Thermal diffusion device and cooling system

Abstract

A thermal diffusion device according to one aspect of the present disclosure comprises a container, a working liquid, and a boiling-promoting member. The container has a first outer surface, a second outer surface, and an internal space. The first outer surface contacts the heat-generating element and has an area greater than the area of contact with the heat-generating element. The second outer surface is positioned oppositely from the first outer surface. The internal space is positioned between the first outer surface and the second outer surface. The working liquid is sealed in the internal space. The boiling-promoting member is disposed on a first inner surface which is the reverse surface to the first outer surface among a plurality of inner surfaces facing the internal space, and promotes boiling of the working liquid. The area of contact between the boiling-promoting member and the first inner surface is less than the area of the first inner surface. In a state in which the first outer surface faces downward, at least half of the boiling-promoting member is immersed in the working liquid.

Description

Heat-dissipating devices and cooling systems

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to heat spreading devices and cooling systems.

[0002] Conventionally, a cooling method using a cold plate has been known as a method for cooling a heat-generating body such as a central processing unit (CPU). The cold plate has a flow path formed therein through which a coolant such as cold water flows. When the cold plate is brought into contact with the heat-generating body, the coolant flowing through the cold plate removes heat from the heat-generating body, thereby cooling the heat-generating body.

[0003] When a heating element is small relative to the heat-receiving surface of a cold plate, heat is concentrated at the attachment point of the heating element, making it difficult to efficiently exchange heat with the refrigerant. In particular, in the field of CPUs, the heat density is increasing as CPUs become smaller, making it difficult to keep up with cooling methods using cold plates. Therefore, it has been proposed to interpose a vapor chamber, a heat diffusion device, between the heating element and the cold plate (see Patent Document 1).

[0004] A vapor chamber has a hollow metal container filled with a working fluid, and utilizes the vaporization and liquefaction cycle of the working fluid to transport heat away from the heat source. By placing such a vapor chamber between the heating element and the cold plate, the heat from the heating element can be spread in the planar direction and transferred to the cold plate. This allows for efficient heat exchange with the refrigerant flowing through the cold plate.

[0005] Japanese Patent Application Laid-Open No. 2021-196086

[0006] The above-mentioned conventional techniques have room for further improvement in terms of increasing the efficiency of heat diffusion from the heat generating element.

[0007] The present disclosure provides a technique that can increase the heat diffusion efficiency of a heat generating element.

[0008] A heat spreading device according to one aspect of the present disclosure includes a container, a working liquid, and a boiling promotion member. The container has a first outer surface, a second outer surface, and an interior space. The first outer surface is in contact with a heating element and has an area larger than the contact area with the heating element. The second outer surface is located opposite the first outer surface. The interior space is located between the first outer surface and the second outer surface. The working liquid is sealed in the interior space. The boiling promotion member is located on a first inner surface, which is the reverse side of the first outer surface, among multiple interior surfaces facing the interior space, and promotes boiling of the working liquid. The contact area between the boiling promotion member and the first inner surface is smaller than the area of ​​the first inner surface. When the first outer surface is facing downward, at least half of the boiling promotion member is immersed in the working liquid.

[0009] According to the present disclosure, the heat diffusion efficiency of a heat generating element can be increased.

[0010] Fig. 1 is a schematic exploded perspective view of a heat diffusing device according to an embodiment. Fig. 2 is a schematic cross-sectional view of a heat diffusing device according to an embodiment. Fig. 3 is a schematic plan view of a heat diffusing device according to an embodiment. Fig. 4 is an enlarged plan view of a boiling promotion member according to an embodiment. Fig. 5 is a schematic cross-sectional view showing another example of a heat diffusing device according to an embodiment. Fig. 6 is a block diagram showing an example of the configuration of a cooling system according to an embodiment.

[0011] Hereinafter, a detailed description will be given of a heat diffusion device and a cooling system according to the present disclosure (hereinafter referred to as "embodiments") with reference to the drawings. Note that the present disclosure is not limited to these embodiments. Furthermore, the embodiments can be appropriately combined as long as the processing content is not contradictory. Furthermore, the same components in the following embodiments are designated by the same reference numerals, and redundant explanations will be omitted.

[0012] In addition, in the drawings referred to below, for ease of understanding, an orthogonal coordinate system may be shown in which the X-axis direction, Y-axis direction, and Z-axis direction, which are perpendicular to each other, are defined, and the Z-axis direction is the vertically upward direction.

[0013] (Embodiment) <Configuration of Heat Diffusing Device> First, the configuration of a heat diffusing device 100 according to an embodiment will be described with reference to Figs. 1 to 3. Fig. 1 is a schematic exploded perspective view of the heat diffusing device 100 according to an embodiment. Fig. 2 is a schematic cross-sectional view of the heat diffusing device 100 according to an embodiment. Fig. 3 is a schematic plan view of the heat diffusing device 100 according to an embodiment. For ease of understanding, a heat generating element 300 is illustrated in Figs. 2 and 3.

[0014] As shown in FIG. 1, the heat spreading device 100 includes a container 10 and a boiling promotion member 20 .

[0015] The container 10 is a container having an internal space 13 formed therein that can accommodate the boiling promotion member 20. The container 10 has a first member 11 and a second member 12. The container 10 is formed by joining the first member 11 and the second member 12. The container 10 may be formed of a metal such as copper.

[0016] As shown in Fig. 2, the container 10 has a first outer surface 10a that contacts the heating element 300 and a second outer surface 10b that is located opposite the first outer surface 10a. The first outer surface 10a has an area larger than the contact area with the heating element 300. The first outer surface 10a and the second outer surface 10b may be rectangular in plan view. In other words, as shown in Fig. 3, the container 10 may be rectangular in plan view when viewed from a direction perpendicular to the first outer surface 10a (here, the Z-axis direction).

[0017] The internal space 13 is located between the first outer surface 10a and the second outer surface 10b. A hydraulic fluid is sealed in the internal space 13. Examples of the hydraulic fluid that can be used include water, hydrocarbon compounds, organic liquids (such as ethanol and methanol), and ammonia.

[0018] Of the multiple inner surfaces facing the internal space 13, the first inner surface 13a, which is the reverse side of the first outer surface 10a, may have a recess 14 in its center. In a plan view seen from a direction perpendicular to the first outer surface 10a (here, the Z-axis direction), the recess 14 may be circular. The recess 14 accommodates a part of a boiling promotion member 20, which will be described later.

[0019] Furthermore, the area of ​​the first inner surface 13a other than the area where the boiling promotion member 20 is disposed may be a flat surface.

[0020] The boiling promotion member 20 is disposed on the first inner surface 13a of the internal space 13. Specifically, a portion of the boiling promotion member 20 is accommodated in the recess 14 of the first inner surface 13a. This reduces the height of the heat spreading device 100 in the Z-axis direction. The contact area between the boiling promotion member 20 and the first inner surface 13a is smaller than the area of ​​the first inner surface 13a.

[0021] 3, the boiling promotion member 20 may have a circular shape in a plan view seen from a direction perpendicular to the first outer surface 10a (here, the Z-axis direction). The boiling promotion member 20 promotes boiling of the working fluid.

[0022] The boiling promotion member 20 is a porous body. The porous body may be, for example, a porous metal body. Examples of the porous metal body that can be used include a porous stainless steel body, a porous titanium body, a porous nickel body, and a porous aluminum body.

[0023] As shown in FIG. 2, with the first outer surface 10a facing downward, at least half of the boiling promotion member 20 is immersed in the working fluid.

[0024] Conventional vapor chambers have the problem of film boiling hindering the vaporization of the working fluid. Film boiling is a boiling mode in which a vapor film is interposed between the liquid and the heated surface, and evaporation occurs in the vapor film due to heat transferred from the heated surface through the vapor film. When film boiling occurs, the vaporization of the working fluid is hindered because the vapor film acts as a thermal resistance. When vaporization of the working fluid is hindered, the vaporization and liquefaction cycle of the working fluid, i.e., the heat transport cycle, is hindered, and the heat diffusion efficiency of the heating element decreases.

[0025] On the other hand, in the heat diffusion device 100 according to the embodiment, the boiling promotion member 20 is porous, and at least half of the member is immersed in the working fluid. Therefore, the vaporized working fluid is quickly discharged from the porous member before a vapor film forms, and moves toward the second outer surface 10b. This makes it difficult for film boiling to occur, and promotes the vaporization of the working fluid. Therefore, the heat diffusion device 100 according to the embodiment can improve the heat diffusion efficiency of the heating element 300.

[0026] Next, the configuration of the boiling promotion member 20 according to the embodiment will be described with further reference to Fig. 4. Fig. 4 is an enlarged plan view of the boiling promotion member 20 according to the embodiment.

[0027] The boiling promotion member 20 may have a plurality of holes 21 oriented in a direction perpendicular to the first outer surface 10a (here, the Z-axis direction). With this configuration, the vaporized working fluid is likely to pass through the holes 21 and move toward the first outer surface 10a (here, the positive Z-axis direction). This makes it easier for the vaporized working fluid to be discharged from the boiling promotion member 20 more quickly, and the vaporization of the working fluid is more active.

[0028] The holes 21 may penetrate the boiling promotion member 20 in a direction perpendicular to the first outer surface 10a. The boiling promotion member 20 may be, for example, a lotus-type or honeycomb-type.

[0029] Although the boiling promotion member 20 has a circular hole 21 in this example, the shape of the hole 21 is not limited to this. For example, the shape of the hole 21 may be polygonal or elliptical.

[0030] As shown in FIGS. 2 and 3, the contact area between the boiling promotion member 20 and the first inner surface 13 a may be larger than the contact area between the first outer surface 10 a and the heating element 300 .

[0031] If the area of ​​the first inner surface 13a is the first area, the contact area between the boiling promotion member 20 and the first inner surface 13a is the second area, and the contact area between the first outer surface 10a and the heating element 300 is the third area, the difference between the second area and the third area may be smaller than the difference between the first area and the second area.

[0032] Next, another example of the heat spreading device 100 according to the embodiment will be described with reference to Fig. 5. Fig. 5 is a schematic cross-sectional view showing another example of the heat spreading device 100 according to the embodiment.

[0033] As shown in FIG. 5, the boiling promotion member 20 may be entirely immersed in the working liquid with the first outer surface 10a facing downward.

[0034] <Configuration of Cooling System> Next, a configuration example of the cooling system 1 according to the embodiment will be described with reference to Fig. 6. Fig. 6 is a block diagram showing the configuration example of the cooling system 1 according to the embodiment. The cooling system 1 includes the above-described thermal diffusion device 100, a cooler 200, a refrigerant supply line 210, a refrigerant discharge line 220, and a circulation device 400.

[0035] The heat spreading device 100 is located between the heat generating element 300 and the cooler 200. The heat spreading device 100 transfers the heat from the heat generating element 300 to the cooler 200.

[0036] The coolers 200 are, for example, cold plates, and a plurality of coolers 200 are provided corresponding to the respective heat spreading devices 100. The coolers 200 are in contact with the corresponding heat spreading devices 100. Specifically, the coolers 200 are disposed on the second outer surface 10b (see FIG. 2 ) of the heat spreading devices 100.

[0037] The cooler 200 cools the second outer surface 10b (see FIG. 2) using a refrigerant passing through the interior thereof. The refrigerant is, for example, water. The refrigerant is supplied to the cooler 200 through a refrigerant supply line 210, and the refrigerant is discharged from the cooler 200 through a refrigerant discharge line 220.

[0038] The refrigerant supply line 210 supplies the refrigerant in the circulation device 400 to each cooler 200. The refrigerant supply line 210 includes a common supply line 210a and individual supply lines 210b.

[0039] One end of the common supply line 210a is connected to the circulation device 400, and the other end is connected to the individual supply lines 210b. The common supply line 210a guides the refrigerant cooled by the circulation device 400 to each individual supply line 210b. A plurality of individual supply lines 210b are provided corresponding to each cooler 200. One end of the individual supply line 210b is connected to the common supply line 210a, and the other end is connected to the corresponding cooler 200. The individual supply line 210b guides the refrigerant from the common supply line 210a to each cooler 200.

[0040] The refrigerant discharge line 220 returns the refrigerant that has passed through each cooler 200 to the circulation device 400. The refrigerant discharge line 220 has a common discharge line 220a and individual discharge lines 220b.

[0041] One end of the common discharge line 220a is connected to the circulation device 400, and the other end is connected to the individual discharge lines 220b. The common discharge line 220a guides the refrigerant from each individual supply line 210b to the circulation device 400. A plurality of individual discharge lines 220b are provided to correspond to each cooler 200. One end of the individual discharge line 220b is connected to the common discharge line 220a, and the other end is connected to the corresponding cooler 200. The individual discharge line 220b guides the refrigerant flowing out of each cooler 200 to the common discharge line 220a.

[0042] The circulation device 400 cools the refrigerant flowing out of the cooler 200 and returns the refrigerant to the cooler 200. The circulation device 400 is, for example, a CDU (Cooling Distribution Unit).

[0043] In the cooling system 1 described above, the refrigerant in the circulation device 400 is supplied to the cooler 200 via the refrigerant supply line 210. In the cooler 200, the refrigerant exchanges heat with the thermal diffusion device 100. The refrigerant then returns from the cooler 200 to the circulation device 400 via the refrigerant discharge line 220. According to this cooling system 1, the heat-generating element 300 can be efficiently cooled.

[0044] Furthermore, in the cooling system 1, the heat diffusion device 100 is located between the heat generating element 300 and the cooler 200, so that the heat from the heat generating element 300 can be spread in the planar direction and then transferred to the cooler 200. This allows for efficient heat exchange with the refrigerant flowing through the cooler 200.

[0045] Although the cooling system 1 includes a plurality of heat diffusion devices 100, coolers 200, individual supply lines 210b, and individual discharge lines 220b in this example, the numbers of the heat diffusion devices 100, coolers 200, individual supply lines 210b, and individual discharge lines 220b are not limited to this. For example, the cooling system 1 may include one each of the heat diffusion devices 100, coolers 200, individual supply lines 210b, and individual discharge lines 220b.

[0046] The present technology may also be configured as follows. (1) A heat diffusing device comprising: a container having a first outer surface that contacts a heating element and has an area larger than the contact area with the heating element, a second outer surface located opposite the first outer surface, and an internal space located between the first outer surface and the second outer surface; a working fluid sealed in the internal space; and a boiling promotion member that is arranged on a first inner surface that is the backside of the first outer surface among a plurality of internal surfaces facing the internal space and that promotes boiling of the working fluid, the contact area between the boiling promotion member and the first inner surface being smaller than the area of ​​the first inner surface, and at least half of the boiling promotion member being immersed in the working fluid when the first outer surface is facing downward. (2) The heat diffusing device according to (1), wherein the boiling promotion member is porous. (3) The heat diffusing device according to (2), wherein the boiling promotion member has a plurality of pores oriented in a direction perpendicular to the first outer surface. (4) The heat diffusing device according to (3), wherein the holes penetrate the boiling promotion member in a direction perpendicular to the first outer surface. (5) The heat diffusing device according to any one of (1) to (4), wherein the boiling promotion member is entirely immersed in the working liquid when the first outer surface faces downward. (6) The heat diffusing device according to any one of (1) to (5), wherein the contact area between the boiling promotion member and the first inner surface is larger than the contact area between the first outer surface and the heat generating element. (7) The heat diffusing device according to (6), wherein, when the area of ​​the first inner surface is a first area, the contact area between the boiling promotion member and the first inner surface is a second area, and the contact area between the first outer surface and the heat generating element is a third area, the difference between the second area and the third area is smaller than the difference between the first area and the second area. (8) The heat diffusing device according to any one of (1) to (7), wherein the area of ​​the first inner surface other than the area where the boiling promotion member is disposed is a flat surface. (9) The heat diffusion device according to any one of (1) to (8), wherein the container is rectangular and the boiling promotion member is circular in a plan view seen from a direction perpendicular to the first outer surface.(10) The heat diffusing device according to any one of (1) to (9), wherein the first inner surface has a recess in the center, and a portion of the boiling promotion member is accommodated in the recess. (11) A cooling system comprising: the heat diffusing device according to any one of (1) to (10), a cooler disposed on the second outer surface of the heat diffusing device and configured to cool the second outer surface using a refrigerant passing through an interior of the cooler, and a circulation device configured to cool the refrigerant flowing out of the cooler and return it to the cooler.

[0047] The disclosed embodiments should be considered in all respects as illustrative and not restrictive. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims.

[0048] REFERENCE SIGNS LIST 1 Cooling system 10 Container 10a First outer surface 10b Second outer surface 11 First member 12 Second member 13 Internal space 13a First inner surface 14 Recess 20 Boiling promotion member 21 Hole 100 Heat diffusion device 200 Cooler 210 Refrigerant supply line 210a Common supply line 210b Individual supply line 220 Refrigerant discharge line 220a Common discharge line 220b Individual discharge line 300 Heat generating element 400 Circulation device

Claims

1. A heat diffusion device comprising: a container having a first outer surface that contacts a heating element and has an area larger than the contact area with the heating element; a second outer surface located opposite the first outer surface; and an internal space located between the first and second outer surfaces; a working fluid sealed in the internal space; and a boiling promotion member that promotes boiling of the working fluid and is arranged on a first inner surface that is the backside of the first outer surface among multiple internal surfaces facing the internal space, the first inner surface being one of the surfaces that faces the internal space; wherein the contact area between the boiling promotion member and the first inner surface is smaller than the area of ​​the first inner surface; and when the first outer surface is facing downward, at least half of the boiling promotion member is immersed in the working fluid.

2. The heat spreading device according to claim 1, wherein the boiling promoting member is a porous body.

3. The heat spreading device of claim 2, wherein said boiling promotion member has a plurality of holes oriented in a direction perpendicular to said first outer surface.

4. The heat spreading device of claim 3, wherein said holes extend through said boiling promotion member in a direction perpendicular to said first outer surface.

5. The heat spreading device according to claim 1, wherein the boiling promotion member is entirely immersed in the working liquid with the first outer surface facing downward.

6. The heat spreading device of claim 1, wherein the contact area between said boiling promotion member and said first inner surface is greater than the contact area between said first outer surface and said heating element.

7. The heat spreading device of claim 6, wherein, when the area of ​​the first inner surface is defined as a first area, the contact area between the boiling promotion member and the first inner surface is defined as a second area, and the contact area between the first outer surface and the heating element is defined as a third area, the difference between the second area and the third area is smaller than the difference between the first area and the second area.

8. The heat spreading device according to claim 1, wherein the first inner surface has a flat surface other than the area where the boiling promotion member is disposed.

9. The heat spreading device of claim 1, wherein the container is rectangular and the boiling promotion member is circular in plan view perpendicular to the first outer surface.

10. The heat spreading device of claim 1, wherein the first inner surface has a recess in the center, and the boiling promotion member is partially housed in the recess.

11. A cooling system comprising: a heat diffusion device according to any one of claims 1 to 10; a cooler disposed on the second outer surface of the heat diffusion device and cooling the second outer surface using a refrigerant passing through the inside of the cooler; and a circulation device that cools the refrigerant flowing out of the cooler and returns the refrigerant to the cooler.

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