Cooling system

Abstract

To provide a cooling system capable of improving cooling efficiency.SOLUTION: A cooling system includes: a heat exchange part that includes a heat transfer pipe group comprising a plurality of heat transfer pipes each extending vertically and having an inner side as an air passage and having a refrigerant flow passage formed between the heat transfer pipes, a casing covering the heat transfer pipe group, a refrigerant supply part for supplying a refrigerant, and a refrigerant discharge part for discharging the refrigerant; and an air blowing part that blows air to the heat transfer pipe group from the lower side. The casing includes: a cylindrical part covering the heat transfer pipe group from the outer peripheral side; an upper header that surrounds the cylindrical part from the outer peripheral side on the upper side of the cylindrical part and that has one of the refrigerant supply part and the refrigerant discharge part; and a lower header that surrounds the cylindrical part from the outer peripheral side on the lower side of the cylindrical part and that has the other of the refrigerant supply part and the refrigerant discharge part. The cylindrical part includes: an upper communication hole for communicating a space in the upper header with a space in the cylindrical part; and a lower communication hole for communicating a space in the lower header with the space in the cylindrical part.SELECTED DRAWING: Figure 19

Description

[Technical Field]

[0001] The present disclosure relates to cooling systems. [Background technology]

[0002] Patent Document 1 discloses a cooling system that cools an electronic device with a working fluid and cools the evaporated working fluid with a heat pipe. Patent Document 2 discloses a cooling system in which an electronic device is immersed in a coolant, and the evaporated coolant is cooled via fins. Patent Document 3 discloses a cooling system in which an electronic device is cooled by immersing it in a refrigerant, and the refrigerant is cooled by a heat pipe.

[0003] Patent Document 4 discloses a cooling system in which an electronic device is cooled with a refrigerant, and the evaporated refrigerant is transported through a heat pipe for cooling and condensation. Patent Document 5 discloses a cooling system in which an electronic device is immersed in a refrigerant, and the evaporated refrigerant is condensed in a cooling pipe. Patent Document 6 discloses a cooling system in which a heat pipe is connected to a computer and the evaporated working fluid in the heat pipe is cooled by a heat exchanger at the bottom of a chimney.

[0004] Patent Document 7 discloses a cooling system in which a primary refrigerant for cooling a server is cooled by a secondary refrigerant, and the secondary refrigerant is cooled by heat exchange with outside air. Patent Document 8 discloses a heat exchanger in which the flow directions of air and refrigerant are the same. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 6-21279 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-54248 [Patent Document 3] Japanese Patent Application Publication No. 2018-88433 [Patent Document 4] International Publication No. 2015 / 128951 [Patent Document 5] Special Publication No. 2019-516195 [Patent Document 6] Patent No. 5797758 [Patent Document 7] Japanese Patent Publication No. 2020-136335 [Patent Document 8] Patent No. 4347990 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, in recent years, the heat generation density of electronic devices has been increasing, and there is a demand for further improvement in cooling efficiency. Furthermore, when transporting the evaporated refrigerant to a location suitable for cooling and condensing, it is preferable from the viewpoint of energy conservation that the transport can be performed without using external energy such as a pump. Furthermore, when the heat generation density of the electronic device is high, the above-mentioned film is formed by the refrigerant at the contact point between the refrigerant and the electronic device, which causes a problem of reduced heat removal capability. Furthermore, it is preferable that the equipment for cooling the evaporated refrigerant be easy to maintain.

[0007] The present disclosure has been made to solve the above-mentioned problems, and a first object of the present disclosure is to provide a cooling system that can improve cooling efficiency. A second object of the present disclosure is to provide a cooling system that can achieve energy savings when transferring a refrigerant. A third object of the present disclosure is to provide a cooling system that can maintain a high level of heat removal capacity from a heat-generating body by a refrigerant. A fourth object of the present disclosure is to provide a cooling system that is easy to maintain. [Means for solving the problem]

[0008] In order to solve the above problems, a cooling system according to a first aspect of the present disclosure includes a heat transfer tube group having a plurality of heat transfer tubes extending linearly in the vertical direction and having air passages on the inside, the heat transfer tubes being bundled together at intervals to form refrigerant passages between the heat transfer tubes, a casing covering the heat transfer tube group such that both ends of each heat transfer tube are open to the outside, a heat exchange unit having a refrigerant supply unit that supplies refrigerant into the casing and a refrigerant discharge unit that discharges refrigerant from inside the casing, and an air blower provided below the heat exchange unit that blows air from below to the heat transfer tube group, The casing has a cylindrical portion that surrounds the heat transfer tube group from the outer periphery, an upper header that surrounds the cylindrical portion from the outer periphery at an upper part of the cylindrical portion and is provided with one of the refrigerant supply portion and the refrigerant discharge portion, and a lower header that surrounds the cylindrical portion from the outer periphery at a lower part of the cylindrical portion and is provided with the other of the refrigerant supply portion and the refrigerant discharge portion, and the cylindrical portion has upper communication holes that communicate between the space in the upper header and the space in the cylindrical portion and are formed in a plurality of spaces spaced apart in the circumferential direction, and lower communication holes that communicate between the space in the lower header and the space in the cylindrical portion and are formed in a plurality of spaces spaced apart in the circumferential direction.

[0009] A cooling system according to a second aspect of the present disclosure includes a heat transfer tube group having a plurality of heat transfer tubes extending linearly in the vertical direction and having an air passage on the inside, the heat transfer tubes being bundled together at intervals to form refrigerant passages between the heat transfer tubes, a casing covering the heat transfer tube group such that both ends of each heat transfer tube are open to the outside, a heat exchange unit having a refrigerant supply unit that supplies refrigerant into the casing and a refrigerant discharge unit that discharges refrigerant from inside the casing, and a blower that is provided below the heat exchange unit and blows air from below to the heat transfer tube group, The compressor has an impeller that can rotate around an axis that extends downward, and a drive unit that is arranged below the impeller and drives the impeller to rotate, and is equipped with an upper housing that is cylindrical and extends in the vertical direction so as to surround the impeller from the outer periphery, the inside of which is an air flow path and the upper end of which is connected to the lower end of the heat exchange unit, and a lower housing that has an inner wall that covers the drive unit from the outer periphery and whose diameter decreases as it extends upward, and an outer wall that covers the inner wall from the outer periphery and whose diameter decreases as it extends upward and which, together with the inner wall, forms an introduction flow path for air to the impeller. [Effects of the Invention]

[0010] According to the present disclosure, a first object is to provide a cooling system that can improve cooling efficiency. Furthermore, according to the present disclosure, energy savings can be achieved when transporting a refrigerant. Furthermore, according to the present disclosure, the ability of the refrigerant to remove heat from the heat-generating body can be maintained at a high level. Furthermore, according to the present disclosure, a cooling system that is easy to maintain can be provided. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a longitudinal cross-sectional view showing the overall configuration of a first cooling system according to the first embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic horizontal cross-sectional view of a heat pipe group in the first cooling system according to the first embodiment of the present disclosure. [Figure 3]FIG. 2 is a horizontal cross-sectional view of a heat pipe in the first cooling system according to the first embodiment of the present disclosure, illustrating the flow of air caused by a fan and the flow of refrigerant in the heat pipe. [Figure 4] FIG. 2 is a longitudinal cross-sectional view of a heat pipe in the first cooling system according to the first embodiment of the present disclosure, illustrating the flow of a refrigerant. [Figure 5] FIG. 10 is a schematic horizontal cross-sectional view of a heat pipe group according to a first modified example of the first embodiment of the present disclosure. [Figure 6] FIG. 10 is a horizontal cross-sectional view of a heat pipe according to a second modified example of the first embodiment of the present disclosure. [Figure 7] FIG. 10 is a longitudinal cross-sectional view of a heat pipe according to a third modified example of the first embodiment of the present disclosure. [Figure 8] FIG. 10 is a longitudinal cross-sectional view showing the overall configuration of a fourth modified example of the first embodiment of the present disclosure. [Figure 9] FIG. 10 is a schematic overall configuration diagram of a second cooling system according to a second embodiment of the present disclosure. [Figure 10] FIG. 10 is a schematic overall configuration diagram of a first modified example of the second embodiment of the present disclosure. [Figure 11] FIG. 10 is a diagram illustrating a configuration of a heat exchanger according to a first modified example of the second embodiment of the present disclosure. [Figure 12] FIG. 10 is a schematic overall configuration diagram of a second modified example of the second embodiment of the present disclosure. [Figure 13] FIG. 10 is a schematic overall configuration diagram of a third cooling system according to a third embodiment of the present disclosure. [Figure 14] FIG. 11 is a schematic overall configuration diagram of a first modified example of the third embodiment of the present disclosure. [Figure 15] FIG. 10 is a schematic overall configuration diagram of a second modified example of the third embodiment of the present disclosure. [Figure 16] FIG. 10 is a schematic overall configuration diagram of a third modified example of the third embodiment of the present disclosure. [Figure 17] FIG. 10 is a schematic overall configuration diagram of a fourth modified example of the third embodiment of the present disclosure. [Figure 18] FIG. 10 is a schematic overall configuration diagram of a fifth modified example of the third embodiment of the present disclosure. [Figure 19]FIG. 10 is a schematic overall configuration diagram of a third cooling system according to a fourth embodiment of the present disclosure. [Figure 20] 20 is a cross-sectional view taken along the line AA in FIG. 19. [Figure 21] 19 is a cross-sectional view of FIG. [Figure 22] FIG. 21 is an enlarged view of a main part of FIGS. 19 and 20, showing a horizontal cross section of a heat transfer tube group. [Figure 23] FIG. 10 is a horizontal cross-sectional view of a heat transfer tube group according to a first modified example of the fourth embodiment of the present disclosure. [Figure 24] FIG. 10 is a horizontal cross-sectional view of a heat exchange section of a second modified example of the fourth embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] First Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. <First cooling system> As shown in FIGS. 1 and 2, the first cooling system 1 includes a server 2, a refrigerant tank 3, a heat pipe 10, plate-like fins 20, a cover 25, and a blower fan 27.

[0013] <server> The server 2 is a heat-generating body to be cooled in the first cooling system 1. The server 2 has a housing in which devices constituting a computer, such as a CPU, are housed. The server 2 in this embodiment has a substantially rectangular parallelepiped shape.

[0014] <Refrigerant tank 3> The refrigerant tank 3 is provided so as to be in contact with the server 2. In this embodiment, the refrigerant tank 3 is installed on the upper surface of the server 2. The refrigerant tank 3 is composed of a tank bottom wall 3a, a tank side wall 3b, and a tank top wall 3c. The tank bottom wall 3a is a plate-like structure that extends horizontally and is provided so as to contact the upper surface of the server 2. The tank bottom wall 3a extends further horizontally from the upper surface of the server 2. The tank bottom wall 3a is made of a metal with high thermal conductivity, such as a material containing aluminum or copper.

[0015] The tank side wall 3b is a wall that rises upward from the outer peripheral edge of the tank bottom wall 3a. The upper part of the tank side wall 3b is inclined so as to recede from the outer peripheral edge of the tank bottom wall 3a as it extends upward. The tank top wall 3c is a plate-like member extending horizontally, and is provided so as to close the upper end opening of the tank side wall 3b. The refrigerant vessel 3 has a hollow box shape with the interior space enclosed by a vessel bottom wall 3a, a vessel side wall 3b, and a vessel top wall 3c. A refrigerant C is accommodated inside the refrigerant vessel 3. As the refrigerant C, a substance that is volatile and liquid at room temperature (for example, water or an air-conditioning refrigerant) can be used.

[0016] <Heat pipe> A plurality of heat pipes 10 are arranged so as to extend from the refrigerant tank 3 outward from the refrigerant tank 3. The heat pipes 10 of this embodiment are provided so as to extend upward from the upper surface of the refrigerant tank 3, i.e., from the upper surface of the tank top wall 3c of the refrigerant tank 3.

[0017] The heat pipe 10 is made of a metal with high thermal conductivity, such as a material containing copper or aluminum. The heat pipe 10 is a hollow cylindrical member that extends vertically. The upper end of the heat pipe 10 is closed. The inner surface of the upper end of the heat pipe 10 is concavely curved upward.

[0018] The lower end of the heat pipe 10 is connected downward and fixed to the upper surface of the tank top wall 3c. The heat pipe 10 is connected to the inside of the refrigerant tank 3 via its lower end. That is, the internal space of the refrigerant tank 3 and the internal space of the heat pipe 10 that is connected to it are both closed spaces isolated from the outside. This allows the inside of the heat pipe 10 to serve as a passage for the refrigerant C that has entered the heat pipe 10. The internal spaces of the refrigerant vessel 3 and the heat pipe 10 are preferably evacuated while containing the refrigerant C. The refrigerant C is contained in the internal spaces in the gas and liquid phases.

[0019] Such heat pipes 10 are arranged in the horizontal direction as shown in Figures 1 and 2. That is, the heat pipes 10 are arranged in a first horizontal direction (the left-right direction in Figures 1 and 2) and a second horizontal direction (the depth direction in Figure 1, the up-down direction in Figure 2) perpendicular to the first horizontal direction. Each heat pipe 10 has the same structure.

[0020] 2 and 3, the cross-sectional shape of the heat pipe 10 perpendicular to the extension direction, i.e., the horizontal cross-sectional shape of the heat pipe 10, is flat with the longitudinal direction being the first horizontal direction. The horizontal cross-sectional shape of the heat pipe 10 is a streamlined shape with a leading edge 11 on one side in the first horizontal direction (the left side in FIGS. 1 to 3) and a trailing edge 12 on the other side in the first horizontal direction (the right side in FIGS. 1 to 3). The horizontal cross-sectional shape of the heat pipe 10 may be an ellipse with the major axis in the first horizontal direction and the minor axis in the second horizontal direction. The horizontal cross-sectional shape of the heat pipe 10 may be an airfoil shape having the leading edge 11 and the trailing edge 12.

[0021] <Plate fin 20> As shown in Fig. 1, the plate fins 20 are plate-shaped and extend horizontally, with multiple fins provided at intervals in the vertical direction. Multiple heat pipes 10 are in contact with each plate fin 20 so as to penetrate vertically. That is, each plate fin 20 is fixed to the outer circumferential surface of each heat pipe 10 via the inner periphery of the hole through which the multiple heat pipes 10 penetrate. The plate fins 20 are made of a material with high thermal conductivity, such as a metal containing copper or aluminum.

[0022] <Cover> 1, the cover 25 is provided to surround the heat pipes 10 and the plate fins 20 from above and from the second horizontal direction. This defines an air flow path extending in the first horizontal direction within the cover 25. That is, the heat pipes 10 and the plate fins 20 are housed within the flow path defined by the cover 25.

[0023] <Blower fan> The blower fan 27 blows air in the horizontal direction, which is the arrangement direction of the multiple heat pipes 10. The blower fan 27 is provided on one side in the horizontal first direction of the flow path formed by the cover 25. The blower fan 27 blows air from one side in the horizontal first direction to the other side along the air flow path inside the cover 25. The one side in the horizontal first direction is the upstream side of the air flow, and the other side in the horizontal first direction is the downstream side of the air flow.

[0024] <Effects of the First Embodiment> As shown in FIG. 1, when a server 2 generates heat during operation, the heat from the server 2 is transferred to the liquid-phase refrigerant C (condensate) in the refrigerant tank 3 through the tank bottom wall 3a of the refrigerant tank 3. This heat causes the condensate to evaporate and boil into vapor, removing the heat from the server 2 and cooling the server 2. The vaporized refrigerant C moves above the liquid surface of the refrigerant C and is introduced into the heat pipe 10 from its lower end. The vaporized refrigerant C introduced into the heat pipe 10 moves upward within the heat pipe 10. When the refrigerant C reaches the upper end of the heat pipe 10, it turns downward according to the concave curve of the upper end. As a result, the refrigerant C moves downward along the inner surface of the heat pipe 10.

[0025] As the refrigerant C moves along the inner surface of the heat pipe 10, it exchanges heat with the air blown by the blower fan 27 via the plate-like fins 20 and the inner surface of the heat pipe 10. As a result, heat is removed from the refrigerant C, causing the refrigerant C to change phase from gas to liquid and become condensed water, which drips to the bottom of the refrigerant tank 3. In this way, in the first cooling system 1, the refrigerant C circulates inside the refrigerant tank 3 and the heat pipe 10, thereby releasing the heat of the server 2 to the outside. This allows continuous cooling of the server 2 without requiring power such as a pump to circulate the refrigerant C.

[0026] 3, the horizontal cross section of each heat pipe 10 is flattened with a leading edge 11 on the upstream side in the direction of air blown by the blower fan 27 and a trailing edge 12 on the downstream side. This reduces the air pressure loss on the outer surface of each heat pipe 10, and allows air to be properly blown to the heat pipe 10 located downstream in the air blowing direction.

[0027] Furthermore, on the leading edge 11 side of the heat pipe 10, heat exchange between the blown air and the refrigerant C inside the heat pipe 10 is active. In contrast, on the trailing edge 12 side of the heat pipe 10, the air separates from the outer surface of the heat pipe 10, resulting in a decrease in the heat transfer coefficient between the heat pipe 10 and the air. Therefore, on the trailing edge 12 side of the heat pipe 10, heat exchange between the blown air and the refrigerant C inside the heat pipe 10 is less frequent than on the leading edge 11 side. In other words, cooling by air is promoted on the leading edge 11 side of the heat pipe 10, while cooling by air is hindered on the trailing edge 12 side.

[0028] 3 and 4, condensation of the refrigerant C is inhibited in the region on the trailing edge 12 side of the heat pipe 10, forming a gas-phase flow F1, which is a flow of the refrigerant C in a gas phase. On the other hand, condensation of the refrigerant C is promoted in the region on the leading edge 11 side of the heat pipe 10, forming a liquid-phase flow F2, which is a flow of condensed water.

[0029] In this way, the upward gas-phase flow F1 is dominant in the region inside the heat pipe 10 on the trailing edge 12 side, while the downward liquid-phase flow F2 is dominant in the region inside the heat pipe 10 on the leading edge 11 side. As a result, the paths of the gas-phase flow F1 and the liquid-phase flow F2 can be separated inside the heat pipe 10, and interference between the gas-phase flow F1 and the liquid-phase flow F2 can be suppressed. This allows for efficient heat transfer through the heat pipe 10, improving the cooling efficiency of the server 2.

[0030] In this embodiment, the inside of the heat pipe 10 is simply hollow and is not provided with a wick that promotes the movement of condensed water by capillary action, but a wick may be provided inside the heat pipe 10. In this case, the wick may be provided in the region inside the heat pipe 10 on the front edge 11 side.

[0031] <First Modification of First Embodiment> 5, the heat pipes 10 may be arranged more densely on the upstream side and more sparsely on the downstream side. That is, the interval between adjacent heat pipes 10 may be relatively small in the upstream portion of the group of heat pipes 10, while the interval between adjacent heat pipes 10 may be relatively large in the downstream portion of the group of heat pipes 10.

[0032] Generally, the air density decreases and the volumetric flow rate increases downstream where the air temperature rises. Therefore, by arranging the heat pipes 10 more sparsely as they approach the downstream side, it is possible to optimize the pressure loss. It is also possible to configure the heat pipes 10 on the downstream side to be thinner than the heat pipes 10 on the upstream side, so that the heat pipes 10 are spaced apart more downstream. This also provides the same effect as above.

[0033] <Second Modification of First Embodiment> As shown in Figure 6, the portion of the outer surface of the heat pipe 10 on the leading edge 11 side, including the leading edge 11, may be in contact with the plate-shaped fins 20, while the portion of the outer surface of the heat pipe 10 on the trailing edge 12 side, including the trailing edge 12, may not be in contact with the plate-shaped fins 20.

[0034] That is, the upstream portion of the inner peripheral edge of the through hole 21 in the plate-like fin 20, through which the heat pipe 10 passes, is an abutting edge 21a shaped to fit the outer surface of the heat pipe 10. On the other hand, the downstream portion of the inner peripheral edge of the through hole 21 is shaped, for example, as a rectangular cutout. As a result, the downstream portion of the inner peripheral edge of the through hole 21 is an abutted edge 21b that does not abut against the outer surface of the heat pipe 10.

[0035] This configuration can further promote cooling and condensation of the refrigerant C in the portion of the heat pipe 10 on the leading edge 11 side that contacts the plate fins 20. On the other hand, cooling is hindered in the portion of the heat pipe 10 on the trailing edge 12 side that does not contact the plate fins 20, thereby hindering condensation of the refrigerant C. As a result, similar to the first embodiment, the flow regions of the gas phase flow F1 and the liquid phase flow F2 of the refrigerant C can be appropriately separated, and the heat transfer efficiency can be further improved.

[0036] <Third Modification of First Embodiment> 7, a partition 15 may be provided to separate the passages in each heat pipe 10 into upstream leading-edge passages 16 and downstream trailing-edge passages 17. The upper end of the partition 15 does not contact the upper end of the inner surface of the heat pipe 10. Therefore, the leading-edge passages 16 and the trailing-edge passages 17 communicate with each other at the upper ends of the passages of the heat pipe 10. This also makes it possible to appropriately separate the flow areas of the gas phase flow F1 and the liquid phase flow F2 of the refrigerant C, thereby further improving the efficiency of heat transfer.

[0037] <Fourth Modification of First Embodiment> 8, the lower end of the heat pipe 10 (the end on the inner side of the refrigerant tank 3) may be closed in the same manner as the upper end of the heat pipe 10 (the end on the outer side of the refrigerant tank 3), and may extend downward into the refrigerant tank 3 and be immersed in the liquid-phase refrigerant C. In this case, the refrigerant C contained in the refrigerant tank 3 (first refrigerant C1) and the refrigerant C contained in the heat pipe 10 (second refrigerant C2) may be different.

[0038] According to this configuration, the first refrigerant C1, which has turned to vapor due to the heat of the server 2, condenses by exchanging heat with the second refrigerant C2 as a condensed liquid inside the heat pipe 10. After absorbing heat from the first refrigerant C1, the second refrigerant C2 inside the heat pipe 10 flows upward as vapor, condenses by exchanging heat with the outside air, and flows downward. As in the first embodiment, this also makes it possible to continuously cool the server 2 by circulating the first refrigerant C1 and the second refrigerant C2 without requiring power from a pump or the like. Furthermore, since the refrigerant C can be selected to suit the temperature of the server 2 and the outside air, the heat exchange efficiency can be further improved.

[0039] In the first embodiment, the heat pipes 10 only need to extend outward from the refrigerant tank 3, i.e., in a direction away from the refrigerant tank 3. For example, the heat pipes 10 may extend horizontally or obliquely upward. In this case, the heat pipes 10 may be arranged vertically. Air may be blown vertically by the blower fan 27.

[0040] Second Embodiment Next, a second embodiment of the present invention will be described with reference to Fig. 9. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. <Second cooling system> Similar to the first embodiment, the second cooling system 30 according to the second embodiment is a system that cools the servers 2. The second cooling system 30 includes a container 31, the servers 2, a refrigerant tank 3, a heat exchanger 40, a gas phase pipe 47, a liquid phase pipe 48, and a blower fan 27.

[0041] <container> The container 31 has a rectangular box shape that defines a living room or equipment room inside. The container 31 has a bottom wall 32 that extends horizontally and is placed on the floor or ground, side walls 33 that rise upward from the bottom wall 32, and a top wall 34 that contacts the upper ends of the side walls 33 and closes off the interior of the container 31 from above. In other words, the container 31 has outer walls that are composed of the bottom wall 32, the side walls 33, and the top wall 34. The inside of the container 31 is referred to as an interior room R, and the outside of the container 31 is referred to as an exterior room E.

[0042] <Server and refrigerant tank> A server 2 and a refrigerant tank 3 are installed inside the container 31. In this embodiment, the refrigerant tank 3 is installed so as to be in contact with the side of the server 2. A refrigerant C is accommodated in the closed space inside the refrigerant tank 3. The refrigerant C removes heat from the server 2 through the contact portion between the server 2 and the refrigerant tank 3.

[0043] <Heat exchanger> The heat exchanger 40 is installed above the refrigerant tank 3 in the outdoor space E. The heat exchanger 40 exchanges heat between the refrigerant C and the outside air. The heat exchanger 40 has an external heat transfer pipe 41, an upstream header 42, and a downstream header 43. The external heat transfer tubes 41 are, for example, tubular and extend in the vertical direction, and a plurality of them are arranged side by side at intervals in the horizontal direction. The interior of each external heat transfer tube 41 serves as a passage for the refrigerant C that extends in the vertical direction. The upper side of the passage for the refrigerant C is the upstream side, and the lower side is the downstream side.

[0044] The upstream header 42 and the downstream header 43 extend in the horizontal direction and have a hollow interior. The upstream header 42 is disposed above the plurality of external heat transfer tubes 41. The interior of the upstream header 42 is in communication with the upper ends of the respective external heat transfer tubes 41. In other words, the upstream header 42 connects the upper ends of the plurality of external heat transfer tubes 41. The downstream header 43 is disposed below the plurality of external heat transfer tubes 41. The interior of the downstream header 43 is in communication with the lower ends of the respective external heat transfer tubes 41. In other words, the downstream header 43 connects the lower ends of the plurality of external heat transfer tubes 41.

[0045] <Gas phase pipe> The gas phase pipe 47 connects the refrigerant vessel 3 and the upstream header 42 of the heat exchanger 40. One end, which is the upstream end of the gas phase pipe 47, is connected to the upper end of the refrigerant vessel 3 in a state of communication with the interior of the refrigerant vessel 3. The other end, which is the downstream end of the gas phase pipe 47, is connected to the interior of the upstream header 42 in a state of communication.

[0046] <Liquid phase tube> The liquid phase pipe 48 connects the downstream header 43 of the heat exchanger 40 and the refrigerant tank 3. One end, which is the upstream end of the liquid phase pipe 48, is connected to the downstream header 43 from below. One end of the liquid phase pipe 48 is in communication with the interior of the downstream header 43. The gas phase pipe 47 extends downward and horizontally from one end, and the other end, which is the other end, is connected to the refrigerant tank 3 in communication.

[0047] <Blower fan> The blower fan 27 blows air to the external heat transfer tubes 41 of the heat exchanger 40, thereby cooling the external heat transfer tubes 41 and the refrigerant C flowing through the external heat transfer tubes 41.

[0048] <Effects of the Second Embodiment> The refrigerant C in liquid phase within the refrigerant tank 3 cools the servers 2 by removing heat from them. At this time, the refrigerant C evaporates and boils to become vapor, i.e., gas-phase refrigerant C. The gas-phase refrigerant C is introduced into the gas-phase pipe 47 and guided through the gas-phase pipe 47 as a gas-phase flow F1 to the heat exchanger 40 outside the room E. The refrigerant C as the gas-phase flow F1 that has reached the heat exchanger 40 is introduced into each external heat transfer pipe 41 via the upstream header 42.

[0049] of As the refrigerant C flows from top to bottom through the external heat transfer pipe 41, it is cooled and condensed by exchanging heat with the air blown by the blower fan 27. As a result, the refrigerant C flows as a liquid-phase flow F2 of condensed water through the downstream header 43 and the liquid-phase pipe 48 due to gravity, and is returned to the refrigerant tank 3. As described above, the second cooling system 30 of the second embodiment constitutes a loop thermosiphon heat pipe that does not require a pump or the like to circulate the refrigerant C. This allows the server 2 to be continuously cooled without the need for external power.

[0050] <First Modification of Second Embodiment> 10, a duct forming section 49 for accommodating the heat exchanger 40 may be provided on the outer wall of the container 31. The duct forming section 49 extends in the vertical direction along the outer wall of the container 31 and forms a duct that is open at both the upper and lower ends.

[0051] 11, the external heat transfer tubes 41 of the heat exchanger 40 may be arranged so as to extend horizontally and be arranged side by side in the vertical direction, with an upstream header 42 and a downstream header 43 provided on both sides of the external heat transfer tubes 41 in the horizontal direction. Each external heat transfer tube 41 may be provided with a plurality of external fins 44 in contact with the outer circumferential surface of the external heat transfer tube 41.

[0052] According to this configuration, when high-temperature refrigerant C is introduced into heat exchanger 40, an ascending air current is generated in the duct. As a result, a continuous air flow is formed from the bottom end to the top end of the duct. This allows refrigerant C to be cooled more efficiently in heat exchanger 40, and allows servers 2 to be cooled even more efficiently.

[0053] <Second Modification of Second Embodiment> 12, the heat exchanger 40 may be provided integrally with the outer wall of the container 31 so as to extend along the outer surface of the outer wall. In this case, a plurality of external heat transfer tubes 41 are arranged along the outer wall, and an upstream header 42 and a downstream header 43 connecting these are also arranged along the outer wall.

[0054] By providing the heat exchanger 40 integrally with the outer wall of the container 31, there is no need to secure a separate space for accommodating the heat exchanger 40, and an overall compact configuration can be achieved. Furthermore, since the outer wall itself can be used as a heat dissipation section, heat exchange between the refrigerant C and the outside air in the heat exchanger 40 can be further promoted, and the condensation performance of the refrigerant C can be improved. As a result, the servers 2 can be cooled even more efficiently.

[0055] Third Embodiment Next, a second embodiment of the present invention will be described with reference to Fig. 13. In the third embodiment, the same components as those in the other embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted. <Third cooling system> As shown in FIG. 13, a third cooling system 50 of the third embodiment includes a server 2, a refrigerant vessel 3, a heat dissipator 51, and a vapor film remover 60 as a heat transfer promoter.

[0056] The server 2 and the refrigerant tank 3 have the same configuration as in the second embodiment. That is, the configuration is such that heat from the server 2 is removed by the refrigerant C in the refrigerant tank 3.

[0057] <Heat dissipator> The heat sink 51 is made of a material containing a metal with high thermal conductivity, such as aluminum or copper. The heat sink 51 is provided in the refrigerant tank 3 so as to be immersed in the refrigerant C in the refrigerant tank 3. The heat sink 51 is provided so as to be in contact with the inner wall surface of the refrigerant tank 3 on the side that comes into contact with the server 2. In other words, the heat sink 51 is in thermal contact with the server 2 via the inner wall surface of the refrigerant tank 3. The heat sink 51 has a flat plate shape that extends along the inner wall surface of the refrigerant tank 3, that is, it has a plate shape that extends in the vertical and horizontal directions.

[0058] One of a pair of plate surfaces of the heat dissipating body 51 is fixed and integrated to the inner wall surface of the refrigerant tank 3. The other of the pair of plate surfaces of the heat dissipating body 51 serves as a heat dissipating surface 51a of the heat dissipating body 51, and faces the refrigerant C in the refrigerant tank 3.

[0059] <Vapor film removal section> The vapor film removing portion 60 prevents a vapor film of the refrigerant C from adhering to the heat radiating surface 51 a of the heat radiating body 51 . <Ultrasonic generator> In this embodiment, an ultrasonic generator 61 is used as the vapor film removal unit 60. The ultrasonic generator 61 is disposed in the refrigerant tank 3, for example, directly below the heat radiator 51 on the bottom surface of the refrigerant tank 3. The ultrasonic generator 61 irradiates ultrasonic waves upward, i.e., toward the heat radiating surface 51a of the heat radiator 51. The irradiated ultrasonic waves are transmitted to the heat radiating surface 51a of the heat radiator 51 via the refrigerant C as a medium.

[0060] <Effects of the Third Embodiment> In the third cooling system 50 as described above, heat generated by the server 2 is transferred to the heat radiator 51 and removed by evaporation and boiling of the refrigerant C on the heat radiating surface 51a of the heat radiator 51. Here, if the density of heat generated by the server 2 is high and the condition exceeds the critical heat flux from the heat radiator 51 to the refrigerant C, a film of vapor of the refrigerant C (vapor film) is formed over the entire heat radiating surface 51a of the heat radiator 51. When such a vapor film is formed, the coefficient of heat transfer from the heat radiator 51 to the refrigerant C drops sharply, and there are cases where the heat radiator 51 is unable to sufficiently radiate heat.

[0061] In contrast, in this embodiment, even if a vapor film is generated on the heat dissipation surface 51a of the heat dissipator 51, the ultrasonic generator 61 serving as the vapor film removal unit 60 can remove the vapor film by applying ultrasonic waves to the heat dissipation surface 51a of the heat dissipator 51. That is, applying ultrasonic waves to the heat dissipation surface 51a of the heat dissipator 51 can break down the vapor film into fine particles and cause it to collapse. This allows the refrigerant C to come into direct contact with the heat dissipation surface 51a of the heat dissipator 51, so that the refrigerant C can effectively remove heat from the heat dissipator 51. This allows the server 2 to be cooled more effectively.

[0062] Furthermore, the vapor film on the heat dissipation surface 51a can be removed by the vapor film removal unit 60, thereby increasing the critical heat flux. If the critical heat flux is improved, the refrigerant C can be operated at a higher temperature. This increases the temperature difference between the refrigerant C and the atmosphere, allowing for a more compact size of the equipment that cools the refrigerant C. Furthermore, waste heat can be easily recovered from the refrigerant C, and heat can be effectively recovered by using, for example, an organic Rankine cycle.

[0063] <First Modification of Third Embodiment> 14, for example, a jet injector 62 may be employed as the vapor film removal unit 60. The jet injector 62 supplies a jet of refrigerant C to the heat radiating surface 51a from directly below the heat radiating surface 51a in the refrigerant tank 3. That is, the jet is sprayed along the heat radiating surface 51a. This makes it possible to easily remove the vapor film from the heat dissipation surface 51a, similarly to the third embodiment.

[0064] <Second Modification of Third Embodiment> For example, as shown in FIG. 15, in addition to the jet injectors 62, a flow path forming portion 63 may be formed on the heat dissipation surface 51a. The flow path forming portion 63 may be, for example, a fin-like structure rising from the heat dissipation surface 51a and extending in the vertical direction, or a cover 25-like member that forms a flow path extending in the vertical direction on the heat dissipation surface 51a. This allows the jet injectors 62 to be supplied locally along the surface of the heat dissipation surface 51a, making it easy to remove the vapor film. Furthermore, this promotes heat exchange between the refrigerant C in the form of a jet flow and the heat dissipation surface 51a, thereby more effectively removing heat from the server 2.

[0065] <Third Modification of Third Embodiment> For example, as shown in FIG. 16, a swirl flow generator 64 may be employed as the vapor film removal section 60. The swirl flow generator 64 has a propeller 64a that can rotate around an axis that extends vertically directly below the heat dissipation surface 51a. The propeller 64a supplies a swirling flow around the vertical axis O to the heat dissipation surface 51a, which not only makes it easy to remove the vapor film on the heat dissipation surface 51a but also promotes heat exchange between the refrigerant C as a swirling flow and the heat dissipation surface 51a, making it easier to remove heat from the server 2.

[0066] <Fourth Modification of Third Embodiment> 17, a binder 65 may be provided along the heat dissipation surface 51a as the vapor film removal unit 60. The binder 65 may be made of, for example, a fiber with high thermal conductivity and other materials such as metals. The binder 65 may also be made of, for example, a composite of carbon fiber with aluminum or copper. By providing a binder 65 having a higher thermal conductivity than the heat dissipation surface 51a of the heat dissipation body 51, it is possible to increase the critical heat flux between the heat dissipation body 51 and the refrigerant C. This provides the same advantages as those described above.

[0067] <Fourth Modification of Third Embodiment> 18, for example, a plurality of fins standing up from the heat dissipation surface 51a of the heat dissipation body 51 may be provided as the vapor film removal section 60. The fins are made of the same material as the heat dissipation body 51. This increases the area of the heat dissipation surface 51a, thereby raising the critical heat flux. When fins are provided on the heat sink 51, a binder 65 may be interposed between the fins and the heat sink 51. This not only reduces the thermal resistance at the joint surface between the fins and the heat sink 51, but also provides the same effects as when the binder 65 is provided.

[0068] <Other Modifications of the Third Embodiment> Furthermore, in the third embodiment and its modified example, an example in which the vapor film removal unit 60 is provided as a heat transfer promotion unit has been described, but the present invention is not limited to this. Even if a vapor film is not formed on the heat dissipation surface 51a of the heat dissipation body 51, the flow of the refrigerant C along the heat dissipation surface 51a can be disturbed by using each component of the vapor film removal unit 60 configured as described above as a heat transfer promotion unit. This increases the heat transfer coefficient on the heat dissipation surface 51a, making it possible to cool the server more efficiently and reduce temperature unevenness, thereby enabling appropriate management of the operating temperature.

[0069] <Fourth embodiment> Next, a fourth embodiment of the present invention will be described with reference to FIGS. <Fourth Cooling System> The fourth cooling system 70 according to the fourth embodiment is used, for example, to cool the refrigerant C obtained by removing heat from the server 2. The fourth cooling system 70 extends vertically along a vertical axis O. The fourth cooling system 70 includes a lower housing 80, an air blower 90, an upper housing 100, a flow regulator 110, a water injection unit 112, and a heat exchanger 120.

[0070] <Lower housing> The lower housing 80 is a part that constitutes the lowest part of the fourth cooling system 70. The lower housing 80 has a cylindrical housing outer peripheral wall 81 that surrounds the vertical axis O. The housing outer peripheral wall 81 has, for example, a rectangular cross section perpendicular to the vertical axis O. An outer peripheral opening 81a is formed in an upper part of the housing outer peripheral wall 81, penetrating the housing outer peripheral wall 81 in the radial direction of the vertical axis O. The outer peripheral opening 81a serves as an air intake port for the fourth cooling system 70.

[0071] A housing bottom wall 82 extending radially inward from the lower end of the housing outer peripheral wall 81 is connected around the entire periphery to the lower end of the housing outer peripheral wall 81. The housing bottom wall 82 has an annular shape in a plan view.

[0072] A housing top wall 83 extending radially inward from the upper end of the housing outer peripheral wall 81 is connected to the entire periphery of the upper end of the housing outer peripheral wall 81. The housing top wall 83 is annular in plan view and is parallel to and has approximately the same outer shape as the housing bottom wall 82. The housing top wall 83 has an upper opening 83a that passes through the housing top wall 83 in the vertical direction. The upper opening 83a serves as an air intake port for the fourth cooling system 70.

[0073] The lower housing 80 has an inner annular wall 84 and an outer annular wall 85 formed therein. The inner annular wall 84 has a truncated cone shape centered on the vertical axis O and gradually decreasing in diameter from bottom to top. The lower end of the inner annular wall 84 is connected to the inner peripheral edge of the housing bottom wall 82 along its entire circumference. The upper end of the inner annular wall 84 is at approximately the same height as the housing top wall 83.

[0074] The outer annular wall 85 is disposed on the outer peripheral side of the inner annular wall 84 and has a truncated cone shape centered on the vertical axis O and gradually decreasing in diameter from bottom to top. The upper end of the outer annular wall 85 is connected to the inner peripheral edge of the housing top wall 83 along its entire circumference. The space between the outer annular wall 85 and the inner annular wall 84 serves as an air introduction flow path whose diameter gradually decreases from bottom to top. The lower housing 80 configured as described above is supported from below by legs 88. That is, the lower housing 80 is placed on the floor surface via the legs 88.

[0075] <Blower section> The blower 90 includes a drive unit 91 , a shaft 92 , and an impeller 93 . The drive unit 91 is, for example, an electric motor, and is driven to rotate about a vertical axis O by external power supply. The drive unit 91 is disposed radially inside the inner annular wall 84. That is, the inner annular wall 84 covers the drive unit 91 from the outer circumferential side. The shaft portion 92 extends upward from the drive portion 91 along a vertical axis O. The drive portion 91 is driven to rotate the shaft portion 92 around the vertical axis O.

[0076] The impeller 93 has a boss portion 94 and a plurality of blades 95. The boss portion 94 is integrally provided on the upper end of the shaft portion 92. The plurality of blades 95 extend radially outward from the outer peripheral surface of the boss portion 94 and are provided at intervals in the circumferential direction. The plurality of blades 95 are disposed on the outlet side of the introduction flow passage formed by the inner annular wall 84 and the outer annular wall 85, i.e., directly above the introduction flow passage. When the drive portion 91 is driven to rotate, the impeller 93 rotates and air is blown from below to above.

[0077] <Upper housing> The upper housing 100 has a cylindrical shape that extends vertically about its axis. The lower end of the upper housing 100 is fixed around the entire circumference to the upper surface of the housing top wall 83 of the lower housing 80. The upper housing 100 surrounds the impeller 93 of the blower 90 from the entire circumference. A clearance is formed between the radially outer end of the impeller 93 and the inner peripheral surface of the upper housing 100. The space inside the upper housing 100 serves as an upward flow path for the air blown by the blower 90.

[0078] The inner circumferential surface of the upper housing 100 is a first inner circumferential surface 100a that extends with a uniform flow path cross-sectional area from the lower end upward to a predetermined height. The inner circumferential surface of the upper housing 100 above the first inner circumferential surface 100a is a second inner circumferential surface 100b that gradually increases in diameter as it extends upward.

[0079] In this embodiment, a sound-absorbing material is provided on the inner peripheral surface of the upper housing 100. For example, an acoustic liner such as an acoustic damper can be used as the sound-absorbing material. Alternatively, a porous material, foam material, or the like may be provided on the inner peripheral surface of the upper housing 100 as the sound-absorbing material.

[0080] <Fluid rectifier> The flow straightener 110 is provided at a height position at the boundary between the first inner circumferential surface 100a and the second inner circumferential surface 100b inside the upper housing 100. The flow straightener 110 has a flat plate shape perpendicular to the vertical axis O, and extends so as to close the flow path inside the upper housing 100. The flow straightener 110 has a plurality of flow straightening holes 110a that penetrate in the vertical direction and are arranged at intervals in the horizontal direction. The flow regulator 110 may be a honeycomb structure having a certain thickness in the vertical direction and having a plurality of holes formed therein that penetrate the honeycomb structure in the vertical direction.

[0081] <Water injection part> A plurality of water injection units 112 are provided at intervals in the circumferential direction on the inner circumferential surface of the upper housing 100. The water injection units 112 are provided on a first inner circumferential surface 100a that is below the flow straightener 110 within the upper housing 100. The water injection units 112 may also be provided on a second inner circumferential surface 100b that is above the flow straightener 110 within the upper housing 100. Each water injection unit 112 is configured to be able to inject water in a radially inward and obliquely upward direction within the upper housing 100.

[0082] <Heat exchange section> Next, the heat exchanger 120 will be described. The heat exchanger 120 is provided at the top of the fourth cooling system 70. The heat exchanger 120 is fixed integrally to the upper end of the upper housing 100. The heat exchanger 120 has a heat transfer tube group 130, a casing 140, a refrigerant supply section 180, and a refrigerant discharge section 190.

[0083] <Heat transfer tube group> As shown in Figures 19 to 22, the heat transfer tube group 130 is an assembly of a plurality of heat transfer tubes 131. Each heat transfer tube 131 extends in the vertical direction. The space inside each heat transfer tube 131 serves as an air passage P1 that extends in the vertical direction and has open upper and lower ends.

[0084] The horizontal cross-sectional shape of each heat transfer tube 131 is such that both the inner and outer circumferential surfaces are regular hexagonal. The horizontal cross-sectional shape of each heat transfer tube 131 may be polygonal or circular. The thickness of the heat transfer tube 131 is uniform around the entire circumference. On the inner circumferential surface of each heat transfer tube 131, inner fins 131a are formed, which protrude radially inward from the inner circumferential surface of the heat transfer tube 131 and extend over the entire area in the up-down direction. One inner fin 131a is formed on each of the six inner surfaces that make up the inner surface of the heat transfer tube 131. That is, a plurality of inner fins 131a (six in this embodiment) are formed on the inner circumferential surface of the heat transfer tube 131 at equal intervals in the circumferential direction.

[0085] The plurality of heat transfer tubes 131 are collectively provided at equal intervals. Adjacent heat transfer tubes 131 are regularly arranged with the flat surfaces constituting their outer circumferential surfaces facing each other. As a result, refrigerant passages P2 extending in the vertical and horizontal directions are formed between the heat transfer tubes 131. In plan view, the refrigerant passages P2 are formed in a mesh pattern so as to avoid the regular hexagonal heat transfer tubes 131.

[0086] <Casing> 19 to 21 , the casing 140 is provided so as to cover the outer periphery of the heat transfer tube group 130. The casing 140 has a cylindrical portion 150, an upper tube plate 155, a lower tube plate 156, an upper header 160, and a lower header 170.

[0087] The tubular portion 150 has a tubular shape extending in the up-down direction about a vertical axis O, and is cylindrical in this embodiment. The vertical dimension of the tubular portion 150 is substantially the same as the vertical dimension of the heat transfer tube group 130. As a result, the tubular portion 150 covers the entire heat transfer tube group 130 from the outer periphery over the entire area in the up-down direction.

[0088] The upper tube plate 155 is provided so as to close the upper end opening of the tubular portion 150. The upper tube plate 155 has a large number of holes formed therethrough in the vertical direction. The upper ends of the heat transfer tubes 131 of the heat transfer tube group 130 are fitted into these holes. The upper end openings of the heat transfer tubes 131 are flush with the upper surface of the upper tube plate 155. As a result, the upper end openings of the heat transfer tubes 131 are not closed by the upper tube plate 155, and are in communication with the space above.

[0089] The lower tube plate 156 is provided so as to close the lower end opening of the tubular portion 150. The lower tube plate 156 has a large number of holes formed therethrough in the vertical direction. The lower ends of the heat transfer tubes 131 of the heat transfer tube group 130 are fitted into these holes. The lower end openings of the heat transfer tubes 131 are flush with the lower surface of the lower tube plate 156. As a result, the lower end openings of the heat transfer tubes 131 are not closed by the lower tube plate, and are in communication with the space above.

[0090] That is, the heat transfer tube group 130, in which the heat transfer tubes 131 are gathered at intervals, is supported by the upper tube plate 155 and the lower tube plate 156. The space surrounded by the cylindrical portion 150, the upper tube plate 155, and the lower tube plate 156 serves as a refrigerant chamber into which a refrigerant C supplied from the outside is introduced. Refrigerant passages P2 between the heat transfer tubes 131 in the heat transfer tube group 130 are located within the refrigerant chamber.

[0091] <Top Header> As shown in Fig. 19, the upper header 160 is provided in an annular shape on the outer periphery of the upper end of the tubular portion 150. An annular flow path surrounding the tubular portion 150 is defined within the upper header 160. As shown in Fig. 20, a plurality of upper communication holes 151 are provided in the tubular portion 150 at a height position corresponding to the upper header 160, the upper communication holes 151 penetrating the tubular portion 150 in the radial direction and spaced apart in the circumferential direction. That is, the space within the upper header 160 and the refrigerant chamber within the tubular portion 150 are in communication with each other via the upper communication holes 151.

[0092] <Bottom Header> As shown in Fig. 19, the lower header 170 is provided in an annular shape on the outer periphery of the lower end of the tubular portion 150. An annular flow path surrounding the tubular portion 150 is defined within the lower header 170. As shown in Fig. 20, a plurality of lower communication holes 152 are provided in the tubular portion 150 at a height position corresponding to the lower header 170, the lower communication holes 152 penetrating the tubular portion 150 in the radial direction and spaced apart in the circumferential direction. That is, the space within the lower header 170 and the refrigerant chamber within the tubular portion 150 are in communication with each other via the lower communication holes 152.

[0093] <Refrigerant supply section> The refrigerant supply unit 180 supplies the refrigerant C into the upper header 160. A plurality of refrigerant supply units 180 (four in this embodiment, equally spaced apart in the circumferential direction) are provided on the outer circumferential surface of the upper header 160 at intervals in the circumferential direction.

[0094] <Refrigerant discharge section> The refrigerant discharge portions 190 supply the refrigerant C into the lower header 170. A plurality of the refrigerant discharge portions 190 (four in this embodiment, equally spaced apart in the circumferential direction) are provided on the outer circumferential surface of the lower header 170 at intervals in the circumferential direction.

[0095] <Operation and effect of the fourth embodiment> The fourth cooling system 70 cools and condenses the refrigerant C that has evaporated into vapor by, for example, removing heat from the server 2. When the drive unit 91 of the blower unit 90 is driven to rotate, the impeller 93 rotates accordingly. The impeller 93 then blows air from below upward. That is, air that flows into the lower housing 80 through the outer peripheral opening 81a and the upper opening 83a of the lower housing 80 passes through the introduction flow path between the inner annular wall 84 and the outer annular wall 85, passes between the blades 95 of the impeller 93, and is blown upward within the upper housing 100. As the air flows through the upper housing 100, water is mixed into the air by the water injection unit 112. The air then passes through the rectifying holes 110a of the flow rectifier 110, and becomes a rectified flow directed upward, with swirling components removed.

[0096] The air flowing in this manner is introduced from below into air passages P1 in each heat transfer tube 131 that constitutes the heat transfer tube group 130 at the lower end of the heat exchange section 120. The air introduced into the heat transfer tubes 131 flows from below to above through the air passages P1 in accordance with the linear shape of the heat transfer tubes 131, and is discharged to the outside from the upper ends of the heat transfer tubes 131.

[0097] Meanwhile, the refrigerant C in a vapor state is introduced into the upper header 160 in the casing 140 of the heat exchange section 120 via the refrigerant supply unit 180. The refrigerant C introduced into the upper header 160 moves circumferentially within the upper header 160 and is introduced into the refrigerant chamber in the tubular section 150 through one of the plurality of upper communication holes 151. The refrigerant C flows horizontally and downward through the refrigerant passages P2 between the heat transfer tubes 131 within the refrigerant chamber. At this time, heat is exchanged between the refrigerant C flowing through the refrigerant passages P2 and the air flowing through the air passages P1 via the heat transfer tubes 131. That is, the refrigerant C is cooled by the heat transfer of the refrigerant C to the air, and the refrigerant C condenses into a liquid phase refrigerant C while flowing through the refrigerant passages P2.

[0098] The refrigerant C thus condensed moves downward in accordance with its weight and the supply pressure of the refrigerant C, and is discharged into the lower header 170 through the lower communication holes 152 formed at the lower end of the tubular portion 150. Then, the refrigerant C in the lower header 170 moves in the circumferential direction and is discharged to the outside of the heat exchange portion 120 from one of the plurality of refrigerant discharge portions 190. Such refrigerant C is transferred again to the server 2 and cools the server 2.

[0099] According to the fourth cooling system 70 configured as described above, the air passage P1 in the heat transfer tubes 131 is linear and extends in the vertical direction in all of the heat transfer tubes 131. Therefore, dust and dirt that enters the air passage P1 will be forced downward by its own weight or forced upward by the air blown by the blower 90. This makes it possible to prevent dust and dirt from accumulating in the air passage P1. Furthermore, the air passage P1 in each heat transfer tube 131 can be seen from one direction by, for example, a maintenance worker. Therefore, it is easy to determine which air passage P1 contains a foreign object. Furthermore, because the air passage P1 is linear, it can be easily cleaned. In other words, maintainability can be improved.

[0100] Furthermore, the heat transfer tubes 131 are formed with inner fins 131a protruding from the inner peripheral surfaces of the heat transfer tubes 131. This increases the contact area between the air flowing through the air passage P1 and the heat transfer tubes 131, thereby promoting heat exchange between the refrigerant C and the air. Therefore, the refrigerant C can be sufficiently cooled even if the total number of heat transfer tubes 131 is reduced. Furthermore, since the fins extend uniformly in the vertical direction, the linearity of the air passage P1 is not impaired, which makes it possible to maintain high maintainability.

[0101] Furthermore, because the casing 140 is configured to introduce the refrigerant C into the refrigerant chamber from the entire circumferential area via the upper header 160, it is possible to prevent the refrigerant C from being introduced unevenly to one part of the circumferential area of the heat transfer tube group 130. Furthermore, because the refrigerant C that has circulated within the refrigerant chamber is discharged to the lower housing 80 from the entire circumferential area, it is possible to prevent the refrigerant C from being unevenly distributed to one part of the circumferential area even in the lower part of the refrigerant chamber. This makes it possible to uniformly distribute the flow rate of the refrigerant C to the refrigerant C flow paths, thereby enabling efficient heat exchange with the air.

[0102] Furthermore, the drive unit 91 of the blower unit 90 is provided radially inside the inner annular wall 84 that defines the introduction flow path to the impeller 93. Therefore, the drive unit 91 does not obstruct the flow of air. This prevents the flow of air from becoming uneven, and allows the flow rate to be appropriately distributed to each heat transfer tube 131 of the heat exchange unit 120. Furthermore, because the drive unit 91 is disposed in a dead space, such as the inside of the inner annular wall 84, there is no need to provide extra space for the drive unit 91. This prevents the fourth cooling system 70 from becoming large overall.

[0103] Furthermore, since the upper housing 100 is provided with a sound-absorbing material, the sound generated by driving the impeller 93 can be absorbed by the sound-absorbing material. This reduces the impact of noise generated by driving the fourth cooling system 70 on the surrounding area. Note that sound absorbing material may be provided in the lower housing 80 in addition to or instead of the upper housing 100. This also provides the same operational effect.

[0104] Furthermore, since the flow rectifier 110 is provided inside the upper housing 100, air can be introduced into the air flow path inside the heat transfer tube 131 along the air passage P1 of the heat transfer tube 131 by passing through the flow rectifier holes 110a of the flow rectifier 110. Therefore, the air is less susceptible to the influence of wind in the external environment, and the cooling performance can be stabilized.

[0105] Furthermore, water can be mixed into the air by the water injection unit 112 as it passes through the upper housing 100. As a result, even when the outside air temperature is high, the apparent air temperature can be lowered by utilizing the heat of vaporization generated when the water evaporates. This improves the cooling performance of the refrigerant C in the heat exchange unit 120. Furthermore, because water is injected inside the upper housing 100, the process can be completed within the space inside the fourth cooling system 70, eliminating the need for a separate, large-scale configuration. This allows for improved cooling performance while maintaining a compact size and low cost.

[0106] <First Modification of Fourth Embodiment> For example, as shown in Fig. 23, a configuration may be adopted in which resistors 200 are provided in a refrigerant passage P2 in a heat transfer tube group 130. A plurality of resistors 200 are provided at intervals in the vertical direction, and each resistor 200 is plate-shaped with its thickness in the vertical direction. In a plan view, the resistors 200 extend horizontally along the refrigerant passage P2. The resistors 200 extend in a mesh-like pattern in a plan view, similar to the refrigerant passage P2, with a predetermined passage distance D from the outer peripheral surface of the heat transfer tube 131. The passage distance D is formed on both sides of the resistor 200 extending through the refrigerant passage P2.

[0107] With this configuration, the resistance element 200 restricts the movement of the refrigerant C in the vertical direction. That is, the resistance of the refrigerant C in the vertical direction increases, and the refrigerant C tends to move in the horizontal direction. This allows the refrigerant C to be properly distributed even inside the heat transfer tube group 130 in the radial direction, and makes the flow rate distribution of the heat exchanger 40 uniform as a whole.

[0108] For example, the size of the passage gap D between the resistor 200 and the outer peripheral surface of the heat transfer tube 131 may be configured to increase toward the inside of the heat transfer tube group 130, i.e., toward the radially inward direction. This allows the refrigerant C to actively reach the radially inner portions of the heat transfer tube group 130, which are difficult for the refrigerant C to reach. Therefore, the flow rate distribution can be made even more uniform.

[0109] <First Modification of Fourth Embodiment> 24 , a blocking portion 210 may be provided that blocks the space between the inner circumferential surface of the cylindrical portion 150 of the casing 140 and the outermost surface of the heat transfer tube group 130. The blocking portion 210 is, for example, a brush that protrudes radially inward from the inner circumferential surface of the cylindrical portion 150 and has brush bristles arranged circumferentially. Note that the blocking portion 210 may be any material that can fill the space between the inner circumferential surface of the cylindrical portion 150 of the casing 140 and the outermost surface of the heat transfer tube group 130, and may be, for example, an elastic material such as sponge or rubber.

[0110] This prevents the refrigerant C from flowing through gaps between the heat transfer tube group 130 that do not contribute to heat exchange and the casing 140. Therefore, the refrigerant C can be actively introduced into the refrigerant passages P2 between the heat transfer tubes 131 that can perform heat exchange, thereby improving the heat exchange efficiency.

[0111] <Other embodiments> Although the embodiment of the present invention has been described above, the present invention is not limited to this and can be modified as appropriate within the scope of the technical idea of the invention.

[0112] For example, the refrigerant tank 3 of the first cooling system 1 of the first embodiment may be placed in the room R inside the container 31 of the second cooling system 30, and a part of the heat pipe 10 and the plate-shaped fins 20 may be placed outside the room E outside the container 31.

[0113] The third cooling system 50 of the third embodiment may be applied to the refrigerant tank 3 of the first and second embodiments. Moreover, instead of the heat exchanger 40 of the second embodiment, a fourth cooling system 70 of the fourth embodiment may be provided.

[0114] <Additional Notes> The following can be understood, for example, as described in each embodiment.

[0115] The cooling system (1) is a cooling system including: a refrigerant tank 3 that stores a refrigerant C, which removes heat from a heat-generating element, in a closed space; a plurality of heat pipes 10 that are arranged to extend from the refrigerant tank 3 to the outside of the refrigerant tank 3, each having a passage formed therein through which the refrigerant C, which serves as a working fluid, can move; and a blower fan 27 that is located outside the refrigerant tank 3 and blows air to the plurality of heat pipes 10 in the direction in which the heat pipes 10 are arranged. Each of the heat pipes 10 has a cross-sectional shape that is perpendicular to the direction in which the heat pipes 10 extend, with the air blowing direction as its longitudinal direction, and has a flat shape with a leading edge 11 on the upstream side of the air blowing direction and a trailing edge 12 on the downstream side of the air blowing direction.

[0116] As a result, cooling is promoted at the leading edge 11 of the heat pipe 10, while cooling is hindered at the trailing edge 12. As a result, the refrigerant C is more likely to condense on the leading edge 11 side of the heat pipe 10, providing a path for liquid-phase refrigerant C, while the refrigerant C is more likely to condense on the trailing edge 12 side, providing a path for gas-phase refrigerant C. This promotes the movement of refrigerant C within the heat pipe 10, allowing for efficient heat transfer.

[0117] The cooling system (2) is the cooling system (1) in which the heat pipes 10 are arranged so that they are more sparsely arranged downstream of the airflow direction than upstream.

[0118] On the downstream side where the air temperature rises, the air density decreases and the volumetric flow rate increases. Therefore, by making the downstream side of the group of heat pipes 10 sparse, it is possible to optimize the pressure loss.

[0119] The cooling system (3) is the cooling system of (1) or (2), further comprising plate-shaped fins (20) extending outside the refrigerant tank (3) in a direction perpendicular to the extension direction of the heat pipes (10) and having through holes (21) through which the heat pipes (10) pass, wherein the leading edges (11) of the heat pipes (10) are in contact with the inner peripheral edges of the through holes (21) of the plate-shaped fins (20), and a gap is formed between the trailing edges (12) of the heat pipes (10) and the inner peripheral edges of the through holes (21) of the plate-shaped fins (20).

[0120] This makes it possible to promote condensation of the refrigerant C on the leading edge 11 side of the heat pipe 10, while preventing condensation of the refrigerant C on the trailing edge 12 side.

[0121] The cooling system (4) is a cooling system described in any one of (1) to (3), wherein the heat pipe 10 further has a partition 15 that separates the passage within the heat pipe 10 into the upstream leading edge side passage 16 and the downstream trailing edge side passage 17.

[0122] This allows the heat pipe 10 to separate a gas phase path (vapor flow path) and a liquid phase path (condensate flow path) of the refrigerant C, thereby improving transfer efficiency.

[0123] The cooling system (5) is any one of the cooling systems (1) to (4) in which the inner end of the heat pipe 10 is connected to the inside of the refrigerant tank 3, and the refrigerant C in the refrigerant tank 3 and the refrigerant C in the heat pipe 10 are the same.

[0124] This makes it possible to eliminate the need for a pump or the like for circulating the coolant C.

[0125] The cooling system (6) is any one of the cooling systems (1) to (4), in which the heat pipe 10 has an end on the inner side of the refrigerant tank 3 closed and extends into the interior of the refrigerant tank 3 and is immersed in the refrigerant C, the refrigerant C inside the refrigerant tank 3 is a first refrigerant C1, and the refrigerant C inside the heat pipe 10 is a second refrigerant C2.

[0126] This also makes it possible to eliminate the need for a pump or the like for circulating the refrigerant C.

[0127] The cooling system (7) is a cooling system including an exterior wall separating an indoor space R from an outdoor space E, a refrigerant tank 3 arranged inside the indoor space R and containing a refrigerant C for removing heat from a heat-generating element in a closed space, a heat exchanger 40 arranged outside the indoor space E, a gas-phase pipe 47 that guides the refrigerant C, which has evaporated in the refrigerant tank 3 and become a gas phase working fluid, to the heat exchanger 40, and a liquid-phase pipe 48 that guides the refrigerant C, which has changed from a gas phase to a liquid phase in the heat exchanger 40, to the refrigerant tank 3.

[0128] The refrigerant C that has turned into vapor by removing heat from the heat-generating element in the refrigerant tank 3 is introduced into the vapor-phase pipe 47 and led to the heat exchanger 40 located outside the room E. The refrigerant C condenses into condensed water in the heat exchanger 40, which flows through the liquid-phase pipe 48 due to its own weight and is introduced into the refrigerant tank 3. Therefore, the heat-generating element can be efficiently cooled without providing a pump or the like for circulating the refrigerant C.

[0129] The cooling system of (8) is a cooling system described in (7) further comprising a duct forming portion 49 that, together with the outer surface of the outer wall, forms a duct passage that passes from bottom to top, and the heat exchanger 40 is provided within the duct passage.

[0130] When the high-temperature refrigerant C is introduced into the heat exchanger 40, an ascending air current is generated in the duct, and outside air is introduced into the duct. This allows the refrigerant C to be cooled more efficiently in the heat exchanger 40.

[0131] The cooling system of (9) is the cooling system according to (7) or (8), in which the heat exchanger 40 is integrally provided along the outer surface of the outer wall.

[0132] By providing heat exchanger 40 integrally with the outer wall itself, the outer wall itself can be used as heat radiator 51. This makes it possible to realize heat exchanger 40 that is compact and has high condensation performance for refrigerant C.

[0133] The cooling system (10) is any one of the cooling systems (1) to (9), further comprising a heat sink (51) that is immersed in the refrigerant (C) within the refrigerant tank (3) and receives heat from the heat generating element, and a heat transfer promotion unit that promotes heat transfer from the heat dissipation surface (51a) of the heat sink (51) to the refrigerant.

[0134] This makes it possible to suppress, for example, adhesion of a vapor film to the heat dissipating body 51, and therefore the heat transfer coefficient between the refrigerant C and the heat dissipating body 51 can be maintained high. Furthermore, when a single-phase flow of the refrigerant is formed on the heat dissipation surface of the heat dissipation body, heat transfer can be promoted by disturbing the single-phase flow.

[0135] The cooling system (11) is a cooling system including a refrigerant tank 3 that contains a refrigerant C that removes heat from a heat-generating body in a closed space, a heat dissipating body 51 that is immersed in the refrigerant C in the refrigerant tank 3 and to which heat from the heat-generating body is transferred, and a heat transfer promoting unit 60 that promotes heat transfer from a heat dissipating surface 51a of the heat dissipating body 51 to the refrigerant.

[0136] In addition to being able to prevent a vapor film from adhering to heat radiator 51, the heat transfer coefficient between refrigerant C and heat radiator 51 can be maintained high by turbulent flow.

[0137] The cooling system of (12) is the cooling system according to (10) or (11), wherein the heat transfer promotion unit includes an ultrasonic generator 61 that irradiates the heat dissipation surface 51a of the heat dissipation body 51 with ultrasonic waves.

[0138] This makes it possible to suppress adhesion of a vapor film to the heat dissipation surface 51a of the heat dissipation body 51 and to disturb the flow on the heat dissipation surface, leading to, for example, a transition from a laminar flow region to a turbulent flow region.

[0139] The cooling system (13) is any one of the cooling systems (10) to (12), in which the heat transfer promotion unit includes a jet injector 62 that injects a jet of the refrigerant C onto the heat dissipation surface 51a of the heat dissipation body 51.

[0140] This makes it possible to suppress adhesion of a vapor film to the heat dissipation surface 51a of the heat dissipation body 51 and also to disrupt the flow on the heat dissipation surface.

[0141] The cooling system (14) is the cooling system (13), wherein the heat transfer promotion section further includes a flow path forming section (63) that forms a flow path extending in the direction of flow of the jet flow on the heat dissipation surface (51a) of the heat dissipation body (51).

[0142] This makes it possible to suppress adhesion of a vapor film to the heat dissipation surface 51a of the heat dissipation body 51 and also to disrupt the flow on the heat dissipation surface.

[0143] The cooling system (15) is any of the cooling systems (10) to (14), in which the heat transfer promotion section includes a swirling flow generator 64 that generates a swirling flow of the refrigerant C on the heat dissipation surface 51a of the heat dissipation body 51.

[0144] This makes it possible to suppress adhesion of a vapor film to the heat dissipation surface 51a of the heat dissipation body 51 and also to disrupt the flow on the heat dissipation surface.

[0145] The cooling system (16) is any one of the cooling systems (10) to (15), in which the heat transfer promotion portion is provided on the heat dissipation surface 51a of the heat dissipation body 51 and contains a binder 65 having a higher thermal conductivity than the heat dissipation body 51.

[0146] This makes it possible to suppress adhesion of a vapor film to the heat dissipation surface 51a of the heat dissipation body 51 and also to disrupt the flow on the heat dissipation surface.

[0147] The cooling system (17) is any one of the cooling systems (10) to (15), in which the heat transfer promotion part (60) includes a heat dissipation fin (66) provided so as to protrude from the heat dissipation surface (51a) of the heat dissipation body (51).

[0148] This makes it possible to suppress adhesion of a vapor film to the heat dissipation surface 51a of the heat dissipation body 51 and also to disrupt the flow on the heat dissipation surface.

[0149] The cooling system (18) is a cooling system including a heat transfer tube group 130 having a plurality of heat transfer tubes 131 extending linearly in the vertical direction and having an air passage P1 on the inside, and these heat transfer tubes 131 are bundled together at intervals to form refrigerant passages P2 between the heat transfer tubes 131; a casing 140 covering the heat transfer tube group 130 so that both ends of each heat transfer tube 131 open to the outside; a heat exchange unit 120 having a refrigerant supply unit 180 that supplies refrigerant C into the casing 140 and a refrigerant discharge unit 190 that discharges refrigerant C from inside the casing 140; and an air blower unit 90 that is provided below the heat exchange unit 120 and blows air to the heat transfer tube group 130 from below.

[0150] The air passage P1 in the heat transfer tubes 131 is linear and extends in the vertical direction in all of the heat transfer tubes 131. Therefore, dust and dirt are less likely to accumulate in the air passage P1, and the air passage P1 can be seen from one direction, making it easy to clean.

[0151] The cooling system (19) is the cooling system (18) in which the heat transfer tube 131 has inner surface fins 131a that protrude from the inner circumferential surface of the heat transfer tube 131 and extend in the vertical direction.

[0152] This can promote heat exchange between the refrigerant C and the air. Therefore, even if the total number of heat transfer tubes 131 is reduced, the refrigerant C can be sufficiently cooled, and manufacturability and maintainability can be improved.

[0153] In the cooling system (20), the casing 140 includes a cylindrical portion 150 that surrounds the heat transfer tube group 130 from the outer periphery, an upper header 160 that forms an annular shape that surrounds the cylindrical portion 150 from the outer periphery at the top of the cylindrical portion 150 and is provided with one of the refrigerant supply portion 180 and the refrigerant discharge portion 190, and a lower header 160 that forms an annular shape that surrounds the cylindrical portion 150 from the outer periphery at the bottom of the cylindrical portion 150 and is provided with one of the refrigerant supply portion 180 and the refrigerant discharge portion 190. The cooling system is (18) or (19), in which the lower header 170 on which the other is provided and the tubular portion 150 have upper communication holes 151 which connect the space in the upper header 160 with the space in the tubular portion 150 and are formed in plurality at intervals in the circumferential direction, and lower communication holes 152 which connect the space in the lower header 170 with the space in the tubular portion 150 and are formed in plurality at intervals in the circumferential direction.

[0154] This makes it possible to uniformly distribute the flow rate of the refrigerant C to the refrigerant C flow paths.

[0155] The cooling system (21) is any one of the cooling systems (18) to (20), in which the heat exchange section 120 further has resistors 200 extending horizontally at predetermined intervals on the outer circumferential surface of the heat transfer tube 131 within the refrigerant passage P2.

[0156] The resistor 200 makes it easier to introduce the refrigerant C not only in the vertical direction but also in the horizontal direction, thereby making it possible to make the flow rate distribution throughout the heat exchange section 120 more uniform.

[0157] The cooling system (22) is the cooling system (21) in which the resistor 200 is formed so that the distance between the resistor 200 and the heat transfer tube 131 increases as the distance from the outside to the inside of the heat exchange section 120 in the radial direction.

[0158] This makes it easier for the refrigerant C to reach the radially inner side, which is difficult for the refrigerant C to reach. Therefore, the flow rate distribution can be made even more uniform.

[0159] The cooling system (23) is any of the cooling systems (18) to (22), in which the heat exchange section 120 further includes a blocking section 210 that blocks the space between the inner surface of the casing 140 and the outermost surface of the heat transfer tube group 130.

[0160] This makes it possible to prevent the refrigerant C from flowing through the gap between the heat transfer tube group 130 and the casing 140, which does not contribute to heat exchange.

[0161] The cooling system (24) is a cooling system of any of (18) to (23), in which the blower unit 90 has an impeller 93 that can rotate around an axis extending in the vertical direction, and a drive unit 91 that is arranged below the impeller 93 and drives the impeller 93 to rotate; the cooling system further includes an upper housing 100 that is cylindrical and extends in the vertical direction so as to surround the impeller 93 from the outer periphery, the inside of which is an air flow path, and the upper end of the upper housing 100 is connected to the lower end of the heat exchange unit 120; and a lower housing 80 that has an inner annular wall 84 that covers the drive unit 91 from the outer periphery and whose diameter decreases as it extends upward, and an outer annular wall 85 that covers the inner annular wall 84 from the outer periphery and whose diameter decreases as it extends upward, and which forms an air introduction flow path to the impeller 93 together with the inner annular wall 84.

[0162] This prevents the drive unit 91 from obstructing the air flow, making it possible to avoid drifting of the air. Also, a compact overall configuration can be achieved.

[0163] The cooling system (25) is the cooling system (24) in which a part of at least one of the upper housing 100 and the lower housing 80 is formed from a sound absorbing material.

[0164] This reduces noise to the surroundings.

[0165] The cooling system (26) is the cooling system (24) or (25), further comprising a flow straightener 110 provided in the air flow path within the upper housing 100, with a plurality of flow straightener holes 110a extending vertically and arranged horizontally.

[0166] This allows air to be introduced along the air passage P1 of the heat transfer tube 131. Therefore, the cooling performance can be stabilized without being affected by wind in the external environment.

[0167] The cooling system (27) is any one of the cooling systems (24) to (26) further including a water supply unit that supplies water to the air flow path in the upper housing 100.

[0168] This allows the cooling performance of the refrigerant C in the heat exchange section 120 to be further improved. [Explanation of symbols]

[0169] 1...First cooling system 2...Server 3...Refrigerant vessel 3a...Vessel bottom wall 3b...Vessel side wall 3c...Vessel top wall 10...Heat pipe 11...Leading edge 12...Trailing edge 13...Leading edge region 14...Trailing edge region 15...Partition section 16...Leading edge side passage 17...Trailing edge side passage 20...Plate-shaped fin 21...Through hole 21a...Abutting edge portion 21b...Abutted edge portion 25...Cover 27...Blower fan 30...Second cooling system 31...Container 32...Bottom wall 33...Side wall 34...Top wall 40...Heat exchanger 41...External heat transfer tube 42...Upstream header 43...Downstream header 44...External fin 47...Gas phase tube 48...Liquid phase tube 49...Duct forming section 50...Third cooling system 51...Heat radiator 51a...Heat radiating surface 60...Vapor film removal section (heat transfer promotion section) 61...Ultrasonic generator 62...Jet injector 63...Flow path forming section 64...Swirl flow generator 64a...Propeller 65...Binder 66...Heat dissipation fin 70...Fourth cooling system 80...Lower housing 81...Housing outer peripheral wall 81a...Outer peripheral opening 82...Housing bottom wall 83...Housing top wall 83a...Upper opening 84...Inner annular wall 85...Outer annular wall 88...Leg 90...Blower section 91...Drive section 92...Shaft section 93...Impeller 94...Boss section 95...Blade 100...Upper housing 100a...First inner peripheral surface 100b...Second inner peripheral surface 110...Flow straightener 110a...Flow straightening hole 112...Water injection section 120...Heat exchange section 130...Heat transfer tube group 131...heat transfer tube 131a...inner surface fin 140...casing 150...tubular portion 151...upper communicating hole 152...lower communicating hole 155...upper tube plate 156...lower tube plate 160...upper header 170...lower header 180...refrigerant supply portion 190...refrigerant discharge portion 200...resistance element 210...blocking portion C...refrigerant C1...first refrigerant C2...second refrigerant R...indoor E...outdoor F1...gas phase flow F2...liquid phase flow O...vertical axis P1...air passage P2...refrigerant passage D...passage interval

Claims

1. a heat transfer tube group having a plurality of heat transfer tubes extending linearly in the vertical direction and having air passages on the inside, the heat transfer tubes being bundled together at intervals to form refrigerant passages between the heat transfer tubes; a casing covering the heat transfer tube group such that both ends of each heat transfer tube are open to the outside; and a heat exchange unit having a refrigerant supply unit that supplies refrigerant into the casing and a refrigerant discharge unit that discharges refrigerant from the casing; a blower section provided below the heat exchange section and configured to blow air to the heat transfer tube group from below, The casing comprises: a cylindrical portion surrounding the heat transfer tube group from an outer periphery side; an upper header that surrounds the cylindrical portion from an outer circumferential side at an upper portion of the cylindrical portion and is provided with one of the refrigerant supply portion and the refrigerant discharge portion; a lower header that surrounds the cylindrical portion from an outer circumferential side at a lower portion of the cylindrical portion and is provided with the other of the refrigerant supply portion and the refrigerant discharge portion; The cylindrical portion is a plurality of upper communication holes that communicate a space within the upper header with a space within the cylindrical portion and are formed at intervals in the circumferential direction; a plurality of lower communication holes that communicate a space within the lower header with a space within the cylindrical portion and are formed at intervals in the circumferential direction; A cooling system having:

2. The heat exchange unit is 2. The cooling system according to claim 1, further comprising resistors extending horizontally at predetermined intervals on the outer circumferential surface of the heat transfer tube within the refrigerant passage.

3. The cooling system according to claim 2 , wherein the resistor is formed so that the distance between the resistor and the heat transfer tube increases from the outside to the inside in the radial direction of the heat exchange portion.

4. The cooling system according to claim 1 , wherein the heat exchanger further comprises a blocking portion that blocks a space between an inner surface of the casing and an outermost surface of the heat transfer tube group.

5. a heat transfer tube group having a plurality of heat transfer tubes extending linearly in the vertical direction and having air passages on the inside, the heat transfer tubes being bundled together at intervals to form refrigerant passages between the heat transfer tubes; a casing covering the heat transfer tube group such that both ends of each heat transfer tube are open to the outside; and a heat exchange unit having a refrigerant supply unit that supplies refrigerant into the casing and a refrigerant discharge unit that discharges refrigerant from the casing; a blower section provided below the heat exchange section and configured to blow air to the heat transfer tube group from below, The blower unit is an impeller that can rotate around an axis that extends in the vertical direction; a drive unit disposed below the impeller to drive the impeller to rotate; and an upper housing having a cylindrical shape extending in a vertical direction so as to surround the outer periphery of the impeller, the inside of which serves as an air flow path, and the upper end of which is connected to the lower end of the heat exchange unit; a lower housing including an inner wall that covers the drive unit from the outer periphery and tapers upward in diameter, and an outer wall that covers the inner wall from the outer periphery and tapers upward in diameter, and that, together with the inner wall, forms an introduction passage for air to the impeller; A cooling system comprising:

6. The cooling system of claim 5 , wherein a portion of at least one of the upper housing and the lower housing is formed from a sound-absorbing material.

7. 7. The cooling system according to claim 5, further comprising a flow rectifier provided in the air flow path within the upper housing, the flow rectifier having a plurality of flow rectifier holes that penetrate vertically and are arranged horizontally.

8. The cooling system according to claim 5 , further comprising a water supply unit that supplies water to the air flow path in the upper housing.

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