WO2010104080A1 - Ebullient cooling device - Google Patents

Abstract

An ebullient cooling device having a simple structure and capable of limiting the bubbles to an appropriate volume. The ebullient cooling device for cooling a heat generating element is provided with a plurality of vertically arranged cooling channels comprising a lower channel (2), a middle channel (3) and un upper channel (4). Each cooling channel has cooling fins (12) for guiding a refrigerant to flow in a vertical direction, and a vapor discharge path (16) formed at the side of the cooling fins (12) that is opposite the side in contact with the heat generating element. Furthermore, flow path partition/vapor discharge guiding plates (18) are provided between the cooling channels so that the bubbles that have been generated are guided to the vapor discharge path (16) and prevented from moving into the subsequent cooling channel.

Description

Boiling cooler

The present invention relates to a boiling cooling device, and more particularly to improvement of cooling performance in a cooling device using boiling / two-phase flow (gas-liquid two-phase flow).

Conventionally, cooling devices using boiling / two-phase flow under forced convection have been developed and applied to inverter cooling systems for hybrid vehicles.

Patent Document 1 is composed of a cooling base body having a coolant channel and a plurality of power semiconductors mounted thereon, optimally determining the mounting position of the power semiconductor element to optimize the temperature rise of the coolant, and cooling A power semiconductor module with improved efficiency is disclosed.

Patent Document 2 discloses a boiling cooling device that prevents a decrease in heat dissipation performance in the upper part (downstream area) of the module in boiling cooling. In the lower part (upstream area) of the module due to heat transfer from the power semiconductor. It is disclosed that a generated partition prevents the generated steam from entering the upper part (downstream area) of the module.

JP 2007-12722 A Japanese Patent Laid-Open No. 9-23081

By the way, in a cooling device using boiling / two-phase flow, it is necessary to suppress the reduction of the critical heat flow rate and the heat transfer coefficient during boiling, and to design the device as small as possible. Generally, in boiling, heat transfer is determined by gas-liquid behavior at the bottom of a bubble. Specifically, a region where heat transfer is promoted by the formation of a thin liquid film and a portion where heat transfer deteriorates due to the progress of the dry portion coexist. The bubble adhesion area has a great influence on which phenomenon is dominant. However, if the adhesion area increases due to the growth of bubbles, the heat transfer may shift to deterioration.

FIG. 8A and FIG. 8B show a state of small heat transfer promotion in nucleate boiling heat transfer accompanying the growth of small bubbles. This is the case when the bubble size is small in the open flow path. 8A is a plan view and FIG. 8B is a side view. The bubble size increases as the pressure decreases, and decreases as the temperature of the surrounding liquid becomes lower than the saturation temperature (subcool state). When the bubble size is small, the area of the dry portion 50 is small, but the area occupied by the thin liquid film 52 is also small. As a result, the feature of boiling heat transfer is diminished, and the contribution of heat transfer to the liquid single phase around the bubbles is still large. Therefore, the heat transfer promotion ratio when compared with heat transfer to the liquid single phase is small.

9A and 9B show a state of large heat transfer promotion in the nucleate boiling heat transfer accompanying the growth of large bubbles. This is when the bubble size is medium to large in the open channel. As the bubble size increases, the area of the dry portion 50 also increases, but the area occupied by the thin liquid film 52 increases. As a result, the feature of boiling heat transfer becomes remarkable, and the heat transfer promotion ratio when compared with heat transfer to the liquid single phase is large.

FIG. 10A and FIG. 10B show the state of heat transfer deterioration in nucleate boiling heat transfer accompanying the growth of giant bubbles. This is the case when the bubble size is very large in the open channel. When the bubbles become excessively large, the area occupied by the dry portion 50 increases, and the heat transfer deterioration in this portion becomes more conspicuous than the heat transfer promotion by evaporation of the thin liquid film 52, and the heat transfer surface as a whole is deteriorated in heat transfer. It will take on an aspect.

11A and 11B show the state of heat transfer promotion in nucleate boiling heat transfer accompanying flat bubble growth between cooling fins 12 (hereinafter simply referred to as fins). This is a case where the bubble size is medium in a narrow flow path between fins. By generating and growing a flat having an appropriate size, it is possible to satisfy both an increase in heat transfer area and an increase in heat transfer coefficient due to the fins 12.

FIG. 12 shows the relationship between the bubble volume and heat transfer acceleration / degradation. The horizontal axis represents the bubble volume, and the vertical axis represents heat transfer. An arrow P on the vertical axis indicates heat transfer promotion, and an arrow Q indicates heat transfer deterioration. Both the open channel (indicated by symbol a) and the narrow fin channel (indicated by symbol b in the diagram) cannot be expected to promote heat transfer if the bubble volume is too small or too large. It is necessary to keep the size as large as possible (in the figure, the optimum value is indicated by OPT). For this reason, it is important that the contact time with the heat transfer surface is controlled so as not to be excessively long.

An object of the present invention is to provide a cooling device that can keep a bubble volume to an appropriate size with a simple configuration, thereby improving heat transfer characteristics.

The present invention relates to a boiling cooling device for cooling a heating element, having at least first and second cooling channels arranged in a vertical direction, wherein the first cooling channel and the second cooling channel supply a refrigerant in a vertical direction. A cooling fin for flowing, and a steam discharge passage formed on the opposite side of the cooling fin to the heating element contact side, and further, between the first cooling channel and the second cooling channel, It has a guide part which inhibits the advance of the bubbles generated in the cooling channel to the second cooling channel and guides it to the vapor discharge flow path.

In one embodiment of the present invention, it further includes a partition plate arranged between the cooling fin and the steam discharge flow path, and the guide portion is formed as a part of the partition plate.

In another embodiment of the present invention, the partition plate has an opening at a position corresponding to between the first cooling channel and the second cooling channel, and the guide portion is cooled from the edge of the opening. The fin is formed so as to protrude toward the heating element contact side of the fin.

In another embodiment of the present invention, it further includes a liquid supply pipe that is provided between the first cooling channel and the second cooling channel and supplies a refrigerant to the second cooling channel, and the tip of the guide portion. The portion comes into contact with the liquid supply pipe.

In another embodiment of the present invention, the first cooling channel is disposed vertically below the second cooling channel, and the guide portion extends from the cooling fin of the second cooling channel to the first cooling channel. An inclination is formed toward the cooling fin.

According to the present invention, it is possible to keep the bubble volume at an appropriate size with a simple configuration and improve the heat transfer characteristics.

It is a front view of the cooling device of an embodiment. It is a side view of the cooling device of an embodiment. It is a B-B 'sectional view of the cooling device of an embodiment. It is A-A 'sectional drawing of the cooling device of embodiment. It is a block diagram of a liquid supply pipe | tube. It is another block diagram of a liquid supply pipe. It is a front view of a flow-path partition plate and steam discharge guide plate. It is a side view of a flow path partition plate and steam discharge guide plate. It is a disassembled perspective view of a fin and a flow-path partition plate and steam discharge guide plate. It is a whole block diagram of the cooling device of an embodiment. It is a system configuration figure of an embodiment. It is another system configuration figure of an embodiment. It is a top view which shows the heat transfer characteristic in case a bubble size is small with an open flow path. It is a side view which shows the heat transfer characteristic when bubble size is small with an open flow path. It is a top view which shows the heat transfer characteristic in case a bubble size is medium in an open flow path. It is a side view which shows the heat transfer characteristic in case a bubble size is medium in an open flow path. It is a top view which shows the heat transfer characteristic in case a bubble size is too large by an open flow path. It is a side view which shows the heat transfer characteristic in case a bubble size is too large by an open flow path. It is a plane which shows the heat transfer characteristic in case a bubble size is medium in the narrow flow path between fins. It is a side view which shows the heat transfer characteristic in case a bubble size is medium in the narrow flow path between fins. It is a graph which shows the relationship between bubble volume and a heat transfer characteristic.

1 boil cooling device, 2 lower channel, 3 middle channel, 4 upper channel, 10 feed pipe, 12 fins, 13 fin base, 14 cooling surface, 16 steam discharge flow path, 18 flow path partition plate and steam discharge guide plate, 19 guide parts, 20 partition plates.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1A to FIG. 1D show the main configuration of the boiling cooling device in the present embodiment. 1A is a front view, FIG. 1B is a side view, FIG. 1C is a B-B ′ sectional view, and FIG. 1D is an A-A ′ sectional view.

The boiling cooling device 1 includes a liquid supply pipe 10, fins 12, fin bases 13, a cooling surface 14, a steam discharge channel 16, and a channel partition plate / steam discharge guide plate 18.

A plurality of fins 12 are erected on the fin base 13 at a predetermined interval, and each fin 12 forms a cooling channel. As shown in the front view of FIG. 1A, the boiling cooling device 1 is arranged in the vertical direction (vertical placement), and each fin 12 extends in the vertical direction. In the figure, three channels of the lower channel 2, the middle channel 3, and the upper channel 4 are illustrated, and a total of six channels are shown by being partitioned left and right by the partition plate 20, but the present invention is not limited to this. Each fin 12 is formed of, for example, aluminum having high thermal conductivity, and a coolant channel is formed in the vertical direction. The refrigerant is forcedly convected vertically upward by the pump. The fin 12 enlarges the surface area of the fin base 13 constituting the cooling surface 14 and increases the heat transfer coefficient. For example, a power element unit (IGBT module) of a hybrid vehicle abuts on the cooling surface 14 of the fin 12.

The liquid supply pipe 10 is arranged between the fins 12 and supplies a cooling liquid as a refrigerant to the fins 12. As shown in FIG. 1A, the liquid supply pipe 10 is arranged in the horizontal direction for each channel. The lower channel 2 is supplied with a refrigerant vertically upward from a liquid supply pipe 10 disposed at the lower portion of the lower channel 2, and the lower channel of the middle channel 3, that is, the middle channel 3 and the lower channel 2 is supplied to the middle channel 3. The refrigerant is supplied vertically upward from the liquid supply pipe 10 disposed between them, and the liquid supply pipe 10 disposed between the upper channel 4 and the lower channel 4, that is, between the upper channel 4 and the middle channel 3, is supplied to the upper channel 4. The refrigerant is supplied vertically upward. The liquid supply pipes 10 are arranged in the horizontal direction as described above, and each of the liquid supply pipes 10 positioned on the right side of the partition plate 20 is supplied with refrigerant from the right side as indicated by an arrow in the figure, and is positioned on the left side of the partition plate 20. Refrigerant is supplied to each liquid supply pipe 10 from the left side. The refrigerant is heated by each fin 12 of each channel and boiled to generate bubbles.

The vapor discharge flow path 16 is provided on the upper surface of each fin 12, that is, the surface opposite to the cooling surface 14 of the fin 12 with which the heating element abuts. The steam discharge flow path 16 is provided in common to each cooling channel, and discharges bubbles generated in each cooling channel.

The flow path partition plate / steam discharge guide plate 18 is disposed in contact with the upper surface of each fin 12, that is, the surface opposite to the fin base portion 13, that is, the surface opposite to the cooling surface of the fin 12. The vapor discharge channel 16 is partitioned. Further, the flow path partition plate / steam discharge guide plate 18 is opened between the fins 12 of the lower channel 2 and the fins 12 of the middle channel 3 and between the fins 12 of the middle channel 3 and the fins 12 of the upper channel 4. And a guide portion 19 that protrudes at an angle toward the fin base portion 13 at an edge portion of the opening portion. As shown in FIG. 1B, the guide portion 19 of the flow path partition plate / steam discharge guide plate 18 is focused on between the lower channel 2 and the middle channel 3, and the fin base from the vertically lower end of the fin 12 of the middle channel. It protrudes toward 13 and contacts the liquid supply pipe 10. The same applies to the middle channel 3 and the upper channel 4, and the guide portion 19 protrudes from the vertically lower end of the fin 12 of the upper channel 4 toward the fin base portion 13 and comes into contact with the liquid supply pipe 10. The guide portion 19 may be formed separately from the flow path partition plate / steam discharge guide plate 18 and joined to the flow path partition plate / steam discharge guide plate 18. The portion may be bent on the fin base 13 side. Since the guide portion 19 protrudes at a predetermined angle from the vertically lower end of the fin 12 of the middle channel 3 toward the fin base 13 and abuts against the liquid supply pipe 10, the guide portion 19 is formed by the fin 12 of the lower channel 2. The bubbles that have been generated and have passed through the fins 12 are blocked by the guide portion 19 and are prevented from proceeding to the middle channel 3 and are guided to the vapor discharge passage 16. Further, since the guide portion 19 protrudes at a predetermined angle from the vertically lower end of the fin 12 of the upper channel 4 toward the fin base 13 and contacts the liquid supply pipe 10, the fin of the middle channel 3 The bubbles generated at 12 and passing through the fins 12 are blocked by the guide portion 19 and are prevented from proceeding to the upper channel 4 and are guided to the vapor discharge flow path 16.

2A and 2B show an example of the shape of the liquid supply pipe 10. FIG. 2A shows a case where a plurality of refrigerant supply holes whose opening diameters are sequentially increased are formed at predetermined intervals on the side surface of the liquid supply pipe 10. FIG. 2B shows a case where a refrigerant supply slit whose opening area is sequentially increased is formed on the side surface of the liquid supply pipe 10. In any case, the opening diameter or the opening area is increased toward the downstream side of the refrigerant.

3A and 3B show the configuration of the flow path partition plate / steam discharge guide plate 18. 3A is a front view and FIG. 3B is a side view. The flow path partition plate / steam discharge guide plate 18 is formed by pressing a metal plate, and has openings 18a and 18b between the lower channel 2 and the middle channel 3 and between the middle channel 3 and the upper channel 4 respectively. Is formed. Bubbles generated and grown in the lower channel 2 are discharged from the opening 18a to the vapor discharge channel 16, and bubbles generated and grown in the middle channel 3 are discharged from the opening 18b to the vapor discharge channel 16.

The guide portion 19 is formed at the opening end of the opening 18a, specifically, the vertically lower end of the fin 12 of the middle channel 3, and the opening end of the opening 18b, that is, the fin 12 of the upper channel 4 is formed. A guide portion 19 is formed at the end portion on the vertically lower side. The guide portion 19 may be formed by bending a part of the flow path partition plate / steam discharge guide plate 18.

4A and 4B are exploded perspective views of the fins 12 and the flow path partition plate / steam discharge guide plate 18. Bubbles generated in the fins 12 of the lower channel 2 collide with the guide portion 19, and are discharged from the opening 18 a to the vapor discharge channel 16 without proceeding to the middle channel 3. In addition, bubbles generated in the fins 12 of the middle channel 3 also collide with the guide portion 19 and are discharged from the opening 18 b to the vapor discharge flow path 16 without proceeding to the upper channel 4. Bubbles generated in the fins 12 of the upper channel 4 are discharged as they are to the vapor discharge flow path 16.

FIG. 5 shows the overall configuration of the boiling cooling device 1. The cooling unit 28, which is a main part, is disposed between the heating elements 26 such as a power element unit. A refrigerant supply jacket 22 and a liquid quantity distribution plate 24 are provided vertically below the cooling unit 28, store the refrigerant supplied by the pump from below the vertical, and distribute the refrigerant in an appropriate amount to each of the cooling units 28. Supply to the supply pipe 10. On the other hand, a steam discharge jacket 30 is provided vertically above the cooling unit 28 and connected to the steam discharge channel 16 of the cooling unit 28. Bubbles discharged to the steam discharge passage 16 by the guide portion 19 are collected in the steam discharge jacket 30 and discharged to the outside.

As described above, in this embodiment, the flow path partition plate / steam discharge guide plate 18 is interposed between the fins 12 and the steam discharge flow path 16 so that bubbles generated in each cooling channel advance to the next cooling channel. Thus, it is possible to prevent the bubbles from becoming excessively large, and to prevent deterioration in heat transfer performance and reduction in the critical heat flow rate.

Further, in the present embodiment, since the steam discharge channel 16 is arranged on the upper surface side of the fin 12, that is, on the side opposite to the power element unit that is a heating element, the size in the width direction of the cooling device can be reduced.

Moreover, since the flow path partition plate / steam discharge guide plate 18 in the present embodiment only needs to be disposed on the fins 12, the structure is simplified and the assemblability at the time of manufacture is improved.

Further, as in the present embodiment, the boiling cooling device 1 is placed vertically, and the fins 12 are also placed vertically, so that there is an effect of improving the discharge of generated bubbles due to buoyancy.

In addition, the boiling cooling device of this embodiment can be applied not only to inverter cooling of a hybrid vehicle but also to any heating element. Although the system configuration using the cooling device of this embodiment is also arbitrary, an example is shown in FIGS.

In FIG. 6, the gas-liquid two-phase flow discharged from the boiling cooling device 1 is supplied to the gas-liquid separator 106. In addition, a condenser 108 is connected to the gas-liquid separator 106, and a second gas-liquid separator 110 is further connected to the condenser 108. The cooling liquid from the gas-liquid separators 106 and 110 is supplied to the supercooler 102 via the adjustment valve 112 and is circulated to the boiling cooling device 1 by the pump 104. The accumulator 100 is connected between the adjustment valve 112 and the subcooler 102, and the coolant is supplied to the subcooler 102 using the gas pressure.

In FIG. 7, the gas-liquid two-phase flow discharged from the boiling cooling device 1 is supplied to the condenser 108, and the gas-liquid separator 116 is connected to the condenser 108. The coolant from the gas-liquid separator 116 is circulated to the boiling cooling device 1 by the pump 104. The accumulator 100 is connected between the pump 104 and the gas-liquid separator 116, and supplies the cooling liquid to the pump 104 using gas pressure.

Claims (5)

In the boiling cooling device that cools the heating element,
Having at least first and second cooling channels arranged vertically;
The first cooling channel and the second cooling channel are:
Cooling fins that allow the refrigerant to flow vertically;
A steam discharge passage formed on the opposite side of the cooling fin to the heating element contact side;
In addition,
Between the first cooling channel and the second cooling channel, there is a guide portion that inhibits the bubble generated in the first cooling channel from proceeding to the second cooling channel and guides it to the vapor discharge flow path. Boiling cooling device. The apparatus of claim 1, further comprising:
A boiling cooling device comprising: a partition plate disposed between the cooling fin and the steam discharge flow path, wherein the guide portion is formed as a part of the partition plate. The apparatus of claim 2.
The partition plate has an opening at a position corresponding to the space between the first cooling channel and the second cooling channel, and the guide portion extends from an edge of the opening to the heating element contact side of the cooling fin. A boiling cooling device characterized by being formed to project toward. The apparatus of claim 3, further comprising:
A liquid supply pipe that is provided between the first cooling channel and the second cooling channel and supplies a refrigerant to the second cooling channel; To boil cooling device. The apparatus of claim 3.
The first cooling channel is disposed vertically below the second cooling channel;
The boiling cooling device, wherein the guide portion is inclined from the cooling fin of the second cooling channel toward the cooling fin of the first cooling channel.

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