Cold plate

Abstract

A cold plate according to the present disclosure is provided with: a casing that is attached to an outer surface of a heating element and that takes heat from the heating element by boiling a refrigerant flowing inside; and a plurality of fins that are arranged in the casing at intervals in a second direction intersecting a first direction. The fins protrude in the first direction from a bottom surface of an inner surface of the casing, the bottom surface extending along the outer surface, and extend in a direction intersecting both the first direction and the second direction. The plurality of fins form, between the adjacent fins, flow paths through which the refrigerant can flow. The plurality of fins include: a plurality of first fins extending from upstream ends to downstream ends of the flow paths; and a plurality of second fins disposed between the adjacent first fins. The heights of the second fins in the first direction on the upstream side in the flow direction of the flow paths are higher than the heights of the second fins in the first direction on the downstream side in the flow direction.

Description

Cold Plate

[0001] This application claims priority to Japanese Patent Application No. 2024-025576, filed on February 22, 2024, the contents of which are incorporated herein by reference.

[0002] Electronic devices such as CPUs and GPUs installed in servers generate heat during operation. Cold plates are used to cool these heat-generating devices. A refrigerant flows through the cold plate. The refrigerant in the cold plate removes heat from the heat-generating device, thereby cooling it. For example, there is a boiling cooling type cold plate, which boils the refrigerant and removes heat from the heat-generating device using the heat of vaporization.

[0003] Furthermore, Patent Document 1 below discloses a technology for increasing the heat transfer area by providing fins in a flow path through which a refrigerant flows. By forming such fins in the cold plate, the heat transfer area increases, and it is expected that the cooling capacity will improve.

[0004] Japanese Patent Application Laid-Open No. 2000-35295

[0005] However, when fins are installed inside the cold plate, backflow and unstable flow may occur between the fins, which may hinder heat transfer from the heat source to the refrigerant and reduce cooling performance.

[0006] Furthermore, if the flow path width between the fins is narrow, in the upstream region where the bubble volume is small, the bubbles flatten, expanding the thin liquid film region. This liquid film region promotes heat transfer from the heating element to the refrigerant. On the other hand, in the downstream region where the bubble volume is large, the bubbles flatten further, expanding the dryout region where heat transfer performance is poor. As a result, heat transfer performance deteriorates from the upstream side to the downstream side, and there is a risk of cooling performance decreasing.

[0007] Another method to prevent unstable flow is to change the shape of the casing that contains the refrigerant, gradually expanding the space above the fins toward the downstream side, making it easier for air bubbles to escape into the space above the fins as the amount of steam increases due to boiling. However, this method results in a larger cold plate, which can make it difficult to install in a server.

[0008] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a cold plate that can improve cooling capacity without increasing the size of the server.

[0009] In order to solve the above problem, the cold plate of the present disclosure comprises a casing arranged adjacent to a heating element in a first direction and attached to the outer surface of the heating element, which boils a refrigerant flowing inside to remove heat from the heating element, and a plurality of fins arranged within the casing at intervals in a second direction intersecting the first direction, wherein the fins protrude in the first direction from a bottom surface of the inner surface of the casing that is along the outer surface and extend in a direction intersecting both the first direction and the second direction, the plurality of fins form a flow path between adjacent fins through which the refrigerant can flow, and the plurality of fins include a plurality of first fins extending from the upstream end to the downstream end of the flow path and a plurality of second fins arranged between adjacent first fins, and the height in the first direction of the second fins on the upstream side of the flow direction of the flow path is greater than the height in the first direction of the second fins on the downstream side of the flow direction.

[0010] The cold plate of the present disclosure comprises a casing arranged adjacent to a heating element in a first direction and attached to the outer surface of the heating element, which boils a refrigerant flowing inside to remove heat from the heating element, and a plurality of fins arranged within the casing at intervals in a second direction intersecting the first direction, wherein the fins protrude in the first direction from a bottom surface of the inner surface of the casing that is aligned with the outer surface and extend in a direction intersecting both the first direction and the second direction, and the plurality of fins form flow paths between adjacent fins through which the refrigerant can flow, and the height of the fins in the first direction on the upstream side of the flow path in the flow direction is greater than the height of the fins in the first direction on the downstream side of the flow direction.

[0011] The cold plate of the present disclosure can improve cooling performance.

[0012] FIG. 1 is a plan view of a cold plate according to a first embodiment of the present disclosure. FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1. FIG. 3 is a plan view of a fin according to a first embodiment of the present disclosure. FIG. 4 is a front view of a fin according to a first embodiment of the present disclosure. FIG. 5 is a side view of a fin according to a first embodiment of the present disclosure. FIG. 6 is a diagram illustrating a function of a fin according to the first embodiment of the present disclosure. FIG. 7 is a plan view of a fin according to a second embodiment of the present disclosure. FIG. 8 is a front view of a fin according to a second embodiment of the present disclosure. FIG. 9 is a side view of a fin according to a second embodiment of the present disclosure. FIG. 10 is a plan view of a fin according to a third embodiment of the present disclosure. FIG. 11 is a front view of a fin according to a third embodiment of the present disclosure. FIG. 12 is a side view of a fin according to a third embodiment of the present disclosure. FIG. 13 is a plan view of a fin according to a fourth embodiment of the present disclosure. FIG. 14 is a front view of a fin according to a fourth embodiment of the present disclosure. FIG. 15 is a side view of a fin according to a modified example of the fourth embodiment of the present disclosure.

[0013] First Embodiment A cold plate 1 according to a first embodiment of the present disclosure will be described below with reference to FIGS. 1 to 7. A server has multiple chips, such as CPUs and GPUs, mounted on a substrate 2. These chips generate heat during operation. The cold plate 1 according to the present disclosure is used to cool these chips. Hereinafter, these chips will be referred to as heat-generating elements 3. These chips are an example of heat-generating elements 3.

[0014] The heating element 3 is disposed so as to extend in the horizontal direction. Hereinafter, the vertical direction may be referred to as the first direction D1. One of the horizontal directions may be referred to as the "second direction D2," and the horizontal direction perpendicular to the second direction D2 may be referred to as the "third direction D3." The first direction D1, the second direction D2, and the third direction D3 are perpendicular to one another.

[0015] 1 and 2 , the cold plate 1 is placed on the heating element 3 from above and is arranged to extend horizontally in the same manner as the heating element 3. The cold plate 1 includes a casing 10, a flow path wall 20, and fins 30.

[0016] (Casing) The casing 10 is disposed adjacent to the heating element 3 in the first direction D1. The casing 10 can be filled with a refrigerant R that cools the heating element 3. The refrigerant R flows inside the casing 10. The casing 10 boils the refrigerant R to remove heat from the heating element 3. The casing 10 extends in the second direction D2 and the third direction D3. The casing 10 is formed in a rectangular plate shape with the second direction D2 as its longitudinal direction. Hereinafter, an imaginary plane that passes through the center of the casing 10 in the third direction D3 and extends in the first direction D1 and the second direction D2 will be referred to as the central plane C. The casing 10 is formed of a thermally conductive material such as a metal material. The casing 10 has a base plate 11 and a cover 12.

[0017] The base plate 11 is attached to the outer surface 3a of the heating element 3 on the side opposite to the substrate 2 in the first direction D1. The base plate 11 extends in the second direction D2 and the third direction D3. The base plate 11 is formed in a rectangular plate shape with the second direction D2 as its longitudinal direction.

[0018] The cover 12 is superimposed on the base plate 11 from the opposite side to the heating element 3 in the first direction D1. The cover 12 is open toward the base plate 11 in the first direction D1. The cover 12 covers the flow path walls 20 and the fins 30, which will be described later. The cover 12 has side walls 13 and an upper wall 14. A total of four side walls 13 are provided along each edge of the base plate 11. The side walls 13 rise from the base plate 11 in the first direction D1. Hereinafter, of the side walls 13, a pair of side walls 13 facing in the second direction D2 will be referred to as first side walls 13a, and a pair of side walls 13 facing in the third direction D3 will be referred to as second side walls 13b.

[0019] A supply hole 15 is formed in one of the two first side walls 13a. The supply hole 15 penetrates the first side wall 13a in the second direction D2. The supply port 4 is connected to the supply hole 15. The supply port 4 supplies the refrigerant R into the casing 10. The refrigerant R is supplied into the casing 10 through the supply hole 15. In this embodiment, the supply hole 15 is formed in a circular shape. The center of the supply hole 15 is located on the central plane C.

[0020] The top wall 14 is provided at the end of each side wall 13 opposite the base plate 11 in the first direction D1. The top wall 14 closes the space surrounded by the four side walls 13. The top wall 14 extends in the second direction D2 and the third direction D3. The top wall 14 is formed in the shape of a rectangular plate with the second direction D2 as its longitudinal direction.

[0021] A discharge hole 16 is formed in the upper wall 14. The discharge hole 16 penetrates the upper wall 14 in the first direction D1. The discharge outlet extends in the second direction D2. The discharge hole 16 is connected to a discharge port 5. The discharge port 5 discharges the refrigerant R from inside the casing 10. The refrigerant R is discharged to the outside of the casing 10 through the discharge hole 16. A center line that passes through the center of the discharge hole 16 in the third direction D3 and extends in the second direction D2 is located on the center plane C.

[0022] (Flow Channel Walls) When viewed from the first direction D1, the flow channel walls 20 are arranged in pairs on both outer sides of the discharge hole 16 in the second direction D2. The flow channel walls 20 extend in the third direction D3. The flow channel walls 20 also protrude from the base plate 11 in the first direction D1 and connect the base plate 11 and the upper wall 14. The flow channel walls 20 are also arranged in a position opposite the first side wall 13a in the second direction D2. The flow of the refrigerant R supplied into the casing 10 is changed from the second direction D2 to the third direction D3 by the flow channel walls 20.

[0023] (Fins) The fins 30 are arranged in the casing 10 at intervals in the second direction D2. In this embodiment, the fins 30 are arranged at equal intervals in the second direction D2. The fins 30 extend in the third direction D3. The fins 30 protrude from the bottom surface 17a on the base plate 11 of the inner surface 17 of the casing 10 and connect the base plate 11 to the upper wall 14. The bottom surface 17a is aligned with the outer surface 3a of the heating element 3. The fins 30 form flow paths 6 between adjacent fins 30 in the casing 10, through which the refrigerant R can flow. The refrigerant R flows in this flow path 6 from the second side wall 13b toward the discharge hole 16 in the third direction D3. Hereinafter, the flow direction Df of this flow path 6 will be simply referred to as the flow direction Df. In this embodiment, the flow direction Df coincides with the third direction D3. The upstream side Dfu in the flow direction Df is simply referred to as the upstream side Dfu, and the downstream side Dfd in the flow direction Df is simply referred to as the downstream side Dfd. The width W1 of the flow path 6 in the second direction D2 is constant at all positions in the flow direction Df.

[0024] Furthermore, the fins 30 are formed, for example, from the same material as the casing 10. That is, the fins 30 are formed, for example, from a heat-conductive material such as a metal material. The width W2 of the fins 30 in the second direction D2 is constant at all positions in the flow direction Df. The width W2 of the fins 30 is smaller than the distance between the fins 30 (the width W1 of the flow path 6). Furthermore, the height H of each fin 30 in the first direction D1 is designed to be larger than the width W2 of the fin 30 and the distance between the fins 30 (the width W1 of the flow path 6), at least at the end of each fin 30 on the most upstream side Dfu.

[0025] In this embodiment, the fins 30 are provided in pairs on both sides of the central plane C in the third direction D3. These pairs of fins 30 are formed symmetrically with respect to the central plane C. Each pair of fins 30 includes a plurality of first fins 31 and a plurality of second fins 32. In this embodiment, the first fins 31 and the second fins 32 both extend from the upstream end 6a to the downstream end 6b of the flow path 6 in the flow direction Df. That is, the length L1 of the first fins 31 in the second direction D2 and the length L2 of the second fins 32 in the second direction D2 are equal.

[0026] (First Fin) The first fin 31 extends from the upstream end 6a to the downstream end 6b of the flow path 6. The first fins 31 adjacent to each other in the third direction D3 across the center plane C (the first fins 31 formed at the same position in the second direction D2) are connected to each other at the center plane C and are integrated. Note that the first fins 31 adjacent to each other in the third direction D3 (the first fins 31 formed at the same position in the second direction D2) may be formed separately or may be spaced apart in the third direction D3.

[0027] 3 to 5, the first fins 31 have a uniform height H in the first direction D1 that extends in the flow direction Df. That is, the height H of the first fins 31 in the first direction D1 is constant at all positions in the flow direction Df.

[0028] The first fin 31 has a plurality of slits 33 formed at intervals in the flow direction Df. The slits 33 are formed at equal intervals in the flow direction Df. When viewed from the second direction D2, the slits 33 are formed in a triangular shape that tapers toward the base plate 11 in the first direction D1. That is, the length L3 of the slits 33 in the flow direction Df gradually decreases toward the base plate 11 in the first direction D1. The slits 33 are formed across the entire area in the first direction D1, from the edge of the first fin 31 opposite the bottom surface 17a in the first direction D1 to the bottom surface 17a. Note that the slits 33 do not necessarily have to extend to the bottom surface 17a. The slits 33 may be formed all at once when the fin 30 is formed by casting, or may be formed by cutting the fin 30 after it is formed. The slits 33 do not necessarily have to be formed at equal intervals in the flow direction Df. The shape of the slits 33 can be changed as appropriate. The slit 33 may be formed in a rectangular shape extending in the first direction D1 when viewed from the second direction D2.

[0029] The first fin 31 is divided into a plurality of small pieces 31a in the flow direction Df by a plurality of slits 33. The small pieces 31a are formed in a trapezoidal shape. The length of the small pieces 31a in the flow direction Df narrows as they move away from the bottom surface 17a in the first direction D1. The length L4 in the flow direction Df of the edge of each small piece 31a on the bottom surface 17a side is the same for all of the small pieces 31a. Furthermore, the length L4 in the flow direction Df of each small piece 31a is greater than the length L3 of the slits 33 in the flow direction Df.

[0030] (Second Fins) The second fins 32 are arranged between adjacent first fins 31. One second fin 32 is arranged in each gap between adjacent first fins 31. Note that the second fins 32 adjacent to each other in the third direction D3 across the center plane C (the second fins 32 formed at the same position in the second direction D2) are in contact with each other at the center plane C. Note that the second fins 32 adjacent to each other in the third direction D3 (the second fins 32 formed at the same position in the second direction D2) may be spaced apart in the third direction D3 or may be formed integrally.

[0031] The height H of the second fin 32 in the first direction D1 on the upstream side Dfu is higher than the height H of the second fin 32 in the first direction D1 on the downstream side Dfd. In other words, the height H of the second fin 32 in the first direction D1 on the downstream side Dfd is lower than the height H of the second fin 32 in the first direction D1 on the upstream side Dfu. In this embodiment, the second fin 32 is tapered in the second direction D2 such that the height H in the first direction D1 gradually decreases from the upstream side Dfu to the downstream side Dfd. In the illustrated example, the second fin 32 is triangular in the second direction D2 such that the height H in the first direction D1 decreases. Therefore, only the end of the second fin 32 on the upstream side Dfu is connected to the top wall 14 of the casing 10.

[0032] In other words, the second fin 32 has a leading edge 34 formed on the side of the second fin 32 opposite the bottom surface 17a in the first direction D1, and this leading edge 34 is formed in a linear shape that extends in the flow direction Df and slopes toward the bottom surface 17a in the first direction D1 from the upstream side Dfu toward the downstream side Dfd. The end of the second fin 32 on the downstream side Dfd is located on the bottom surface 17a.

[0033] (Operations and Effects) The operations and effects of the cold plate 1 of this embodiment are described below. The refrigerant R supplied into the casing 10 through the supply holes 15 hits the flow path wall 20 and splits into two directions. The refrigerant R then flows along the second side wall 13b and flows into each flow path 6 between the fins 30. The refrigerant R flows from the second side wall 13b toward the center plane C. As the refrigerant R flows through the flow paths 6, heat is transferred from the heating element 3 to the refrigerant R. Because the heat transfer area of ​​the cold plate 1 is increased by the fins 30, heat transfer from the heating element 3 to the refrigerant R is efficient, and the refrigerant R boils due to the heat from the heating element 3. At this time, the heat of vaporization of the refrigerant R is removed from the heating element 3, cooling the heating element 3. The vaporized refrigerant R is discharged outside the casing 10 through the outlet. The refrigerant R then circulates through piping (not shown), passes through a condenser, and is again supplied into the casing 10 through the supply holes 15. The coolant R may be circulated only by natural convection caused by the heat of the heating element 3, or the coolant R may be pressure-fed by providing a pump or the like.

[0034] In this embodiment, the cold plate 1 includes a casing 10 and a plurality of fins 30. The casing 10 is disposed adjacent to the heat generating element 3 in a first direction D1 and is attached to the outer surface 3a of the heat generating element 3. A refrigerant R flows through the casing 10. The casing 10 removes heat from the heat generating element 3 by boiling the refrigerant R flowing through the casing 10. The plurality of fins 30 are disposed within the casing 10 at intervals in a second direction D2 intersecting the first direction D1. The fins 30 protrude in the first direction D1 from a bottom surface 17a of the inner surface 17 of the casing 10 that is aligned with the outer surface 3a, and extend in a third direction D3 intersecting both the first direction D1 and the second direction D2. The plurality of fins 30 form flow paths 6 between adjacent fins 30, through which the refrigerant R can flow. The multiple fins 30 include multiple first fins 31 extending from the upstream end 6a to the downstream end 6b of the flow path 6 and multiple second fins 32 arranged between adjacent first fins 31. A height H in the first direction D1 of the second fins 32 on the upstream side Dfu of the flow path 6 in the flow direction Df is greater than a height H in the first direction D1 of the second fins 32 on the downstream side Dfd of the flow direction Df.

[0035] As shown in Figures 6 and 7, when the refrigerant R boils, bubbles 50 are generated within the cold plate 1. The bubbles 50 are flattened by the fins 30. The flat bubbles 50 have a liquid film region 51 with good heat transfer performance and a dryout region 52 with poor heat transfer performance. The volume of the bubbles 50 decreases toward the upstream side Dfu and increases toward the downstream side Dfd. The volume of the bubbles 50 decreases toward the base (lower side) of the fin 30, which is closer to the heat generating element 3 in the first direction D1 (vertical direction), and increases toward the tip (upper side) of the fin 30, which is farther from the heat generating element 3 in the first direction D1 (vertical direction). When the volume of the bubbles 50 increases within the narrow flow path 6, the bubbles 50 obstruct the flow of the refrigerant R. Furthermore, the dryout region 52 increases, which may result in a deterioration in heat transfer performance and a decrease in cooling performance.

[0036] In this embodiment, the first fins 31 and the second fins 32 are arranged alternately, and the height H of the second fins 32 on the upstream side Dfu in the flow direction Df of the flow path 6 is greater than the height H of the second fins 32 on the downstream side Dfd in the flow direction Df. This allows the gaps between the fins 30 in the upper part of the casing 10 (flow path 6) to be enlarged as the gaps move toward the downstream side Dfd and away from the heating element 3. Therefore, as the volume of the bubbles 50 increases, the bubbles 50 are more likely to flow toward the downstream side Dfd and upward, suppressing backflow and unstable flow of the refrigerant R. Furthermore, in the narrow gaps between adjacent fins 30, the dryout region 52 with poor heat transfer performance within the bubbles 50 gradually increases toward the downstream side Dfd. According to this embodiment, the bubbles 50 are more likely to flow from the narrow gaps between adjacent fins 30 into a larger space above the second fins 32 as the gaps move toward the downstream side Dfd. When the bubbles 50 flow into the wider space, the dryout region 52 shrinks. In this way, backflow and unstable flow of the refrigerant R are suppressed, and the dryout region 52 of the bubbles 50 on the downstream side Dfd can be reduced, thereby suppressing deterioration of heat transfer performance and improving cooling performance. Furthermore, improved cooling performance reduces the energy required to cool the heat-generating element. Furthermore, because there is no need to change the volume of the casing 10, the cold plate 1 can be prevented from becoming larger.

[0037] In this embodiment, the second fin 32 has a leading edge 34 formed on the opposite side of the bottom surface 17a in the first direction D1 and extending in the flow direction Df. The leading edge 34 is inclined in the first direction D1 so as to approach the bottom surface 17a from the upstream side Dfu to the downstream side Dfd.

[0038] According to this embodiment, the flow path area between the fins 30 gradually increases from the upstream side Dfu to the downstream side Dfd. This reduces the increase in pressure loss associated with the volumetric flow rate of the refrigerant R from the upstream side Dfu to the downstream side Dfd, thereby suppressing the occurrence of unstable flow accompanied by abrupt changes in the flow rate of the refrigerant R or increased pressure loss. While the present embodiment describes a case in which the leading edge 34 is linear, this is not limiting. The leading edge 34 may also be curved such that the height H of the second fin 32 in the first direction D1 decreases. Even in this case, the cold plate 1 can achieve the same advantageous effects.

[0039] Second Embodiment A cold plate 201 according to a second embodiment of the present disclosure will be described below with reference to Figures 8 to 10. Among the configurations of the second embodiment, configurations common to the above-described embodiments will be designated by the same names and reference numerals, and descriptions thereof will be omitted as appropriate.

[0040] As shown in FIGS. 8 to 10 , in this embodiment, the multiple fins 230 include multiple first fins 31 and multiple second fins 232. The second fins 232 extend in the flow direction Df from the upstream end 6a of the flow path 6, but the length L2 of the second fins 232 in the flow direction Df is shorter than the length L1 of the first fins 31 in the flow direction Df. The second fins 232 are formed on the opposite side of the bottom surface 17a in the first direction D1 and have leading edges 234 extending in the flow direction Df. The leading edges 234 are formed in a stepped shape that gradually approaches the bottom surface 17a in the first direction D1 from the upstream side Dfu to the downstream side Dfd. That is, the leading edge 234 has multiple step surfaces 235 aligned in the flow direction Df. Each step surface 235 extends in the flow direction Df parallel to the bottom surface 17a. The plurality of step surfaces 235 are positioned closer to the bottom surface 17a in the first direction D1 as they move from the upstream side Dfu to the downstream side Dfd. The distance in the first direction D1 between adjacent step surfaces 235 in the flow direction Df is equal. Furthermore, of the plurality of step surfaces 235, only the step surface 235 on the most upstream side Dfu is connected to the upper wall 14 of the casing 10.

[0041] (Effects) The following describes the effects of the cold plate 201 of this embodiment. The cold plate 201 of this embodiment provides the same fluid and thermal effects as the first embodiment described above, as well as the following effects. In this embodiment, the leading edge 234 is formed in a stepped shape that gradually approaches the bottom surface 17a in the first direction D1 from the upstream side Dfu toward the downstream side Dfd.

[0042] This makes it easy to change the design of the height H of the second fins 232, and makes it possible to design the second fins 232 to match the specifications of the cold plate 201, such as the heat generation amount and the type of refrigerant R.

[0043] Third Embodiment A cold plate 301 according to a third embodiment of the present disclosure will be described below with reference to Figures 11 to 13. Among the configurations of the third embodiment, configurations common to the above-described embodiments will be designated by the same names and reference numerals, and descriptions thereof will be omitted as appropriate.

[0044] As shown in FIGS. 11 to 13 , in this embodiment, the multiple fins 330 include multiple first fins 31 and multiple second fins 332. The center 332a of the second fin 332 in the flow direction Df is located on the upstream side Dfu, and the length L2 of the second fin 332 in the flow direction Df is shorter than the length L1 of the first fin 31 in the flow direction Df. In this embodiment, the end of the second fin 332 on the upstream side Dfu is located at the upstream end 6a of the flow channel 6, and the end of the second fin 332 on the downstream side Dfd is located at the middle position in the flow direction Df of the flow channel 6. The length L2 of the second fin 332 in the flow direction Df is half the length L1 of the first fin 31. Note that the position of the end of the upstream side Dfu of the second fin 332 can be changed as appropriate. The end of the upstream side Dfu of the second fin 332 on the upstream side Dfd may be located downstream of the upstream end 6a of the flow channel 6.

[0045] In this embodiment, similar to the first fin 31, the second fin 332 has a height H in the first direction D1 that extends uniformly in the flow direction Df. That is, the height H of the second fin 332 in the first direction D1 is constant at all positions in the flow direction Df. The entire area of ​​the second fin 332 in the flow direction Df is connected to the upper wall 14 of the casing 10. Similarly to the first fin 31, the second fin 332 has a plurality of slits 33 formed therein at intervals in the flow direction Df. The slits 33 of the second fin 332 are formed at the same positions in the flow direction Df as the slits 33 of the first fin 31. That is, the slits 33 of the second fin 332 overlap with the slits 33 of the first fin 31 in the second direction D2.

[0046] (Effects) The following describes the effects of the cold plate 301 of this embodiment. The cold plate 301 of this embodiment provides the same fluid and thermal effects as the first embodiment described above, as well as the following effects. In this embodiment, the center 332a of the second fin 332 in the flow direction Df is located on the upstream side Dfu, and the length of the second fin 332 in the flow direction Df is shorter than the length of the first fin 31 in the flow direction Df.

[0047] This allows the cooling performance to be improved as described above simply by shortening the length of the second fin 332, while the second fin 332 and the first fin 31 can be designed to have similar shapes, thereby improving the manufacturing efficiency of the fin 330.

[0048] Fourth Embodiment A cold plate 401 according to a fourth embodiment of the present disclosure will be described below with reference to Figures 14 to 16. Among the configurations of the fourth embodiment, configurations common to the above-described embodiments will be designated by the same names and reference numerals, and descriptions thereof will be omitted as appropriate.

[0049] As shown in FIGS. 14 to 16 , the cold plate 401 has a plurality of fins 430. In this embodiment, the cold plate 401 includes a casing 10 and a plurality of fins 430. The fins 430 are all formed to have the same shape. The fins 430 form flow paths 6 between adjacent fins 430, through which the refrigerant R can flow. The height H in the first direction D1 of the fins 430 on the upstream side Dfu in the flow direction Df of the flow path 6 is higher than the height H in the first direction D1 of the fins 430 on the downstream side Dfd in the flow direction Df. In other words, the height H in the first direction D1 of the fins 430 on the downstream side Dfd is lower than the height H in the first direction D1 of the fins 430 on the upstream side Dfu.

[0050] In this embodiment, the leading edge 434 of the fin 430 has a parallel portion 434a on the upstream side Dfu and an inclined portion 434b on the downstream side Dfd. The parallel portion 434a extends parallel to the bottom surface 17a. The inclined portion 434b extends from the downstream end 434c of the parallel portion 434a further toward the downstream side Dfd. The inclined portion 434b inclines toward the bottom surface 17a as it extends toward the downstream side Dfd. The end of the inclined portion 434b on the downstream side Dfd is located on the bottom surface 17a. Of the fin 430, only the parallel portion 434a is connected to the top wall 14 of the casing 10.

[0051] (Effects) The effects of the cold plate 401 of this embodiment are described below. In this embodiment, the cold plate 401 includes a casing 10 and a plurality of fins 430. The fins 430 are arranged at intervals within the casing 10 in a second direction D2 intersecting the first direction D1. The fins 430 protrude in the first direction D1 from a bottom surface 17a of the inner surface 17 of the casing 10 that is aligned with the outer surface 3a, and extend in a third direction D3 intersecting both the first direction D1 and the second direction D2. The fins 430 form flow paths 6 between adjacent fins 430 through which the refrigerant R can flow. The height H of the fins 430 in the first direction D1 at an upstream side Dfu in the flow direction Df of the flow path 6 is greater than the height H of the fins 430 in the first direction D1 at a downstream side Dfd in the flow direction Df.

[0052] In this embodiment, the height H of the fins 430 on the upstream side Dfu in the flow direction Df of the flow path 6 is higher than the height H of the fins 430 on the downstream side Dfd in the flow direction Df. This allows the gaps between the fins 430 (flow path 6) in the upper part of the casing 10 to be enlarged toward the downstream side Dfd. Therefore, as the volume of the bubbles 50 increases, the bubbles 50 are more likely to flow downstream Dfd and upward, suppressing backflow and unstable flow of the refrigerant R. Furthermore, in the narrow gaps between adjacent fins 430, the dryout region 52 with poor heat transfer performance within the bubbles 50 gradually increases toward the downstream side Dfd. According to this embodiment, the bubbles 50 are more likely to flow from the narrow gaps between adjacent fins 430 into a larger space above the fins 430 toward the downstream side Dfd. When the bubbles 50 flow into a larger space, the dryout region 52 shrinks. In this way, backflow and unstable flow of the refrigerant R are suppressed, and the dry-out region 52 of the bubbles 50 on the downstream side Dfd can be reduced, thereby suppressing deterioration of heat transfer performance and improving cooling performance. Furthermore, improved cooling performance reduces the energy required to cool the heat-generating element. Furthermore, because there is no need to change the volume of the casing 10, the cold plate 401 can be prevented from becoming larger.

[0053] In the present embodiment, the downstream end of the inclined portion 434b of the leading edge 434 is located on the bottom surface 17a, but this is not limited to this. The shape of the fin 430 can be changed as appropriate. For example, as shown in FIG. 17 , the downstream end of the inclined portion 434b of the leading edge 434 may be spaced apart from the bottom surface 17a in the first direction D1. (The downstream end of the inclined portion 434b may be located above the bottom surface 17a.) Furthermore, the position of the boundary between the parallel portion 434a and the inclined portion 434b can be changed as appropriate.

[0054] In addition, in this embodiment, the plurality of fins 430 are all formed in the same shape, but this is not limited thereto. Some of the fins 430 may be formed in different shapes.

[0055] (Other Embodiments) Although the embodiments of the present disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like within the scope that does not deviate from the gist of the present disclosure are also included.

[0056] In the above embodiment, the cold plates 1, 201, 301, and 401 are arranged to extend horizontally, but this is not limiting. The orientation of the cold plates 1, 201, 301, and 401 can be changed as appropriate depending on the shape and orientation of the heating element 3. For example, the cold plates 1, 201, 301, and 401 may be arranged at an angle relative to the horizontal.

[0057] In the first to third embodiments, the first fins 31 and the second fins 32, 232, 332 are alternately arranged one by one in the second direction D2, but this is not limiting. For example, a plurality of second fins 32, 232, 332 may be provided between adjacent first fins 31, or a plurality of first fins 31 may be provided between adjacent second fins 32, 232, 332.

[0058] In the first to third embodiments, the slits 33 are formed in the first fin 31 and the second fin 32, 232, 332, but this is not limited to this. The slits 33 do not have to be formed in the first fin 31 and the second fin 32, 232, 332. In the fourth embodiment, the slits 33 are not formed in the fin 430, but this is not limited to this. In the fourth embodiment, the slits 33 may be formed in the fin 430, as in the first to third embodiments.

[0059] <Additional Notes> The cold plates 1, 201, 301, and 401 described in the respective embodiments can be understood, for example, as follows.

[0060] (1) A cold plate 1, 201, 301 according to a first aspect includes a casing 10 that is disposed adjacent to a heat generating element 3 in a first direction D1 and is attached to an outer surface 3a of the heat generating element 3, and that removes heat from the heat generating element 3 by boiling a refrigerant R flowing inside the casing 10, and a plurality of fins 30, 230, 330 that are disposed within the casing 10 at intervals in a second direction D2 that intersects with the first direction D1, and the fins 30, 230, 330 protrude in the first direction D1 from a bottom surface 17a of an inner surface 17 of the casing 10 that is along the outer surface 3a, and are arranged in a direction that intersects both the first direction D1 and the second direction D2. The fins 30, 230, 330 form a flow path 6 between adjacent fins 30, 230, 330 through which the refrigerant R can flow, and the fins 30, 230, 330 include a plurality of first fins 31 extending from an upstream end 6a to a downstream end 6b of the flow path 6 and a plurality of second fins 32, 232, 332 arranged between adjacent first fins 31, and a height H in the first direction D1 of the second fins 32, 232, 332 on the upstream side Dfu of the flow direction Df of the flow path 6 is higher than a height H in the first direction D1 of the second fins 32, 232, 332 on the downstream side Dfd of the flow direction Df.

[0061] In this embodiment, the first fins 31 and the second fins 32, 232, 332 are arranged alternately, and the height H of the second fins 32, 232, 332 on the upstream side Dfu in the flow direction Df of the flow path 6 is greater than the height H of the second fins 32, 232, 332 on the downstream side Dfd in the flow direction Df. This allows the gaps (flow paths 6) between the fins 30, 230, 330 to be enlarged toward the downstream side Dfd. Therefore, as the volume of the bubbles 50 increases, the bubbles 50 are more likely to flow toward the downstream side Dfd, suppressing backflow and unstable flow of the refrigerant R. Furthermore, in the narrow gaps between adjacent fins 30, 230, 330, the dryout regions 52 with poor heat transfer performance within the bubbles 50 gradually increase toward the downstream side Dfd. According to this aspect, the bubbles 50 are more likely to flow out of the narrow gaps between adjacent fins 30, 230, and 330 toward the downstream side Dfd and into a wider space. When the bubbles 50 flow into a wider space, the dryout region 52 shrinks. This suppresses backflow and unstable flow of the refrigerant R and reduces the dryout region 52 of the bubbles 50 on the downstream side Dfd, thereby suppressing deterioration of heat transfer performance and improving cooling performance. Furthermore, because there is no need to change the volume of the casing 10, the cold plate 1, 201, and 301 can be prevented from becoming larger.

[0062] (2) A second aspect of the cold plate 1 is the cold plate 1 of (1), wherein the second fin 232 is formed on the opposite side of the bottom surface 17a in the first direction D1 and has a leading edge 34 extending in the flow direction Df, and the leading edge 34 may be inclined so as to approach the bottom surface 17a in the first direction D1 as it moves from the upstream side Dfu to the downstream side Dfd.

[0063] According to this aspect, the flow path area between the fins 30 gradually increases from the upstream side Dfu to the downstream side Dfd, thereby reducing the increase in pressure loss associated with the volumetric flow rate of the refrigerant R from the upstream side Dfu to the downstream side Dfd, thereby suppressing the occurrence of unstable flow accompanied by abrupt changes in the flow rate of the refrigerant R and an increase in pressure loss.

[0064] (3) A third aspect of the cold plate 201 is the cold plate 201 of (1), wherein the second fin 232 is formed on the opposite side of the bottom surface 17a in the first direction D1 and has a leading edge 234 extending in the flow direction Df, and the leading edge 234 may be formed in a stepped shape that gradually approaches the bottom surface 17a in the first direction D1 as it moves from the upstream side Dfu to the downstream side Dfd.

[0065] This makes it easy to change the design of the height H of the second fins 232, and makes it possible to design the second fins 232 to match the specifications of the cold plate 201, such as the heat generation amount and the type of refrigerant R.

[0066] (4) The cold plate 301 of the fourth aspect is the cold plate 301 of (1), wherein the center 332a of the flow direction Df of the second fin 332 is located on the upstream side Dfu, and the length of the flow direction Df of the second fin 332 may be shorter than the length of the flow direction Df of the first fin 31.

[0067] This allows the cooling performance to be improved as described above simply by shortening the length of the second fin 332, while the second fin 332 and the first fin 31 can be designed to have similar shapes, thereby improving the manufacturing efficiency of the fin 330.

[0068] (5) A cold plate 401 according to a fifth aspect includes a casing 10 that is disposed adjacent to a heat generating element 3 in a first direction D1 and is attached to an outer surface 3a of the heat generating element 3, and that removes heat from the heat generating element 3 by boiling a refrigerant R flowing therethrough, and a plurality of fins 430 that are disposed within the casing 10 at intervals in a second direction D2 that intersects with the first direction D1, and the fins 430 are disposed on an inner surface 17 of the casing 10 adjacent to the outer surface 3a. The fins 430 protrude in the first direction D1 from a bottom surface 17a along the axial direction of the fins 430 and extend in a direction intersecting both the first direction D1 and the second direction D2, and the fins 430 form a flow path 6 between adjacent fins 430 through which the refrigerant R can flow, and a height H in the first direction D1 of the fins 430 on the upstream side Dfu of the flow direction Df of the flow path 6 is higher than a height H in the first direction D1 of the fins 430 on the downstream side Dfd of the flow direction Df.

[0069] In this embodiment, the height H of the fins 430 on the upstream side Dfu in the flow direction Df of the flow path 6 is higher than the height H of the fins 430 on the downstream side Dfd in the flow direction Df. This allows the gaps between the fins 430 (flow path 6) to be enlarged toward the downstream side Dfd. Therefore, as the volume of the bubbles 50 increases, the bubbles 50 are more likely to flow toward the downstream side Dfd, suppressing backflow and unstable flow of the refrigerant R. Furthermore, in the narrow gaps between adjacent fins 430, the dryout region 52 with poor heat transfer performance within the bubbles 50 gradually increases toward the downstream side Dfd. According to this embodiment, the bubbles 50 are more likely to flow from the narrow gaps between adjacent fins 430 into a larger space toward the downstream side Dfd. When the bubbles 50 flow into a larger space, the dryout region 52 shrinks. In this way, backflow and unstable flow of the refrigerant R are suppressed, and the dry-out region 52 of the bubbles 50 on the downstream side Dfd can be reduced, thereby suppressing deterioration of heat transfer performance and improving cooling performance. Furthermore, since there is no need to change the volume of the casing 10, an increase in the size of the cold plate 401 can be suppressed.

[0070] The cold plate of the present disclosure can improve cooling performance.

[0071] 1...cold plate, 2...substrate, 3...heat generating element, 3a...outer surface, 4...supply port, 5...exhaust port, 6...flow path, 6a...upstream end, 6b...downstream end, 10...casing, 11...base plate, 12...cover, 13...side wall, 13a...first side wall, 13b...second side wall, 14...upper wall, 15...supply hole, 16...exhaust hole, 17...inner surface, 17a...bottom surface, 20...flow path wall, 30...fin, 31...first fin, 31a...small piece, 32...second fin, 33...slit, 34...tip edge, 50...air bubble, 51...liquid film region, 52...dry-out region, 201...cold plate cold plate, 230...fin, 232...second fin, 234...leading edge, 235...step surface, 301...cold plate, 330...fin, 332...second fin, 332a...center, 401...cold plate, 430...fin, 434...leading edge, 434a...parallel portion, 434b...inclined portion, 434c...downstream end, C...center surface, D1...first direction, D2...second direction, D3...third direction, Df...flow direction, Dfu...upstream side, Dfd...downstream side, H...height, L1...length, L2...length, L3...length, L4...length, R...refrigerant, W1...width, W2...width

Claims

1. A cold plate comprising: a casing arranged adjacent to a heating element in a first direction and attached to the outer surface of the heating element, the casing boiling a refrigerant flowing inside to remove heat from the heating element; and a plurality of fins arranged within the casing at intervals in a second direction intersecting the first direction, wherein the fins protrude in the first direction from a bottom surface of the inner surface of the casing that is aligned with the outer surface, and extend in a direction intersecting both the first and second directions, the plurality of fins forming a flow path between adjacent fins through which the refrigerant can flow, the plurality of fins including: a plurality of first fins extending from the upstream end to the downstream end of the flow path; and a plurality of second fins arranged between adjacent first fins, wherein the height in the first direction of the second fins on the upstream side of the flow direction of the flow path is greater than the height in the first direction of the second fins on the downstream side of the flow direction.

2. A cold plate as described in claim 1, wherein the second fin is formed on the opposite side of the bottom surface in the first direction and has a leading edge extending in the flow direction, the leading edge being inclined so as to approach the bottom surface side in the first direction as it moves from the upstream side to the downstream side.

3. A cold plate as described in claim 1, wherein the second fin is formed on the opposite side of the bottom surface in the first direction and has a leading edge extending in the flow direction, and the leading edge is formed in a stepped shape that gradually approaches the bottom surface side in the first direction as it moves from the upstream side to the downstream side.

4. The cold plate according to claim 1, wherein the center of the second fin in the flow direction is located on the upstream side, and the length of the second fin in the flow direction is shorter than the length of the first fin in the flow direction.

5. A cold plate comprising: a casing arranged adjacent to a heating element in a first direction and attached to the outer surface of the heating element, which removes heat from the heating element by boiling a refrigerant flowing inside; and a plurality of fins arranged within the casing at intervals in a second direction intersecting the first direction, wherein the fins protrude in the first direction from a bottom surface of the inner surface of the casing that is along the outer surface and extend in a direction intersecting both the first direction and the second direction, the plurality of fins form flow paths between adjacent fins through which the refrigerant can flow, and the height in the first direction of the fins on the upstream side of the flow path in the flow direction is greater than the height in the first direction of the fins on the downstream side of the flow direction.

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