Heat exhaust device and server cooling system

Abstract

In a server cooling system S according to the present embodiment, a heat exhaust device 1 comprises: an air-cooled heat exchanger 30 that has a heat exchange core 30 including a first surface 30A and a second surface 30B; and a plurality of blowers 20 that cause air to flow by means of the rotation of impellers such that air gas flows from the first surface 30A to the second surface 30B. The heat exchange core 30 has a plurality of tubes 313, 323 for circulating a heat medium to undergo heat exchange with air. The tubes 313, 323 each extend from the second surface 30B side toward the first surface 30A side in a meandering manner. The heat medium flows through each of the tubes 313, 323 from the second surface 30B side toward the first surface 30A side.

Description

Heat dissipation devices and server cooling systems

[0001] FIELD An embodiment of the present invention relates to a heat dissipation device and a server cooling system.

[0002] Recently, demand for cloud services and artificial intelligence (AI) has been increasing rapidly, and as a result, the construction of new data centers is expanding rapidly.

[0003] Data centers are equipped with various devices such as servers. The servers installed in modern data centers are equipped with many computing devices such as CPUs and GPUs. These computing devices are performing computational processes that are much heavier than those used in the past.

[0004] The power consumption of a computing device increases in proportion to the load of the computing process on the computing device. As a result, the power consumption of devices such as servers in recent data centers has become extremely high.

[0005] Furthermore, the heat generation and temperature of a computing device increase in proportion to the processing load and power consumption of the device. Although the guaranteed operating temperature of a computing device is generally set relatively high, excessive temperature rise of the computing device can cause the computing device to malfunction. Therefore, in data centers, it is necessary to properly cool equipment such as servers.

[0006] Cooling of equipment such as servers has been performed for some time (e.g., JP2017-33427A). However, in recent data centers, the amount of heat generated by equipment such as servers has increased significantly compared to the past, and cooling of the equipment with significantly greater cooling capacity than before is required.

[0007] As described above, the computing devices in devices such as servers installed in modern data centers are performing computational processes with much heavier loads than before. As a result, the power consumption of devices such as servers is becoming much larger. In addition, the amount of heat generated by computing devices tends to be significantly larger than before. Therefore, in modern data centers, the increase in power consumption for computing and cooling is becoming a problem.

[0008] COP (Coefficient of Performance) is an index used to evaluate the efficiency of cooling relative to power consumption. COP is determined by cooling capacity / power consumption, with the higher the COP, the higher the cooling efficiency. In previous data centers, power consumption related to computing and cooling was not excessive, so it cannot be said that cooling equipment was necessarily constructed with an emphasis on COP. However, in future data center cooling, it is desirable to improve COP as much as possible.

[0009] Furthermore, when constructing cooling equipment in current and future data centers where large amounts of heat are expected to be generated, effective cooling cannot be achieved unless more careful consideration is given than before to factors such as installation costs and the characteristics of the data center's interior.

[0010] Specifically, in conventional data centers, equipment could generally be adequately cooled using only low-power, air-cooled heat rejection devices. However, such conventional heat rejection devices cannot adequately reject the heat generated by equipment in modern data centers, and therefore cannot adequately provide the desired cooling. In such situations, it may be considered possible to efficiently cool equipment by installing cooling towers, as in semiconductor manufacturing plants, in data centers. However, installing cooling towers may be over-specified for cooling data centers, and the introduction costs may become an issue. Furthermore, considering the operation of cooling towers, it cannot necessarily be said that they are efficient in terms of power consumption.

[0011] On the other hand, if an air-cooled heat dissipation device is used as before, a large cooling capacity can be secured by driving the fan with a large air volume. However, in this case, the COP may increase. Also, dust may fly up, creating an undesirable situation for equipment maintenance. Furthermore, noise may become a problem. Furthermore, increasing the air volume increases pressure loss, which may lead to saturation of cooling performance.

[0012] Furthermore, the use of cooling towers and large-volume fans can lead to an increase in the size of the heat dissipation equipment or the entire facility including the heat dissipation equipment. Although data centers generally have a relatively large installation space for equipment, if the space occupied by cooling equipment such as heat dissipation equipment can be reduced, the number of servers and other equipment installed can be increased. Therefore, it is naturally desirable to provide efficient cooling while reducing the space occupied by cooling equipment.

[0013] As described above, there are various points to consider regarding the cooling required in future data centers, and establishing effective cooling methods is currently in the trial and error stage.

[0014] In particular, the inventors of this invention predict that server racks with specifications that generate about 150 kW of heat per unit will be introduced in large numbers in future data centers. Specifically, if server racks with such specifications can be cooled in a manner suitable for data centers and extremely efficiently, this can contribute greatly to solving the power consumption problems expected in future data centers.

[0015] The present disclosure has been devised against the above background, and aims to provide a heat dissipation device and a server cooling system that can suitably achieve efficient cooling while reducing implementation costs and the space occupied by the device.

[0016] The embodiments of the present invention relate to the following aspects.

[0017] <1> A heat dissipation device comprising: an air-cooled heat exchanger having a heat exchange core including a first surface and a second surface opposite to the first surface; and a plurality of fans that move gas from the first surface to the second surface by rotating an impeller, wherein the heat exchange core has a plurality of tubes that carry a heat medium that exchanges heat with the gas, and each of the tubes extends in a serpentine manner from the second surface side toward the first surface side, and the heat medium flows in each of the tubes from the second surface side toward the first surface side.

[0018] <2> The heat dissipation device according to <1>, wherein the heat exchanger has an inlet portion that receives the heat medium from the outside and causes the heat medium to flow into the tubes, and the tubes each branch off in parallel from the inlet portion.

[0019] <3> The heat dissipation device according to <1> or <2>, wherein the tube forms a serpentine shape by alternately and sequentially connecting linearly extending main flow path elements and U-shaped turn-back flow path elements, the plurality of blowers are arranged such that extension lines of the rotation axes of the impellers are perpendicular to the second surface, and adjacent main flow path elements connected by the turn-back flow path elements do not overlap at least partially when viewed in a direction from the first surface toward the second surface.

[0020] <4> The heat dissipation device described in any one of <1> to <3>, wherein the heat exchanger has a plurality of plate fins extending parallel to a direction from the first surface toward the second surface and arranged in a direction perpendicular to the direction from the first surface toward the second surface, and the tube extends in a serpentine manner from the second surface side toward the first surface side while penetrating the plurality of plate fins and contacts the plate fins.

[0021] <5> The heat dissipation device according to claim 1, wherein the plurality of fans are arranged in a plurality of rows and a plurality of columns.

[0022] <6> The areas of the first surface and the second surface of the heat exchange core are each 1.5 m ２ 1.7m or more ２ The air volume of the gas flowed by the plurality of blowers is set to 345 m ３ / min or more 375m ３ / min or less, the heat medium is selected and the flow rate of the heat medium is set so that a value (C·L) obtained by multiplying a specific heat C (kJ / kg·K) of the heat medium at 20°C to 40°C and a flow rate L (L / min) of the heat medium is between 250 and 320, and a cooling capacity of 140 kW or more and 160 kW or less is output.

[0023] <7> The heat dissipation device according to <6>, wherein a heat medium cooling efficiency (LPM / kW) determined by dividing a flow rate (L / min: LPM) of the heat medium by the cooling capacity is 1.4 or more.

[0024] <8> The heat dissipation device according to <6> or <7>, which has a COP of 15 or more and outputs a cooling capacity of 140 kW or more and 160 kW or less.

[0025] <9> The heat exchanger has a plurality of plate fins extending parallel to a direction from the first surface toward the second surface and arranged in a direction perpendicular to the direction from the first surface toward the second surface, the tubes extend in a serpentine manner from the second surface side toward the first surface side while penetrating the plurality of plate fins and contacting the plate fins, and the sum of the area of ​​the heat exchange surfaces of the plurality of plate fins and the area of ​​the heat exchange surface of the tubes is 600 m ２ The heat dissipation device according to any one of <1> to <8> above.

[0026] <10> The heat dissipation device according to <2>, wherein the heat exchange cores include a first heat exchange core and a second heat exchange core, and the first heat exchange core and the second heat exchange core are arranged adjacent to each other, the heat exchanger includes, as the inlet portion, an inlet portion connected to the tube of the first heat exchange core and an inlet portion connected to the tube of the second heat exchange core, which are separated from each other, the inlet portion connected to the tube of the first heat exchange core and the inlet portion connected to the tube of the second heat exchange core each extend in a direction in which the first heat exchange core and the second heat exchange core are adjacent to each other, and the inlet portion connected to the tube of the first heat exchange core and the inlet portion connected to the tube of the second heat exchange core are arranged so as to be offset in a direction from the first surface toward the second surface, and so that, when viewed in the direction from the first surface toward the second surface, an end portion of the inlet portion connected to the tube of the first heat exchange core, which is on the second heat exchange core side, overlaps an end portion of the inlet portion connected to the tube of the second heat exchange core, which is on the first heat exchange core side.

[0027] <11> The heat dissipation device according to <10>, wherein the heat medium inlet at the inlet portion connected to the tubes of the first heat exchange core and the heat medium inlet at the inlet portion connected to the tubes of the second heat exchange core open in a direction from the first surface toward the second surface or in the opposite direction.

[0028] <12> The heat dissipation device according to any one of <1> to <11>, wherein the heat dissipation device includes two of the heat exchangers, the two heat exchangers being arranged to form a V-shape, and some of the plurality of blowers being arranged adjacent to one of the two heat exchangers in a state where an extension line of the rotation axis of the impeller intersects the second surface of one of the two heat exchangers, and another part of the plurality of blowers being arranged adjacent to the other of the two heat exchangers in a state where an extension line of the rotation axis of the impeller intersects the second surface of the other of the two heat exchangers.

[0029] <13> The heat dissipation device according to <12>, wherein the setting of the air volume of the gas circulated by the plurality of fans or the setting of the rotation speed of the plurality of fans differs depending on the distance between each of the fans and the adjacent heat exchanger.

[0030] <14> A server cooling system comprising: the heat dissipation device according to any one of <1> to <13> above; and a server rack to which the heat medium is supplied from the heat dissipation device, wherein the server rack has a cooling flow path that receives and circulates the heat medium after heat exchange with the gas, and returns the heat medium flowing out of the cooling flow path to the heat dissipation device.

[0031] According to the embodiment of the present invention, efficient cooling can be suitably achieved while reducing the introduction cost and the space occupied by the device.

[0032] 1. A perspective view of a server cooling system according to an embodiment. 1. A view of a heat dissipation device constituting the server cooling system shown in FIG. 1, as seen in the direction of arrow II in FIG. 1. 2. A cross-sectional view of the heat dissipation device taken along line III-III in FIG. 2. 3. A view of a heat exchanger constituting the heat dissipation device, as seen in the direction of arrow IV in FIG. 3. 4. A side view of the heat exchanger shown in FIG. 4. 5. A top view of a heat exchange core (upper heat exchange core) in the heat exchanger shown in FIG. 5. 6. A view of the heat exchange core with plate fins removed, as shown in FIG. 7. 7. A cross-sectional view taken along line VIII-VIII in FIG. 7. 8. A view explaining a connection mode between a heat dissipation device and a server rack constituting the server cooling system shown in FIG. 1. 9. A table explaining an example of specifications of the server cooling system shown in FIG. 1. 10. A view of a heat dissipation device according to a first modified example. 11. A view of a heat dissipation device according to a second modified example. 12. A view of a heat dissipation device according to a third modified example. 13. A view of a heat dissipation device according to a fourth modified example. 14. A view of a heat dissipation device according to a fifth modified example. 15. A cross-sectional view of the fifth modified example taken along line XVI-XVI in FIG. 15.

[0033] An embodiment will be described below.

[0034] 1 is a perspective view of a server cooling system S according to an embodiment. The server cooling system S includes a heat dissipation device 1 and a server rack 100.

[0035] The heat dissipation device 1 and the server rack 100 are installed adjacent to each other in the horizontal direction. Fig. 1 shows an example in which the server cooling system S is installed in a data center. However, the location in which the server cooling system S is used is not limited to a data center.

[0036] The server rack 100 houses multiple servers 102 as electronic devices inside a rack body 101. The rack body 101 has shelves (not shown) arranged vertically. In the example shown, a server 102 is installed on each of the multiple shelves in the rack body 101. As a result, the multiple servers 102 are housed in the rack body 101 stacked vertically. The server 102 may be configured to include, for example, a computing device such as a CPU or GPU, a memory, etc.

[0037] <Heat Exhaust Device> The heat exhaust device 1 is a device that removes heat generated from the servers 102 inside the rack body 101, thereby cooling the servers 102. The heat exhaust device 1 includes a rectangular parallelepiped housing 10, an air-cooled heat exchanger 30 (see FIGS. 3 and 4, etc.), and a blower 20.

[0038] The housing 10 is open on both sides in a direction perpendicular to the horizontal plane and the direction in which the heat dissipation device 1 and the server rack 100 are adjacent to each other. The housing 10 houses a heat exchanger 30 therein. The blower 20 is held in the housing 10 so as to fill the open portion on one side of the housing 10.

[0039] The heat exchanger 30 is an air-cooled type that cools the heat medium by exchanging heat between the heat medium, which is a liquid, circulating inside the heat exchanger 30 and air, which is a gas. The blower 20 moves the air through the heat exchanger 30, thereby promoting heat exchange between the heat medium and the air.

[0040] In the heat dissipation device 1, the heat medium cooled in the heat exchanger 30 is supplied to the server rack 100, where it absorbs heat from the servers 102 to cool them. After cooling the servers 102, the heat medium returns to the heat exchanger 30. The heat medium that has returned to the heat exchanger 30 is cooled again by air and then supplied again to the server rack 100. The fan 20 and heat exchanger 30 that constitute the heat dissipation device 1 will be described in detail below.

[0041] (Blower) Fig. 2 is a view of the heat exhaust device 1 as seen in the direction of arrow II in Fig. 1. Fig. 3 is a cross-sectional view of the heat exhaust device 1 taken along line III-III in Fig. 2.

[0042] As shown in Fig. 2, the heat dissipation device 1 includes a plurality of fans 20. In this embodiment, the plurality of fans 20 are arranged adjacent to the heat exchanger 30, and are arranged in a plurality of rows and a plurality of columns. Specifically, the fans 20 are adjacent to the heat exchanger 30 in the horizontal direction. A state in which the fans 20 are adjacent to the heat exchanger 30 in the horizontal direction refers to a positional relationship between the fans 20 and the heat exchanger 30 in which a straight line extending horizontally from any part of the fans 20 passes through any part of the heat exchanger 30.

[0043] In FIG. 3 , the reference numeral 30C denotes a heat exchange core 30C in a heat exchanger 30 that exchanges heat between a heat medium and air. The heat exchange core 30C includes a first surface 30A and a second surface 30B opposite the first surface 30A. Specifically, the plurality of blowers 20 are arranged adjacent to the second surface 30B of the heat exchange core 30C. In particular, the blowers 20 are preferably arranged adjacent to the second surface 30B of the heat exchange core 30C such that an extension line of the rotation axis Ax of the impeller 21 (described later) intersects with the second surface 30B of the heat exchange core 30C, as is the case in this embodiment. The first surface 30A of the heat exchange core 30C faces one side in the opening direction of the housing 10, and the second surface 30B of the heat exchange core 30C faces the other side in the opening direction of the housing 10.

[0044] The blower 20 includes an impeller 21 and a casing 22 that supports the impeller 21 so that it can rotate about a rotation axis Ax. The blower 20 is an axial flow type. The rotation of the impeller 21 causes the air to flow from the first surface 30A to the second surface 30B of the heat exchange core 30C. Specifically, each of the multiple blowers 20 is arranged adjacent to the second surface 30B of the heat exchange core 30C, with an extension of the rotation axis Ax of the impeller 21 intersecting, specifically, perpendicular to, the second surface 30B. In this embodiment, the rotation axis Ax of the impeller 21 of each blower 20 is aligned (parallel) to the horizontal direction; however, the blowers 20 may be arranged so that the rotation axis Ax of the impeller 21 is inclined relative to the horizontal direction.

[0045] In this embodiment, the multiple fans 20 are specifically arranged in eight rows and four columns. That is, the heat exchanger 30 includes 32 fans 20. The number and arrangement of the fans 20 are not limited, and only one fan 20 may be used. However, when multiple fans 20 are used, if one of the fans 20 is damaged, the remaining fans 20 can circulate air, thereby preventing a decrease in the performance of the heat dissipation device 1. Furthermore, compared to using one large fan, the power required to obtain the desired cooling capacity can be reduced.

[0046] In particular, when the fans 20 are arranged in four or more rows or columns, allocating two or more fans 20 vertically or horizontally based on or near the center of the heat exchange core 30C can effectively prevent a performance degradation of the heat dissipation device 1 when one of the fans 20 is damaged. In this embodiment, 16 fans 20 are allocated vertically and horizontally based on the center of the heat exchange core 30C. When multiple fans 20 are used, each fan 20 may have the same structure and size, or may have different structures and / or sizes. In this embodiment, each fan 20 has the same structure and size and is basically driven at the same rotational speed and outputs the same air volume when supplied with the same power. In this embodiment, all of the multiple fans 20 are driven to output the same air volume, but the air volume or rotational speed of some fans 20 may be different from that of the other fans. For example, within the housing 10 or a matrix of fans 20, frictional resistance to air flow may be greater on the periphery than on the center. Taking this into consideration, the air volume or rotation speed of the blower 20 located on the outer periphery (closer to the housing 10) among the multiple blowers 20 may be made larger than that of the blower 20 located closer to the center than the blower on the outer periphery.

[0047] Furthermore, when the blowers 20 are arranged in four or more rows or columns, the amount of air passing linearly from the first surface 30A to the second surface 30B can be increased. This can be advantageous in terms of suppressing pressure loss and improving heat exchange efficiency. In this embodiment, the blowers 20 are arranged adjacent to the second surface 30B. However, the blowers 20 may be arranged adjacent to the first surface 30A and cause the gas to flow from the first surface 30A to the second surface 30B. However, since the temperature of the gas increases as it passes through the blowers 20, from the viewpoint of cooling efficiency, it is preferable to arrange the blowers 20 downstream of the heat exchange core 30C, i.e., adjacent to the second surface 30B.

[0048] (Heat Exchanger) The heat exchanger 30 includes a heat exchange core 30C including the first surface 30A and the second surface 30B described above. As shown in Fig. 3, the heat exchange core 30C has a plurality of tubes 313, 323 through which a heat medium flows. The heat exchange core 30C cools the heat medium by exchanging heat between the heat medium flowing through the tubes 313, 323 and air passing through the heat exchange core 30C. The first surface 30A and the second surface 30B are parallel to each other, but may be non-parallel.

[0049] Fig. 4 is a view of the heat exchanger 30 as viewed in the direction of arrow IV in Fig. 3. Fig. 5 is a side view of the heat exchanger 30 shown in Fig. 4. As shown in Figs. 3 to 5, the heat exchange core 30C in this embodiment includes an upper heat exchange core 310 and a lower heat exchange core 320. The upper heat exchange core 310 is stacked on the lower heat exchange core 320 from above. The upper heat exchange core 310 corresponds to the first heat exchange core, and the lower heat exchange core 320 corresponds to the second heat exchange core, and are arranged adjacent to each other.

[0050] The upper heat exchange core 310 includes an upper first surface 310A and an upper second surface 310B opposite the upper first surface 310A. The lower heat exchange core 320 includes a lower first surface 320A and a lower second surface 320B opposite the lower first surface 320A. The upper first surface 310A and the lower first surface 320A are aligned vertically to form the first surface 30A of the heat exchange core 30C. The upper second surface 310B and the lower second surface 320B are aligned vertically to form the second surface 30B of the heat exchange core 30C.

[0051] Both the upper heat exchange core 310 and the lower heat exchange core 320 are generally rectangular parallelepipeds. The upper and both side portions of the upper heat exchange core 310 are covered by and connected to an upper frame 311. The lower and both side portions of the lower heat exchange core 320 are covered by and connected to a lower frame 321. The upper and lower heat exchange cores 310, 320 are integrated by vertically connecting the upper frame 311 and the lower frame 321 to form the heat exchange core 30C.

[0052] The heat exchanger 30 has inlet sections 315, 325 that receive the heat medium from the outside (server rack 100 side) and allow it to flow into the tubes 313, 323, and outlet sections 316, 326 that receive the heat medium flowing out of the tubes 313, 323 and allow it to flow out to the outside (server rack 100 side).

[0053] In this embodiment, the upper heat exchange core 310 has tubes 313, and the lower heat exchange core 320 has tubes 323. As shown in Figures 4 and 5, the heat exchanger 30 includes, as inlet sections 315, 325, an upper inlet section 315 connected to the tubes 313 of the upper heat exchange core 310 and a lower inlet section 325 connected to the tubes 323 of the lower heat exchange core 320, which are separate from each other. The heat exchanger 30 also includes, as outlet sections 316, 326, an upper outlet section 316 connected to the tubes 313 of the upper heat exchange core 310 and a lower outlet section 326 connected to the tubes 323 of the lower heat exchange core 320, which are separate from each other.

[0054] The tubes 313 in the upper heat exchange core 310 each have an upstream end connected to the upper inlet section 315 so as to branch off in parallel from the upper inlet section 315. The downstream ends of the tubes 313 in the upper heat exchange core 310 are connected to the upper outlet section 316. Similarly, the tubes 323 in the lower heat exchange core 320 each have an upstream end connected to the lower inlet section 325 so as to branch off in parallel from the lower inlet section 325. The downstream ends of the tubes 323 in the lower heat exchange core 320 are connected to the lower outlet section 326.

[0055] Specifically, an upper inlet pipe 315P having a heat medium inlet 315a and a plurality of upper first relay pipes 315b are connected to the upper inlet section 315. A plurality of upper second relay pipes 316a and an upper outlet pipe 316P having a heat medium outlet 316b are connected to the upper outlet section 316. The plurality of upper first relay pipes 315b are connected to the upstream ends of the corresponding tubes 313. The plurality of upper second relay pipes 316a are connected to the downstream ends of the corresponding tubes 313. The plurality of upper first relay pipes 315b and the plurality of upper second relay pipes 316a are aligned vertically, and the plurality of tubes 313 to which they are connected are also aligned vertically.

[0056] With the above-described connection configuration, in the upper heat exchange core 310, the heat medium flowing into the upper inlet 315 from the inlet 315a flows from the upper inlet 315 through the upper first relay pipes 315b into each tube 313. Then, the heat medium flowing out from the downstream end of each tube 313 flows into the upper outlet 316 through the upper second relay pipes 316a and can flow out from the outlet 316b of the upper outlet 316.

[0057] Similarly, a lower inlet pipe 325P having a heat medium inlet 325a and a plurality of lower first relay pipes 325b are connected to the lower inflow section 325. A plurality of lower second relay pipes 326a and a lower outlet pipe 326P having a heat medium outlet 326b are connected to the lower outflow section 326. The plurality of lower first relay pipes 325b are connected to the upstream ends of the corresponding tubes 323. The plurality of lower second relay pipes 326a are connected to the downstream ends of the corresponding tubes 323. The flow of the heat medium on the lower side is similar to the flow of the heat medium on the upper side described above.

[0058] In this embodiment, the heat medium inlets 315a, 325a in the upper inlet section 315 and the lower inlet section 325 and the heat medium outlets 316b, 326b in the upper outlet section 316 and the lower outlet section 326 open in a direction from the second surface 30B toward the first surface 30A. The upper inlet pipe 315P, the upper outlet pipe 316P, the lower inlet pipe 325P, and the lower outlet pipe 326P extend in a direction from the second surface 30B toward the first surface 30A. In this case, the lateral protrusion of the heat medium inlet and outlet portions is suppressed, which is advantageous in terms of reducing the overall size of the heat exchanger 30 and ensuring the area of ​​the heat exchange core 30C. Note that the inlets 315a, 325a and the outlets 316b, 326b may also open in a direction from the first surface 30A toward the second surface 30B. Furthermore, the heat medium inlets 315a, 325a in the upper inlet section 315 and the lower inlet section 325 are formed on the lower side of the corresponding heat exchange core. The heat medium outlets 316b, 326b in the upper outlet section 316 and the lower outlet section 326 are formed on the upper side of the corresponding heat exchange core. In this case, the flow path lengths of the heat medium branching in parallel become uniform, enabling uniform cooling throughout the entire heat exchange core.

[0059] As shown in FIG. 5 , the upper inlet section 315 and the lower inlet section 325 are each a tubular body. The upper inlet section 315 and the lower inlet section 325 are located on one side of the heat exchange core 30C, closer to the second surface 30B. The upper inlet section 315 and the lower inlet section 325 extend vertically, in other words, in the direction in which the upper heat exchange core 310 and the lower heat exchange core 320 are adjacent to each other. The upper inlet section 315 and the lower inlet section 325 are positioned so as to be offset from each other in the direction from the first surface 30A toward the second surface 30B. Furthermore, the upper inlet section 315 and the lower inlet section 325 are positioned so that the lower part of the upper inlet section 315 overlaps the upper part of the lower inlet section 325 when viewed in the direction from the first surface 30A toward the second surface 30B (see also FIG. 4 ). In other words, the upper end of the lower inlet section 325 is located higher than the lower end of the upper inlet section 315, and the upper part of the lower inlet section 325 including the upper end of the lower inlet section 325 overlaps with the upper inlet section 315.

[0060] Similarly, the upper outlet section 316 and the lower outlet section 326 are also tubular bodies. The upper outlet section 316 and the lower outlet section 326 are disposed on one side of the heat exchange core 30C, closer to the first surface 30A. The upper outlet section 316 and the lower outlet section 326 extend in the vertical direction. The upper outlet section 316 and the lower outlet section 326 are also disposed so as to be offset in the direction from the first surface 30A toward the second surface 30B. Furthermore, the upper outlet section 316 and the lower outlet section 326 are disposed so that the lower part of the upper outlet section 316 overlaps the upper part of the lower outlet section 326 when viewed in the direction from the first surface 30A toward the second surface 30B.

[0061] In this embodiment, as described above, the upper inlet section 315 and the lower inlet section 325 are arranged so as to be offset in the direction from the first surface 30A to the second surface 30B. Furthermore, the upper outlet section 316 and the lower outlet section 326 are arranged so as to be offset in the direction from the first surface 30A to the second surface 30B. In this case, it is possible to bring the upper heat exchange core 310 and the lower heat exchange core 320 closer to each other in the vertical direction while avoiding undesired interference between the components, which is advantageous in terms of reducing the overall size and ensuring the area of ​​the heat exchange core 30C.

[0062] 5, in the present embodiment, the upstream ends of the tubes 313 of the upper heat exchange core 310 are positioned at the same position as the upstream ends of the tubes 323 of the lower heat exchange core 320 in the direction from the first surface 30A to the second surface 30B. On the other hand, as described above, the upper inlet section 315 and the lower inlet section 325 are shifted in the direction from the first surface 30A to the second surface 30B.

[0063] Here, the upper-stage first relay pipe 315b connected to the upper-stage inlet section 315 is formed in an arc-shaped or substantially L-shaped pipe, and the lower-stage first relay pipe 325b is formed in a straight pipe shape. The upper-stage inlet section 315 is located closer to the first surface 30A than the lower-stage inlet section 325, and the arc-shaped or substantially L-shaped upper-stage first relay pipe 315b moves in a direction from the first surface 30A toward the second surface 30B, approaching the upstream ends of the tubes 313 and connecting with the tubes 313. The lower-stage inlet section 325 is located so as to face the upstream ends of each tube 323 of the lower-stage heat exchange core 320, and is connected to the upstream ends of each tube 323 by the straight lower-stage first relay pipe 325b in the shortest distance. This ensures fluid connection between each tube 313 of the upper heat exchange core 310 and the upper inlet section 315, and fluid connection between each tube 323 of the lower heat exchange core 320 and the lower inlet section 325, without shifting the position of the upstream end of each tube 313 of the upper heat exchange core 310 and the position of the upstream end of each tube 323 of the lower heat exchange core 320.

[0064] On the other hand, the upper-stage second relay pipe 316a connected to the upper-stage outlet section 316 is formed as a straight pipe, and the lower-stage second relay pipe 326a is formed as a circular arc or a substantially L-shaped pipe. This ensures fluid connection between each tube 313 of the upper-stage heat exchange core 310 and the upper-stage outlet section 316, and between each tube 323 of the lower-stage heat exchange core 320 and the lower-stage outlet section 326, without misaligning the downstream ends of the tubes 313 of the upper-stage heat exchange core 310 and the lower-stage heat exchange core 320. This connection configuration allows the upper-stage heat exchange core 310 and the lower-stage heat exchange core 320 to share a common structure, which is advantageous in terms of ease of manufacture. Furthermore, differences in heat exchange performance between the upper and lower heat exchange cores are suppressed, enabling effective heat exchange.

[0065] FIG. 6 is a top view of the heat exchange core 30C (upper heat exchange core 310) in the heat exchanger 30 shown in FIG. 5 . FIG. 6 shows plate fins 314 provided on the upper heat exchange core 310. The plate fins 314 extend parallel to the direction from the first surface 30A to the second surface 30B and are spaced apart in a direction perpendicular to the direction. The tubes 313 penetrate the plate fins 314, extending in a serpentine manner from the second surface 30B toward the first surface 30A, and contact the plate fins 314. Specifically, the tubes 313 penetrate the plate fins 314 in a direction perpendicular to the plate fins 314. In this embodiment, the plate fins 314 are provided so that their heat exchange surfaces (two surfaces facing opposite each other in the thickness direction) are parallel to each other in the vertical direction. As shown in FIG. 4 , the lower heat exchange core 320 also has plate fins 324 similar to the plate fins 314.

[0066] As described above, the upper inlet section 315 and the lower inlet section 325 are positioned closer to the second surface 30B. The upper outlet section 316 and the lower outlet section 326 are positioned closer to the first surface 30A. Here, the tubes 313, 323 each extend from the second surface 30B side toward the first surface 30A side, meandering in the left-right direction in this example. As a result, in the heat exchanger 30, the heat medium flows in each of the tubes 313, 323 from the second surface 30B side toward the first surface 30A side. Meanwhile, air flows from the first surface 30A side toward the second surface 30B side due to the drive of the blower 20. In other words, the heat exchanger 30 is configured as a counterflow heat exchanger in which the heat medium and air travel in opposite directions to exchange heat.

[0067] Fig. 7 is a diagram showing the upper heat exchange core 310 shown in Fig. 6 with the plate fins 314 removed. Fig. 8 is a cross-sectional view taken along line VIII-VIII in Fig. 7. The shape of the tubes 313 will be described in detail below with reference to Figs. 6 to 8.

[0068] 6 and 7 , the tube 313 forms a serpentine shape by alternately and sequentially connecting linearly extending main flow path elements 313a and U-shaped return flow path elements 313b. The multiple main flow path elements 313a are arranged parallel to each other and aligned in the direction of air flow caused by the drive of the blower 20. The main flow path element 313a located most upstream in the air flow direction constitutes the first surface 30A, and the main flow path element 313a located most downstream in the air flow direction constitutes the second surface 30B. The heat exchange core 30C has a generally rectangular parallelepiped shape, and the first surface 30A and the second surface 30B correspond to two opposite faces of the generally rectangular parallelepiped shape.

[0069] The main flow path element 313a constituting the second surface 30B has an end opposite to the end connected to the return flow path element 313b connected to the upper-stage first relay pipe 315b. The main flow path element 313a constituting the first surface 30A has an end opposite to the end connected to the return flow path element 313b connected to the upper-stage second relay pipe 316a.

[0070] 8, two adjacent main flow path elements 313a connected by a turn-back flow path element 313b do not overlap at least partially when viewed in the direction from the first surface 30A to the second surface 30B (from left to right in FIG. 8). Specifically, in this embodiment, two adjacent main flow path elements 313a connected by a turn-back flow path element 313b are spaced apart by a distance d1 in the vertical direction and do not entirely overlap when viewed in the direction from the first surface 30A to the second surface 30B. Furthermore, between two adjacent tubes 313 in the vertical direction, the main flow path elements 313a of one tube 313 and the main flow path elements 313a of the other tube 313 that are close to each other are also spaced apart by a distance d2 in the vertical direction.

[0071] When the main flow path elements 313a are arranged as described above, air can easily come into contact with each of the main flow path elements 313a, which can be advantageous in terms of improving heat exchange efficiency and suppressing excessive increases in pressure loss. Note that the tubes 323 in the lower heat exchange core 320 also have a shape similar to that of the tubes 313.

[0072] In addition, in this embodiment, plate fins 314, 324 are used as the fins in the heat exchanger 30, but corrugated fins or disk-shaped aerofins may also be used. However, in this embodiment, plate fins are used from the viewpoint of suppressing an excessive increase in pressure loss.

[0073] (Connection between heat dissipation device and server rack) Hereinafter, a connection between the heat dissipation device 1 and the server rack 100 will be described with reference to Fig. 9. The heat dissipation device 1 includes a first pump 41 and a second pump 42 for circulating the heat medium. The first pump 41 and the second pump 42 may be, for example, centrifugal pumps driven by electric motors, but the type thereof is not particularly limited.

[0074] The first pump 41 is connected to the inlet 315a of the upper inlet 315 connected to the upper heat exchange core 310. The second pump 42 is connected to the inlet 325a of the lower inlet 325 connected to the lower heat exchange core 320. That is, in this embodiment, the heat medium is supplied to the upper heat exchange core 310 and the lower heat exchange core 320 from separate pumps 41 and 42. This reduces the load on each pump 41 and 42. In particular, in this embodiment, since the upper heat exchange core 310 and the lower heat exchange core 320 are stacked vertically, using a single pump would require a large amount of power to ensure the required head, so using separate pumps has a significant energy-saving effect. However, the heat medium may be supplied to the entire heat exchange core 30C from a single pump.

[0075] The heat medium that flows into the tubes 313 from the upper inlet 315 flows in a serpentine pattern from the second surface 30B toward the first surface 30A and then flows out from the outlet 316b. The heat medium that flows into the tubes 323 from the lower inlet 325 flows in a serpentine pattern from the second surface 30B toward the first surface 30A and then flows out from the outlet 326b. The heat medium that flows out from the outlets 316b and 326b then join together and flows into the server rack 100.

[0076] The server rack 100 has a plurality of cooling channels 110 that receive and circulate the heat medium after heat exchange with the air, and returns the heat medium flowing out of the cooling channels 110 to the heat dissipation device 1. The heat medium flowing through the cooling channels 110 removes heat from the servers 102. The heat medium flowing out of the cooling channels 110 is then sucked by the first pump 41 and the second pump 42, returns to the heat dissipation device 1, and is cooled again.

[0077] 9, arrows α indicate the direction of air flow caused by the driving of the blower 20. Arrows β indicate the direction of the heat medium flowing from the second surface 30B side to the first surface 30A side in the upper heat exchange core 310 and the lower heat exchange core 320. Heat exchange between the air and the heat medium is performed in a counterflow manner.

[0078] In the server cooling system S according to the present embodiment described above, the heat dissipation device 1 includes an air-cooled heat exchanger 30 having a heat exchange core 30C including a first surface 30A and an opposite second surface 30B, and a plurality of fans 20 arranged adjacent to the second surface 30B. The fans 20 rotate impellers to move air as gas from the first surface 30A to the second surface 30B. The heat exchange core 30C includes a plurality of tubes 313, 323 through which a heat medium flows, exchanging heat with the air. The tubes 313, 323 each extend in a serpentine pattern from the second surface 30B toward the first surface 30A, and the heat medium flows through the tubes 313, 323 from the second surface 30B toward the first surface 30A.

[0079] In this configuration, the air and the heat medium exchange heat in a counterflow manner in the heat exchanger core 30C, thereby uniformly exchanging heat with the entire tubes 313 and 323, thereby improving heat exchange efficiency. Furthermore, by using multiple blowers 20, the load on each blower required to achieve the desired cooling capacity can be reduced. This reduces the power, noise, and size of the heat exchanger core required to achieve the desired cooling capacity. Furthermore, by circulating the heat medium through multiple tubes 313 and 323, the overall flow path length and complexity of the flow path shape of the tubes 313 and 323 can be reduced. This reduces the power required for the pump to circulate the heat medium and the pump's power consumption required to achieve the desired cooling capacity. As a result, the COP can be improved. Furthermore, the adoption of air cooling reduces installation costs, and the reduction in the blower power required to achieve the desired cooling capacity as described above reduces the dispersion of dust and other particles. Therefore, efficient cooling can be achieved while reducing installation costs and the space required for the device.

[0080] The heat exchanger 30 also has inlet portions 315, 325 that receive the heat medium from the outside and allow it to flow into the tubes 313, 323. The tubes 313, 323 are connected to the inlet portions 315, 325 so as to branch in parallel from appropriate positions of the inlet portions 315, 325. In this case, by allowing the heat medium to flow in parallel from the inlet portions 315, 325 into the corresponding plurality of tubes 313, 323, the power of the pumps (41, 42) that circulate the heat medium can be effectively reduced and the structure of the inlet path of the heat medium into the tubes 313, 323 can be simplified.

[0081] The blowers 20 are arranged such that the extension of the rotation axis Ax of the impeller 21 is perpendicular to the second surface 30B, and the tubes 313 are formed in a serpentine shape by alternately connecting linear main flow path elements 313a and U-shaped return flow path elements 313b. Adjacent main flow path elements 313a connected by return flow path elements 313b do not overlap at least partially when viewed from the first surface 30A toward the second surface 30B. This facilitates air contact with each main flow path element 313a, improving heat exchange efficiency and effectively reducing the power consumption of the blowers 20. The tubes 323 have a similar structure to the tubes 313.

[0082] The heat exchanger 30 also has a plurality of plate fins 314, 324 that extend parallel to the direction from the first surface 30A to the second surface 30B and are aligned in a direction perpendicular to the direction from the first surface 30A to the second surface 30B (in this example, horizontally). The tubes 313, 323 extend in a serpentine manner from the second surface 30B side to the first surface 30A side while penetrating the plate fins 314, 324 and come into contact with the plate fins 314, 324. In this case, heat dissipation from the plate fins 314, 324 improves heat exchange efficiency. In particular, the extension of the plate fins 314, 324 parallel to the axial flow direction reduces pressure loss, effectively reducing the power consumption of the blower 20.

[0083] Furthermore, the multiple fans 20 are arranged in multiple rows and multiple columns. In this case, even if one of the fans 20 fails, the fan function can be effectively maintained and a decrease in cooling performance can be suppressed. Furthermore, compared to a configuration in which a single fan is provided to cover a wide area of ​​the heat exchange core 30C, the power required to obtain a desired air volume can be reduced and a large effective area for heat exchange of the heat exchange core 30C can be ensured. This effectively reduces the power required for the fans 20 to obtain the desired cooling capacity and improves cooling efficiency.

[0084] The heat exchange core 30C includes an upper heat exchange core 310 and a lower heat exchange core 320, with the upper heat exchange core 310 stacked on top of the lower heat exchange core 320. The heat exchanger 30 includes inlet sections 315, 325: an upper inlet section 315 connected to the tubes 313 in the upper heat exchange core 310, and a lower inlet section 325 connected to the tubes 323 in the lower heat exchange core 320. The upper inlet section 315 and the lower inlet section 325 each extend in the vertical direction. The upper inlet section 315 and the lower inlet section 325 are positioned so as to be offset from each other in the direction from the first surface 30A to the second surface 30B, and so that the lower part of the upper inlet section 315 overlaps the upper part of the lower inlet section 325 when viewed in the direction from the first surface 30A to the second surface 30B.

[0085] In this case, the heat medium can be branched and supplied to the upper heat exchange core 310 and the lower heat exchange core 320 from the two pumps 41, 42, thereby reducing the power required for the pumps 41, 42. Furthermore, by arranging the lower part of the upper inlet section 315 to overlap the upper part of the lower inlet section 325, the overall size of the heat exchange core 30C can be increased while reducing the area occupied by the entire heat exchanger 30, thereby improving the heat exchange efficiency.

[0086] (Example of Condition Settings) Below, we will explain a specific example of how the above-mentioned server cooling system S is used. The inventors predict that a large number of server racks with specifications that generate heat per unit of approximately 150 kW will be introduced into data centers in the future. The above-mentioned server cooling system S can be configured to function extremely effectively at a cooling capacity of 150 kW or thereabouts. Specifically, by setting the following conditions (1) to (3) for the heat dissipation device 1, it is possible for the heat dissipation device 1 to perform cooling at or near 150 kW with an extremely high coefficient of performance (COP).

[0087] Condition (1): The areas of the first surface 30A and the second surface 30B of the heat exchange core 30C are each 1.5 m ２ 1.7m or more ２ The following conditions are set: Condition (2): The volume of gas (air) circulated by the plurality of fans 20 is set to 345 m ３ / min or more 375m ３ Condition (3): The heat medium is selected and the flow rate of the heat medium is set so that the product (C·L) of the specific heat C (kJ / kg·K) of the heat medium at 20°C to 40°C and the flow rate L (L / min) of the heat medium is between 250 and 320.

[0088] Under the above conditions, the server cooling system S can output a cooling capacity of 140 kW or more and 160 kW or less with a COP of 15 or more. More specifically, the inventors have confirmed that the server cooling system S can output a cooling capacity of 140 kW or more and 160 kW or less with an average COP of 20 or more, and with a COP of at least 15 or more even if there are fluctuations due to various conditions.

[0089] When the condition (1) is set, the size of the fins and the size of the heat exchange portion that can be installed are roughly determined. Preferably, the total area of ​​the heat exchange surfaces of the plate fins 314 and 324 provided in the heat exchanger 30 and the heat exchange surfaces of the tubes 313 and 323 is 600 m ２ It is preferable to set the heat exchange surface of the plate fins 314, 324 to a value equal to or greater than 1 mm. The heat exchange surface of the plate fins 314, 324 refers to the two surfaces of the plate fins 314, 324 that face opposite each other in the thickness direction. The heat exchange surface of the tubes 313, 323 refers to the outer surfaces of the tubes 313, 323 that are exposed to the outside. The total area of ​​both surfaces is determined by multiplying the total area of ​​the two surfaces of the plate fins 314, 324 by the total number of plate fins 314, 324, and adding this to the surface area of ​​the outer surfaces of the tubes 313, 323 excluding the connection portions with the plate fins 314, 324. The outer diameter D of the tubes 313, 323 may be 8 mm or more and 20 mm or less. For example, the spacing between adjacent tubes 313, 323 in the vertical direction in FIG. 5 may be 0.5D or more and 0.45D or less.

[0090] The air volume determined under the condition (2) above is not excessively large, but is a value that is beneficial in terms of power saving. In addition, it is also desirable from the viewpoint of suppressing noise and dust scattering. The air volume of the gas (air) circulated by the multiple fans 20 under the condition (2) is determined by the total air volume set for each fan 20.

[0091] In addition to the above conditions (1) to (3), it is desirable that the heat exchange core 30C be configured so that the pressure loss when air having a velocity of 5.5 m / s passes through it is 5 Pa or less.

[0092] 10 shows a table illustrating an example of specifications for a server cooling system S that satisfies the above conditions (1) to (3) and uses a polyethylene glycol aqueous solution with a specific heat capacity of 3.841 (kJ / kg·K) at 40°C as a heat medium, outputting a cooling capacity of 150 kW. In this example of specifications, when the servers 102 in the server rack 100 heat up to 70°C and generate 150 kW of heat, the servers 102 are cooled to 40°C and absorb 150 kW of heat. In the example of specifications in FIG. 10, a COP of 15 or higher is achieved, and 150 kW of cooling is achieved.

[0093] According to the inventors' knowledge, when attempting to cool 150 kW using a typical cooling system previously used in data centers, the COP is approximately 5 to 10. Compared to this previous system, the server cooling system S according to this embodiment can output the same cooling capacity with a COP that is roughly twice as high (in this example, 15 or higher). Such cooling capacity of the server cooling system S contributes greatly to energy conservation.

[0094] The heat medium circulated through the heat exchanger 30 is not particularly limited. For example, a fluorine-based inert liquid having a specific heat capacity of approximately 1.000 to 1.200 (kJ / kg·K) at 20°C may be used as the heat medium. In this case, the flow rate of the heat medium is set to approximately 195 to 320 (L / min). When the flow rate is set relatively high, it is expected that effective cooling can be achieved by increasing the number of flow paths in the server rack 100 or by increasing the complexity of the flow path configuration and circulating a large amount of heat medium. Furthermore, since the viscosity of the fluorine-based inert liquid is relatively low, the pump power does not become excessively large. When using a heat medium with a relatively low specific heat capacity, it is preferable to set the heat medium cooling efficiency (LPM / kW), determined by dividing the heat medium flow rate (L / min: LPM) by the cooling capacity, to 1.4 or higher. This heat medium cooling efficiency may be 1.4 to 1.6 or 1.45 to 1.55.

[0095] <Modifications> Modifications will be described below. Configurations in the following modifications that are the same as those in the above-described embodiment will be assigned the same reference numerals, and duplicated descriptions will be omitted.

[0096] (First Modification) Fig. 11 shows a heat dissipation device according to a first modification. In this modification, four fans 20 are arranged in a vertical row. In the heat exchanger 30, a first pump 41 is connected to the upper side, and a second pump 42 is connected to the lower side. The use of multiple pumps is beneficial in a specification where the heat exchanger is long in the vertical direction.

[0097] (Second Modification) Fig. 12 shows a heat dissipation device according to a second modification. In this modification, the heat exchange core 30C of the heat exchanger 30 does not have a multi-stage structure. The heat exchange core 30C is composed only of a portion corresponding to the upper heat exchange core 310. A plurality of fans 20 are arranged adjacent to the heat exchange core 30C in four rows and four columns. In the above-described embodiment, the heat exchange core 30C is configured to connect the upper heat exchange core 310 and the lower heat exchange core 320, but the heat exchange core 30C may be configured to connect three or more heat exchange core elements.

[0098] (Third Modification) Fig. 13 shows a heat dissipation device according to a third modification. More specifically, Fig. 13 is a view showing the inside of the heat dissipation device along a horizontal direction perpendicular to the direction in which gaseous air flows due to the blower 20. The heat dissipation device according to the third modification includes a first heat exchanger 30-1 and a second heat exchanger 30-2. The first heat exchanger 30-1 and the second heat exchanger 30-2 are separate from each other and are not connected to each other.

[0099] The first heat exchanger 30-1 and the second heat exchanger 30-2 are rectangular parallelepiped or plate-shaped, and are arranged adjacent to each other vertically to form a V-shape when viewed horizontally.

[0100] The first heat exchanger 30-1 and the second heat exchanger 30-2 each include the upper heat exchange core 310 described in the above embodiment as their main component. In FIG. 13, the same reference numerals are used to designate the same components of the upper heat exchange core 310 as those of the first heat exchanger 30-1 and the second heat exchanger 30-2. Although not shown, the first heat exchanger 30-1 and the second heat exchanger 30-2 each have a plurality of plate fins 314 that extend parallel to the direction from the first surface 30A to the second surface 30B and are aligned in a direction perpendicular to the direction from the first surface 30A to the second surface 30B, i.e., horizontally in this example. The tubes 313 in the first heat exchanger 30-1 and the second heat exchanger 30-2 are arranged so as to be aligned in the direction in which the first heat exchanger 30-1 and the second heat exchanger 30-2 are inclined. On the other hand, when the first heat exchanger 30-1 and the second heat exchanger 30-2 are arranged to form a V-shape as in this modified example, the tubes 313 may be arranged in a matrix rather than a staggered arrangement as in the above-described embodiment, since suitable heat exchange can be achieved even if the tubes are arranged in a matrix.

[0101] The multiple fans 20 are arranged adjacent to the first heat exchanger 30-1 (second surface 30B) and the second heat exchanger 30-2 (second surface 30B), which are arranged to form a V-shape. The multiple fans 20 are arranged on the same plane. More specifically, some of the multiple fans 20 are arranged adjacent to the first heat exchanger 30-1, and other parts of the multiple fans 20 are arranged adjacent to the second heat exchanger 30-2. Although not shown in the drawings, in this example, 16 fans 20 arranged in four rows and four columns are arranged adjacent to the first heat exchanger 30-1, and 16 fans 20 arranged in four rows and four columns are arranged adjacent to the second heat exchanger 30-2. More specifically, 16 fans 20, which are a part of the plurality of fans 20, are arranged adjacent to the first heat exchanger 30-1, with an extension line of the rotation axis Ax of each impeller 21 intersecting the second surface 30B of the heat exchange core 30C of the first heat exchanger 30-1. Another 16 fans 20, which are a part of the plurality of fans 20, are arranged adjacent to the second heat exchanger 30-2, with an extension line of the rotation axis Ax of each impeller 21 intersecting the second surface 30B of the heat exchange core 30C of the second heat exchanger 30-2. However, the number of fans 20 to be used is not particularly limited.

[0102] In the example of Figure 13, the first heat exchanger 30-1 and the second heat exchanger 30-2 are arranged to form an obtuse V-shape, but they may also be arranged to form an acute V-shape, or the first heat exchanger 30-1 and the second heat exchanger 30-2 may be arranged so that they are not inclined symmetrically.

[0103] 13, the symbols L1 to L4 indicate the multiple (four) fans 20 lined up in the vertical direction and the distance from each fan 20 to the first heat exchanger 30-1 (its heat exchange core 30C). The closer to the bottom of the V-shape, the longer the distance from the fan 20 to the heat exchange core 30C, with the relationship L1 > L2 > L3 > L4. Here, in the third modified example, the setting of the airflow rate of the air (gas) circulated by the multiple fans 20 and / or the setting of the rotation speed of the multiple fans 20 differs depending on the distance between each fan 20 and the first heat exchanger 30-1 adjacent to it.

[0104] Specifically, in this modification, each fan 20 has the same structure and size, and basically, when the same power is applied, they are driven at the same rotation speed and output the same air volume. Here, in this modification, the value of the power supplied to fan 20 is changed depending on the distance between fan 20 and first heat exchanger 30-1.

[0105] Specifically, when the first heat exchanger 30-1 is tilted vertically and the rotation axis of the blower 20 is horizontal as in this modification, air flowing horizontally may flow at an angle perpendicular to the first and second surfaces 30A and 30B of the first heat exchanger 30-1. In this case, the air flowing out from the second surface 30B of the first heat exchanger 30-1 may tend to flow with a component that moves from the blower 20 side, where the distance to the heat exchange core 30C is shorter, toward the blower 20 side, where the distance is longer. In this case, the proportion of the air component that is tilted relative to the impeller 21 increases in the air drawn into the blower 20, which may impair the smooth flow of air. Therefore, for example, the air volume of the blower 20 may be set so as to satisfy the relationship: air volume of the blower 20 when the distance to the heat exchange core 30C is L1 < air volume of the blower 20 when the distance to the heat exchange core 30C is L2 < air volume of the blower 20 when the distance to the heat exchange core 30C is L3 < air volume of the blower 20 when the distance to the heat exchange core 30C is L4. In other words, the rotation speed of the blower 20 may be set so as to satisfy the relationship: rotation speed of the blower 20 when the distance to the heat exchange core 30C is L1 < rotation speed of the blower 20 when the distance to the heat exchange core 30C is L2 < rotation speed of the blower 20 when the distance to the heat exchange core 30C is L3 < rotation speed of the blower 20 when the distance to the heat exchange core 30C is L4. For example, such a setting may make it easier for air to pass through the first heat exchanger 30-1, thereby improving cooling efficiency. In other words, the pressure loss can be suppressed, and the cooling efficiency can be improved.

[0106] That is, in the case where the first heat exchanger 30-1 and the second heat exchanger 30-2 are arranged to form a V-shape and the distance from each fan 20 to the heat exchanger is not constant, the air can flow smoothly by increasing the airflow rate or rotation speed of the fan 20 among the multiple fans 20 that is relatively short to the heat exchange core 30C compared to the fan 20 with a longer distance to the heat exchange core 30C than the fan 20 with a relatively short distance. However, depending on the structure of the heat dissipation device, the airflow rate or rotation speed of the fan 20 among the multiple fans 20 that is short to the heat exchange core 30C may be reduced compared to the fan 20 with a longer distance to the heat exchange core 30C, which may be advantageous in some cases.

[0107] (Fourth Modification) Figure 14 shows a heat dissipation device according to a fourth modification. More specifically, Figure 14 is a view showing the inside of the heat dissipation device. The heat dissipation device according to the fourth modification includes a first heat exchanger 30-1 and a second heat exchanger 30-2, similar to those of the third modification. However, it differs from the third modification in that the first heat exchanger 30-1 and the second heat exchanger 30-2 are arranged adjacent to each other in the horizontal direction and form a V-shape when viewed from above.

[0108] 14 , 16 blowers 20 arranged in four rows and four columns are arranged adjacent to the first heat exchanger 30-1, and 16 blowers 20 arranged in four rows and four columns are arranged adjacent to the second heat exchanger 30-2. Specifically, 16 blowers 20, which are a part of the plurality of blowers 20, are arranged adjacent to the first heat exchanger 30-1, with the extension lines of the rotation axes Ax of the impellers 21 intersecting with the second surface 30B of the heat exchange core 30C of the first heat exchanger 30-1. Another part of the plurality of blowers 20, 16 blowers 20, are arranged adjacent to the second heat exchanger 30-2, with the extension lines of the rotation axes Ax of the impellers 21 intersecting with the second surface 30B of the heat exchange core 30C of the second heat exchanger 30-2. However, the number of blowers 20 used is not particularly limited. 14, the first heat exchanger 30-1 and the second heat exchanger 30-2 are arranged to form an obtuse V-shape, but they may also be arranged to form an acute V-shape, or the first heat exchanger 30-1 and the second heat exchanger 30-2 may be arranged symmetrically without tilting. Although not shown, the first heat exchanger 30-1 and the second heat exchanger 30-2 each have a plurality of plate fins 314 that extend parallel to the direction from the first surface 30A to the second surface 30B and are aligned in a direction perpendicular to the direction from the first surface 30A to the second surface 30B, which in this example is horizontal. The tubes 313 in the first heat exchanger 30-1 and the second heat exchanger 30-2 are arranged so that the first heat exchanger 30-1 and the second heat exchanger 30-2 are aligned vertically.

[0109] 14, the reference symbols L1' to L4' indicate the multiple (four) fans 20 arranged horizontally and the distance from each fan 20 to the first heat exchanger 30-1 (its heat exchange core 30C). The closer to the bottom of the V-shape, the longer the distance from the fan 20 to the heat exchange core 30C, with the relationship L1' > L2' > L3' > L4'. In the fourth modification, too, the setting of the airflow rate of the air (gas) circulated by the multiple fans 20 and / or the setting of the rotation speed of the multiple fans 20 differs depending on the distance between each fan 20 and the adjacent first heat exchanger 30-1.

[0110] Specifically, in this modification, each fan 20 has the same structure and size, and basically, when the same power is applied, the fans 20 are driven at the same rotation speed and output the same air volume. Also in this modification, the value of the power supplied to the fan 20 is changed depending on the distance between the fan 20 and the first heat exchanger 30-1.

[0111] Specifically, when the rotation axis of the blower 20 is horizontal and the first heat exchanger 30-1 is inclined relative to a direction perpendicular to the horizontal plane of the rotation axis of the blower 20, as in this modified example, air flowing horizontally may flow at an angle perpendicular to the first and second surfaces 30A and 30B of the first heat exchanger 30-1 as it passes through the first heat exchanger 30-1. In this case, the air flowing out from the second surface 30B of the first heat exchanger 30-1 may tend to flow with a component moving from the blower 20 side, where the distance to the heat exchange core 30C is shorter, toward the blower 20 side, where the distance is longer. This tendency is particularly likely to occur when the plate fins 314 extend parallel to the direction from the first surface 30A to the second surface 30B and are aligned horizontally, as in the configuration of this modified example. In this case, the proportion of the air component inclined relative to the impeller 21 increases in the air drawn into the blower 20, potentially impairing the smooth flow of air.

[0112] Therefore, in this modification, the airflow rate of the blower 20 may be set so as to satisfy the relationship: airflow rate of the blower 20 when the distance to the heat exchange core 30C is L1' < airflow rate of the blower 20 when the distance to the heat exchange core 30C is L2' < airflow rate of the blower 20 when the distance to the heat exchange core 30C is L3' < airflow rate of the blower 20 when the distance to the heat exchange core 30C is L4'. In other words, the rotation speed of the blower 20 may be set so as to satisfy the relationship: rotation speed of the blower 20 when the distance to the heat exchange core 30C is L1' < rotation speed of the blower 20 when the distance to the heat exchange core 30C is L2' < rotation speed of the blower 20 when the distance to the heat exchange core 30C is L3' < rotation speed of the blower 20 when the distance to the heat exchange core 30C is L4'. In this case, the same effects as those described in the third modification can be obtained.

[0113] (Fifth Modification) Figures 15 and 16 show a heat dissipation device according to a fifth modification. More specifically, Figure 15 shows the external appearance of the heat dissipation device according to the fifth modification, and Figure 16 is a cross-sectional view taken along line XVI-XVI in Figure 15. Similar to the fourth modification, the heat dissipation device according to the fifth modification includes a first heat exchanger 30-1 and a second heat exchanger 30-2 arranged to form a V-shape when viewed from above. However, it differs from the fourth modification in that the first heat exchanger 30-1 and the second heat exchanger 30-2 are arranged to form an acute-angled V-shape.

[0114] In this modified example, 40 fans 20 arranged in 20 rows and 2 columns are arranged adjacent to the first heat exchanger 30-1, and 40 fans 20 arranged in 20 rows and 2 columns are arranged adjacent to the second heat exchanger 30-2. More specifically, 40 fans 20 arranged in 20 rows and 2 columns, which are a part of the plurality of fans 20, are arranged adjacent to the first heat exchanger 30-1 in a state where an extension line of the rotation axis Ax of each impeller 21 intersects with the second surface 30B of the heat exchange core 30C of the first heat exchanger 30-1. Another part of the plurality of fans 20, 40 fans 20 arranged in 20 rows and 2 columns, are arranged adjacent to the second heat exchanger 30-2 with the extension line of the rotation axis Ax of each impeller 21 intersecting the second surface 30B of the heat exchange core 30C of the second heat exchanger 30-2. Each fan 20 is arranged on the same plane and held by the housing 10. The number of fans 20 used is not particularly limited, but it is preferable to provide fans arranged in multiple rows and multiple columns for one heat exchanger.

[0115] In FIG. 16, the symbols L1" and L2" indicate the multiple (two) blowers 20 lined up horizontally and the distance from each blower 20 to the first heat exchanger 30-1 (its heat exchange core 30C). The closer to the bottom of the V-shape, the longer the distance from the blower 20 to the heat exchange core 30C, with the relationship L1" > L2". In the fifth modified example as well, the setting of the airflow rate of the air (gas) circulated by the multiple blowers 20 and / or the setting of the rotation speed of the multiple blowers 20 differs depending on the distance between each blower 20 and the adjacent first heat exchanger 30-1.

[0116] Specifically, the air volume of the blower 20 is set so that the relationship is: air volume of the blower 20 when the distance to the heat exchange core 30C is L1" < air volume of the blower 20 when the distance to the heat exchange core 30C is L2". In other words, the rotation speed of the blower 20 is set so that the relationship is: rotation speed of the blower 20 when the distance to the heat exchange core 30C is L1" < rotation speed of the blower 20 when the distance to the heat exchange core 30C is L2".

[0117] That is, in this modification, the air can flow smoothly by setting the air volume or rotation speed of the blower 20 that is located at a relatively short distance to the heat exchange core 30C among the multiple blowers 20 to be larger than that of the blower 20 that is located at a relatively short distance to the heat exchange core 30C. When the first heat exchanger 30-1 and the second heat exchanger 30-2 are arranged to form an acute V-shape, setting the air volume or rotation speed in this manner can be particularly effective.

[0118] In the third to fifth modified examples, the first heat exchanger 30-1 and the second heat exchanger 30-2 are arranged to form a V-shape, with the bottom of the V-shape facing away from the blower 20. Instead of this layout, the first heat exchanger 30-1 and the second heat exchanger 30-2 may be arranged with the bottom of the V-shape facing towards the blower 20.

[0119] The above-described embodiment and modifications are merely examples for realizing the present invention, and the present invention can be implemented in various other forms. For example, various modifications, substitutions, omissions, or combinations thereof are possible without departing from the spirit of the present invention. Forms incorporating such modifications, substitutions, omissions, etc. are also included within the scope of the present invention, and are included in the scope of the inventions described in the claims and their equivalents.

[0120] S...server cooling system, 1...heat dissipation device, 10...housing, 20...blower, 21...impeller, 22...casing, 30...heat exchanger, 30-1...first heat exchanger, 30-2...second heat exchanger, 30A...first surface, 30B...second surface, 30C...heat exchange core, 310...upper heat exchange core, 310A...upper first surface, 310B...upper second surface, 311...upper frame, 313...tube, 313a...main flow path element, 313b...turned flow path element, 314...plate fin, 315...upper inlet section (inlet section), 315a...inlet, 315P...upper inlet pipe, 315b...upper first relay pipe, 316...upper outlet section (Outlet portion), 316a...upper second relay pipe, 316b...outlet, 316P...upper outlet pipe, 320...lower heat exchange core, 320A...lower first surface, 320B...lower second surface, 321...lower frame, 323...tube, 324...plate fin, 325...lower inlet portion (inlet portion), 325a...inlet, 325P...lower inlet pipe, 325b...lower first relay pipe, 326...lower outlet portion (outlet portion), 326a...lower second relay pipe, 326b...outlet, 326P...lower outlet pipe, 41...first pump, 42...second pump, 100...server rack, 101...rack body, 102...server, 110...refrigerant flow path

Claims

1. A heat dissipation device comprising: an air-cooled heat exchanger having a heat exchange core including a first surface and a second surface opposite the first surface; and a plurality of fans that move gas from the first surface to the second surface by rotating impellers, wherein the heat exchange core has a plurality of tubes through which a heat medium that exchanges heat with the gas flows, and each of the tubes extends in a serpentine manner from the second surface side toward the first surface side, and the heat medium flows in each of the tubes from the second surface side toward the first surface side.

2. The heat dissipation device according to claim 1, wherein the heat exchanger has an inlet portion that receives the heat medium from the outside and causes it to flow into the tubes, and the tubes each branch out in parallel from the inlet portion.

3. The heat dissipation device of claim 1, wherein the tube forms a serpentine shape by alternately and sequentially connecting linearly extending main flow path elements and U-shaped turn-back flow path elements, the plurality of blowers are arranged such that an extension line of the rotation axis of the impeller is perpendicular to the second surface, and adjacent main flow path elements connected by the turn-back flow path elements do not overlap at least partially when viewed in a direction from the first surface toward the second surface.

4. The heat dissipation device described in claim 1, wherein the heat exchanger has a plurality of plate fins extending parallel to the direction from the first surface toward the second surface and aligned in a direction perpendicular to the direction from the first surface toward the second surface, and the tube extends in a serpentine manner from the second surface side toward the first surface side while penetrating the plurality of plate fins and contacting the plate fins.

5. The heat dissipation device according to claim 1, wherein the plurality of fans are arranged in a plurality of rows and a plurality of columns.

6. The areas of the first and second surfaces of the heat exchange core are each 1.5 m ２ 1.7m or more ２ The air volume of the gas flowed by the plurality of blowers is set to 345 m ３ / min or more 375m ３ / min or less, the heat medium is selected and the flow rate of the heat medium is set so that a value (C·L) obtained by multiplying a specific heat C (kJ / kg·K) of the heat medium at 20°C to 40°C and a flow rate L (L / min) of the heat medium is between 250 and 320, and a cooling capacity of 140 kW or more and 160 kW or less is output.

7. The heat dissipation device according to claim 6, wherein the heat medium cooling efficiency (LPM / kW) determined by dividing the flow rate (L / min: LPM) of the heat medium by the cooling capacity is 1.4 or more.

8. The heat dissipation device according to claim 6, which has a COP of 15 or more and outputs a cooling capacity of 140 kW or more and 160 kW or less.

9. The heat exchanger has a plurality of plate fins extending parallel to the direction from the first surface toward the second surface and arranged in a direction perpendicular to the direction from the first surface toward the second surface, the tubes extend in a serpentine manner from the second surface side toward the first surface side while penetrating the plurality of plate fins and contacting the plate fins, and the sum of the area of ​​the heat exchange surfaces of the plurality of plate fins and the area of ​​the heat exchange surfaces of the tubes is 600 m ２ The heat dissipation device according to any one of claims 6 to 8.

10. The heat dissipation device described in claim 2, wherein the heat exchange cores include a first heat exchange core and a second heat exchange core, and the first heat exchange core and the second heat exchange core are arranged adjacent to each other, the heat exchanger includes, as the inlet portions, an inlet portion connected to the tubes of the first heat exchange core and an inlet portion connected to the tubes of the second heat exchange core, which are separated from each other, the inlet portion connected to the tubes of the first heat exchange core and the inlet portion connected to the tubes of the second heat exchange core each extend in a direction in which the first heat exchange core and the second heat exchange core are adjacent to each other, and the inlet portion connected to the tubes of the first heat exchange core and the inlet portion connected to the tubes of the second heat exchange core are arranged so as to be offset in a direction from the first surface toward the second surface, and so that, when viewed in a direction from the first surface toward the second surface, the end of the inlet portion connected to the tubes of the first heat exchange core on the second heat exchange core side overlaps the end of the inlet portion connected to the tubes of the second heat exchange core on the first heat exchange core side.

11. A heat dissipation device as described in claim 10, wherein the heat medium inlet at the inlet portion connected to the tubes of the first heat exchange core and the heat medium inlet at the inlet portion connected to the tubes of the second heat exchange core open in a direction from the first surface toward the second surface or in the opposite direction.

12. The heat dissipation device according to claim 1, wherein the heat dissipation device comprises two of the heat exchangers, the two heat exchangers being arranged to form a V-shape, and a portion of the plurality of blowers being arranged adjacent to one of the two heat exchangers with an extension line of the rotation axis of the impeller intersecting the second surface of one of the two heat exchangers, and another portion of the plurality of blowers being arranged adjacent to the other of the two heat exchangers with an extension line of the rotation axis of the impeller intersecting the second surface of the other of the two heat exchangers.

13. A heat dissipation device as described in claim 12, wherein the setting of the volume of the gas circulated by the plurality of fans or the setting of the rotation speed of the plurality of fans differs depending on the distance between each fan and the adjacent heat exchanger.

14. A server cooling system comprising: a heat dissipation device according to claim 1; and a server rack to which the heat medium is supplied from the heat dissipation device, wherein the server rack has a cooling flow path that receives and circulates the heat medium after heat exchange with the gas, and returns the heat medium flowing out of the cooling flow path to the heat dissipation device.

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