JP7833979B2 - cooling device - Google Patents

Description

This disclosure relates to a cooling device.

Patent Document 1 discloses a cooling system for directly cooling electronic equipment having a heat-generating element by immersing it in a liquid refrigerant. The refrigerant used in this cooling system is primarily composed of fluorocarbons.

International Publication No. 2016/075838

Fluorocarbon-based refrigerants are commonly used for localized cooling of chips such as GPUs and CPUs in servers. However, these refrigerants are problematic due to their high global warming potential (GWP).

This disclosure was made to solve the above-mentioned problems and aims to provide a cooling device that can ensure sufficient cooling performance while using a refrigerant with a low GWP.

To solve the above problems, the cooling device according to the present disclosure comprises: a heating section having a storage space inside in which a liquid-phase refrigerant is stored and thermally connected to a heating element, and having a heat transfer surface that transfers heat from the heating element to the refrigerant; a refrigerant discharge pipe connected to the heating section for discharging the refrigerant from the storage space; a cooling section connected to the refrigerant discharge pipe for cooling the refrigerant discharged from the heating section; a refrigerant supply pipe connecting the cooling section and the heating section for supplying the refrigerant cooled in the cooling section to the heating section; and a negative pressure adjustment section that can create a negative pressure in the storage space and adjust the internal pressure of the storage space . The negative pressure adjustment section is an ejector and includes an air supply line that supplies air discharged from the ejector to the cooling section, and the cooling section cools the refrigerant by performing heat exchange between the air discharged from the ejector and the refrigerant .
Furthermore, the cooling device according to this disclosure comprises: a heating section having a storage space inside in which a liquid-phase refrigerant is stored and thermally connected to a heating element, and having a heat transfer surface that transfers heat from the heating element to the refrigerant; a refrigerant discharge pipe connected to the heating section for discharging the refrigerant from the storage space; a cooling section connected to the refrigerant discharge pipe for cooling the refrigerant discharged from the heating section; a refrigerant supply pipe connecting the cooling section and the heating section for supplying the refrigerant cooled in the cooling section to the heating section; and a negative pressure adjustment section that can create a negative pressure in the storage space and adjust the internal pressure of the storage space, wherein the heating section has a plurality of fins rising from the heat transfer surface, and the fins are formed only in the region of the heat transfer surface on the refrigerant supply pipe side.

The cooling device described herein allows for sufficient cooling performance while using a refrigerant with a low GWP (Gross Wave Power).

This is a schematic diagram showing the configuration of a cooling device according to the first embodiment of this disclosure. This is a cross-sectional view of the heating section according to the first embodiment of this disclosure. This is a schematic diagram showing the configuration of a cooling device according to the second embodiment of this disclosure. This is a schematic diagram showing the configuration of a cooling device according to a first modified example of the second embodiment of the present disclosure. This is a schematic diagram showing the configuration of a cooling device according to a second modified example of the second embodiment of the present disclosure. This is a perspective view showing the inside of the heating section according to the third embodiment of this disclosure. This is an enlarged view of the fins relating to the first modified example of the third embodiment of the present disclosure. This is a perspective view showing the inside of the heating section according to a second modified example of the third embodiment of the present disclosure. This is a schematic diagram showing the configuration of a cooling device according to the fourth embodiment of this disclosure. This is a schematic diagram showing the configuration of a cooling device according to a modified example of the fourth embodiment of the present disclosure.

<First Embodiment>
Hereinafter, the cooling device 10 according to the first embodiment of this disclosure will be described with reference to Figures 1 and 2.
As shown in Figure 1, the cooling device 10 is used to cool electronic equipment that performs high-speed calculations. In this embodiment, the cooling device 10 is used for a server 1 in a data center. Multiple servers 1 are provided.

Server 1 has a printed circuit board on which electronic components such as CPU and GPU chips are installed. Because the CPU and GPU are components responsible for high-speed computation, they are subjected to heavy loads. Therefore, the CPU and GPU generate more heat than other parts of Server 1.

Hereafter, the printed circuit board of Server 1 will be simply referred to as "Board 2," and the CPU, GPU, and other chips will be referred to as "Heat-generating elements 3."

The substrate 2 is formed in a rectangular plate shape. The substrate 2 is arranged vertically so as to extend in the vertical direction. In this embodiment, multiple substrates 2 are provided.

One heating element 3 is installed on each substrate 2. The heating elements 3 are installed so as to be attached to the surface of the substrate 2. Therefore, in this embodiment, the heating elements 3 are arranged vertically, extending in the same vertical direction as the substrate 2.

(Cooling system configuration)
Next, the configuration of the cooling device 10 will be described.
The cooling device 10 locally cools chips (heat-generating elements 3) such as CPUs and GPUs installed on the substrate 2. As shown in Figure 1, the cooling device 10 comprises a heating unit 20, a refrigerant discharge pipe 11, a cooling unit 30, a fan 12, a refrigerant charging unit 13, a refrigerant supply pipe 14, and a negative pressure adjustment unit 40.

(heating section)
In this embodiment, the heating section 20 is a rectangular plate-shaped jacket 21 installed on the surface of the heating element 3 opposite to the substrate 2. One heating section 20 is installed for each heating element 3. As shown in Figure 2, the heating section 20 has a storage space S inside in which liquid-phase refrigerant R is stored. The heating section 20 is thermally connected to the heating element 3. The heating section 20 has a heat transfer surface 22 inside that transfers heat from the heating element 3 to the refrigerant R. The heat transfer surface 22 is the inner circumferential surface of the heating section 20 that is relatively close to the heating element 3. In this embodiment, the heating section 20 is arranged vertically so as to extend in the vertical direction, similar to the substrate 2. Therefore, the heat transfer surface 22 extends along the vertical plane.

Heat from the heating element 3 is transferred to the heating unit 20. Furthermore, the heat from the heating element 3 is transferred to the liquid-phase refrigerant R in the storage space S via the heat transfer surface 22. As a result, the liquid-phase refrigerant R in the storage space S is heated. This causes the liquid-phase refrigerant R in the storage space S to expand and its density to decrease. In this embodiment, the liquid-phase refrigerant R in the storage space S boils and changes into a gaseous phase.

Refrigerant R is a low GWP refrigerant with a lower GWP than fluorocarbon refrigerants. In this embodiment, the refrigerant (low GWP refrigerant) R is water. Other low GWP refrigerants besides water include, for example, HFO (hydrofluoroolefin). In the following, the liquid-phase refrigerant R may be simply referred to as "liquid-phase refrigerant RL," and the gas-phase refrigerant R may be referred to as "gas-phase refrigerant RG."
The heating section 20 is provided with a refrigerant discharge pipe 11 for discharging the refrigerant R from the storage space S.

(refrigerant discharge pipe)
As shown in Figure 1, one end 11a of the refrigerant discharge pipe 11 is connected to the upper part of the heating section 20. The other end 11b of the refrigerant discharge pipe 11 is connected to the cooling section 30. The refrigerant discharge pipe 11 guides the refrigerant R heated in the heating section 20 to the cooling section 30. One refrigerant discharge pipe 11 is provided for each heating section 20.

(cooling section)
The cooling unit 30 cools the refrigerant R discharged from the heating unit 20. In this embodiment, the cooling unit 30 is an air-cooled heat exchanger. The cooling unit 30 includes an upstream header 31, a pipe bundle 32, and a downstream header 33.

The upstream header 31 is supplied with refrigerant R heated in the heating unit 20. The upstream header 31 is a manifold header.

The pipe bundle 32 has multiple finned tubes 34. Each finned tube 34 is connected to the upstream header 31. Refrigerant R is supplied to each finned tube 34 from the upstream header 31. Note that the finned portions of the finned tubes 34 are omitted in the drawing.

The downstream header 33 is connected to the pipe bundle 32. Like the upstream header 31, the downstream header 33 is a manifold header. In the downstream header 33, the refrigerant R that has passed through each finned tube 34 converges.

(fan)
A fan 12 is installed near the tube bundle 32. The fan 12 blows air toward the tube bundle 32, supplying air A1 to each fin tube 34. This cools the refrigerant R passing through the fin tubes 34. In this embodiment, the gaseous refrigerant RG condenses and changes into a liquid refrigerant RL.

(Refrigerant filling section)
A refrigerant charging unit 13 is provided in the downstream header 33. The refrigerant charging unit 13 charges the cooling system with refrigerant R. The refrigerant charging unit 13 charges the cooling device 10 with a desired amount of liquid phase refrigerant RL.

(refrigerant supply pipe)
Furthermore, a refrigerant supply pipe 14 is provided in the downstream header 33. The refrigerant supply pipe 14 connects the cooling unit 30 and the heating unit 20. In this embodiment, one end 14a of the refrigerant supply pipe 14 is connected to the downstream header 33 of the cooling unit 30, and the other end 14b of the refrigerant supply pipe 14 is connected to the lower part of the heating unit 20. The refrigerant supply pipe 14 supplies the refrigerant R cooled in the cooling unit 30 to the heating unit 20. One refrigerant supply pipe 14 is provided for each heating unit 20.

(Negative pressure adjustment section)
Furthermore, a negative pressure adjustment unit 40 is connected to the upstream header 31 via a vacuum line 42. In this embodiment, the negative pressure adjustment unit 40 is a vacuum pump 41. The negative pressure adjustment unit 40 creates a negative pressure in the storage space S by performing a vacuum in the cooling device 10. In addition, the negative pressure adjustment unit 40 can adjust the internal pressure of the storage space S.

(Refrigerant circulation)
Next, we will explain the circulation of the refrigerant R within the cooling device 10.
First, the vacuum pump 41 is activated to create a vacuum inside the cooling device 10. This creates a negative pressure inside the cooling device 10, including the storage space S. As a result, the boiling point of the refrigerant R inside the cooling device 10 is lowered. This makes it easier for the refrigerant R to change from the liquid phase to the gas phase.

Furthermore, heat from the heating element 3 is transferred to the heating section 20. The heat transfer surface 22 within the heating section 20 transfers the heat from the heating element 3 to the liquid-phase refrigerant RL in the storage space S. This cools the heating element 3. Meanwhile, the liquid-phase refrigerant RL in the storage space S is heated and expands. In this embodiment, the liquid-phase refrigerant RL boils due to the heat from the heating element 3 and changes into a gaseous refrigerant RG. Since the gaseous refrigerant RG has a lower density than the liquid-phase refrigerant RL, it flows upward. The gaseous refrigerant RG flows from the heating section 20 through the refrigerant discharge pipe 11 into the cooling section 30.

The gaseous refrigerant RG moves from the upstream header 31 to the finned tube 34, and then from the finned tube 34 to the downstream header 33. In the finned tube 34, the gaseous refrigerant RG exchanges heat with the air A1 supplied by the fan 12 and is cooled. As a result, the gaseous refrigerant RG condenses and, by the time it reaches the downstream header 33, it has changed into liquid refrigerant RL.

The liquid-phase refrigerant RL returns to the heating unit 20 from the downstream header 33 through the refrigerant supply pipe 14. Upon returning to the heating unit 20, the liquid-phase refrigerant RL again exchanges heat with the heating element 3. In this way, the refrigerant R circulates within the cooling device 10.

(Effects)
The cooling device 10 of this embodiment can provide the following effects.
In this embodiment, the heating unit 20 has a storage space S inside in which liquid-phase refrigerant R is stored and is thermally connected to the heating element 3. Furthermore, the heating unit 20 has a heat transfer surface 22 that transfers heat from the heating element 3 to the refrigerant R. In addition, the negative pressure adjustment unit 40 can create a negative pressure in the storage space S and adjust the internal pressure of the storage space S.

According to this embodiment, the heating element 3 is cooled by heat exchange with the refrigerant R in the storage space S via the heating unit 20. On the other hand, the refrigerant R in the storage space S is heated by the heat of the heating element 3. By creating a negative pressure in the storage space S, the boiling point of the refrigerant R is lowered, making it easier for the refrigerant R to expand. When the refrigerant R expands, its density decreases. This makes it easier for the refrigerant R to circulate within the cooling device 10. Therefore, refrigerants that have a low GWP but a high boiling point and are unsuitable for circulation within the cycle can be used in the cooling device 10. Thus, refrigerants R with a low GWP can be used in the cooling device 10. Consequently, sufficient cooling performance can be ensured while using a refrigerant R with a lower GWP than fluorocarbon refrigerants (low GWP refrigerant). This reduces the impact on global warming.
Furthermore, for example, during maintenance of the cooling device 10, the degree of negative pressure in the storage space S can be adjusted to suit the environment of the cooling device 10 by operating the negative pressure adjustment unit 40. For example, the degree of negative pressure in the storage space S can be adjusted according to the ambient temperature of the location where the cooling device 10 is installed and the load of the heat-generating element 3.

Furthermore, in this embodiment, the refrigerant discharge pipe 11 is connected to the upper part of the heating unit 20. The refrigerant supply pipe 14 is connected to the lower part of the heating unit 20. The heat transfer surface 22 extends along a vertical plane.

According to this embodiment, the liquid-phase refrigerant RL flows upward within the heating section 20. This allows bubbles B to easily flow into the refrigerant discharge pipe 11 above, even if bubbles B are generated within the heating section 20 (see Figure 2). Therefore, bubbles B can easily escape to the cooling section 30 through the refrigerant discharge pipe 11. This prevents bubbles B from accumulating within the heating section 20 and forming a vapor film on the heat transfer surface 22. Thus, the flow of refrigerant R and heat exchange between the heating element 3 and the refrigerant R proceed smoothly.

<Second Embodiment>
Hereinafter, the cooling device 210 according to the second embodiment of this disclosure will be described with reference to Figure 3. For configurations similar to those of the first embodiment described above, the same names and reference numerals will be used, and the description will be omitted as appropriate.

As shown in Figure 3, in this embodiment, the negative pressure adjustment unit 240 is an ejector 243. The ejector 243 drives the airflow supplied from outside the cooling device 210 as the driving flow A2. The ejector 243 is connected to the upstream header 31 of the cooling unit 30 by a vacuum line 42. The ejector 243 draws in gas A3 from within the cooling device 210 using the driving flow A2, creating negative pressure within the cooling device 210, including the storage space S.

(Effects and Benefits)
The cooling device 210 of this embodiment provides the following effects.
In this embodiment, the negative pressure adjustment unit 240 is an ejector 243.

This allows the cooling device 210 to drive the ejector 243 using, for example, air discharged from a factory as the driving flow A2. As a result, the cooling device 210 can perform vacuuming inside the device, including the storage space S, with less power consumption compared to a case where the negative pressure adjustment unit 240 is a vacuum pump.

(First modified example of the second embodiment)
Next, a first modified example of the second embodiment will be described with reference to Figure 4.
As shown in Figure 4, in this modified example, the cooling device 210 is further equipped with an air supply line 244. One end 244a of the air supply line 244 is connected to the outlet of the ejector 243. The other end 244b of the air supply line 244 is positioned opposite the pipe bundle 32 of the cooling unit 30. The air supply line 244 supplies the air A1 discharged from the ejector 243 to the cooling unit 30. The cooling unit 30 cools the refrigerant R by performing heat exchange between the air A1 discharged from the ejector 243 and the refrigerant R.

As a result, the cooling device 210 can cool the refrigerant R in the cooling section 30 with the air A1 discharged from the ejector 243. Therefore, compared to the case where a blower such as a fan 12 is used to supply air A1 to the cooling section 30, the power consumption of the cooling device 210 can be reduced.

(Second modified example of the second embodiment)
Next, a second modified example of the second embodiment will be described with reference to Figure 5.
As shown in Figure 5, in this modified example, the cooling device 210 includes an outer cylinder 215 that surrounds the cooling section 30 and opens in the vertical direction. The outer cylinder 215 is formed in a rectangular cylindrical shape. The shape of the outer cylinder 215 can be changed as appropriate. For example, the outer cylinder 215 may be formed in a cylindrical shape.

According to this modification, the air A1 surrounding the cooling unit 30, which has been heated by heat exchange with the refrigerant R inside the cooling unit 30, rises, creating an upward flow that blows through the outer cylinder 215. This ensures that the cooling unit 30 is continuously supplied with fresh air A1 to cool the refrigerant R. Therefore, there is no need to provide a blower such as a fan 12 to supply air A1 to the cooling unit 30. This suppresses the need to increase the size of the cooling device 210. Furthermore, the power consumption of the cooling device 210 can be reduced.

<Third Embodiment>
Hereinafter, the cooling device 310 according to the third embodiment of this disclosure will be described with reference to Figure 6. For configurations similar to those of the first embodiment described above, the same names and reference numerals will be used, and the description will be omitted as appropriate.

As shown in Figure 6, in this embodiment, the heating section 320 (jacket 321) has a plurality of fins 323 rising from the heat transfer surface 22 within the storage space S. The fins 323 extend perpendicularly from the heat transfer surface 22. The fins 323 are formed in a conical shape that tapers as they move away from the heat transfer surface 22. The plurality of fins 323 are arranged in a square grid pattern when viewed from the direction perpendicular to the heat transfer surface 22.

(Effects)
The cooling device 310 of this embodiment provides the following effects.
In this embodiment, the heating section 320 has a plurality of fins 323 that rise from the heat transfer surface 22.

This increases the area of the heat transfer surface 22. Therefore, the apparent heat flux within the heating section 320 can be reduced. Furthermore, the detachment of bubbles B generated on the heat transfer surface 22 is promoted. This suppresses the merging of multiple bubbles B on the heat transfer surface 22. Additionally, within the heating section 320, the refrigerant R flows in a meandering manner, promoting the mixing of the refrigerant R. This suppresses the formation of a vapor film on the heat transfer surface 22. Consequently, the critical heat flux in the heating section 320 increases, raising the limit value of heat transport.

(First modified example of the third embodiment)
Next, a first modified example of the third embodiment will be described with reference to Figure 7.
As shown in Figure 7, in this modified example, the fin 323 is formed in the shape of a cylindrical pin.
This further increases the area of the heat transfer surface 22. Therefore, the apparent heat flux within the heating section 320 can be further reduced.

(Second modified example of the third embodiment)
Next, a second modified example of the third embodiment will be described with reference to Figure 8.
As shown in Figure 8, in this modified example, the fins 323 are formed only in the region of the heat transfer surface 22 on the refrigerant supply pipe 14 side. For example, the fins 323 are formed on the half of the heat transfer surface 22 on the refrigerant supply pipe 14 side.

For example, in the region of the heat transfer surface 22 on the refrigerant supply pipe 14 side, the refrigerant R may exist in the liquid phase, while on the refrigerant discharge pipe 11 side, the refrigerant R may exist in the gas phase. According to this modification, the cooling device 310 can mix the liquid phase refrigerant R stored in the region on the refrigerant supply pipe 14 side of the refrigerant R within the heating section 20 using the fins 323. This allows the cooling device 310 to stabilize the flow of the refrigerant R. Therefore, the cooling efficiency of the cooling device 310 can be improved.

<Fourth Embodiment>
Hereinafter, the cooling device 410 according to the fourth embodiment of this disclosure will be described with reference to Figure 9. For configurations similar to those of the first embodiment described above, the same names and reference numerals will be used, and the description will be omitted as appropriate.

As shown in Figure 9, in this embodiment, the heating section 420 of the cooling device 410 is a substrate 424 on which electronic components are installed. A storage space S is formed inside the substrate 424. The storage space S is formed, for example, across the entire surface of the substrate 424. Furthermore, the substrate 424 has a heat transfer surface 425 inside. The heat transfer surface 425 transfers heat from the heating element 3 to the refrigerant R in the storage space S.

This allows the refrigerant R to travel a longer distance within the heating section 420. Therefore, the evaporation of the refrigerant R is promoted. Consequently, the refrigerant R circulates more easily within the cooling device 410. Furthermore, the cooling device 410 can dissipate the heat from the heating element 3 to the substrate 424. Thus, the cooling efficiency of the cooling device 410 can be improved.

(Variation of the fourth embodiment)
Next, a modified example of the fourth embodiment will be described with reference to Figure 10.
As shown in Figure 10, in this modified example, multiple heating elements 3 are thermally connected to the heating section 420.

This allows the cooling device 410 to uniformly heat multiple heating elements 3 within a single heating section 420. Therefore, controlling each heating element 3 becomes easier.

(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.
In the above embodiment, multiple substrates 2 and 424 are provided, but this is not limited to this. For example, only one substrate 2 or 424 may be provided. The number of substrates 2 and 424 can be appropriately changed according to the required load.

In the above embodiment, the heating units 20, 320, and 420 are described as evaporating the refrigerant R and changing it from the liquid phase to the gas phase, but this is not the only possible configuration. In the heating units 20, 320, and 420, the refrigerant R may remain in the liquid phase without evaporating, as long as it expands.

In the above embodiment, the cooling unit 30 is an air-cooled heat exchanger, but it is not limited to this.

<Note>
The cooling devices 10, 210, 310, and 410 described in each embodiment can be understood, for example, as follows.

(1) The cooling devices 10, 210, 310, and 410 according to the first embodiment include heating units 20, 320, and 420 having a storage space S inside in which liquid-phase refrigerant R is stored and thermally connected to a heating element 3, and having heat transfer surfaces 22 and 425 that transfer heat from the heating element 3 to the refrigerant R, and a refrigerant discharge pipe 11 connected to the heating units 20, 320, and 420 that discharges the refrigerant R from the storage space S, and the refrigerant discharge pipe The system comprises: a cooling unit 30 connected to the outlet pipe 11 for cooling the refrigerant R discharged from the heating units 20, 320, and 420; a refrigerant supply pipe 14 connecting the cooling unit 30 to the heating units 20, 320, and 420 and supplying the refrigerant R cooled by the cooling unit 30 to the heating units 20, 320, and 420; and negative pressure adjustment units 40 and 240 capable of creating negative pressure in the storage space S and adjusting the internal pressure of the storage space S.

According to this embodiment, the heating element 3 is cooled by heat exchange with the refrigerant R in the storage space S via the heating sections 20, 320, and 420. Meanwhile, the refrigerant R in the storage space S is heated by the heat from the heating element 3. By creating a negative pressure in the storage space S, the boiling point of the refrigerant R is lowered, making it more prone to expansion. When the refrigerant R expands, its density decreases. This makes it easier for the refrigerant R to circulate within the cooling devices 10, 210, 310, and 410. Therefore, refrigerants with low GWP but high boiling points, which were previously unsuitable for circulation within the cycle, can be used in the cooling devices 10, 210, 310, and 410. Thus, refrigerants with low GWP can be used in the cooling devices 10, 210, 310, and 410.

(2) The cooling devices 10, 210, 310, and 410 of the second embodiment are the cooling devices 10, 210, 310, and 410 of (1), wherein the refrigerant discharge pipe 11 is connected to the upper part of the heating units 20, 320, and 420, the refrigerant supply pipe 14 is connected to the lower part of the heating units 20, 320, and 420, and the heat transfer surfaces 22 and 425 may extend along a vertical plane.

This makes it easier for bubbles B to escape to the cooling section 30 through the refrigerant discharge pipe 11, even if bubbles B are generated within the heating sections 20, 320, and 420.

(3) The cooling device 210 of the third embodiment is the cooling device 210 of (1) or (2), and the negative pressure adjustment unit 240 may be an ejector 243.

This allows the cooling device 210 to drive the ejector 243 using, for example, air discharged from a factory as the driving flow A2.

(4) The cooling device 210 of the fourth embodiment is the cooling device 210 of (3), further comprising a blower line 244 that supplies air A1 discharged from the ejector 243 to the cooling unit 30, wherein the cooling unit 30 cools the refrigerant R by performing heat exchange between the air A1 discharged from the ejector 243 and the refrigerant R.

As a result, the cooling device 210 can cool the refrigerant R in the cooling section 30 with the air A1 discharged from the ejector 243.

(5) The cooling device 210 of the fifth embodiment may be any of the cooling devices 210 described in (1) to (4), and may include an outer cylinder 215 that surrounds the cooling unit 30 and has an opening in the vertical direction.

This causes the air A1 surrounding the cooling unit 30, which has been heated by heat exchange with the refrigerant R inside the cooling unit 30, to rise, creating an upward airflow into the outer cylinder 215. As a result, the cooling unit 30 is continuously supplied with fresh air A1 to cool the refrigerant R.

(6) The cooling device 310 of the sixth embodiment is any of the cooling devices 310 of (1) to (5), wherein the heating unit 320 may have a plurality of fins 323 rising from the heat transfer surface 22.

This increases the area of the heat transfer surface 22. Furthermore, the detachment of bubbles B generated on the heat transfer surfaces 22 and 425 is promoted. Additionally, within the heating section 320, the refrigerant R flows in a meandering manner, promoting the mixing of the refrigerant R.

(7) The cooling device 310 of the seventh embodiment is the cooling device 310 of (6), wherein the fins 323 may be formed only in the region of the heat transfer surface 22 on the side of the refrigerant supply pipe 14.

For example, in the region of the heat transfer surface 22 on the refrigerant supply pipe 14 side, the refrigerant R may exist in the liquid phase, while on the refrigerant discharge pipe 11 side, the refrigerant R may exist in the gas phase. According to this embodiment, the cooling device 310 can mix the liquid phase refrigerant R stored in the region on the refrigerant supply pipe 14 side of the refrigerant R within the heating section 20 using the fins 323.

(8) The cooling device 410 of the eighth embodiment is any of the cooling devices 410 of (1) to (7), wherein the heating unit 420 is a substrate 424 on which electronic components are installed, and the storage space S may be formed inside the substrate 424.

This allows the refrigerant R to travel a longer distance within the heating section 420. Therefore, the evaporation of the refrigerant R is promoted.

(9) The cooling device 410 of the ninth embodiment is any of the cooling devices 410 described in (1) to (8), wherein the heating unit 420 may be thermally connected to a plurality of the heating elements 3.

This allows the cooling device 410 to equalize the temperature of the multiple heat-generating elements 3.

(10) The cooling devices 10, 210, 310, 410 of the tenth embodiment are the cooling devices 10, 210, 310, 410 of (1) to (9), wherein the refrigerant R may be a low GWP refrigerant having a lower GWP than a fluorocarbon refrigerant.
Examples of low GWP refrigerants include water and HFO (hydrofluoroolefin).

1…Server 2…Circuit board 3…Heating element 10…Cooling device 11…Refrigerant discharge pipe 11a…One end 11b…Other end 12…Fan 13…Refrigerant charging section 14…Refrigerant supply pipe 14a…One end 14b…Other end 20…Heating section 21…Jacket 22…Heat transfer surface 30…Cooling section 31…Upstream header 32…Tube bundle 33…Downstream header 34…Fin tube 40…Negative pressure adjustment section 41…Vacuum pump 42…Vacuum line 210…Cooling device 215…Outer cylinder 240…Negative pressure adjustment section 243…Ejector 244…Air blower line 244a…One end 244b…Other end 310…Cooling device 320…Heating section 321…Jacket 323…Fin 410…Cooling device 420…Heating section 424…Circuit board 425…Heat transfer surface A1…Air A2…Drive flow A3…Gas R…Refrigerant RG…Gas-phase refrigerant RL…Liquid-phase refrigerant S…Storage space

Claims (7)

A heating section having a storage space inside in which a liquid-phase refrigerant is stored, and which is thermally connected to a heating element and has a heat transfer surface that transfers heat from the heating element to the refrigerant,
A refrigerant discharge pipe is connected to the heating unit and discharges the refrigerant from the storage space,
A cooling unit connected to the refrigerant discharge pipe, which cools the refrigerant discharged from the heating unit,
A refrigerant supply pipe connects the cooling unit and the heating unit, and supplies the refrigerant cooled in the cooling unit to the heating unit.
A negative pressure adjustment unit that can create a negative pressure in the storage space and adjust the internal pressure of the storage space,
Equipped with ,
The aforementioned negative pressure adjustment unit is an ejector,
The system includes an air supply line that supplies the air discharged from the ejector to the cooling unit,
The cooling unit is a cooling device that cools the refrigerant by performing heat exchange between the air discharged from the ejector and the refrigerant . A heating section having a storage space inside in which a liquid-phase refrigerant is stored, and which is thermally connected to a heating element and has a heat transfer surface that transfers heat from the heating element to the refrigerant,
A refrigerant discharge pipe is connected to the heating unit and discharges the refrigerant from the storage space,
A cooling unit connected to the refrigerant discharge pipe, which cools the refrigerant discharged from the heating unit,
A refrigerant supply pipe connects the cooling unit and the heating unit, and supplies the refrigerant cooled in the cooling unit to the heating unit.
A negative pressure adjustment unit that can create a negative pressure in the storage space and adjust the internal pressure of the storage space,
Equipped with ,
The heating section has a plurality of fins rising from the heat transfer surface,
A cooling device in which the fins are formed only on the region of the heat transfer surface on the side of the refrigerant supply pipe . The refrigerant discharge pipe is connected to the upper part of the heating section,
The refrigerant supply pipe is connected to the lower part of the heating section,
The cooling device according to claim 1 or 2 , wherein the heat transfer surface extends along a vertical plane. The cooling device according to claim 1 or 2, comprising an outer cylinder that encloses the cooling section and has an opening in the vertical direction. The heating section is a substrate on which electronic components are installed.
The cooling device according to claim 1 or 2, wherein the storage space is formed inside the substrate. The cooling device according to claim 1 or 2, wherein a plurality of the heating elements are thermally connected to the heating section. The cooling device according to claim 1 or 2, wherein the refrigerant is a low-GWP refrigerant with a lower GWP than a fluorocarbon refrigerant.