution order of these sub-steps or stages is not necessarily to perform in sequence, but can be performed in turn or alternately with at least a portion of other steps or sub-steps or stages of other steps.

[0113] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A liquid cooling system, characterized in that: The liquid cooling heat dissipation system comprises a primary side cooling unit (1), a secondary side cooling unit (2) and a heat exchange unit (3); the outlet of the primary side cooling unit (1) is connected to the primary side inlet of the heat exchange unit (3), and the primary side outlet of the heat exchange unit (3) is connected to the inlet of the primary side cooling unit (1); the secondary side cooling unit (2) comprises a pump drive unit (204), a static pressure water tank (205) and a load unit (202); the inlet of the pump drive unit (204) is connected to the outlet of the load unit (202), the outlet of the pump drive unit (204) is connected to the static pressure water tank (205), the static pressure water tank (205) is connected to the atmosphere, the static pressure water tank (205) is connected to the secondary side inlet of the heat exchange unit (3), and the secondary side outlet of the heat exchange unit (3) is connected to the inlet of the load unit (202); wherein the pump drive unit is a water pump for pumping water from its inlet side.

2. The liquid cooling system according to claim 1, characterized in that: The secondary side cooling unit (2) comprises a secondary side liquid return unit (203), the secondary side liquid return unit (203) comprises an exhaust tank (206), the bottom outlet of the static pressure water tank (205) and the outlet of the load unit (202) are both connected to the top inlet of the exhaust tank (206), the bottom outlet of the exhaust tank (206) is connected to the inlet of the pump drive unit (204), and a pressure-stabilizing exhaust valve (207) is provided at the top of the exhaust tank (206).

3. The liquid cooling system according to claim 2, characterized in that: An exhaust stabilizing pressure sensor (208) is also provided at the top of the exhaust tank (206), and the exhaust stabilizing pressure sensor (208) is connected to the interior of the exhaust tank (206). The bottom outlet of the static pressure water tank (205) and the top inlet of the exhaust tank (206) are connected via a secondary side bypass liquid return pipeline (209), and a secondary side bypass regulating unit (210) and a secondary side bypass non-return valve (211) are provided on the secondary side bypass liquid return pipeline (209).

4. The liquid cooling system according to claim 2, characterized in that: A system fluid replenishment pipeline (212) is provided between the bottom of the static pressure water tank (205) and the top inlet of the exhaust tank (206), and a secondary side system fluid replenishment pump (213) and a secondary side system fluid replenishment check valve (214) are provided on the system fluid replenishment pipeline (212).

5. The liquid cooling system according to claim 2, characterized in that: The top of the static pressure water tank (205) is connected to an automatic water tank refilling pipeline (215) and a manual water tank refilling pipeline (216). The manual water tank refilling pipeline (216) comprises a secondary side manual refilling on-off valve (217), a secondary side refilling filter (218) and a secondary side water tank refilling pump (219) which are connected in sequence. The secondary side manual refilling on-off valve (217) is connected to the top of the static pressure water tank (205), and the secondary side water tank refilling pump (219) is connected to the refilling water tank. One end of the automatic water tank refilling pipeline (215) is connected to the top of the static pressure water tank (205), and the other end is connected to a pressurized coolant delivery pipeline.

6. The liquid cooling system according to claim 2, characterized in that: The bottom of the static pressure water tank (205) is connected to a drainage pipeline (220), and a solenoid valve (221) is provided on the drainage pipeline (220). The top of the static pressure water tank (205) is connected to an overflow pipeline (222), and the overflow pipeline (222) is in communication with the drainage pipeline (220).

7. The liquid cooling system according to claim 2, characterized in that: The bottom of the static pressure water tank (205) is connected to a secondary side water quality automatic detection and monitoring unit (223), and the secondary side water quality automatic detection and monitoring unit (223) is used to detect the water quality status of the secondary side coolant.

8. The liquid cooling system according to claim 2, characterized in that: The pump drive unit (204) comprises a first pump drive unit (224) and a second pump drive unit (225) which are arranged in parallel. The first pump drive unit (224) and the second pump drive unit (225) both comprise a secondary side liquid return inlet on-off valve (226), a secondary side drive pump (228) inlet shock absorber pipe (227), a secondary side drive pump, a secondary side drive pump outlet shock absorber pipe (229), a secondary side liquid return one-way valve (230) and a secondary side liquid return outlet on-off valve (231) which are connected in sequence. The secondary side liquid return inlet on-off valve (226) is connected to the bottom outlet of the exhaust tank (206), and the secondary side liquid return outlet on-off valve (231) is connected to the top of the static pressure water tank (205).

9. The liquid cooling system according to claim 2, characterized in that: A secondary side liquid return main circuit on-off valve (232), a secondary side ultraviolet sterilization device (233), a secondary side liquid return pressure sensor (234), a secondary side liquid return temperature sensor (235) and a secondary side liquid return flow sensor (236) are sequentially connected between the load unit (202) and the top of the exhaust tank (206); the secondary side liquid return flow sensor (236) is connected to the top of the exhaust tank (206), and the secondary side liquid return main circuit on-off valve (232) is connected to the load unit (202).

10. The liquid cooling system according to claim 9, characterized in that: A secondary side liquid leakage detection device (237) is connected in parallel between the secondary side liquid return pressure sensor (234) and the secondary side liquid return flow sensor (236), and the secondary side liquid leakage detection device (237) is a liquid bubble detector.

11. The liquid cooling system according to claim 2, characterized in that: The secondary side cooling unit (2) comprises a secondary side liquid supply unit (201), wherein the secondary side liquid supply unit (201) comprises a secondary side liquid supply pressure sensor, three secondary side liquid supply temperature sensors (238), a secondary side coolant visualization monitoring device (239) and a secondary side liquid supply main line on-off valve (240) which are connected in sequence, wherein the secondary side liquid supply pressure sensor is connected to the secondary side outlet of the heat exchange unit (3), and the secondary side liquid supply main line on-off valve (240) is connected to the load unit (202).

12. The liquid cooling system according to claim 11, characterized in that: The secondary side liquid supply pressure sensor comprises a secondary side liquid supply inlet pressure sensor (241) and a secondary side liquid supply outlet pressure sensor (242); a secondary side first liquid supply module (243) and a secondary side second liquid supply module (244) arranged in parallel are connected between the secondary side liquid supply inlet pressure sensor (241) and the secondary side liquid supply outlet pressure sensor (242); the secondary side first liquid supply module (243) and the secondary side second liquid supply module (244) both comprise a secondary side inlet on-off valve (245), a secondary side liquid discharge and water quality sampling valve (246), a secondary side filter (247), and a secondary side outlet on-off valve (248) connected in sequence; the secondary side inlet on-off valve (245) is communicated with the secondary side liquid supply inlet pressure sensor (241); and the secondary side outlet on-off valve (248) is communicated with the secondary side liquid supply outlet pressure sensor (242).

13. The liquid cooling system according to claim 2, characterized in that: The primary side cooling unit (1) comprises a primary side liquid supply unit (101) and a primary side chiller pump drive device (102); the primary side liquid supply unit (101) comprises a primary side liquid supply main line on-off valve (104), a primary side ultraviolet sterilization device (105), a primary side liquid supply temperature sensor (106), a primary side liquid supply pressure sensor, and a primary side liquid supply automatic exhaust valve (107) which are connected in sequence; the primary side liquid supply main line on-off valve (104) is connected to the outlet of the primary side chiller pump drive device (102), and the primary side liquid supply automatic exhaust valve (107) is connected to the primary side inlet of the heat exchange unit (3).

14. The liquid cooling system according to claim 13, characterized in that: The primary side liquid supply pressure sensor comprises a primary side inlet pressure sensor (108) and a primary side outlet pressure sensor (109); a primary side first liquid supply module (110) and a primary side second liquid supply module (111) arranged in parallel are connected between the primary side inlet pressure sensor (108) and the primary side outlet pressure sensor (109); the primary side first liquid supply module (110) and the primary side second liquid supply module (111) both comprise a primary side inlet on-off valve (112), a primary side liquid discharge and water quality sampling valve (113), a primary side filter (114) and a primary side outlet on-off valve (115) connected in sequence; the primary side inlet on-off valve (112) is in communication with the primary side inlet pressure sensor (108); and the primary side outlet on-off valve (115) is in communication with the primary side outlet pressure sensor (109).

15. The liquid cooling system according to claim 13, characterized in that: The primary side cooling unit (1) comprises a primary side liquid return unit (103), wherein the primary side liquid return unit (103) comprises a primary side liquid return main circuit on-off valve (116), a primary side coolant visual monitoring device (117), a primary side coolant flow sensor (118), a primary side liquid return temperature sensor (119), a primary side liquid return pressure sensor (120) and a primary side coolant regulating device (121) which are connected in sequence, wherein the primary side liquid return main circuit on-off valve (116) is connected to an inlet of the primary side chiller pump drive device (102), and the primary side coolant regulating device (121) is connected to a primary side outlet of the heat exchange unit (3).

16. The liquid cooling system according to any one of claims 1 to 15, characterized in that: The liquid cooling system also includes a tube leakage detection device, and the tube leakage detection device includes a resistance sensor.

17. The liquid cooling system according to any one of claims 13 to 15, characterized in that: The primary side cooling machine pump drive device (102) comprises an outdoor cooling machine, a primary side cooling liquid drive pump, a constant pressure water replenishment device and an automatic drug adding device.

18. A liquid cooling system, characterized in that: The liquid cooling system comprises: A pump drive unit (204) is used to perform a water pumping operation on the inlet side of the pump drive unit (204) so ​​that the pipeline in the secondary cooling unit (2) flowing from the static pressure water tank (205) to the pump drive unit (204) is in a negative pressure state, so as to form a negative pressure pipeline; A static pressure water tank (205) is connected to the external atmospheric pressure and is used to establish a pressure difference between the external atmospheric pressure and the negative pressure in the negative pressure pipeline, so as to establish a circulating flow power of the coolant in the secondary cooling unit (2) through the pressure difference; The load unit (202) is used to transport the low-temperature coolant to the load under the circulating flow power and form a high-temperature coolant after performing heat exchange with the load.

19. The liquid cooling system according to claim 18, characterized in that: The liquid cooling system comprises: The secondary side liquid return temperature sensor (235) is used to collect the temperature value of the secondary side liquid return unit (203), and establish a temperature feedback mechanism through the collected temperature value, the preset temperature value and the pump drive unit (204); in response to the temperature value collected by the secondary side liquid return temperature sensor (235) being higher than the preset temperature value, the pumping power of the pump drive unit (204) is increased to reduce the negative pressure of the negative pressure pipeline; and the circulating flow power is increased by increasing the pressure difference to further increase the flow rate in the pipeline of the secondary side cooling unit (2), so that the temperature value of the secondary side liquid return temperature sensor (235) is lower than the preset temperature value.

20. The liquid cooling system according to claim 18, characterized in that: The system further comprises: A secondary bypass regulating unit (210) is used to adjust the valve opening of the secondary bypass regulating unit (210) in response to the cooling liquid demand of the load unit (202) being lower than the minimum flow rate at the outlet side of the pump drive unit (204), so that the flow rate at the outlet side of the pump drive unit (204) exceeding the cooling liquid demand of the load unit (202) flows to the exhaust tank (206) and returns to the inlet side of the pump drive unit (204).

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