Cooling system and server rack

Abstract

The present invention comprises: a cold plate that comes into contact with a heat-generating element and evaporates at least a portion of an internally circulating refrigerant using heat from the heat-generating element; a first line through which a refrigerant discharged from the cold plate circulates; a heat exchanger that cools the refrigerant introduced from the first line; a second line that introduces the refrigerant discharged from the heat exchanger into the cold plate; a negative pressure adjustment unit that is driven to lower the pressure in the first line; a pressure sensor that measures the pressure in the first line; and a pressure monitoring device that drives the negative pressure adjustment unit when the value of the pressure measured by the pressure sensor exceeds a threshold value.

Description

Cooling System and Server Rack

[0001] This disclosure relates to a cooling system and a server rack. This application claims priority from Japanese Patent Application No. 2024-220123 filed in Japan on December 16, 2024, and incorporates its content herein by reference.

[0002] In a data center, a server rack accommodating a plurality of servers is installed. In recent years, with the improvement in the performance of elements such as CPUs and GPUs, the heat generation amount of the elements accommodated in the server has been increasing. Therefore, in a data center or the like where these elements are intensively arranged, it is required to cool the elements more efficiently.

[0003] For example, Patent Document 1 discloses a cooling device that boils a refrigerant and utilizes the latent heat of vaporization. In this device, a heat exchange section is brought into a vacuum state by a vacuum generator, and a gas-liquid two-phase cooling system is realized by lowering the evaporation temperature of the refrigerant.

[0004] U.S. Patent Application Publication No. 2018 / 0317344

[0005] By the way, in the above-described cooling system, in order to maintain the cooling efficiency and avoid various problems, it is necessary to appropriately maintain the negative pressure in the refrigerant system.

[0006] This disclosure has been made to solve the above problems, and an object thereof is to provide a cooling system and a server rack capable of appropriately performing pressure management of a refrigerant system.

[0007] To solve the above problems, the cooling system according to the present disclosure includes a cold plate that contacts a heat-generating body and evaporates at least a part of a refrigerant flowing inside by the heat from the heat-generating body, a first line through which the refrigerant discharged from the cold plate flows, a heat exchanger that cools the refrigerant introduced from the first line, a second line that introduces the refrigerant discharged from the heat exchanger to the cold plate, a negative pressure adjustment unit that is driven to lower the pressure in the first line, a pressure sensor that measures the pressure in the first line, and a pressure monitoring device that drives the negative pressure adjustment unit when the value of the pressure measured by the pressure sensor exceeds a threshold value.

[0008] The server rack according to this disclosure comprises the above-mentioned cooling system, a server housing the heat-generating element, a rack body housing the cooling system and the server, and a lower equipment room located below the server within the rack body, which houses the heat exchanger, the negative pressure adjustment unit, and the refrigerant pump.

[0009] The server rack according to this disclosure comprises the above-mentioned cooling system, a server housing the heat-generating element, a rack body housing the cooling system and the server, a lower equipment room located below the server within the rack body and housing the refrigerant pump and the negative pressure adjustment unit, and an upper equipment room located above the server within the rack body and housing the heat exchanger.

[0010] According to this disclosure, the pressure of the refrigerant system can be properly managed.

[0011] This is a schematic front view showing the general configuration of a server rack according to the first embodiment of this disclosure. This is a schematic diagram showing the general configuration of a cooling system according to the first embodiment of this disclosure. This is a cross-sectional view. This is a functional block diagram of a pressure monitoring device in the cooling system according to the first embodiment of this disclosure. This is a flowchart showing the processing flow of a pressure monitoring device in the cooling system according to the first embodiment of this disclosure. This is a schematic front view showing the general configuration of a server rack according to the second embodiment of this disclosure. This is a schematic front view showing the general configuration of a server rack according to the third embodiment of this disclosure. This is a diagram showing the hardware configuration of a pressure monitoring device in the cooling system according to an embodiment of this disclosure.

[0012] <First Embodiment> Hereinafter, a server rack 1 equipped with a cooling system 40 according to the first embodiment of this disclosure will be described in detail with reference to Figures 1 to 4.

[0013] <Server Rack> The server rack 1 shown in Figure 1 is installed in a data center. The server rack 1 comprises a rack body 10, servers 20, a lower equipment room 31, a cooling water supply line 35, a cooling water discharge line 36, and a cooling system 40 (see Figure 2).

[0014] <Rack Body> The rack body 10 is box-shaped with its longitudinal direction extending vertically. The inside of the rack body 10 is a hollow storage space. Part of the side panels that make up the outer shape of the rack body 10 are openable and closable. This allows workers to access the storage space of the rack body 10.

[0015] <Server> The server 20 has a vertically thin, rectangular box-shaped casing 21 and a semiconductor substrate housed within the casing 21. The semiconductor substrate has elements such as a CPU and a GPU. When the data center is in operation, these elements generate heat as a heat source 22. Multiple servers 20 are stacked in the housing space of the rack body 10 with spacing between them in the vertical direction.

[0016] <Lower Equipment Room> The lower equipment room 31 is located at the very bottom of the storage space of the rack body 10, that is, below each server 20. Various components of the cooling system 40 are housed in the lower equipment room 31.

[0017] <Cooling water supply line> The cooling water supply line 35 supplies cooling water from outside the server rack 1 to inside the server rack 1.

[0018] <Cooling Water Discharge Line> Cooling water is discharged from the inside of the server rack 1 to the external structure of the server rack 1. That is, the cooling water supplied into the server rack 1 by the cooling water supply line 35 is introduced into the cooling water discharge line 36 after it has circulated inside the server rack 1. The cooling water circulating in the cooling water discharge line 36 is cooled by a cooling device (not shown) and then introduced back into the cooling water supply line 35.

[0019] <Cooling System> Next, the cooling system 40 will be described in detail with reference to Figure 2. The cooling system 40 cools the heat-generating element 22 with a refrigerant. In this embodiment, water is used as the refrigerant. The cooling system 40 includes a cold plate 41, a first line 50, a heat exchanger 60, a second line 70, a first switching valve 81, a second switching valve 82, a refrigerant pump 85, a storage tank 90, a negative pressure adjustment unit 100, a pressure sensor 160, and a pressure monitoring device 200.

[0020] <Cold Plate> Multiple cold plates 41 are provided, corresponding to the number of heating elements 22, with each heating element 22 corresponding to one of the heating elements 22. The cold plates 41 are provided inside the casing 21 of the server 20 so as to be in contact with the heating elements 22. The cold plates 41 are provided so as to cover the heating elements 22 from above. An internal space R is formed inside the cold plate body 42 through which refrigerant is introduced. The cold plate 41 has supply holes 42a and discharge holes 42b.

[0021] The supply hole 42a is provided, for example, at the horizontal end of the cold plate 41, so as to penetrate the cold plate 41 horizontally. Coolant is introduced into the internal space R of the cold plate 41 from the outside through the supply hole 42a.

[0022] The discharge hole 42b is provided, for example, in the center of the upper surface of the cold plate 41, penetrating the cold plate 41 in the vertical direction. The refrigerant is discharged to the outside from the internal space R of the cold plate 41 through the discharge hole 42b.

[0023] Within the cold plate 41, the refrigerant supplied from the supply hole 42a flows so that it spreads across the entire outer circumference of the internal space R in a plan view. Then, the refrigerant that has spread in this way flows so that it gathers in the center of the internal space R in a plan view, and is discharged from the discharge hole 42b. This refrigerant flow path can be realized by forming fin-shaped guides in the internal space R.

[0024] <First Line> The first line 50 is part of the refrigerant system through which the refrigerant flows. The refrigerant discharged from the cold plate 41 flows through the first line 50. The first line 50 has a plate discharge line 51, a discharge manifold 52, and a gas-liquid line 53.

[0025] Multiple plate discharge lines 51 are provided so that each cold plate 41 is corresponding to one of them. One upstream end of each plate discharge line 51 is connected to the discharge hole 42b of each cold plate 41.

[0026] The discharge manifold 52 is connected to the downstream end of each plate discharge line 51. The refrigerant flowing through the multiple plate discharge lines 51 converges at the discharge manifold 52. As shown in Figure 1, the discharge manifold 52 is tubular in shape, extending vertically to the side of the multiple servers 20 within the rack body 10.

[0027] The upstream end of the gas-liquid line 53 is connected to the discharge manifold 52. The upstream end of the gas-liquid line 53 is connected to the upper end of the discharge manifold 52.

[0028] <Heat Exchanger> The heat exchanger 60 exchanges heat between the refrigerant introduced via the first line 50 and cooling water supplied from the outside. The heat exchanger 60 has a supply-side header 61, a discharge-side header 62, and heat transfer tubes 63.

[0029] The supply-side header 61 is tubular in shape and extends horizontally. The downstream end of the first header, that is, the downstream end of the gas-liquid line 53, is connected to the supply-side header 61. The discharge-side header 62 is tubular in shape and extends horizontally below the supply-side header 61.

[0030] The heat transfer tubes 63 extend vertically to connect the supply-side header 61 and the discharge-side header 62 vertically. Multiple heat transfer tubes 63 are provided at intervals in the horizontal direction. The refrigerant introduced into the supply-side header 61 is introduced into the discharge-side header 62 via each heat transfer tube 63. Cooling water introduced from the outside via the cooling water supply line 35 flows around each heat transfer tube 63. After passing around the heat transfer tubes 63, the cooling water is led to the cooling water discharge line 36.

[0031] <Second Line> The second line 70 is part of the refrigerant system through which the refrigerant flows. The second line 70 introduces the refrigerant discharged from the heat exchanger 60 to the cold plate 41. The second line 70 includes a liquid line 71, a first branch line 72, a second branch line 73, a merging line 74, a supply-side manifold 75, and a plate supply line 76.

[0032] The upstream end of the liquid line 71 is connected to the discharge header 62 of the heat exchanger 60. The first branch line 72 and the second branch line 73 are connected to the downstream end of the liquid line 71, that is, they are lines that branch off into two from the downstream end of the liquid line 71. The merging line 74 is the line formed by the merging of the first branch line 72 and the second branch line 73. That is, the upstream end of the merging line 74 is connected to the downstream ends of the first branch line 72 and the second branch line 73, respectively.

[0033] As shown in Figure 1, the supply-side manifold 75 is tubular in shape and is provided to extend vertically to the side of the multiple servers 20 within the rack body 10. As shown in Figure 2, the downstream end of the merging line 74 is connected to the lower end of the supply-side manifold 75.

[0034] Multiple plate supply lines 76 are provided, each corresponding to one cold plate 41. The downstream ends of the plate discharge lines 51 are each connected to the supply holes 42a of the cold plates 41. The upstream ends of the plate discharge lines 51 are each connected to the supply-side manifolds 75.

[0035] The first line 50 and the second line 70 described above constitute a refrigerant system that circulates between the cold plate 41 and the heat exchanger 60. The supply side header 61 of the heat exchanger 60 may be included in the first line 50. The discharge side header 62 of the heat exchanger 60 may be included in the second line 70.

[0036] <First Valve> The first valve 81 is located on the first branch line 72. The first valve 81 is configured to be openable and closable.

[0037] <Second switching valve 82> The second switching valve 82 is installed on the second branch line 73. The second switching valve 82 is configured to be openable and closable.

[0038] <Refrigerant Pump> The refrigerant pump 85 is installed on the first branch line 72. When the refrigerant pump 85 is driven, it pumps the refrigerant in the first branch line 72 from the upstream side to the downstream side, that is, from the heat exchanger 60 side to the cold plate 41 side.

[0039] <Storage Tank> The storage tank 90 is installed midway through the liquid line 71 in the second line 70. The storage tank 90 serves to temporarily store the liquid phase refrigerant.

[0040] <Negative Pressure Adjustment Unit> The negative pressure adjustment unit 100 is capable of adjusting the pressure within the refrigerant system. The negative pressure adjustment unit 100 includes an ejector 110, a circulation line 120, an ejector tank 130, an ejector pump 140, a connection line 150, and an on / off valve 151.

[0041] The ejector 110 is a device for generating negative pressure and includes an inlet pipe 111, a diffuser pipe 112, and a suction section 113. The inlet pipe 111 has an inner diameter that decreases from the upstream inlet end toward the downstream end. The diffuser pipe 112 is connected to the downstream end of the inlet pipe 111. The diffuser pipe 112 has an inner diameter that gradually increases toward the downstream end. The suction section 113 is a tubular or passage-shaped part connected to the point where the inner diameter is narrowest, which is the connection point between the inlet pipe 111 and the diffuser pipe 112.

[0042] The ejector 110 receives high-speed fluid from the open end of the inlet pipe 111 and discharges it from the outlet end of the diffuser pipe 112. At this time, the ejector 110 draws fluid from the outside into the diffuser pipe 112 via the suction section 113.

[0043] The upstream end of the circulation line 120 is connected to the outlet end of the diffuser pipe 112 in the ejector 110. The downstream end of the circulation line 120 is connected to the inlet end of the inlet pipe 111 in the ejector 110.

[0044] The ejector tank 130 is provided in the middle of the circulation line 120. The ejector tank 130 temporarily stores the fluid flowing through the circulation line 120.

[0045] The ejector pump 140 is provided between the ejector tank 130 and the introduction pipe 111 of the ejector 110 in the circulation line 120. The ejector pump 140 pumps the fluid from the ejector tank 130 toward the introduction pipe 111. As a result, a high-speed fluid is introduced into the ejector 110, and the ejector 110 draws in the fluid from the outside through the suction portion 113.

[0046] One end of the connection line 150 is connected to the first line 50, and the other end is externally connected to the suction portion 113 of the ejector 110. The on-off valve 151 is provided on the connection line 150 and can open and close the connection line 150.

[0047] <Pressure Sensor> The pressure sensor 160 is a sensor capable of measuring the pressure in the first line 50. The pressure sensor 160 of the present embodiment measures the pressure of the fluid in the gas-liquid line 53.

[0048] <Equipment Housed in the Lower Equipment Room> Among the above configurations, the heat exchanger 60, the storage tank 90, the refrigerant pump 85, and the negative pressure adjustment unit 100 (ejector pump 140, ejector tank 130) are housed in the lower equipment room 31 in the rack body 10.

[0049] <Pressure Monitoring Device> Next, the pressure monitoring device 200 will be described with reference to FIG. 3. The pressure monitoring device 200 controls the pressure in the refrigerant system to be an appropriate value. The pressure monitoring device 200 includes a set value acquisition unit 201, a pressure measurement value acquisition unit 202, a determination unit 203, a negative pressure control unit 204, and an alarm unit 205.

[0050] The setting value acquisition unit 201 acquires various setting values ​​predetermined by the operator. The pressure measurement value acquisition unit 202 acquires the pressure measurement value in the refrigerant system measured by the pressure sensor 160. The determination unit 203 compares the measured pressure in the refrigerant system with the setting values. The negative pressure control unit 204 controls the negative pressure adjustment unit 100. The alarm unit 205 outputs a signal to issue an alarm.

[0051] <Operation of Server Rack and Cooling System> Next, the operation of the server rack 1 and cooling system 40 configured as described above will be explained.

[0052] <Initial Operation> Before the server 20 starts operating, or simultaneously with the start of operation of the server 20, the cooling system 40 is started. When the cooling system 40 is started, the negative pressure adjustment unit 100 is first activated to reduce the pressure of the refrigerant system, including the first and second refrigerants, to a predetermined value. That is, the on / off valve 151 of the negative pressure adjustment unit 100 shown in Figure 2 is opened, and the ejector pump 140 is driven.

[0053] This activates the ejector 110, drawing the refrigerant fluid into the ejector 110 via the connection line 150. As a result, the pressure inside the refrigerant system becomes a negative pressure, lower than the external pressure. When the pressure inside the refrigerant system reaches a predetermined pressure, the on / off valve 151 is closed, and the ejector pump 140 stops. In this way, an initial operation is performed to create a negative pressure inside the refrigerant system before the cooling system 40 is put into operation.

[0054] This initial operation is performed by the negative pressure control unit 204 of the pressure monitoring device 200, or by a separately provided operating device. Specifically, upon receiving an operation start command, the negative pressure control unit 204 or the operating device opens the on-off valve 151 from the closed state and drives the ejector pump 140. Then, while acquiring the pressure value of the refrigerant system measured by the pressure sensor 160, the negative pressure control unit 204 or the operating device controls the valve to close from the open state and stops the ejector pump 140 when the pressure value reaches a predetermined negative pressure setting value.

[0055] <Operation of the Cooling System> Next, the operation of the cooling system 40 is started. Specifically, the operating device opens the first valve 81 and closes the second valve 82, and drives the refrigerant pump 85. As a result, within the refrigerant system, the refrigerant circulates from the cold plate 41 to the heat exchanger 60, and after heat exchange in the heat exchanger 60, it returns to the cold plate 41 again.

[0056] In this embodiment, the negative pressure adjustment unit 100 keeps the pressure within the refrigerant system lower than the external pressure (atmospheric pressure). As a result, the water used as the refrigerant boils at a lower temperature than at atmospheric pressure. Consequently, the refrigerant boils vigorously within the cold plate 41 as the heating element 22 generates heat, effectively utilizing the latent heat of vaporization to remove heat.

[0057] Within the first line 50, the refrigerant circulates in a gas-liquid two-phase state. As it circulates through the heat transfer tubes 63 of the heat exchanger 60, it exchanges heat with cooling water supplied from the outside. As a result, the refrigerant changes from a gas-liquid two-phase state to a liquid single-phase state and is reintroduced to the cold plate 41 via the second line 70. In this way, the refrigerant circulates within the refrigerant system while undergoing a phase change, allowing for efficient cooling of the heat-generating element 22.

[0058] <Operation of the Pressure Monitoring Device> Next, the operation of the pressure monitoring device 200 will be explained with reference to Figure 4. When the cooling system 40 is in operation, the internal pressure of the refrigerant system may change due to refrigerant leakage from the refrigerant system or air in leakage from the outside. Such leaks or in-leaks occur from joints in the piping that make up the refrigerant system, various valves, etc. In this case, the boiling point of the refrigerant may change, which may hinder efficient cooling. Therefore, the pressure monitoring device 200 is operated as follows.

[0059] First, the pressure monitoring device 200 acquires various set values, including a preset pressure limit value Pc, a measurement interval △T, and an operating time T (step S1).

[0060] The pressure limit value Pc is a threshold value representing the upper limit of the pressure within the refrigerant system. If the pressure within the refrigerant system exceeds this pressure limit value Pc, the boiling point of the refrigerant will rise above the desired value, making effective cooling using the latent heat of vaporization impossible. The measurement interval ΔT is the time interval at which the pressure value within the refrigerant system is acquired from the pressure sensor 160. The operating time T is the time for operating the negative pressure adjustment unit 100, that is, the time for driving the ejector pump 140 while keeping the on / off valve 151 open.

[0061] Next, the pressure measurement value acquisition unit 202 acquires the pressure measurement value of the refrigerant system measured by the pressure sensor 160 (step S2).

[0062] Subsequently, the determination unit 203 determines whether the measured pressure exceeds the pressure limit value Pc (step S3). If it determines that the measured pressure does not exceed the pressure limit value Pc (step S3: No), the pressure measurement acquisition unit 202 determines whether the measurement interval △T has elapsed (step S4). If the pressure measurement acquisition unit 202 determines that the measurement interval △T has not elapsed (step S4: No), the pressure monitoring device 200 waits until the measurement interval △T has elapsed. If the pressure measurement acquisition unit 202 determines that the measurement interval △T has elapsed (step S4: Yes), it acquires the pressure measurement again (step S2).

[0063] If the pressure measurement value is determined to have exceeded the pressure limit value Pc (Step S3: Yes), the negative pressure control unit 204 controls the negative pressure adjustment unit 100 to drive it (Step S5). As a result, the negative pressure adjustment unit 100 is driven, and refrigerant is drawn in from the refrigerant system, causing the pressure in the refrigerant system to decrease. Subsequently, the negative pressure adjustment unit 100 determines whether a predetermined operating time T has elapsed (Step S6).

[0064] If it is determined that the operating time T has not elapsed (Step S6: No), the pressure monitoring device 200 waits until the operating time T has elapsed. If it is determined that the operating time T has elapsed (Step S6: Yes), the pressure measurement value acquisition unit 202 acquires the pressure measurement value again (Step S7).

[0065] Next, the determination unit 203 determines whether the acquired pressure measurement value exceeds the pressure limit value Pc (step S8). If it is determined that the pressure measurement value does not exceed the pressure limit value Pc (step S8: No), the pressure in the refrigerant system returns to an appropriate value and there is no problem in the operation of the cooling system 40, so the process returns to step S2 and pressure monitoring continues. On the other hand, if it is determined that the pressure measurement value exceeds the pressure limit value Pc (step S8: Yes), the pressure in the refrigerant system does not return to an appropriate value and proper cooling cannot be continued, so the alarm unit 205 outputs an alarm signal to the operator (step S9).

[0066] As described above, this embodiment allows for proper pressure management within the refrigerant system. That is, even if refrigerant leaks from the refrigerant system or air leaks into the refrigerant system, the pressure rise within the refrigerant system can be suppressed and negative pressure maintained. In other words, the vacuum level of the refrigerant system can be maintained, and efficient cooling can be continued with a lowered boiling point for water. Furthermore, since water as a refrigerant does not leak to the outside, it is possible to prevent water from short-circuiting the electrical equipment of the server 20. Thus, safety can be ensured.

[0067] Furthermore, since the heavy components such as the heat exchanger 60, storage tank 90, refrigerant pump 85, ejector pump 140, and ejector tank 130 are housed in the lower equipment compartment 31 within the rack body 10, the center of gravity of the server rack 1 can be lowered, maintaining stability. In addition, by consolidating various components in one location, maintainability can be improved.

[0068] <Second Embodiment> Next, a second embodiment of the present disclosure will be described with reference to Figure 5. In the second embodiment, the same reference numerals are used for components similar to those in the first embodiment, and detailed descriptions are omitted. The server rack 1 of the second embodiment includes an upper equipment compartment 32 in addition to the lower equipment compartment 31.

[0069] The lower equipment room 31 is equipped with a refrigerant pump 85 and a negative pressure adjustment unit 100. The upper equipment room 32 is equipped with a heat exchanger 60 and a storage tank 90. ​​The upper equipment room 32 is located above the multiple servers 20 within the rack body 10.

[0070] As the heat exchanger 60 is installed in the above-mentioned equipment room, the cooling water supply line 35 and the cooling water discharge line 36 are connected to the upper equipment room 32.

[0071] In this embodiment, the heat exchanger 60 and the storage tank 90 are located in the upper equipment room 32. Therefore, the head of the liquid phase refrigerant, which is converted from a gas-liquid two-phase system to a liquid phase in the heat exchanger 60 and stored in the storage tank 90, can be utilized. That is, a head difference can be provided between the supply manifold (single-phase liquid) and the discharge manifold 52 (gas-liquid two-phase gas), and this head difference can be used as a driving source for refrigerant transfer. As a result, even when the refrigerant pump 85 is stopped, the refrigerant can be circulated, improving energy efficiency.

[0072] Furthermore, if the refrigerant pump 85 malfunctions, the refrigerant circulation can continue even if the power supply to the refrigerant pump 85 is stopped. This increases the availability of the cooling system 40.

[0073] <Third Embodiment> Next, a third embodiment of the present disclosure will be described with reference to Figure 6. In the third embodiment, the same reference numerals are used for the first components, and detailed descriptions are omitted.

[0074] The heat exchanger 60 of the third embodiment is an air-cooled type that exchanges heat between the refrigerant in the refrigerant system and outside air, rather than a water-cooled type that exchanges heat between the refrigerant in the refrigerant system and outside cooling water. Therefore, the third embodiment does not have the cooling water supply line 35 and cooling water discharge line 36 of the first embodiment.

[0075] For example, if the total heat generated by the heat-generating element 22 of the server 20 is relatively small, costs can be reduced by using an air-cooled heat exchanger 60 (radiator). Furthermore, the server rack 1 of this disclosure can be introduced even in locations where cooling water piping cannot be installed.

[0076] <Other Embodiments> Although embodiments of this disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and may include design changes and the like that do not depart from the gist of this disclosure.

[0077] In the embodiment, an example in which water is used as the refrigerant flowing through the refrigerant system has been described, but the system is not limited to this. In addition to water, various organic solvents can be used as refrigerants.

[0078] In this embodiment, a configuration using an ejector 110 as the negative pressure adjustment unit 100 has been described. However, the invention is not limited to this configuration, and other configurations such as a negative pressure pump may be used as the negative pressure adjustment unit 100.

[0079] In the first and second embodiments, as in the third embodiment, the heat exchanger 60 may be air-cooled. In this case, a fan may be provided to circulate air to the heat exchanger 60.

[0080] A refrigerant supply system may be provided to allow the addition of water or other organic solvents as a refrigerant to the refrigerant system. Instead of the cooling water flowing through the cooling water supply line 35 and the cooling water discharge line 36, antifreeze or organic solvents may be used. The ejector tank 130 of the negative pressure adjustment unit 100 stores the refrigerant sucked in from the refrigerant system via the ejector 110. Therefore, a path may be provided to return the refrigerant from the ejector tank 130 to the refrigerant system.

[0081] Note that only one server 20 may be provided within the storage space of the rack body 10.

[0082] The processing steps performed by the pressure monitoring device 200 and the operating device described above are stored in program format on a computer-readable recording medium, and the above processing is carried out by the computer reading and executing this program. A specific example of the computer is shown below.

[0083] As shown in Figure 7, the computer comprises a CPU 300, main memory 301, storage 302, and interface 303. For example, the pressure monitoring device 200 and the operating device described above are implemented in the computer. The operation of each processing unit described above is stored in the storage 302 in the form of a program. The CPU 300 reads the program from the storage 302, loads it into the main memory 301, and executes the above processing according to the program. The CPU 300 also allocates storage space in the main memory 301 according to the program.

[0084] Examples of storage 302 include HDD (Hard Disk Drive), SSD (Solid State Drive), magnetic disk, magneto-optical disk, CD-ROM (Compact Disc Read Only Memory), DVD-ROM (Digital Versatile Disc Read Only Memory), and semiconductor memory. Storage 302 may be an internal medium directly connected to the computer's bus, or an external medium connected to the computer via interface 303 or a communication line. Furthermore, if this program is distributed to the computer via a communication line, the receiving computer may expand the program into main memory 301 and execute the above processing. Note that storage 302 is a tangible storage medium that is not temporary.

[0085] Furthermore, the above program may implement some of the functions described above. Moreover, the above program may be a file that can implement the above functions in combination with a program already recorded on the computer, a so-called differential file (differential program).

[0086] In addition to the above configuration, or in place of the above configuration, a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device), an ASIC (Application Specific Integrated Circuit), a GPU (Graphics Processing Unit), and similar processing units may be provided. Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array). In this case, some or all of the functions implemented by the processor may be implemented by the integrated circuit.

[0087] <Note> The cooling system 40 and server rack 1 described in each embodiment can be understood, for example, as follows.

[0088] (1) In the first embodiment, the cooling system 40 includes a cold plate 41 that is in contact with a heating element 22 and evaporates at least a portion of the refrigerant circulating inside due to the heat from the heating element 22; a first line 50 through which the refrigerant discharged from the cold plate 41 flows; a heat exchanger 60 that cools the refrigerant introduced from the first line 50; a second line 70 that introduces the refrigerant discharged from the heat exchanger 60 into the cold plate 41; a negative pressure adjustment unit 100 that is driven to reduce the pressure in the first line 50; a pressure sensor 160 that measures the pressure in the first line 50; and a pressure monitoring device 200 that drives the negative pressure adjustment unit 100 when the pressure value measured by the pressure sensor 160 exceeds a threshold.

[0089] If refrigerant leaks from the refrigerant system or outside air leaks into the refrigerant system, the pressure in the first line 50 will rise. In such cases, the pressure monitoring device 200 drives the negative pressure adjustment unit 100. This suppresses the pressure rise within the refrigerant system.

[0090] (2) In a second embodiment, the cooling system 40 is the cooling system 40 of (1) further comprising a refrigerant pump 85 capable of circulating the refrigerant in the order of the cold plate 41, the first line 50, the heat exchanger 60, and the second line 70.

[0091] This allows the refrigerant within the refrigerant system to circulate properly.

[0092] (3) The server rack 1 according to the third embodiment comprises the cooling system 40 described in (2), a plurality of servers 20 arranged vertically and each containing the heating element 22, a rack body 10 housing the cooling system 40 and the plurality of servers 20, and a lower equipment room 31 located below the servers 20 within the rack body 10 and housing the heat exchanger 60, the negative pressure adjustment unit 100 and the refrigerant pump 85.

[0093] By consolidating heavy equipment at the bottom of the rack body 10, maintenance can be made easier while improving stability.

[0094] (4) The server rack 1 according to the fourth embodiment is the server rack 1 according to (3), further comprising a storage tank 90 provided in the second line 70 and capable of storing the refrigerant, wherein the storage tank 90 is housed in the lower equipment room 31.

[0095] This allows for improvements in maintainability and stability, similar to (3).

[0096] (5) The server rack 1 according to the fifth embodiment comprises the cooling system 40 described in (2), a plurality of servers 20 arranged vertically and each containing the heating element 22, a rack body 10 housing the cooling system 40 and the plurality of servers 20, a lower equipment room 31 located below the servers 20 within the rack body 10 and housing the refrigerant pump 85 and the negative pressure adjustment unit 100, and an upper equipment room 32 located above the servers 20 within the tank body and housing the heat exchanger 60.

[0097] This promotes the natural circulation of the refrigerant.

[0098] (6) The server rack 1 according to the sixth embodiment is the server rack 1 according to (5), further comprising a storage tank 90 provided in the second line 70 and capable of storing the refrigerant, wherein the storage tank 90 is housed in the upper equipment room 32.

[0099] This, like (5), promotes the natural circulation of the refrigerant.

[0100] According to this disclosure, the pressure of the refrigerant system can be properly managed.

[0101] 1 Server rack 10 Rack body 20 Server 21 Casing 22 Heating element 31 Lower equipment room 32 Upper equipment room 35 Cooling water supply line 36 Cooling water discharge line 40 Cooling system 41 Cold plate 42 Cold plate body 42a Supply hole 42b Discharge hole 50 First line 51 Plate discharge line 52 Discharge manifold 53 Gas-liquid line 60 Heat exchanger 61 Supply side header 62 Discharge side header 63 Heat transfer tube 70 Second line 71 Liquid line 72 First branch line 73 Second branch line 74 Confluence line 75 Supply side manifold 76 Plate supply line 81 First changeover valve 82 Second changeover valve 85 Refrigerant pump 90 Storage tank 100 Negative pressure adjustment unit 110 Ejector 111 Inlet pipe 112 Diffuser tube 113 Suction section 120 Circulation line 130 Ejector tank 140 Ejector pump 150 Connection line 151 On / off valve 160 Pressure sensor 200 Pressure monitoring device 201 Set value acquisition unit 202 Pressure measurement value acquisition unit 203 Judgment unit 204 Negative pressure control unit 205 Alarm unit 300 CPU 301 Main memory 302 Storage 303 Interface R Internal space Pc Pressure limit value △T Measurement interval T Operating time

Claims

1. A cooling system comprising: a cold plate that comes into contact with a heating element and evaporates at least a portion of the refrigerant circulating inside it by the heat from the heating element; a first line through which the refrigerant discharged from the cold plate flows; a heat exchanger that cools the refrigerant introduced from the first line; a second line that introduces the refrigerant discharged from the heat exchanger into the cold plate; a negative pressure adjustment unit that, when driven, reduces the pressure in the first line; a pressure sensor that measures the pressure in the first line; and a pressure monitoring device that drives the negative pressure adjustment unit when the pressure value measured by the pressure sensor exceeds a threshold.

2. The cooling system according to claim 1, further comprising a refrigerant pump capable of circulating the refrigerant in the order of the cold plate, the first line, the heat exchanger, and the second line.

3. A server rack comprising: a cooling system according to claim 2; a server housing the heat-generating element; a rack body housing the cooling system and the server; and a lower equipment room located below the server within the rack body, housing the heat exchanger, the negative pressure adjustment unit, and the refrigerant pump.

4. The server rack according to claim 3, further comprising a storage tank provided in the second line and capable of storing the refrigerant, wherein the storage tank is housed in the lower equipment room.

5. A server rack comprising: a cooling system according to claim 2; a server housing the heating element; a rack body housing the cooling system and the server; a lower equipment room located below the server within the rack body and housing the refrigerant pump and the negative pressure adjustment unit; and an upper equipment room located above the server within the rack body and housing the heat exchanger.

6. The server rack according to claim 5, further comprising a storage tank provided in the second line and capable of storing the refrigerant, wherein the storage tank is housed in the upper equipment room.

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