Liquid cooling device and liquid cooling method

Abstract

The preset invention can effectively cool an electronic device. A liquid cooling device 1 comprises: an ice-making unit 2 which freezes a portion of water W to generate an ice slurry I; a cooling tank 4 to which the ice slurry I generated by the ice-making unit 2 is supplied; and an accommodating case 8 which accommodates an electronic device 9 and which is disposed in the ice slurry I in the cooling tank 4, wherein the electronic device 9 does not make contact with the ice slurry I, and the electronic device 9 is cooled by exchange of heat between the ice slurry I and the electronic device 9 via the accommodating case 8.

Description

Liquid Immersion Cooling Device and Liquid Immersion Cooling Method

[0001] The present invention relates to a liquid immersion cooling device and a liquid immersion cooling method.

[0002] For example, Patent Document 1 describes a liquid immersion cooling device for liquid immersion cooling of an electronic device with an insulating liquid refrigerant.

[0003] Japanese Patent Application Laid-Open No. 2024-073716

[0004] However, in the liquid immersion cooling device described in Patent Document 1, since the refrigerant for cooling the electronic device is a liquid, there is a problem that only cooling by sensible heat can be performed and the cooling efficiency of the electronic device is poor.

[0005] An object of the present invention is to provide a liquid immersion cooling device and a liquid immersion cooling method capable of effectively cooling an electronic device using latent heat by using ice slurry as a refrigerant.

[0006] Such an object is achieved by the present invention described below.

[0007] (1) An ice-making unit that freezes at least a part of a liquid refrigerant to generate a cooled liquid refrigerant containing a solid component, a cooling tank to which the cooled liquid refrigerant generated by the ice-making unit is supplied, and a housing case that houses an electronic device and is disposed in the cooled liquid refrigerant in the cooling tank, wherein the electronic device is non-contact with the cooled liquid refrigerant, and the electronic device is cooled by performing heat exchange between the cooled liquid refrigerant and the electronic device through the housing case. A liquid immersion cooling device characterized by the above

[0008] (2) The liquid immersion cooling device according to (1) above, wherein the cooled liquid refrigerant is an ice slurry in which a part of the liquid refrigerant is frozen.

[0009] [[ID=2,7]] (3) The liquid immersion cooling device according to (1) above, wherein the housing case is rigid and the electronic device can be taken in and out without being damaged.

[0010] (4) The liquid immersion cooling device according to (3) above, wherein the housing case has an opening for taking in and out the electronic device, and is disposed in the cooled liquid refrigerant so that the opening is located outside the cooled liquid refrigerant.

[0011] (5) The liquid immersion cooling device according to (1) above, wherein the electronic device comprises a substrate and a processor mounted on the substrate, and when the electronic device is housed in the housing case, the processor and the inner surface of the housing case are in contact.

[0012] (6) The immersion cooling device described in (5) above, wherein the processor is a GPU (Graphics Processing Unit).

[0013] (7) The immersion cooling device according to (5) above, wherein the housing case has a biasing portion that biases the processor toward the inner surface.

[0014] (8) The immersion cooling device described in (1) above, wherein the housing case is made of metal.

[0015] (9) The immersion cooling apparatus according to (1) above, comprising: a storage tank for storing the cooled liquid refrigerant produced in the ice-making unit; a first circulation path for circulating the liquid refrigerant between the ice-making unit and the storage tank; and a second circulation path for circulating the cooled liquid refrigerant between the storage tank and the cooling tank.

[0016] (10) The immersion cooling device according to (1) above, wherein the liquid coolant is water.

[0017] (11) A liquid immersion cooling method characterized by placing a housing case containing electronic equipment in a cooled liquid refrigerant in which at least a portion of the liquid refrigerant has been frozen, and cooling the electronic equipment by performing heat exchange between the cooled liquid refrigerant and the electronic equipment via the housing case while keeping the electronic equipment and the cooled liquid refrigerant in a non-contact state.

[0018] According to the immersion cooling apparatus and method of the present invention, electronic equipment is cooled by heat exchange with a cooled liquid refrigerant containing solid components, thus the latent heat of the solid components can be used to cool the electronic equipment. Therefore, compared to conventional configurations that cool electronic equipment using the sensible heat of the liquid refrigerant, the electronic equipment can be cooled more effectively. Consequently, it can adequately handle the cooling of electronic equipment that generates a large amount of heat. Furthermore, since the electronic equipment and the cooled liquid refrigerant are not in contact, the cooled liquid refrigerant does not adhere to the electronic equipment, making maintenance such as repair and replacement of the electronic equipment easier.

[0019] Figure 1 is an overall configuration diagram of the immersion cooling device according to the first embodiment. Figure 2 is a perspective view of the GPU server equipment. Figure 3 is a cross-sectional view of the housing case. Figure 4 is a cross-sectional view showing the GPU server equipment housed in the housing case. Figure 5 is a cross-sectional view of the housing case according to the second embodiment. Figure 6 is a cross-sectional view of the housing case according to the third embodiment. Figure 7 is a cross-sectional view illustrating a method for housing the GPU server equipment in the housing case. Figure 8 is a cross-sectional view showing a modified example of the housing case. Figure 9 is a cross-sectional view of the housing case according to the fourth embodiment. Figure 10 is an overall configuration diagram of the immersion cooling device according to the fifth embodiment. Figure 11 is an overall configuration diagram of the immersion cooling device according to the sixth embodiment. Figure 12 is a cross-sectional view showing the configuration of the ice-making section.

[0020] The liquid immersion cooling apparatus and liquid immersion cooling method of the present invention will be described in detail below based on the embodiments shown in the attached drawings. Note that the upper side of the paper is the upper side in the vertical direction, and the lower side of the paper is the lower side in the vertical direction.

[0021] <First Embodiment> The liquid immersion cooling device 1 shown in Figure 1 is a device for cooling electronic equipment 9 by placing it in an ice slurry I. The electronic equipment 9 is not particularly limited, but examples include computer equipment equipped with a processor such as a CPU (Central Processing Unit), in particular server equipment, and among these, GPU (Graphics Processing Unit) server equipment which is indispensable for processing artificial intelligence. As shown in Figure 2, the electronic equipment 9 in this embodiment is a GPU server equipment 90 having a graphics board 91 as a substrate, a GPU 92 as a processor mounted on the graphics board 91, and an output interface 93 having at least one port. The demand for GPU server equipment 90 has been increasing with the recent spread of artificial intelligence, and it generates significantly more heat than conventional server equipment. The liquid immersion cooling device 1 can effectively cool even such a heat-generating GPU server equipment 90 (electronic equipment 9).

[0022] As shown in Figure 1, the immersion cooling system 1 is located, for example, within a data center (DC). However, the location of the immersion cooling system 1 is not particularly limited. A large number of GPU server devices 90 are installed within the data center (DC).

[0023] Furthermore, the immersion cooling device 1 includes an ice-making unit 2 that freezes at least a portion of the liquid refrigerant water W to produce an ice slurry I, which is a cooled liquid refrigerant containing solid components; a storage tank 3 for storing the ice slurry I produced in the ice-making unit 2; a cooling tank 4 to which the ice slurry I stored in the storage tank 3 is supplied; a first circulation path 5 for circulating water W between the ice-making unit 2 and the storage tank 3; and a second circulation path 6 for circulating the ice slurry I between the storage tank 3 and the cooling tank 4.

[0024] The ice-making unit 2 is a device that cools water W as a liquid refrigerant, freezes a portion of this water W, and produces ice slurry I as a cooled liquid refrigerant containing ice (solid components). Ice slurry I is a sherbet-like ice in which fine ice (solid components) is mixed in water W, and is sometimes referred to as slurry ice, ice slurry, or slurry ice. By using ice slurry I as the cooled liquid refrigerant in this way, the cooled liquid refrigerant can be given fluidity, making it easier to circulate within the device. Furthermore, by using water W as the liquid refrigerant, the liquid refrigerant can be prepared inexpensively and easily. Moreover, there is virtually no environmental burden, and the liquid refrigerant can be easily disposed of.

[0025] The liquid refrigerant is not particularly limited, and may be any liquid with a lower freezing point (melting point) than water W, such as saline solution (sodium chloride aqueous solution), calcium chloride aqueous solution, monohydric alcohols such as methanol and ethanol, dihydric alcohols such as ethylene glycol and propylene glycol, or aqueous solutions of these alcohols. The liquid refrigerant and its freezing point can be appropriately set according to the heat generated by the GPU server equipment 90, the operating temperature range of the GPU server equipment 90 (the temperature range suitable for use), etc. In addition, insulating liquids such as fluorine-based inert liquids and silicone oil, which are commonly used in conventional immersion cooling systems, can also be used as the liquid refrigerant.

[0026] As shown in Figure 1, the ice-making unit 2 is equipped with a compressor 23, a condenser 24, an expansion valve 25, and a heat exchanger 21, and has a circuit for circulating refrigerant N. In such an ice-making unit 2, the refrigerant N is compressed in the compressor 23 to become a high-temperature, high-pressure gas. The refrigerant N, which has become a high-temperature, high-pressure gas in the compressor 23, flows into the condenser 24, where it condenses and liquefies to become a high-pressure liquid. The refrigerant N, which has become a high-pressure liquid in the condenser 24, is depressurized by the expansion valve 25 and flows into the heat exchanger 21. The low-pressure liquid refrigerant N that has flowed into the heat exchanger 21 evaporates and vaporizes while absorbing heat from water W, becoming a low-pressure gas. The refrigerant N, which has become a low-pressure gas in the heat exchanger 21, is returned to the compressor 23, compressed by the compressor 23, and discharged again as a high-temperature, high-pressure gas. The ice-making unit 2 generates ice slurry I by continuously cooling the water W circulating between the heat exchanger 21 and the storage tank 3 through a heat exchange cycle in which the refrigerant N is circulated.

[0027] The refrigerant N is not particularly limited, and may be a natural refrigerant such as HCFC (hydrochlorofluorocarbon), HFC (hydrofluorocarbon), HFO (hydrofluoroolefin), propane, propylene, butane, isobutane, hexafluoropropane, heptafluoropropane, ammonia, or carbon dioxide.

[0028] The storage tank 3 stores the water W, which is the raw material for the ice slurry I, and the ice slurry I produced in the ice-making unit 2. By arranging the storage tank 3, a certain amount of ice slurry I can be kept in stock at all times, and the ice slurry I can be quickly supplied to the cooling tank 4 when needed. The storage tank 3 is also connected to the heat exchanger 21 of the ice-making unit 2 by a first circulation path 5. The first circulation path 5 has a forward path 51, a return path 52, and a pump 53 located in the middle of the forward path 51.

[0029] During operation of the ice-making unit 2, the water W in the storage tank 3 is supplied to the heat exchanger 21 via the forward path 51 by the drive of the pump 53, and is cooled by heat exchange with the refrigerant N. The water W cooled in the heat exchanger 21 is returned to the storage tank 3 via the return path 52 and supplied again to the heat exchanger 21 via the forward path 51. By repeating this circulation cycle, the water W in the storage tank 3 is gradually cooled, and ice slurry I is continuously produced. Although not shown in the figures, a stirring device may be provided to agitate the ice slurry I in the storage tank 3 in order to suppress aggregation of the ice slurry I in the storage tank 3.

[0030] The ice slurry I stored in the storage tank 3 is supplied to the cooling tank 4. The storage tank 3 is connected to the cooling tank 4 by a second circulation path 6. The second circulation path 6 has a forward path 61, a return path 62, a pump 63 located in the middle of the forward path 61, and a pump 64 located in the middle of the return path 62. The ice slurry I in the storage tank 3 is supplied to the cooling tank 4 through the forward path 61 by the drive of the pump 63, and the ice slurry I or water W in the cooling tank 4 is returned to the storage tank 3 through the return path 62 by the drive of the pump 64. In this way, by circulating the ice slurry I between the storage tank 3 and the cooling tank 4, the ice slurry I can be properly stored in the cooling tank 4.

[0031] Furthermore, during operation of the immersion cooling device 1, pumps 63 and 64 may be kept running at all times to continuously circulate the ice slurry I between the storage tank 3 and the cooling tank 4. Alternatively, the running / stopping of pumps 63 and 64 may be switched at predetermined intervals (time intervals) to periodically circulate the ice slurry I between the storage tank 3 and the cooling tank 4. With such a method, fresh ice slurry I is continuously or periodically supplied to the cooling tank 4, so that the GPU server equipment 90 can be continuously and stably cooled. Alternatively, for example, a temperature sensor may be placed to detect the temperature of the ice slurry I in the cooling tank 4, and pumps 63 and 64 may be driven when the temperature of the ice slurry I begins to rise from 0°, that is, when all the solid components (ice) contained in the ice slurry I have melted into water W, to fill the cooling tank 4 with fresh ice slurry I, and then pumps 63 and 64 may be stopped until the temperature of the ice slurry I begins to rise from 0° again. This method allows the operating time of pumps 63 and 64 to be kept short, thereby enabling power-saving operation of the immersion cooling device 1.

[0032] Furthermore, multiple housing cases 8 containing GPU server equipment 90 are immersed in the ice slurry I supplied to the cooling tank 4. In other words, the housing cases 8 are placed in the ice slurry I of the cooling tank 4 with the GPU server equipment 90 inside. Therefore, the GPU server equipment 90 is not in contact with the ice slurry I. Heat exchange takes place between the ice slurry I and the GPU server equipment 90 (especially the GPU 92) via the housing cases 8, and the GPU server equipment 90 is cooled.

[0033] The ice slurry I maintains its temperature near its freezing point, i.e., around 0°C, until the solid components (ice) melt due to latent heat. Since the heat of fusion required to turn a solid (ice) into a liquid (water) is higher than the specific heat of the liquid, the ice slurry I can cool the GPU server equipment 90 for a longer period of time. Therefore, the immersion cooling device 1 can effectively cool the GPU server equipment 90. In particular, because the ice slurry I is fluid, it adheres closely to the outer surface of the housing case 8 without creating any gaps between it and the housing case 8. Therefore, the GPU server equipment 90 can be cooled more effectively.

[0034] Furthermore, since the GPU server equipment 90 and the ice slurry I are non-contact, the ice slurry I does not adhere to the GPU server equipment 90, making maintenance such as repair and replacement of the GPU server equipment 90 easier. According to the applicant's research, the failure rate of the GPU 92 for generation AI is 2% to 5% per day. In other words, in a data center DC with 100 GPU server equipment 90, it is calculated that 2 to 5 GPU server equipment 90 will fail per day, and in a data center DC with 1000 GPU server equipment 90, it is calculated that 20 to 50 GPU server equipment 90 will fail per day. When a GPU server equipment 90 fails, it is necessary to repair it or replace it with a new one as soon as possible.

[0035] If the GPU server equipment 90 is in contact with the refrigerant, as in conventional immersion cooling systems, then repairing or replacing the GPU server equipment 90 requires washing away the refrigerant, which is a considerable hassle. In particular, if the refrigerant is a conventional fluorine-based inert liquid, considerable care is required in the treatment of the waste liquid during cleaning, imposing a great responsibility and burden on the user. Furthermore, if the refrigerant is silicone oil, the GPU server equipment 90 becomes sticky (covered in oil), imposing a great burden on the user to wash away all the silicone oil adhering to the GPU server equipment 90, and it is practically impossible to wash away all the silicone oil adhering to the GPU server equipment 90. According to this embodiment, such hassle (burden, responsibility) is completely eliminated, making maintenance such as repair and replacement of the GPU server equipment 90 easier compared to conventional systems. Considering the failure rate (frequency of maintenance) of the GPU 92 mentioned above, this effect is extremely significant in implementing the invention.

[0036] When performing maintenance on a faulty GPU server device 90, the faulty GPU server device 90 may be lifted out of the ice slurry I along with the housing case 8, and then the GPU server device 90 may be pulled out of the housing case 8, or the GPU server device 90 may be pulled out of the housing case 8 while the housing case 8 remains in the ice slurry I. Although not shown in the figures, the housing case 8 may be provided with a gripping part (handle) for gripping the housing case 8. This makes handling the housing case 8 easier.

[0037] Next, the housing case 8 will be described. The housing case 8 is a rigid body with sufficient rigidity to not deform substantially under forces applied during use, and is made of a metallic material such as Fe (iron), copper (Cu), aluminum (Al), brass (copper / zinc alloy), or stainless steel (iron / chromium alloy). By constructing the housing case 8 from a metallic material in this way, the housing case 8 has high thermal conductivity. Therefore, more heat is exchanged between the GPU server equipment 90 and the ice slurry I through the housing case 8, and the GPU server equipment 90 can be cooled more effectively. However, the constituent material of the housing case 8 is not particularly limited. Also, for example, in order to prevent a short circuit of the GPU server equipment 90 through the housing case 8, an insulating treatment (for example, the formation of an insulating film such as an anodized coating) may be applied to the inner surface of the housing case 8.

[0038] Furthermore, as shown in Figure 3, the housing case 8 is box-shaped and has a housing section 81 for housing the GPU server equipment 90 and an opening 82 for inserting and removing the GPU server equipment 90 from the housing section 81. With this configuration, the electronic equipment 9 can be inserted into and removed from the housing section 81 without damaging the housing case 8. Therefore, the housing case 8 can be reused, and the running costs of the immersion cooling device 1 can be effectively reduced. In addition, the shape of the housing section 81 is determined to match the shape of the GPU server equipment 90, and as shown in Figure 4, when the GPU server equipment 90 is housed in the housing section 81, the inner surface 811 of the housing section 81 and the main surface 921 of the GPU 92 are in contact. By bringing the GPU 92 into contact with the inner surface 811 in this way, the efficiency of heat exchange between the ice slurry I and the GPU 92 is further increased, and the GPU 92 can be cooled more effectively.

[0039] As shown in Figure 4, the housing case 8 is submerged in the ice slurry I such that its opening 82 is located vertically above the liquid level F of the ice slurry I. In other words, the housing case 8 is positioned in the ice slurry I such that its opening 82 is located outside the ice slurry I. With this configuration, it is possible to prevent the ice slurry I from entering the housing section 81 in a simple manner. Furthermore, since there is no risk of the ice slurry I entering the housing section 81, there is no need to airtightly seal the opening 82. Therefore, it becomes easy to insert and remove the GPU server equipment 90 from the housing section 81. Moreover, heat from the GPU server equipment 90 is less likely to accumulate inside the housing section 81, allowing the GPU server equipment 90 to be cooled more effectively.

[0040] In particular, in this embodiment, when the housing case 8 is placed in the ice slurry I, the GPU 92 is located below the liquid level F of the ice slurry I. In other words, the GPU 92 is located within the ice slurry I. With this configuration, the GPU 92 can be cooled more effectively.

[0041] Furthermore, as shown in Figure 4, when the storage case 8 is placed in the ice slurry I, the storage case 8 is inserted into the insertion hole 801 formed in the rack 800 located in the cooling tank 4, and the outwardly protruding projection 80 catches on the rack 800, thereby supporting it. This positions the storage case 8 and supports it in a stable posture. Therefore, the intrusion of ice slurry I into the storage section 81 can be prevented more reliably.

[0042] The above describes the housing case 8, but the configuration of the housing case 8 is not particularly limited. For example, in this embodiment, one GPU server device 90 is housed in one housing case 8, but this is not limited to this, and multiple GPU server devices 90 may be housed in one housing case 8.

[0043] The above describes the liquid immersion cooling device 1. As described above, such a liquid immersion cooling device 1 includes an ice making unit 2 that freezes at least a part of water W, which is a liquid refrigerant, to generate an ice slurry I as a cooled liquid refrigerant containing ice as a solid component, a cooling tank 4 to which the ice slurry I generated by the ice making unit 2 is supplied, a housing case 8 that houses the GPU server device 90 as the electronic device 9 and is disposed in the ice slurry I in the cooling tank 4. The GPU server device 90 is non-contact with the ice slurry I and cools the GPU server device 90 by performing heat exchange between the ice slurry I and the GPU server device 90 through the housing case 8. According to such a configuration, the GPU server device 90 can be effectively cooled. Also, maintenance such as repair and replacement of the GPU server device 90 becomes easy.

[0044] Also, as described above, the cooled liquid refrigerant is the ice slurry I in which a part of water W, which is a liquid refrigerant, is frozen. Since the ice slurry I has fluidity, it adheres to the outer peripheral surface of the housing case 8 without forming a gap therebetween. Therefore, the electronic device 9 can be cooled more effectively.

[0045] Also, as described above, the housing case 8 is hard and the GPU server device 90 can be taken in and out without being damaged. According to such a configuration, the housing case 8 can be reused, and the running cost of the liquid immersion cooling device 1 can be effectively suppressed.

[0046] Also, as described above, the housing case 8 has an opening 82 for taking in and out the GPU server device 90 and is disposed in the ice slurry I so that the opening 82 is located outside the ice slurry I. According to such a configuration, the intrusion of the ice slurry I into the housing portion 81 can be prevented. Also, since there is substantially no risk of the ice slurry I intruding into the housing portion 81, it is not necessary to hermetically seal the opening 82. Therefore, the taking in and out of the GPU server device 90 into and from the housing portion 81 becomes easy. Furthermore, the heat of the GPU server device 90 is less likely to be trapped in the housing portion 81.

[0047] Also, as described above, the electronic device 9 is a GPU server device 90 having a graphic board 91 as a substrate and a GPU 92 as a processor mounted on the graphic board 91. When the GPU server device 90 is housed in the housing case 8, the GPU 92 contacts the inner surface of the housing case 8. According to such a configuration, the GPU 92 can be cooled more effectively.

[0048] Also, as described above, the processor is the GPU 92 (Graphics Processing Unit). The GPU 92 generates more heat than a processor such as a CPU, but according to the immersion cooling device 1, the GPU 92 can also be sufficiently cooled.

[0049] Also, as described above, the housing case 8 is made of a metal material. According to such a configuration, the GPU server device 90 can be effectively cooled.

[0050] Also, as described above, the immersion cooling device 1 has a storage tank 3 for storing the ice slurry I generated in the ice making unit 2, a first circulation path 5 for circulating water W between the ice making unit ② and the storage tank 3, and a second circulation path 6 for circulating the ice slurry I between the storage tank 3 and the cooling tank 4. By having the storage tank 3 for storing the ice slurry I in this way, a certain amount of ice slurry I can be stocked and quickly supplied to the cooling tank 4 when needed.

[0051] Also, as described above, the liquid refrigerant is water W. Thereby, the liquid refrigerant can be prepared at a low cost and easily. Furthermore, there is substantially no environmental load, and it can be easily discarded.

[0052] Furthermore, as mentioned above, the immersion cooling method using the immersion cooling device 1 involves placing a housing case 8 containing the electronic device 9, which is the GPU server equipment 90, in an ice slurry I, which is a cooled liquid coolant obtained by freezing at least a portion of the liquid coolant water W. The GPU server equipment 90 is cooled by exchanging heat between the ice slurry I and the GPU server equipment 90 via the housing case 8 while maintaining a non-contact state between the GPU server equipment 90 and the ice slurry I. This method allows for effective cooling of the GPU server equipment 90. In addition, maintenance such as repair and replacement of the GPU server equipment 90 is facilitated.

[0053] <Second Embodiment> The immersion cooling device 1 of this embodiment is the same as the first embodiment described above, except that the configuration of the housing case 8 is different. In the following description, this embodiment will be described mainly for the differences from the first embodiment described above, and similar matters will not be described. Also, in the figures of this embodiment, the same reference numerals are used for components that are the same as in the previously described embodiment.

[0054] As shown in Figure 5, the housing case 8 of this embodiment further has a lid 83 that liquid-tightly seals the opening 82. With the opening 82 sealed by the lid 83, the entire housing case 8 is immersed in the ice slurry I. With this configuration, the entire housing case 8 can be placed in the ice slurry I while maintaining a non-contact state between the GPU server equipment 90 and the ice slurry I. Therefore, the GPU server equipment 90 can be effectively cooled.

[0055] This second embodiment can also achieve the same effects as the first embodiment described above.

[0056] <Third Embodiment> The immersion cooling device 1 of this embodiment is the same as the first embodiment described above, except that the configuration of the housing case 8 is different. In the following description, this embodiment will be described mainly for the differences from the first embodiment described above, and similar matters will not be described. Also, in the figures of this embodiment, the same reference numerals are used for components that are the same as in the previously described embodiment.

[0057] As shown in Figure 6, the housing case 8 of this embodiment has a biasing part 84 that biases the GPU 92 toward the inner surface 811 of the housing section 81. With this configuration, the main surface 921 of the GPU 92 is pressed against the inner surface 811 of the housing section 81 by the biasing part 84, and they come into close contact. Therefore, the GPU 92 can be effectively cooled through the housing case 8.

[0058] The biasing section 84 of this embodiment includes an intermediate plate 841 disposed within the housing section 81 and a leaf spring 842 inserted into the intermediate plate 841 in a compressed state on the side opposite to the electronic device 9. The configuration utilizes the elastic force of the leaf spring 842 to bias the electronic device 9 with the intermediate plate 841. In this configuration, for example, as shown in Figure 7, the GPU server device 90 is inserted into one side of the intermediate plate 841 with the leaf spring 842 pulled out of the housing section 81, and then the leaf spring 842 is inserted into the other side of the intermediate plate 841, thereby biasing the GPU server device 90 so that the main surface 921 of the GPU 92 is in close contact with the inner surface 811. However, the configuration of the biasing section 84 is not particularly limited. For example, the configuration may involve biasing the GPU server device 90 by expanding a balloon disposed within the housing section 81.

[0059] As described above, in this embodiment, the housing case 8 has a biasing portion 84 that biases the GPU 92 toward the inner surface 811. With this configuration, the biasing portion 84 presses the main surface 921 of the GPU 92 against the inner surface 811 of the housing portion 81, causing them to be in close contact. Therefore, the GPU 92 can be effectively cooled through the housing case 8.

[0060] This third embodiment can also achieve the same effects as the first embodiment described above.

[0061] Here, as a modification of this embodiment, for example, as shown in Figure 8, the housing case 8 may have a thermal conductive sheet 89 disposed on its inner surface 811. The thermal conductive sheet 89 is made of various resin materials such as acrylic resin or silicone resin, containing a highly thermally conductive filler such as a metal filler, and has sufficient flexibility and thermal conductivity. When the GPU server equipment 90 is housed in the housing case 8, the main surface 921 of the GPU 92 is in close contact with the inner surface 811 via the thermal conductive sheet 89. With this configuration, it becomes difficult for a gap (an insulating layer composed of air) to form between the main surface 921 of the GPU 92 and the inner surface 811, and the heat of the GPU 92 can be transferred to the inner surface 811 more efficiently. The GPU 92 can be cooled even more effectively through the housing case 8. Note that the thermal conductive sheet 89 may be disposed on the main surface 921 of the GPU 92 instead of the inner surface 811 of the housing case 8.

[0062] <Fourth Embodiment> The immersion cooling device 1 of this embodiment is the same as that of the first embodiment described above, except that the configuration of the electronic equipment 9 is different. In the following description, this embodiment will be described mainly for the differences from the first embodiment described above, and similar matters will not be described. Also, in the figures of this embodiment, the same reference numerals are used for components that are the same as those in the previously described embodiment.

[0063] As shown in Figure 9, the electronic device 9 of this embodiment is a GPU server device 90 having a base 96, a graphics board 91 fixed to the base 96, a GPU 92 and output interface 93 mounted on the graphics board 91, a heatsink 94 positioned in contact with the GPU 92, and a metal fan cover 95 equipped with multiple fans 951 for cooling the heatsink 94. Currently, GPU server devices 90 are often distributed as units of a predetermined size with this configuration. Therefore, in this embodiment, the GPU server device 90 can be inserted into and removed from the housing 81 with the heatsink 94 and fan cover 95 attached. In this configuration, the GPU 92 does not come into contact with the inner surface 811 of the housing 81, but the GPU 92 can be effectively cooled by driving the fans 951 inside the housing 81 which has been sufficiently cooled by the ice slurry I.

[0064] This fourth embodiment can also achieve the same effects as the first embodiment described above.

[0065] <Fifth Embodiment> The immersion cooling device 1 of this embodiment is the same as that of the first embodiment described above, except that the storage tank 3 is omitted. In the following description, this embodiment will be described mainly for the differences from the first embodiment described above, and similar matters will not be described. Also, in the figures of this embodiment, the same reference numerals are used for components that are the same as those in the previously described embodiments.

[0066] As shown in Figure 10, in the immersion cooling device 1 of this embodiment, the storage tank 3 is omitted, and water W (ice slurry I) circulates between the ice-making unit 2 (heat exchanger 21) and the cooling tank 4.

[0067] This fifth embodiment can also achieve the same effects as the first embodiment described above.

[0068] <Sixth Embodiment> The immersion cooling device 1 of this embodiment is the same as the first embodiment described above, except that the configuration of the ice-making unit 2 is different. In the following description, this embodiment will be described mainly for the differences from the first embodiment described above, and similar matters will not be described. Also, in the figures of this embodiment, the same reference numerals are used for components that are the same as in the previously described embodiments.

[0069] In this embodiment, the ice-making unit 2 cools the refrigerant water W through heat exchange with liquefied natural gas (LNG) to produce an ice slurry I, and also evaporates and vaporizes at least a portion of the liquefied natural gas (LNG) to produce natural gas (NG). The liquefied gas is not limited to liquefied natural gas (LNG), but may also be liquefied petroleum gas (LPG), liquefied ammonia gas, etc.

[0070] In Japan, almost all of its natural gas (NG) is imported. To improve transportation efficiency, natural gas (NG) is converted into liquefied natural gas (LNG) at a temperature of approximately -162°C at liquefaction plants located in foreign natural gas fields, and then transported (by sea) to approximately 40 receiving terminals in Japan using LNG tankers.

[0071] As shown in Figure 11, the receiving base 7 is equipped with an LNG tank 71 for temporarily storing the transported liquefied natural gas (LNG), a vaporizer 72 for vaporizing the LNG stored in the LNG tank 71 to produce the required amount of natural gas (NG), and an odorizer 73 for adding an odor to the natural gas (NG) produced by the vaporizer 72. The natural gas (NG) that has been odorized by the odorizer 73 is then temporarily stored in gas holders 74 installed in various locations in urban areas, and is then typically sent from there through gas pipes to each of the client's buildings 75.

[0072] Furthermore, generally, a configuration using a seawater shower as the vaporizer 72 is used, that is, a configuration in which heat exchange is performed between seawater pumped from the sea and liquefied natural gas (LNG). In this case, the cold energy of the liquefied natural gas (LNG) is not utilized and is discarded into the sea, and there is a risk of it leading to an increase in seawater temperature, resulting in a large environmental burden. Therefore, in the immersion cooling device 1 of this embodiment, the cold energy of liquefied natural gas (LNG), which has not been utilized until now, is used to generate an ice slurry I from water W, and at least a portion of the liquefied natural gas (LNG) used is vaporized to become natural gas (NG). With this configuration, the cold energy of liquefied natural gas (LNG) can be effectively utilized, and the amount of liquefied natural gas (LNG) vaporized in the vaporizer 72 can be reduced. Therefore, the immersion cooling device 1 can reduce the environmental burden. In particular, while the freezing point of water W, which is the refrigerant, is 0°C, liquefied natural gas (LNG) is at an extremely low temperature of about -162°C. Therefore, a large amount of heat is exchanged between the two, and ice slurry I and natural gas NG are efficiently produced.

[0073] As shown in Figure 12, the ice-making unit 2 includes a heat exchanger 21 in which heat exchange takes place between liquefied natural gas (LNG) and water (W), and a liquid level measuring unit 22 for measuring the amount of liquefied natural gas (LNG) in the heat exchanger 21. The ice-making unit 2 also includes a pipe 231 connecting the LNG tank 71 and the heat exchanger 21, a pipe 232 connecting the heat exchanger 21 and the odorizer 73, and a liquid level adjustment valve 233 located in the middle of the pipe 231. In other words, the ice-making unit 2 bypasses the space between the LNG tank 71 and the vaporizer 72, and the space between the vaporizer 72 and the odorizer 73, and is arranged in parallel with the vaporizer 72.

[0074] Therefore, liquefied natural gas (LNG) in the LNG tank 71 is supplied to the heat exchanger 21 via piping 231, where it evaporates and vaporizes through heat exchange with water W in the heat exchanger 21 to become natural gas (NG), which is then supplied to the odorizer 73 via piping 232. The amount of liquefied natural gas (LNG) supplied to the heat exchanger 21 is adjusted by a liquid level adjustment valve 233 installed upstream of the heat exchanger 21. The liquid level adjustment valve 233 can be adjusted not only ON / OFF but also in multiple stages or steplessly with an opening of 0 to 100%. During operation of the ice-making unit 2, the amount of liquefied natural gas (LNG) supplied to the heat exchanger 21 is adjusted by the liquid level adjustment valve 233, and the amount of liquefied natural gas (LNG) in the heat exchanger 21, i.e., the liquid level height of the liquefied natural gas (LNG), is maintained at the target liquid level height. This allows for stable and continuous cooling of water W, and enables the efficient production of a homogeneous ice slurry I.

[0075] Furthermore, as shown in Figure 12, the heat exchanger 21 includes a main heat exchanger 211 and a sub-heat exchanger 215. The main heat exchanger 211 includes an outer tube 212 and an inner tube 213 coaxially arranged inside the outer tube 212. The outer tube 212 and inner tube 213 are installed vertically, with their axes oriented vertically. In other words, the main heat exchanger 211 is a vertical double-tube evaporator.

[0076] The main heat exchanger 211 is a liquid-filled type, and almost the entire space between the outer tube 212 and the inner tube 213 is filled with liquefied natural gas (LNG). Hereafter, this space will also be referred to as the "liquefied natural gas storage section 214". Meanwhile, water W flows through the inner tube 213. Therefore, heat exchange occurs between the water W and the liquefied natural gas (LNG) via the wall surface of the inner tube 213. In a liquid-filled main heat exchanger 211, the liquefied natural gas (LNG) is in direct contact with the outer surface of the inner tube 213, which allows for high work efficiency and improves the heat exchange efficiency between the liquefied natural gas (LNG) and the water W. As a result, ice slurry I can be efficiently generated.

[0077] Here, because the liquefied natural gas (LNG) is at an extremely low temperature of about -162°C, the amount of work done by the LNG is large, and the water W can be cooled in a short time. On the other hand, this makes the water W more likely to freeze in the main heat exchanger 211, and there is a high risk that ice will adhere to and grow on the inner wall of the inner tube 213. If ice continues to adhere to and grow on the inner wall of the inner tube 213, the volume inside the inner tube 213 will gradually decrease, and accordingly the cooling efficiency of the water W will gradually decrease, and eventually the inner tube 213 may become blocked, making it impossible to circulate the water W.

[0078] Therefore, although not shown in the diagram, a rotating blade for scraping off ice adhering to the inner wall may be installed inside the inner tube 213. By rotating the rotating blade around the central axis of the inner tube 213, the ice adhering to the inner wall can be scraped off, suppressing ice growth inside the inner tube 213 and preventing a decrease in the efficiency of ice slurry I generation. In addition, the rotation of the rotating blade creates a swirling convection in the water W flowing inside the inner tube 213. As a result, the heat exchange efficiency between liquefied natural gas LNG and water W is increased, and the water W can be cooled efficiently and evenly. The blades of the rotating blade may or may not be in contact with the inner wall of the inner tube 213. In the former case, the ice removal effect is improved, but on the other hand, high precision is required in the dimensions and mounting of the rotating blade. In the latter case, the ice removal effect is slightly inferior to the former, but there is more leeway in the precision of dimensions and mounting, and the device configuration becomes simpler.

[0079] The sub-heat exchanger 215 is installed horizontally alongside the main heat exchanger 211. The sub-heat exchanger 215 is a pipe with its lower end closed. The sub-heat exchanger 215 is also installed vertically, with its axis oriented vertically. This sub-heat exchanger 215 is connected to the liquefied natural gas storage unit 214 via a pair of pipes 216. Therefore, the liquefied natural gas LNG supplied to the liquefied natural gas storage unit 214 is also supplied to the sub-heat exchanger 215 through these pipes 216. The natural gas NG produced by evaporation and vaporization through heat exchange with water W in the main heat exchanger 211 is supplied from the upper end of the sub-heat exchanger 215 through pipe 232 to the odorizer 73.

[0080] The liquid level measuring unit 22 is installed in the sub-heat exchanger 215 and measures the liquid level of the liquefied natural gas (LNG) in the sub-heat exchanger 215. Since the liquid level of the liquefied natural gas (LNG) in the sub-heat exchanger 215 is equal to the liquid level of the liquefied natural gas (LNG) in the main heat exchanger 211, the liquid level of the liquefied natural gas (LNG) in the main heat exchanger 211 can be measured by measuring the liquid level of the liquefied natural gas (LNG) in the sub-heat exchanger 215. In this way, by installing the liquid level measuring unit 22 in a location different from the liquefied natural gas (LNG) storage unit 214, the liquid level of the liquefied natural gas (LNG) in the liquefied natural gas (LNG) storage unit 214 can be detected without hindering the heat exchange between the liquefied natural gas (LNG) and water W.

[0081] During operation of the ice-making unit 2, the water W in the storage tank 3 is supplied to the heat exchanger 21 via the forward path 51 by the drive of the pump 53, and is cooled by heat exchange with liquefied natural gas (LNG). The water W cooled in the heat exchanger 21 is returned to the storage tank 3 via the return path 52 and supplied again to the heat exchanger 21 via the forward path 51. By repeating this circulation cycle, the water W is gradually cooled and ice slurry I is continuously produced. Although not shown in the figures, a stirring device may be provided to agitate the ice slurry I in the storage tank 3 in order to suppress aggregation of the ice slurry I in the storage tank 3.

[0082] This sixth embodiment can also achieve the same effects as the first embodiment described above.

[0083] Although the immersion cooling device and method of the present invention have been described above based on the illustrated embodiments, the present invention is not limited thereto. The configuration of each part can be replaced with any configuration having a similar function. Furthermore, any other configuration may be added to the present invention.

[0084] For example, in the embodiment described above, an ice slurry I in which a portion has turned into ice is used as the cooled liquid refrigerant, but the invention is not limited to this, and ice in which substantially all of the water W has been frozen may be used. Furthermore, the ice is not particularly limited, and for example, snow-like, flake-like ice, block-like crushed ice, etc., can be used.

[0085] Furthermore, although the housing case 8 is rigid in the embodiment described above, it is not limited to this, and the housing case 8 may be soft, that is, flexible. In this case, the housing case 8 can be made of various resin materials such as silicone resin.

[0086] The immersion cooling apparatus of the present invention comprises an ice-making unit that freezes at least a portion of the liquid refrigerant to produce cooled liquid refrigerant containing solid components, a cooling tank to which the cooled liquid refrigerant produced by the ice-making unit is supplied, and a housing case that houses electronic equipment and is placed in the cooled liquid refrigerant in the cooling tank. The electronic equipment is not in contact with the cooled liquid refrigerant, and the electronic equipment is cooled by heat exchange between the cooled liquid refrigerant and the electronic equipment via the housing case. With this configuration, electronic equipment can be cooled effectively. Furthermore, maintenance such as repair and replacement of electronic equipment is facilitated. Therefore, the immersion cooling apparatus of the present invention has industrial applicability.

[0087] The present invention provides an immersion cooling method in which a housing case containing electronic equipment is placed in a cooled liquid refrigerant, which is formed by freezing at least a portion of the liquid refrigerant. The electronic equipment is cooled by heat exchange between the cooled liquid refrigerant and the electronic equipment via the housing case, while maintaining a non-contact state between the electronic equipment and the cooled liquid refrigerant. With this configuration, electronic equipment can be cooled effectively. Furthermore, maintenance such as repair and replacement of the electronic equipment is facilitated. Therefore, the immersion cooling method of the present invention has industrial applicability.

[0088] 1...Immersion cooling system, 2...Ice making section, 21...Heat exchanger, 211...Main heat exchanger, 212...Outer pipe, 213...Inner pipe, 214...Liquefied natural gas storage section, 215...Sub heat exchanger, 216...Piping, 22...Liquid level measuring section, 23...Compressor, 231...Piping, 232...Piping, 233...Liquid level adjustment valve, 24...Condenser, 25...Expansion valve, 3...Storage tank, 4...Cooling tank, 5...First circulation path, 51...Forward path, 52...Return path, 53...Pump, 6...Second circulation path, 61...Forward path, 62...Return path, 63...Pump, 64...Pump, 7...Receiving station, 71...LNG tank, 72...Vaporizer, 73 ...Odor purifier, 74...Gas holder, 75...Building, 8...Housing case, 80...Protrusion, 800...Rack, 801...Through hole, 81...Housing section, 811...Inner surface, 82...Opening, 83...Lid, 84...Biasing section, 841...Middle plate, 842...Leaf spring, 9...Electronic equipment, 90...GPU server equipment, 91...Graphics board, 92...GPU, 921...Main surface, 93...Output interface, 94...Heat sink, 95...Fan cover, 951...Fan, 96...Base, DC...Data center, F...Liquid level, I...Ice slurry, LNG...Liquefied natural gas, N...Refrigerant, W...Water

Claims

1. A liquid immersion cooling device comprising: an ice-making unit that freezes at least a portion of a liquid refrigerant to produce a cooled liquid refrigerant containing solid components; a cooling tank to which the cooled liquid refrigerant produced by the ice-making unit is supplied; and a housing case that houses electronic equipment and is placed in the cooled liquid refrigerant in the cooling tank, wherein the electronic equipment is not in contact with the cooled liquid refrigerant, and the electronic equipment is cooled by heat exchange between the cooled liquid refrigerant and the electronic equipment via the housing case.

2. The immersion cooling apparatus according to claim 1, wherein the cooled liquid refrigerant is an ice slurry in which a portion of the liquid refrigerant has been frozen.

3. The immersion cooling device according to claim 1, wherein the housing case is rigid and allows the electronic equipment to be inserted and removed without damage.

4. The immersion cooling device according to claim 3, wherein the housing case has an opening for inserting and removing the electronic equipment, and is disposed in the cooled liquid refrigerant such that the opening is located outside the cooled liquid refrigerant.

5. The liquid immersion cooling device according to claim 1, wherein the electronic device comprises a substrate and a processor mounted on the substrate, and when the electronic device is housed in the housing case, the processor and the inner surface of the housing case are in contact.

6. The immersion cooling device according to claim 5, wherein the processor is a GPU (Graphics Processing Unit).

7. The immersion cooling device according to claim 5, wherein the housing case has a biasing portion that biases the processor toward the inner surface.

8. The immersion cooling device according to claim 1, wherein the housing case is made of a metal material.

9. The immersion cooling apparatus according to claim 1, comprising: a storage tank for storing the cooled liquid refrigerant produced in the ice-making unit; a first circulation path for circulating the liquid refrigerant between the ice-making unit and the storage tank; and a second circulation path for circulating the cooled liquid refrigerant between the storage tank and the cooling tank.

10. The immersion cooling device according to claim 1, wherein the liquid refrigerant is water.

11. A liquid immersion cooling method characterized by placing a housing case containing electronic equipment in a cooled liquid refrigerant in which at least a portion of the liquid refrigerant has been frozen, and cooling the electronic equipment by performing heat exchange between the cooled liquid refrigerant and the electronic equipment via the housing case while keeping the electronic equipment and the cooled liquid refrigerant in a non-contact state.

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