Cooling device

Abstract

To provide a cooling apparatus capable of suppressing the transition from nucleate boiling to film boiling.SOLUTION: In a cooling system, a cooling apparatus 10 comprises: a hollow casing 11 having a bottom plate 12 placed on a heating element 4c, a top plate 13 opposite the bottom plate, and side plates 14 connecting the bottom plate 12 and the top plate 13 at the outer periphery; a heat exchanger 20 provided in the hollow casing 11 and on the bottom plate 12, through which a refrigerant can circulate inside; a supply section 30 that supplies refrigerant from the outside to the inside of the hollow casing 11; a discharge section 40 that discharges refrigerant from inside the hollow casing 11 to the outside; and an agitator 70 for stirring the refrigerant in the heat exchanger.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This disclosure relates to a cooling device. [Background technology]

[0002] In recent years, with the advancement of high-density semiconductor packaging, the amount of heat generated by CPUs and GPUs has been increasing. As a result, air cooling is insufficient to adequately cool heat-generating components such as CPUs and GPUs, and measures have been taken to locally cool these components using cold plates, such as the one disclosed in Patent Document 1. The cold plate in Patent Document 1 has a plate body in which a refrigerant channel is formed. In this type of cold plate, the refrigerant inside the plate body is boiled to remove heat from the heat-generating components, thereby cooling them. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 4410065 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In cooling systems that utilize the boiling of a refrigerant as described above, as semiconductor density increases, the heat flux on the heating surface of the cooling system rises, making it easier for the system to transition from nucleate boiling to film boiling. In film boiling, a vapor film with a low heat transfer coefficient is interposed between the heating element and the liquid refrigerant, reducing cooling efficiency. Therefore, the cooling system needs to be designed to be somewhat large to prevent the transition from nucleate boiling to film boiling, which naturally limits the density of semiconductor packaging. Given these circumstances, it is necessary to suppress the transition from nucleate boiling to film boiling.

[0005] This disclosure was made to solve the above-mentioned problems and aims to provide a cooling device that can suppress the transition from nucleate boiling to film boiling. [Means for solving the problem]

[0006] To solve the above problems, the cooling device according to the present disclosure comprises a hollow casing having a bottom plate on which a heating element is placed, a top plate opposite to the bottom plate, and side plates connecting the bottom plate and the top plate on the outer periphery; a heat exchanger provided on the bottom plate within the casing, through which a refrigerant can flow; a supply unit for supplying refrigerant into the casing from the outside; a discharge unit for discharging refrigerant from the casing to the outside; and a stirring unit for stirring the refrigerant inside the heat exchanger. The heat exchanger connects the bottom plate and the top plate, and forms a frame-shaped outer peripheral passage that surrounds the entire circumference of the heat exchanger between it and the side plates of the casing. . [Effects of the Invention]

[0007] The cooling device of this disclosure can suppress the transition from nucleate boiling to film boiling. [Brief explanation of the drawing]

[0008] [Figure 1] This is a diagram showing the configuration of a cooling system equipped with a cooling device according to the first embodiment of this disclosure. [Figure 2] This is a perspective view of a cooling device according to the first embodiment of this disclosure. [Figure 3] This is a plan view of a cooling device according to the first embodiment of the present disclosure. [Figure 4] This is an enlarged side view showing the configuration near the plate fins of a cooling device according to the first embodiment of this disclosure. [Figure 5] This is a side view of a cooling device according to the second embodiment of this disclosure. [Figure 6] This is an enlarged plan view showing a heat exchanger according to a second embodiment of the present disclosure. [Figure 7] This is a side view of a cooling device according to a first modification of the second embodiment of the present disclosure. [Figure 8] This is a side view of a cooling device according to a second modification of the second embodiment of the present disclosure. [Figure 9] This is a side view of a cooling device according to a third modification of the second embodiment of the present disclosure. [Figure 10]This is a side view of a cooling device according to the third embodiment of this disclosure. [Modes for carrying out the invention]

[0009] <First Embodiment> Hereinafter, the cooling device 10 according to the first embodiment of this disclosure will be described with reference to Figures 1 to 4. As shown in Figure 1, the cooling device 10 of this embodiment is mounted on a cooling system 1 that cools the server 4. Figure 1 is a schematic diagram showing the overall configuration of the cooling system 1. In the illustrated example, the server 4 is housed in a rack 2 that extends in the vertical direction Dv. Multiple server chassis 3 are inserted into the rack 2. The server chassis 3 is a box-shaped enclosure. Multiple server chassis 3 are arranged in a row in the vertical direction Dv. Furthermore, multiple servers 4 are inserted into the server chassis 3. These multiple servers 4 are inserted horizontally in a sideways orientation.

[0010] Server 4 comprises a server casing 4a, a server board 4b, and chips (heat-generating elements) 4c such as a CPU and GPU. The server casing 4a is a rectangular parallelepiped enclosure extending horizontally. The server board 4b is housed inside the server casing 4a. The server board 4b is equipped with chips 4c. Since chips 4c generate heat during operation, a cooling system 1 is installed to cool the chips 4c.

[0011] (Cooling system configuration) The cooling system 1 includes a cooling device 10, a heat exchanger 5, a pump 6, and a control unit 7. The cooling device 10 is mounted for each chip 4c. A refrigerant F is supplied to the cooling device 10. This refrigerant F is, for example, a refrigerant such as HFC (Hydro Fluoro Carbon) or HFO (Hydro Fluoro Olefin), or water. The cooling device 10 is a cold plate that cools the chip 4c by causing heat exchange between the refrigerant F and the chip 4c. The cooling device 10 of the present embodiment cools a high heat-generating heat source by boiling cooling of the refrigerant F. The cooling device 10 is connected to the heat exchanger 5 and the pump 6 by a refrigerant pipe 8. The refrigerant F heated by heat exchange with the chip 4c in the cooling device 10 is sent to the heat exchanger 5 through the refrigerant pipe 8. The heat exchanger 5 is a so-called condenser. The heat exchanger 5 cools the refrigerant F and condenses the gaseous-phase refrigerant F into a liquid-phase refrigerant F. The refrigerant F cooled by the heat exchanger 5 is sent to the pump 6 through the refrigerant pipe 8. The pump 6 pumps the refrigerant F toward the cooling device 10 again. The refrigerant F pumped to the cooling device 10 exchanges heat with each chip 4c again and cools each chip 4c. Various devices constituting the cooling system 1 such as the cooling device 10, the heat exchanger 5, and the pump 6 are controlled by the control unit 7.

[0012] In FIG. 1, an example is shown in which three chips 4c and cooling devices 10 are provided for each server 4, but the number of chips 4c and cooling devices 10 can be changed as appropriate. For example, about eight chips 4c and cooling devices 10 may be provided for each server 4.

[0013] (Configuration of the cooling device) Hereinafter, the configuration of the cooling device 10 will be described. As shown in FIGS. 2 and 3, the cooling device 10 includes a casing 11, a heat exchanger 20, a supply pipe (supply unit) 30, a discharge pipe (discharge unit) 40, and a stirring unit 70.

[0014] In the following, one predetermined direction intersecting the vertical direction Dv will be referred to as the first direction D1, and the direction intersecting both the vertical direction Dv and the first direction D1 will be referred to as the second direction D2. In this embodiment, both the first direction D1 and the second direction D2 are horizontal. Furthermore, the first direction D1 and the second direction D2 are orthogonal to each other.

[0015] (Casing) The casing 11 is formed in a hollow shape from a material with excellent heat conductivity, such as metal. The outer shape of the casing 11 is formed in a rectangular parallelepiped shape, as if it has been flattened horizontally. In a plan view in the vertical direction Dv, the four corners 11a of the casing 11 are formed in a curved shape that protrudes outward, as if chamfered. In a plan view in the vertical direction Dv, the casing 11 is formed to be approximately the same size as the outer edge of the heating element.

[0016] The casing 11 described above can be designed to any dimensions. For example, in this embodiment, the casing 11 is formed in a square shape when viewed in the vertical direction Dv. The height H1 of the casing 11 in the vertical direction Dv is, for example, about 10 mm, and the width W1 in the first direction D1 and the width L1 in the second direction D2 of the casing 11 are, for example, about 55 mm. The casing 11 may be formed in a rectangular shape, shorter in the second direction D2 compared to the first direction D1. In this case, for example, the width L1 of the casing 11 in the second direction D2 may be about 30 mm.

[0017] The casing 11 has a bottom plate 12, a top plate 13, and side plates 14. The base plate 12 is placed on the chip 4c. The base plate 12 extends horizontally. The top plate 13 is positioned above the bottom plate 12 and faces the bottom plate 12 in the vertical direction Dv. The top plate 13 extends horizontally.

[0018] The side panels 14 connect the bottom panel 12 and the top panel 13 on their outer edges. Four side panels 14 are arranged between the bottom panel 12 and the top panel 13. The four side panels 14 include two first side panels 14a facing the first direction D1 and two second side panels 14b facing the second direction D2. The first side panels 14a extend in the second direction D2, and the second side panels 14b extend in the first direction D1. In addition, each side panel 14 is arranged perpendicular to the top panel 13 and the bottom panel 12.

[0019] (heat exchanger) The heat exchanger 20 is provided on the bottom plate 12 within the casing 11. More specifically, the heat exchanger 20 is positioned in a location that overlaps with the region containing the center of gravity of the casing 11 (hereinafter, this region may be referred to as the central region Ac) in a vertical view Dv plane. In this embodiment, the center of gravity of the heat exchanger 20 is positioned to overlap with the center of gravity of the casing 11 in a vertical view Dv plane. Hereinafter, the region within the casing 11 in which the heat exchanger is formed will be referred to as the heat exchange region A1. The heat exchange region A1 includes the central region Ac of the casing 11 in a vertical view Dv plane. The heat exchanger 20 forms an outer peripheral passage 15 between itself and the side plate 14 of the casing 11. The outer peripheral passage 15 is formed in a rectangular frame shape when viewed from the vertical view Dv. Furthermore, the inside of the heat exchanger 20 is open to the flow of the refrigerant F. Details of the configuration of the heat exchanger 20 will be described later.

[0020] (supply pipe) The supply pipe 30 is connected from outside the casing 11 to a first side plate 14a, one of the multiple side plates 14 that make up the casing 11. The supply pipe 30 is a circular pipe having a supply opening 31 that is connected to the side plate 14 and communicates with the inside of the casing 11. The supply opening 31 opens in a horizontal direction that intersects the vertical direction Dv. In this embodiment, the supply opening 31 is provided in the center of the first side plate 14a. The supply pipe 30 is connected to the pump 6 via the refrigerant pipe 8 and supplies refrigerant F from outside the casing 11 to the outer peripheral passage 15.

[0021] (Exhaust pipe) The discharge pipe 40 is connected from outside the casing 11 to the top plate 13 that constitutes the casing 11. More specifically, the discharge pipe 40 is connected to a region of the top plate 13 that overlaps with the heat exchanger 20 in a plan view in the vertical direction Dv. The discharge pipe 40 is a circular pipe having a discharge opening 41 that is connected to the top plate 13 and communicates with the inside of the casing 11. The discharge opening 41 opens in the vertical direction Dv. The center of the discharge opening 41 is located at a position that overlaps with the central part Ac of the casing 11 in the vertical direction Dv in a plan view in the vertical direction Dv. In this embodiment, the center of the discharge opening 41 is located at a position that overlaps with the center of gravity of the casing 11 in the vertical direction Dv within the central part Ac. Therefore, the discharge opening 41 overlaps with the heat exchanger 20 in the vertical direction Dv. The discharge pipe 40 is connected to the heat exchanger 5 via the refrigerant pipe 8 and discharges the refrigerant F from inside the casing 11 to the outside.

[0022] (Configuration of the heat exchanger) The heat exchanger 20 in this embodiment has a partition portion 21, plate fins 22, and a closing plate 24.

[0023] (Partition section) In this embodiment, the partition portion 21 is formed in a rectangular frame shape so as to surround the discharge pipe 40 in a vertical Dv plan view, using a material with excellent heat conductivity such as metal. More specifically, in a vertical Dv plan view, the four corners 21c of the partition portion 21 are formed in a curved shape that protrudes outward, as if chamfered. That is, the corners 21c of the partition portion 21 are formed in the same shape as the corners 11a of the casing 11.

[0024] The partition section 21 has a first partition wall 21a and a second partition wall 21b. The first partition wall 21a is formed in the shape of a plate extending in the second direction D2 and is provided in a pair spaced apart in the first direction D1. The second partition wall 21b is formed in the shape of a plate extending in the first direction D1 and is provided in a pair spaced apart in the second direction D2. The pair of second partition walls 21b each connect the ends of the first partition wall 21a in the second direction D2. The second partition wall 21b has a plurality of slits 23 that penetrate the second partition wall 21b in the second direction D2. The inlet extends in the first direction D1. The lower edge of the slit 23 is in contact with the bottom plate 12. On the other hand, the upper edge of the slit 23 is located below the top plate 13.

[0025] The partition section 21, with its first partition wall 21a on the supply pipe 30 side, blocks the flow of the refrigerant F supplied from the supply pipe 30 in the first direction D1, and branches the flow of the refrigerant F to both sides in the second direction D2. In this embodiment, the partition 21 connects the bottom plate 12 and the top plate 13.

[0026] (Flat fins) Multiple plate fins 22 are provided inside the partition portion 21, arranged in a first direction D1. Each plate fin 22 is a rectangular plate-shaped member extending in a second direction D2. The plate fins 22 are made of a material with excellent heat conductivity, such as metal. In this embodiment, the plate fins 22 are made of copper. Therefore, the surface temperature of the plate fins 22 is uniform. The plate fins 22 extend upward from the bottom plate 12. The upper edge of the plate fins 22 is spaced apart from the top plate 13, and a predetermined clearance C1 is provided between the plate fins 22 and the top plate 13. The plate fins 22 may be formed to a height similar to that of the partition portion 21. Also, each plate fin 22 is arranged in a position perpendicular to the bottom plate 12.

[0027] Multiple plate fins 22 are arranged to face the second direction D2. Each pair of plate fins 22 facing the second direction D2 is along the second partition wall 21b, and each plate fin 22 extends from the second partition wall 21b in the first direction D1. In a side view in the second direction D2, the multiple plate fins 22 are located below the upper end of each slit 23 formed in the partition portion 21.

[0028] These multiple plate fins 22 create narrow gaps S1 between them that create resistance to the flow of the refrigerant F. These gaps S1 between the plate fins 22 are in communication with the slits 23 of the partition 21. The pitch P1 between the plate fins 22 is, for example, 0.5 mm or more and 1.0 mm or less. The thickness T1 of the plate fins 22 is, for example, about 0.5 mm, and the height H2 of the plate fins 22 is, for example, 5.0 mm.

[0029] (occlusion plate) The closure plate 24 is provided at the inner end of the plate fin 22 in the second direction D2. That is, the closure plate 24 is provided at the end of the plate fin 22 opposite to the second partition wall 21b in the second direction D2. The closure plate 24 extends in the first direction D1 and connects a pair of opposing first partition walls 21a. Furthermore, the closure plate 24 is positioned perpendicular to the bottom plate 12 and connects the bottom plate 12 and the top plate 13. The closure plate 24 is made of a material with excellent heat conductivity, such as metal. The closure plate 24 has a plurality of slits 23 arranged in the first direction D1, similar to the second partition wall 21b of the partition section 21.

[0030] (stirring section) The stirring section 70 stirs the refrigerant F inside the heat exchanger 20. As shown in Figure 4, the stirring section 70 in this embodiment is a plurality of particles 71 arranged inside the heat exchanger 20. The plurality of particles 71 are arranged in the gaps S1 between the plate fins 22. Each particle 71 is formed in a bead shape (spherical shape) from, for example, metal, resin, polymer, etc. The diameter of the particles 71 is larger than the width of the slits 23 provided in the partition section 21 and the closing plate 24. Therefore, while the refrigerant F flows inside the heat exchanger 20, the particles 71 are prevented from flowing out from the gaps between the plate fins 22. The diameter of the particles 71 is, for example, a few μm to about 1 mm.

[0031] In this embodiment, the density of multiple particles 71 within the gap S1 between the slits 23 is 500 kg / m³ 3 More than 2000kg / m 3 Multiple particles 71 are provided as follows:

[0032] (Effects and Benefits) Next, we will explain the effects of the cooling device 10 described above. First, let's explain the flow of the refrigerant F within the cooling device 10. The refrigerant F supplied into the casing 11 from the supply pipe 30 flows into the outer peripheral passage 15. As a result, the refrigerant F branches to both sides of the second direction D2 via the outer peripheral passage 15 and flows around the heat exchanger 20. Subsequently, the refrigerant F is supplied to the heat exchanger 20. In this embodiment, the refrigerant F is supplied from both sides of the second direction D2. The refrigerant F passes between the plate fins 22 and flows from the outer peripheral side to the central Ac side in a plan view. At this time, all of the plate fins 22 are submerged in the refrigerant F. The refrigerant F exchanges heat with the chip 4c via the plate fins 22, the multiple particles 71 and the bottom plate 12. As a result, the chip 4c is cooled. On the other hand, the refrigerant F is heated by the heat of the chip 4c. The refrigerant F boils and evaporates due to the heat of the chip 4c, changing from liquid phase refrigerant F to gaseous phase refrigerant F. The heated refrigerant F is discharged directly outside the casing 11 from the heat exchanger 20 via the discharge pipe 40.

[0033] In this embodiment, the cooling device 10 has a stirring unit 70 that stirs the refrigerant F in the heat exchanger 20. This allows the refrigerant F inside the heat exchanger 20 to be stirred. As a result, bubbles generated when the refrigerant F boils are less likely to coalesce, and the transition point from nucleation boiling to film boiling can be shifted to the high heat flux side (high temperature side). Therefore, the transition from nucleation boiling to film boiling can be suppressed.

[0034] In this embodiment, the stirring section 70 is a plurality of particles 71 arranged on the heat exchanger 20.

[0035] According to this embodiment, fine gaps are formed between the multiple particles 71 through which the refrigerant F can flow. The refrigerant F rises while being dispersed through these gaps between the multiple particles 71. Furthermore, the multiple particles 71 move within the heat exchanger 20 due to the flow of the refrigerant F and the lift generated when the refrigerant F boils. As a result, the refrigerant F is stirred, making it difficult for the bubbles generated by the boiling of the refrigerant F to coalesce. Therefore, the transition point from nucleation boiling to film boiling can be shifted to the high heat flux side. Thus, the transition from nucleation boiling to film boiling can be suppressed with a simple configuration that only involves arranging multiple particles 71.

[0036] Furthermore, as multiple particles 71 move within the heat exchanger 20, the particles 71 repeatedly come into contact with the heat exchanger 20. In more detail, first, the particles 71 come into contact with the heat exchanger 20 and receive heat from the heat-generating element. Then, the particles 71 move away from the heat exchanger 20, and heat exchange takes place between the entire surface of the particles 71 and the refrigerant F, transferring more heat from the heat-generating element to the refrigerant F. Immediately afterward, the particles 71 come into contact with the heat exchanger 20 again and absorb heat from the heat-generating element via the heat exchanger 20. By repeating this process, heat exchange between the refrigerant F and the heat-generating element becomes even more efficient. Therefore, the cooling efficiency can be improved.

[0037] Furthermore, these multiple particles 71 may be given the function of absorbing impurities such as dirt, moisture, and oil. This allows the cooling device 10 to purify the refrigerant F flowing through the heat exchanger 20. As a result, heat exchange between the refrigerant F and the heat-generating element is promoted, and the cooling efficiency can be further improved. Methods for imparting the function of absorbing impurities to multiple particles 71 include forming the particles 71 with a specific adsorbent, and increasing the density of the particles 71 so that impurities are trapped in the gaps between the particles 71.

[0038] In this embodiment, the heat exchanger 20 is provided with multiple plate fins 22 arranged in a first direction D1 and extending in a second direction D2. Multiple particles 71 are arranged in the gaps S1 between the plate fins 22.

[0039] This allows multiple particles 71 to move within the gap S1 between the plate fins 22. This suppresses the uneven distribution of the multiple particles 71, allowing the refrigerant F to be uniformly stirred within the heat exchanger 20. Consequently, the coalescence of bubbles generated by the boiling of the refrigerant F is further suppressed. Thus, the transition point from nucleation boiling to film boiling can be shifted to the higher heat flux side. Therefore, with a simple configuration that only involves arranging multiple particles 71, the transition from nucleation boiling to film boiling can be further suppressed.

[0040] In this embodiment, the density of multiple particles 71 within the gaps between the slits 23 is 500 kg / m³ 3 More than 2000kg / m 3 Multiple particles 71 are provided as follows:

[0041] As a result, when the heat flux increases and boiling of the refrigerant F is promoted, the movement of particles 71 becomes more active. Therefore, the refrigerant F can be more agitated on the boiling surface inside the casing 11. Consequently, the transition point from nucleate boiling to film boiling can be shifted to the higher heat flux side. Therefore, the transition from nucleate boiling to film boiling can be further suppressed.

[0042] In this embodiment, the density of the multiple particles 71 is 500 kg / m³. 3 More than 2000kg / m 3 The following cases have been described, but are not limited to these. The density of the multiple particles 71 can be changed as appropriate depending on the situation. However, the density of the multiple particles 71 is 500 kg / m³.3 More than 2000kg / m 3 The following conditions offer an advantage in terms of activating the movement of particle 71:

[0043] In this embodiment, the second partition wall 21b is provided with a plurality of slits 23 arranged at equal intervals in the second direction D2, but it is not limited to this. Instead of these plurality of slits 23, the second partition wall 21b may be provided with fine circular or polygonal through-holes. These through-holes must be smaller than the diameter of the particles 71. Furthermore, as long as it is possible to prevent the particles 71 from flowing out of the slits 23 while the refrigerant F flows through the heat exchanger 20, a mesh material may be placed instead of the second partition wall 21b with the slits 23. Alternatively, for example, the second partition wall 21b and the closing plate 24 may be omitted, and both ends of the plate fin 22 in the second direction D2 may be made thicker in the first direction D1. This makes the gap S1 between the plate fins 22 at both ends of the plate fin 22 in the second direction D2 smaller than the diameter of the particles 71, preventing the particles 71 from flowing out of the gap between the plate fins 22.

[0044] In this embodiment, the partition 21 is formed to connect the bottom plate 12 and the top plate 13 in the vertical direction Dv, but it is not limited to this. The partition 21 may be formed to extend upward from the bottom plate 12 and be spaced downward from the top plate 13.

[0045] <Second Embodiment> Hereinafter, the cooling device 210 according to the second embodiment of this disclosure will be described with reference to Figures 5 and 6. For components of the second embodiment that are common to the first embodiment, the same names and reference numerals will be used, and their descriptions will be omitted as appropriate. As shown in Figures 5 and 6, in this embodiment, the heat exchanger 220 has a grid fin 60 and pin fins 250.

[0046] (Lattice fins) The grid fins 60 extend horizontally so as to intersect the vertical direction Dv. Each grid 63 of the grid fins 60 is formed in a square shape by combining a first pole 61 extending in a first direction D1 and a second pole 62 extending in a second direction D2. Here, the shortest width between the inner edges of the grid 63 is referred to as the "grid diameter R1". In this embodiment, since the grid 63 is formed in a square shape, the length of one side of the grid 63 is the grid diameter R1.

[0047] The first pole 61 and the second pole 62 are both formed in a cylindrical shape. The shapes of the first pole 61 and the second pole 62 can be changed as appropriate. For example, the first pole 61 and the second pole 62 may both be formed in a rectangular prism shape.

[0048] Multiple grid fins 60 are arranged in the vertical direction Dv at equal intervals. Hereafter, the pitch of the multiple grid fins 60 will be referred to as the first pitch P2. Furthermore, adjacent grid fins 60 are offset from each other in a direction that intersects the vertical direction Dv (the horizontal direction in this embodiment). The multiple grid fins 60 include a first grid fin 60a and a second grid fin 60b. The first grid fin 60a and the second grid fin 60b are arranged alternately in the vertical direction Dv. The first grid fin 60a and the second grid fin 60b are arranged in an alternating pattern. Therefore, in a plan view in the vertical direction Dv, the grid points 64 of the second grid fin 60b are located at the center of the grid 63 of the first grid fin 60a. The first grid fins 60a are arranged at the same horizontal position, and the second grid fins 60b are arranged at the same horizontal position.

[0049] In the illustrated example, two stages of the first grid fin 60a and one stage of the second grid fin 60b are provided, but this is not limited to this configuration. The number of stages of the first grid fin 60a and the number of stages of the second grid fin 60b can be changed as appropriate. Furthermore, a predetermined clearance C1 is provided between the uppermost of the multiple grid fins 60 and the top plate 13.

[0050] (Pinfin) The pin fins 250 are supports that extend in the vertical direction Dv and support the grid fins 60. In a plan view in the vertical direction Dv, the pin fins 250 are arranged in a grid pattern aligned in the first direction D1 and the second direction D2. Here, the row of pin fins 250 extending in the first direction D1 is referred to as the first pin row 251, and the row of pin fins 250 extending in the second direction D2 is referred to as the second pin row 252. Adjacent first pin rows 251 are arranged alternately. Therefore, the multiple pin fins 250 constituting a pair of adjacent first pin rows 251 are arranged in a zigzag pattern extending in the first direction D1. Similarly, adjacent second pin rows 252 are arranged alternately. Therefore, the multiple pin fins 250 constituting a pair of adjacent second pin rows 252 are arranged in a zigzag pattern extending in the second direction D2.

[0051] Furthermore, the pitch between the pin fins 250 constituting the second pin row 252 is narrower than the pitch between the pin fins 250 constituting the first pin row 251. Hereafter, the pitch between the pin fins 250 constituting the second pin row 252 will be referred to as the second pitch P3. Furthermore, the pitch between the pin fins 250 constituting the first pin row 251 may be narrower than the pitch between the pin fins 250 constituting the second pin row 252. In this case, the pitch between the pin fins 250 constituting the first pin row 251 becomes the second pitch P3.

[0052] Each pin fin 250 is perpendicular to the grid fins 60. In this embodiment, the pin fins 250 are formed in a cylindrical shape. The shape of the pin fins 250 can be changed as appropriate. For example, the pin fins 250 may be formed in a rectangular prism shape.

[0053] Next, we will explain the dimensions of the lattice fins 60 and pin fins 250 mentioned above. The grid diameter R1 and first pitch P2 of the grid fins 60, and the second pitch P3 of the pin fins 250 are preferably both several tens of micrometers or more. For example, the grid diameter R1 is designed to be 300 μm, the first pitch P2 to be 150 μm, and the second pitch P3 to be 0.45 mm or more and 0.6 mm or less. Also, the height H3 of the pin fins 250 in the vertical direction Dv is designed to be, for example, 3 mm. The dimensions of the grid fins 60 and pin fins 250 can be changed as appropriate.

[0054] (stirring section) The stirring unit 270 has a valve 72 (flow rate adjustment unit) provided in the supply pipe 30 that adjusts the flow rate of the refrigerant F flowing through the supply pipe 30. The valve 72 adjusts the opening degree of the inlet pipe by receiving control from, for example, a control unit 7 (see Figure 1).

[0055] (Effects and Benefits) Next, we will explain the effects of the cooling device 210 described above. In this embodiment, the stirring unit 270 has a valve 72 provided in the supply pipe 30 that adjusts the flow rate of the refrigerant F flowing through the supply pipe 30.

[0056] According to this embodiment, the amount of refrigerant F supplied into the casing 11 can be changed in a short time. This allows vibrations to be introduced into the flow of refrigerant F. Therefore, the refrigerant F can be stirred on the boiling surface inside the casing 11. Consequently, the transition point from nucleation boiling to film boiling can be shifted to the high heat flux side. Thus, the transition from nucleation boiling to film boiling can be suppressed. Furthermore, the optimal vibration can be adjusted by adjusting the flow rate.

[0057] In the above embodiment, the case in which the flow rate adjustment unit is a valve 72 that adjusts the opening degree of the inlet pipe was described, but it is not limited to this. The flow rate adjustment unit may be a pump. Alternatively, the flow rate adjustment unit may have both a valve 72 and a pump.

[0058] <First modified example of the second embodiment> Next, with reference to Figure 7, a first modified example of the second embodiment will be described. As shown in Figure 7, in this modified example, the stirring section 270 further includes, in addition to the valve 72, a plurality of particles 71, for example, from the first embodiment, arranged on the heat exchanger 220. Preferably, the diameter of these plurality of particles 71 is smaller than the grid diameter R1 and first pitch P2 of the grid fins 60 and the second pitch P3 of the pin fins 250. Furthermore, the particles in the stirring section 270 of this embodiment are not limited to the particles 71 of the first embodiment, and their shape and material can be changed as appropriate.

[0059] As a result, the oscillation of the refrigerant F flow due to changes in the supply rate of refrigerant F causes multiple particles 71 to move actively within the heat exchanger 220. Therefore, in addition to the flow oscillation, the active movement of the multiple particles 71 can introduce movement into the boundary layer near the boiling surface within the casing 11. Thus, mixing of the high-temperature fluid near the boiling surface and the surrounding low-temperature fluid is promoted. Consequently, the transition point from nucleate boiling to film boiling can be shifted to the higher heat flux side. Therefore, the transition from nucleate boiling to film boiling can be further suppressed.

[0060] <Second modified example of the second embodiment> Next, a second modified example of the second embodiment will be described with reference to Figure 8. As shown in Figure 8, in this modified example, the stirring section 270 has a sound wave section 73 that propagates sound waves SW inside the casing 11, in addition to the valve 72.

[0061] As a result, the stirring unit 270 can further stir the refrigerant F by applying ultrasonic waves SW to it. Therefore, the transition point from nucleate boiling to film boiling can be shifted to the higher heat flux side. Consequently, the transition from nucleate boiling to film boiling can be further suppressed.

[0062] <Third modified example of the second embodiment> Next, with reference to Figure 9, a third modified example of the second embodiment will be described. As shown in Figure 9, in this modified example, the stirring section 270 has, in addition to the valve 72, a plurality of particles 71 from the first modified example and an acoustic wave section 73 from the second modified example.

[0063] As a result, the particles 71 in the stirring section 270 move vigorously due to vibrations caused by flow rate adjustment of the valve 72 and sound waves SW propagated from the sound wave section 73. Therefore, the refrigerant F is stirred even more. Thus, the transition point from nucleation boiling to film boiling can be shifted to the higher heat flux side. Consequently, the transition from nucleation boiling to film boiling can be further suppressed.

[0064] <Third Embodiment> Hereinafter, a cooling device 310 according to the third embodiment of this disclosure will be described with reference to Figure 10. For components of the third embodiment that are common to the above embodiments, the same names and reference numerals will be used, and their descriptions will be omitted as appropriate. As shown in Figure 10, in this embodiment, the stirring unit 370 has a plurality of particles (moving bodies) 371 and a magnetic force unit 74. The plurality of particles 371 are made of a magnetic material. The plurality of particles 371 are arranged inside the heat exchanger 320. The magnetic force unit 74 is provided on the outer circumference of the casing 11. In this embodiment, the magnetic force unit 74 is provided so as to sandwich the casing 11 from a first direction D1. The magnetic force unit 74 applies magnetic force to the plurality of particles 371 inside the casing 11.

[0065] (Effects and Benefits) Next, we will explain the effects of the cooling device 310 described above. In this embodiment, the stirring unit 370 may have a plurality of particles 371 arranged on the heat exchanger 320 and a magnetic force unit 74 that applies magnetic force to the plurality of particles 371.

[0066] According to this embodiment, the multiple particles 371 move actively within the heat exchanger 320 due to magnetic force. This further suppresses the coalescence of bubbles generated by the boiling of the refrigerant F. Therefore, the transition point from nucleation boiling to film boiling can be shifted to the higher heat flux side. Consequently, the transition from nucleation boiling to film boiling can be further suppressed.

[0067] In this embodiment, the case where the moving body is a plurality of particles 371 has been described, but it is not limited to this. The moving body may be, for example, a magnetic material formed in a propeller shape.

[0068] (Other embodiments) Although embodiments of this disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and may include design changes and the like that do not depart from the gist of this disclosure. It is also possible to combine the above-described embodiments and their respective modifications as appropriate.

[0069] In the above embodiment, the cooling devices 10, 210, and 310 were described as cold plates that cool chips 4c such as CPUs and GPUs mounted on the server 4, but the embodiment is not limited to this. The cooling devices 10, 210, and 310 may also cool heat-generating elements other than chips 4c.

[0070] In the above embodiment, the case in which the casing 11 is formed in the shape of a rectangular parallelepiped has been described, but it is not limited to this. The casing 11 may be formed in a polygonal shape other than a rectangular parallelepiped, for example, it may be formed in the shape of a disc. Similarly, the shape of the heat exchangers 20, 220, and 320 is not limited to a rectangular parallelepiped, and the shape of the outer peripheral passage 15 is not limited to a rectangular frame. That is, the heat exchangers 20, 220, and 320 may be formed in a polygonal shape other than a rectangular parallelepiped, for example, it may be formed in the shape of a disc. Also, the outer peripheral passage 15 may be formed in a polygonal frame shape other than a rectangle, for example, it may be formed in the shape of a ring.

[0071] In the above embodiment, the supply section is a supply pipe 30 having a supply opening 31, and the discharge section is a discharge pipe 40 having a discharge opening 41, but it is not limited to this. The supply section may consist only of the supply opening 31, and the discharge section may consist only of the discharge opening 41. In this case, the refrigerant pipe 8 is directly connected to the supply opening 31 and the discharge opening 41. Also, although it is stated that the supply opening 31 is connected to the side plate 14, it is not limited to this. The supply opening 31 may be connected, for example, to a position on the top plate 13 that overlaps with the outer peripheral passage 15 in the vertical direction Dv. Also, although it is stated that the discharge opening 41 is connected to the top plate 13 at the central part Ac of the casing 11, it is not limited to this. The discharge opening 41 may be located on the outer periphery side of the central part Ac of the casing 11 in a vertical direction Dv plan view, as long as it overlaps with the heat exchangers 20, 220, and 320 in the vertical direction Dv.

[0072] <Note> The cooling devices 10, 210, and 310 described in each embodiment can be understood, for example, as follows.

[0073] (1) The cooling device 10, 210, 310 according to the first embodiment comprises a hollow casing 11 having a bottom plate 12 on which a heating element is placed, a top plate 13 facing the bottom plate 12, and a side plate 14 connecting the bottom plate 12 and the top plate 13 on the outer circumference; heat exchangers 20, 220, 320 provided on the bottom plate 12 inside the casing 11 and through which a refrigerant F can flow; a supply unit for supplying the refrigerant F from the outside into the casing 11; a discharge unit for discharging the refrigerant F from inside the casing 11 to the outside; and stirring units 70, 270, 370 for stirring the refrigerant F inside the heat exchangers 20, 220, 320. An example of a heating element is the chip 4c of the above embodiment. An example of a supply section is the supply pipe 30 of the above embodiment, and an example of a discharge section is the discharge pipe 40 of the above embodiment.

[0074] As a result, the refrigerant F inside the heat exchangers 20, 220, and 320 can be stirred. Therefore, the bubbles generated during the boiling of the refrigerant F are less likely to coalesce, and the transition point from nucleate boiling to film boiling can be shifted to the high heat flux side (high temperature side).

[0075] (2) The cooling device 10 according to the second aspect is the cooling device 10 of (1), wherein the stirring unit 70 may be a plurality of particles 71 arranged in the heat exchanger 20.

[0076] According to this aspect, fine gaps S1 through which the refrigerant F can flow are formed between the plurality of particles 71. The refrigerant F rises while being dispersed through the gaps S1 between the plurality of particles 71. Further, the plurality of particles 71 move within the heat exchanger due to the flow of the refrigerant F and the lifting force generated when the refrigerant F boils. As a result, the bubbles generated by the boiling of the refrigerant F are less likely to coalesce. Therefore, the transition point from nucleate boiling to film boiling can be shifted to the high heat flux side.

[0077] (3) The cooling device 10 according to the third aspect is the cooling device 10 of (2), wherein the heat exchanger 20 has a plurality of plate fins 22 arranged in a first direction D1 intersecting the vertical direction Dv, and each of the plate fins 22 extends in a second direction D2 intersecting the vertical direction Dv and the first direction D1, and the plurality of particles 71 may be arranged in the gaps S1 between the plate fins 22.

[0078] According to this aspect, the plurality of particles 71 can be moved within the gap S1 between the plate fins 22. As a result, the bias of the plurality of particles 71 is suppressed, and the refrigerant F can be uniformly stirred within the heat exchanger 20.

[0079] (4) The cooling device 10 according to the fourth aspect is the cooling device 10 of (2) or (3), wherein the plurality of particles 71 may be provided such that the density of the plurality of particles 71 is 500 kg / m 3 or more and 2000 kg / m 3 or less.

[0080] As a result, when the heat flux increases and boiling of the refrigerant F is promoted, the movement of particles 71 becomes more active. Therefore, the refrigerant F can be more agitated on the boiling surface inside the casing 11. Consequently, the transition point from nucleate boiling to film boiling can be shifted to the higher heat flux side.

[0081] (5) The cooling device 210 according to the fifth embodiment is the cooling device 210 of (1), wherein the stirring unit 270 may have a flow rate adjustment unit provided in the supply unit for adjusting the flow rate of the refrigerant F flowing through the supply unit. An example of a flow rate adjustment unit is the valve 72 in the above embodiment.

[0082] According to this embodiment, the amount of refrigerant F supplied into the casing 11 can be changed in a short time. This allows vibrations to be introduced into the flow of refrigerant F. Therefore, the refrigerant F can be stirred on the boiling surface inside the casing 11. Consequently, the transition point from nucleate boiling to film boiling can be shifted to the high heat flux side.

[0083] (6) The cooling device 210 according to the sixth embodiment is the cooling device 210 of (5), wherein the stirring unit 270 further comprises a plurality of particles 71 arranged in the heat exchanger 220.

[0084] As a result, the oscillation of the refrigerant F flow due to changes in the supply rate of refrigerant F causes multiple particles 71 to move actively within the heat exchanger 220. Therefore, in addition to the flow oscillation, the active movement of the multiple particles 71 can introduce movement into the boundary layer near the boiling surface within the casing 11. Thus, mixing of the high-temperature fluid near the boiling surface and the surrounding low-temperature fluid is promoted. Consequently, the transition point from nucleate boiling to film boiling can be shifted to the higher heat flux side.

[0085] (7) The cooling device 210 according to the seventh embodiment is the cooling device 210 of (5) or (6), wherein the stirring unit 270 further comprises a sound wave unit 73 for propagating sound waves SW within the casing 11.

[0086] As a result, the stirring unit 270 can further stir the refrigerant F by applying ultrasonic waves SW to it. Therefore, the transition point from nucleate boiling to film boiling can be shifted to the higher heat flux side.

[0087] (8) The cooling device 310 according to the eighth embodiment is the cooling device 310 of (1), wherein the stirring unit 370 is arranged on the heat exchanger 320 and has a moving body made of a magnetic material and a magnetic force unit 74 that applies a magnetic force to the moving body. Examples of moving bodies include the multiple particles 371 in the above embodiment.

[0088] According to this embodiment, the moving body moves actively within the heat exchanger 320 due to magnetic force. This further suppresses the coalescence of bubbles generated by the boiling of the refrigerant F. Therefore, the transition point from nucleate boiling to film boiling can be shifted to the higher heat flux side. [Explanation of Symbols]

[0089] 1...Cooling system, 2...Rack, 3...Server chassis, 4...Server, 4a...Server casing, 4b...Server board, 4c...Chip (heating element), 5...Heat exchanger, 6...Pump, 7...Control unit, 8...Refrigerant pipe, 10...Cooling device, 11...Casing, 11a...Corner, 12...Bottom plate, 13...Top plate, 14...Side plate, 14a...First side plate, 14b...Second side plate, 15...Peripheral passage, 20...Heat exchanger, 21...Partition, 21a...First partition, 21b...Second partition, 21c...Corner, 22...Plate fin, 23...Slit, 24...Closing plate, 30...Supply pipe (supply section), 31...Supply opening, 40...Discharge pipe (discharge section), 41...Discharge opening, 50...Pin fin, 60...Grid fin, 60a...First grid fin, 60b...Second grid Sub-fins, 61...First pole, 62...Second pole, 63...Grid, 64...Grid point, 70...Agitation section, 71...Particles, 72...Valve (flow rate adjustment section), 73...Sonic wave section, 74...Magnetic section, 210...Cooling device, 220...Heat exchanger, 250...Pin fins, 251...First row of pins, 252...Second row of pins, 270...Agitation section, 310...Cooling device, 320...Heat exchanger, 370...Agitation section, 371...Particles (moving bodies), A1...Heat exchange area, Ac...Center section, C1...Clearance, Dv...Vertical direction, D1...First direction, D2...Second direction, F...Refrigerant, H1...Height, H2...Height, H3...Height, L1...Width, P1...Pitch, P2...First pitch, P3...Second pitch, R1...Grid diameter, S1...Gap, SW...Sound wave, T1...Thickness, W1...Width

Claims

1. A hollow casing having a bottom plate on which a heating element is placed, a top plate opposite the bottom plate, and side plates connecting the bottom plate and the top plate on the outer circumference, A heat exchanger is provided on the bottom plate within the casing, and a refrigerant is allowed to circulate inside it. The casing includes a supply unit that supplies refrigerant from the outside, A discharge section for discharging refrigerant from inside the casing to the outside, A stirring unit for stirring the refrigerant inside the heat exchanger, Equipped with, The heat exchanger is a cooling device in which the bottom plate and the top plate are connected, and a frame-shaped outer peripheral passage is partitioned between the heat exchanger and the side plate of the casing, enclosing the entire circumference of the heat exchanger.

2. The cooling device according to claim 1, wherein the stirring section comprises a plurality of particles arranged on the heat exchanger.

3. The heat exchanger has a plurality of plate fins arranged in a first direction that intersects in the vertical direction, Each of the plate fins extends in the vertical direction and in a second direction intersecting the first direction, The cooling device according to claim 2, wherein the plurality of particles are arranged in the gaps between the plate fins.

4. The density of the aforementioned plurality of particles is 500 kg / m³ ３ More than 2000kg / m ３ The cooling device according to claim 2 or 3, wherein the plurality of particles are provided as follows:

5. The cooling device according to claim 1, wherein the stirring section has a flow rate adjustment section provided in the supply section for adjusting the flow rate of the refrigerant flowing through the supply section.

6. The cooling device according to claim 5, wherein the stirring section further comprises a plurality of particles arranged on the heat exchanger.

7. The cooling device according to claim 5 or 6, wherein the stirring section further comprises a sound wave section for propagating sound waves within the casing.

8. The stirring section is A moving body, formed of a magnetic material, is placed in the aforementioned heat exchanger. A magnetic force unit that applies magnetic force to the moving body, A cooling device according to claim 1, having the following features.

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