JPH07176662A - Boiling/cooling unit - Google Patents

Abstract

PURPOSE:To obtain a boiling/cooling unit in which the size can be reduced without sacrifice of heat dissipation characteristics by fixing a condensation accelerating means for increasing the heat transfer area in a heat-exchanger. CONSTITUTION:A heating element, i.e., a semiconductor element 70, is set in a tank 20 to be cooled and sufticient quantity of refrigerant 60 is injected to immerse the semiconductor element 70 therein. An aluminium tube 102 having flat cross-section is fixed airtightly to the upper part of the cooling tank 20 with the upper opening being enclosed. Aluminium corrugated fins 101 are jointed to the side face of the cooling tank 20 thus forming a heat dissipating part, i.e., a heat-exchanger 10. Wavy inner fins 140 are disposed in the heat- exchanger 10. This structure retards the growth of liquid film 150 while increasing the inner surface area of heat-exchanger 10 thus decreasing the thermal resistance of the liquid film 150.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiling cooling device for cooling a heating element such as a semiconductor element that has generated heat.

[0002]

2. Description of the Related Art Conventionally, as a method for cooling a semiconductor element such as an electric device, there is a boiling cooling device for cooling using a refrigerant.
FIG. 18 is a diagram showing a conventional boiling cooling device disclosed in Japanese Patent Laid-Open No. 56-147457. In this figure, the element case part 1 and the heat exchanger 2 are heat transfer tubes 3A and 3B.
Are connected by, and the operation is as follows.
That is, when the semiconductor element 4A generates heat to boil the cooling medium 8, the cooling medium 8 becomes vapor and rises, and the heat transport pipe 3A
And moves to the heat exchanger 2. The vapor reaching the heat exchanger 2 is distributed to the fin tubes 2A, condensed by external cooling, reaches the heat transport pipe 3B, and returns to the element case 1 again.
The semiconductor element is cooled by such a cycle.

[0003]

However, as shown in FIG.
The boil cooling apparatus as shown in FIG. 2 has a structure in which the vaporized cooling medium 8 directly transfers the heat to the inner wall of the heat exchanger 2 to be cooled, so that the heat transfer efficiency thereof is the inner wall of the heat exchanger 2. Depends on the area of. Therefore, when trying to miniaturize the device,
There was a problem that the heat dissipation characteristics deteriorate.

Therefore, the present invention has been made in view of the above problems, and provides a boiling cooling device that solves the above problems by installing condensation promoting means for promoting heat dissipation from the refrigerant to the heat exchanger in the heat exchanger. It is an object.

[0005]

A boiling cooling device of the present invention constructed to achieve the above object is used in an electric circuit or the like, and a heating element for generating extra heat when driven, and the above-mentioned heating element. A refrigerant that absorbs the heat generated by the body and is vaporized by the heat, a cooling tank that contains the refrigerant, and one opening surface is attached to the cooling tank, and the other opening surface is attached in a hermetically sealed manner. And a cylindrical heat radiating section that liquefies the rising refrigerant to liquefy and return it to the cooling tank,
And a condensation promoting unit that is formed in contact with the inside of the heat radiating unit and enhances heat radiation from the refrigerant to the heat radiating unit.

It is preferable that the condensation promoting means is divided into a plurality of upper and lower portions, or holes are formed.

[0007]

According to the present invention having the above construction, the heating element is driven in an electric circuit or the like, thereby generating extra heat. The heat generated in the heating element is absorbed by the refrigerant, and the refrigerant is boiled and vaporized. The generated vapor of the refrigerant rises in the heat radiating portion due to the thermosyphon effect, transfers heat to the condensation promoting means arranged in contact with the inner surface of the heat radiating portion, and is cooled and liquefied again.
The liquefied refrigerant drips downward due to gravity and returns to the lower cooling tank. Therefore, the excess heat generated by the heating element is released to the atmosphere through the refrigerant, the heat absorbing means, and the heat radiating portion. In addition, the area for transmitting heat in the heat radiating portion is increased by providing the condensation promoting means. Further, by increasing the area in this way, the liquid film thickness per unit area of the cooling liquid liquefied and descending is reduced.

Further, by dividing the condensation promoting means into a plurality of parts vertically and forming holes, the growth of the liquid film is prevented and the maximum liquid film thickness is further reduced.

[0009]

According to the present invention having the above-described operation, the heat dissipation area in the heat dissipation part is substantially increased by disposing the condensation promoting means in contact with the heat dissipation part. As a result, the heat transfer area per unit volume of the refrigerant that evaporates by boiling and rises is increased, and the heat dissipation characteristics can be improved. Further, by making the liquid film thickness per unit area of the cooling liquid liquefied and descending as a whole thin, it is possible to prevent deterioration of heat dissipation characteristics due to an increase in thermal resistance of the liquid film, and it is possible to improve heat transfer efficiency. . Further, by preventing the growth of the liquid film, the maximum liquid film thickness can be reduced and the thermal resistance of the liquid film can be reduced. This makes it possible to reduce the size of the entire device without degrading the heat dissipation characteristics.

[0010]

【Example】

(First Embodiment) A boiling cooling apparatus according to a first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 (a) is a schematic diagram when the boiling cooling device according to the first embodiment of the present invention is used in a boiling cooling device for an electric vehicle. Schematically, a semiconductor element 70 (heating element), which is an object to be cooled, is mounted in a cooling tank 20 (cooling tank) made of a rolled steel plate, and a sufficient amount of fluorocarbon-based material for dipping the semiconductor element 70 Refrigerant 60
Has been injected. A plurality of airtight terminals 50 are attached to the wall surface of the cooling tank 20 and wired to the semiconductor element 70. An aluminum tube 102 having a flat cross section is attached to the upper part of the cooling tank 20 so that one opening surface faces downward and the other opening surface is hermetically sealed to form an airtight structure with the cooling tank 20. . An aluminum corrugated fin 101 is connected to the side surface of the cooling tank 20, and the heat exchanger 10
(Heat dissipation part) is configured. Further, inner fins 140 (condensation promoting means) for increasing the internal surface area of the heat exchanger 10 are attached inside the heat exchanger 10 by brazing or the like. FIG. 1B is a schematic view of the heat exchanger 10.
In this embodiment, the inner fin 140 is configured to have a wave shape when viewed from above.

In such a structure, the semiconductor element 70
Is energized in an airtight state through the airtight terminal 50 to generate heat corresponding to the power loss of the element. The heat generated in the semiconductor element 70 is absorbed by the surrounding coolant 60, and the coolant 60 is boiled. The generated vapor of the refrigerant 60 rises in the tube 102 due to the thermosyphon effect, transfers heat to the inner fins 140 and the tube 102, is cooled, and is liquefied again. The liquefied refrigerant 60 returns to the lower cooling tank 20 due to gravity. Therefore, the heat generated in the semiconductor element 70 is
0, the inner fin 140, the tube 102, and the corrugated fin 101 to be released to the atmosphere.

Therefore, in this embodiment, the inner fin 14 is
By increasing the heat transfer area of the heat exchanger 10 by 0, the heat transfer efficiency can be improved. Further, due to the increase of the area, the refrigerant 20 which is cooled and liquefied and descends
Liquid film (150 in FIG. 1 (a)) can be made evenly thin (when the same amount of the refrigerant 20 is lowered, the larger the area, the smaller the amount of the refrigerant per unit area). It is possible to prevent the heat dissipation characteristic from being deteriorated due to the increase of the thermal resistance of the film, and it is possible to further improve the heat transfer efficiency. Therefore, it is possible to reduce the size of the entire device while improving the heat dissipation characteristics.

Here, in this embodiment, the tube 102
By integrating the cooling tank 20 with the cooling tank 20, since the path from the cooling liquid tank of the refrigerant to the cooling tank is vaporized and liquefied to reach the cooling tank again, the change in the liquid surface can be suppressed to a small level. Also, the amount of refrigerant can be reduced. Also tube 102
The flatness makes it possible to easily attach the cooling fins to the flat surface, and since the fins use the corrugated fins 101, which have a very high heat transfer coefficient during ventilation, they are small and have high cooling performance. be able to. Generally, a blower fan for forced cooling is used to obtain high cooling performance, but since a flat tube is used in the boiling cooling device of this embodiment, air is blown as compared to a circular tube tube having the same cross-sectional area. The air resistance at the time can be reduced, and the blowing fan can obtain higher cooling performance only by using a small-sized and low-power thing. This is a great advantage for an electric vehicle whose mileage greatly changes depending on power consumption and vehicle body weight.

(Second Embodiment) A boiling cooling apparatus according to a second embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a diagram showing a boiling cooling device according to a second embodiment of the present invention. In this figure, the difference from the boil cooling apparatus of FIG. 1 is that the inner fins 140 formed inside the heat exchanger 10 are vertically divided into a plurality of parts. Further, FIG. 3 is a schematic view of the heat exchanger 10.

By dividing the inner fin 140 in this way, the growth of the liquid film can be suppressed. FIG. 4 is a diagram showing a state in which the vapor of the refrigerant 60 that has risen due to boiling and vaporization contacts the inner fins 140 to form a very thin liquid film 150. In this case, the refrigerant 60 flows downward with the viscous force and gravity balanced. Since vapor is condensed one after another in the middle of the process, the thickness of the liquid film 150 gradually increases as it goes downward. As described above, the liquid film 150 becomes a resistance against heat transfer from the steam to the inner fins 140. However, by dividing the inner fin 140 as shown in FIG. 4, the liquid film becomes a drop shape before it grows, so that the liquid film can be thinned as a whole.

Therefore, it is possible to prevent the heat dissipation characteristic from being deteriorated due to the increase of the thermal resistance of the liquid film, and to increase the heat transfer efficiency by increasing the heat transfer area. Therefore, it is possible to reduce the size of the entire device while improving the heat dissipation characteristics. (Third Embodiment) A boiling cooling apparatus according to a third embodiment of the present invention will be described below with reference to the drawings. FIG. 5 is a diagram showing a boiling cooling device according to a third embodiment of the present invention. In this figure, the difference from the boil cooling apparatus of FIG. 1 is that the inner fin 140 formed inside the heat exchanger 10 is vertically divided into a plurality of parts, and the peaks and valleys of the divided inner fin 140 are That is, the peaks and valleys of the other inner fins 140 (underneath) that are adjacent to each other are arranged so as to be offset from each other.

FIG. 6 is a diagram showing a state in which the divided inner fin 140 is viewed from above. FIG. 6A shows a case where the inner fins 140 adjacent to each other have the same pitch l and different arrangements. Further, FIG. 6B shows a case in which the pitches l ₁ and l _{2 of the} inner fins 140 adjacent to each other are different. By gradually arranging the divided inner fins 140 in this manner, the inner fins 140 are cooled and liquefied.
It is possible to suppress a phenomenon in which the droplet-shaped coolant 60 that descends along and adheres to the inner fin 140 directly below and the liquid film grows on the inner fin 140 below. Therefore, it is possible to prevent the heat radiation characteristic from being deteriorated due to the increase in the thermal resistance of the liquid film, and it is possible to further improve the heat transfer efficiency. Therefore, it is possible to reduce the size of the entire device while improving the heat dissipation characteristics.

(Fourth Embodiment) A boiling cooling apparatus according to a fourth embodiment of the present invention will be described below with reference to the drawings. FIG. 7 is a diagram showing a boiling cooling device according to a fourth embodiment of the present invention. In this figure, the difference from the boil cooling apparatus of FIG. 1 is that the inner fins 140 formed inside the heat exchanger 10 are formed of corrugated louver fins.

With the configuration shown in FIG. 7, the refrigerant 60 that has been vaporized by boiling and rises easily passes through the holes of the inner fins 140. As a result, vapor diffusion occurs in the heat exchanger 10, and it is possible to prevent uneven heat distribution in the heat exchanger 10. Further, the louver of the corrugated louver fin can suppress the growth of the liquid film as in the case of FIG. 4B, and can prevent the deterioration of the heat radiation property due to the increase of the thermal resistance of the liquid film.

As described above, in this embodiment, the heat can be efficiently absorbed by the inner fins 140, so that the miniaturization of the entire apparatus can be realized while improving the heat dissipation characteristics. Further, since the heat transfer area of the heat exchanger 10 is substantially increased as in the above-described embodiment, the liquid film of the refrigerant 60 which is cooled and liquefied and descends can be made evenly thin. It is possible to prevent the heat dissipation characteristic from deteriorating due to the increase of the heat resistance of the heat exchanger, and to improve the heat transfer efficiency.

Further, in this embodiment, as shown in FIG. 8, the inner fin 140 formed inside the heat exchanger 10 may be vertically divided into a plurality of pieces. Inner fin 1
By dividing 40, the liquid film can be further thinned as a whole, and the heat dissipation efficiency can be further improved by preventing the heat dissipation characteristic from being deteriorated due to the increase in the thermal resistance of the liquid film.

(Fifth Embodiment) A boiling cooling apparatus according to a fifth embodiment of the present invention will be described below with reference to the drawings. FIG. 9 is a diagram showing a boiling cooling device according to a fifth embodiment of the present invention. In this figure, the difference from the boil cooling apparatus of FIG. 1 is that a hole is formed on one surface of the inner fin 140 formed inside the heat exchanger 10.

By doing so, the growth of the liquid film can be suppressed. That is, since the liquid film becomes a drop again before it grows, the liquid film can be made thin as a whole, and the heat dissipation efficiency can be further improved by preventing the heat dissipation characteristic from being deteriorated due to the increase in the thermal resistance of the liquid film. it can. Therefore, it is possible to reduce the size of the entire device while improving the heat dissipation characteristics. In the present embodiment, the hole may have a substantially rectangular shape as shown in FIG. 9 or a substantially circular shape. Further, as shown in FIG. 10, holes may be formed alternately on both surfaces of the inner fin 140. Thereby, not only the growth of the liquid film can be suppressed, but also the uneven distribution of heat in the heat exchanger 10 can be prevented by the diffusion of the vapor in the heat exchanger 10. Therefore, it is possible to reduce the size of the entire device while improving the heat dissipation characteristics. By forming the holes alternately on both sides as shown in FIG. 10, the pitch of the holes can be shortened and the growth of the liquid film can be suppressed.

(Sixth Embodiment) A boiling cooling apparatus according to a sixth embodiment of the present invention will be described below with reference to the drawings. FIG. 11 is a diagram showing a boiling cooling device of a sixth embodiment of the present invention. In this figure, the difference from the boil cooling apparatus of FIG. 1 is that a plate-shaped member having a louver formed by cutting is used as the condensation promoting means formed inside the heat exchanger 10.
Further, FIG. 12 is a schematic view of the heat exchanger 10.

In this embodiment, the refrigerant 60 adhering to the louver falls on the central portion of the tube 102, so that the growth of the liquid film is suppressed, so that the heat dissipation characteristic is prevented from being deteriorated due to the increase of the thermal resistance of the liquid film. The heat transfer efficiency can be further improved. This makes it possible to reduce the size of the entire device while improving the heat dissipation characteristics. (Seventh Embodiment) A boiling cooling apparatus according to a seventh embodiment of the present invention will be described below with reference to the drawings. FIG. 13 shows the seventh aspect of the present invention.
It is a figure which shows the boiling cooling apparatus of an Example. First to sixth
In the embodiment, the heat exchanger 1 including one tube 102
Although the operation and effect have been described using the direct cooling type boiling cooling device having 0, the present invention has the indirect cooling type cooling device having the heat exchanger 10 in which a plurality of tubes 102 are connected in parallel as shown in FIG. May be applied to. In this figure, the boiling cooling device in the present embodiment is the heat exchanger 10,
The inner fin 140, the corrugated fin 101, the cooling tank 20, the coolant 60, and the power pack 110. A cooling medium 60 is enclosed in the cooling tank 20. The heat exchanger 10 and the power pack 110 are attached with a bolt 133 via an O-ring 130. Here, the heat dissipation surface 11
1 is a material having good thermal conductivity such as copper, and the coolant 60 is water. The corrugated fin 101 is adhesively fixed to the heat exchanger 10. Silicon gel 114 is filled in the power pack 110 to protect the semiconductor device 70. As shown in FIG. 13, the heat exchanger 10 is arranged above the power pack 110 so that the refrigerant 60 absorbs heat from the heat radiation surface 111 of the copper plate 113. The corrugated fin 101 expands the heat transfer area of the heat exchanger 10 and improves the heat dissipation efficiency by the front edge effect of the corrugated fin 101. As the inner fin 140, a fin as shown in FIG. 1B may be used, or a corrugated louver fin as shown in FIG. 7 may be used.

A side view of FIG. 13 is shown in FIG. In the present embodiment, the forced cooling fan uses the axial flow fan 302, which blows air to the corrugated fins 101. The blowing direction may be as shown in 602, or
Alternatively, air may be blown in reverse. The heat exchanger 10 and the corrugated fins are made of metal such as Al as described above. At the time of use at a low temperature, an antifreeze liquid or the like is mixed with the refrigerant 6 to lower the freezing point, or a liquid having a low pour point such as fluorocarbon is used as shown in the first to sixth embodiments.

When the semiconductor element 70 generates heat in such a structure, the heat is transferred to the heat radiating surface 111 of the copper plate 113 and the refrigerant 60 is boiled and vaporized. At this time, the refrigerant 60 and the heat dissipation surface 1
Between 11 there is a highly efficient heat transfer by boiling. The heat transfer coefficient during boiling reaches 100 to 1000 times that during natural convection. The refrigerant 60 changes from water to steam, and the vaporized steam evaporates up the tube 102 and circulates in the passage. When the steam comes into contact with the inner fins 140 on the inner surface of the tube 102 and the tube 102, the steam condenses into water and releases latent heat. The heat released is transmitted to the corrugated fins 101, and the corrugated fins are cooled by the air blow from the axial fan 302.

Therefore, in this embodiment as well, the heat transfer efficiency can be increased by substantially increasing the heat transfer area of the heat exchanger 10 by the inner fin 140.
Further, since the area is increased, the liquid film of the coolant 60 that is cooled and liquefied and descended can be made evenly thin, so that it is possible to prevent the heat dissipation characteristic from being deteriorated due to the increase in the thermal resistance of the liquid film, and further improve the heat transfer efficiency. be able to. Therefore, it is possible to reduce the size of the entire device while improving the heat dissipation characteristics.

In this embodiment, the inner fin 140 may be divided in the vertical direction as shown in FIG.
By dividing the inner fins 140 as described above, the liquid film can be further thinned as a whole, and the heat dissipation efficiency can be further improved by preventing the heat dissipation characteristic from being deteriorated due to the increase in the thermal resistance of the liquid film. . Note that FIG. 3, FIG. 5, FIG.
In FIG. 15, as shown in FIG.
By scraping and sharpening a part of the lower part of 0, the refrigerant 60 attached to the inner fins 140 is likely to be a drop shape and easily flows downward. Thereby, the growth of the liquid film can be further suppressed. In addition, in the above-described first to seventh embodiments, the inner surface of the tube 102 and the inner fin 14 are used.
By plating the surface of 0 with a noble metal such as gold, silver, or chromium, it becomes easier to cause droplet condensation instead of film condensation that forms a liquid film, which greatly improves the heat transfer coefficient. be able to. The inner fin 140 is not limited to the corrugated shape, but may have a substantially rectangular shape as shown in FIG. 17, for example.

The present invention is not limited to the electric vehicle, and the structure or shape may be arbitrarily changed within the range not departing from the gist of the present invention, and other power semiconductor elements or heating elements, etc. It can be applied to the heating element.

[Brief description of drawings]

FIG. 1 (a) is a diagram showing a boiling cooling device in a first embodiment of the present invention. FIG. 1B is a diagram showing a heat exchanger of the boiling cooling device shown in FIG.

FIG. 2 is a diagram showing a boiling cooling device in a second embodiment of the present invention.

3 is a diagram showing a heat exchanger of the boiling cooling device shown in FIG.

4 (a) and 4 (b) are views showing a state of a liquid film on an inner fin in the boiling cooling apparatus shown in FIG.

FIG. 5 is a view showing a boiling cooling device in a third embodiment of the present invention.

6 (a) and 6 (b) are top views of the inner fin in the boiling cooling device shown in FIG.

FIG. 7 is a diagram showing a boiling cooling device in a fourth embodiment of the present invention.

FIG. 8 is a diagram showing a boiling cooling device which is an embodiment of the present invention.

FIG. 9 is a diagram showing a boiling cooling device in a fifth embodiment of the present invention.

FIG. 10 is a diagram showing a boiling cooling apparatus which is an embodiment of the present invention.

FIG. 11 is a diagram showing a boiling cooling device in a sixth embodiment of the present invention.

FIG. 12 is a diagram showing a heat exchanger of the boiling cooling device shown in FIG. 9.

FIG. 13 is a view showing a boiling cooling device which is a seventh embodiment of the present invention.

14 is a side view of the boiling cooling device shown in FIG.

FIG. 15 is a diagram showing a boiling cooling apparatus which is an embodiment of the present invention.

FIG. 16 is a diagram showing a boiling cooling device in an eighth embodiment of the present invention.

FIG. 17 is a diagram showing a boiling cooling apparatus which is an embodiment of the present invention.

FIG. 18 is a diagram showing a conventional boiling cooling type semiconductor device.

[Explanation of symbols]

 10 heat exchanger (heat dissipation part) 101 corrugated fin 102 tube 110 power pack 111 heat dissipation surface 113 copper plate 114 silicon gel 130 O-ring 133 bolt 140 inner fin (condensation promoting means) 150 liquid film 20 cooling tank 302 axial fan 50 airtight terminal 60 Refrigerant 602 Heat flow 70 Semiconductor element (heating element)

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[Procedure amendment]

[Submission date] December 27, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

Here, in this embodiment, the tube 102
By integrating the cooling tank 20 with the cooling tank 20, since the path from the cooling liquid tank of the refrigerant to the cooling tank is vaporized and liquefied to reach the cooling tank again, the change in the liquid surface can be suppressed to a small level. Also, the amount of refrigerant can be reduced. Also tube 102
The flatness makes it possible to easily attach the cooling fins to the flat surface, and since the fins use the corrugated fins 101, which have a very high heat transfer coefficient during ventilation, they are small and have high cooling performance. be able to. Generally, a blower fan for forced cooling is used to obtain high cooling performance, but since a flat tube is used in the boiling cooling device of this embodiment, air is blown as compared to a circular tube tube having the same cross-sectional area. The air resistance at the time can be reduced, and the blowing fan can obtain higher cooling performance only by using a small-sized and low-power thing. This is a great advantage for an electric vehicle whose mileage greatly changes depending on power consumption and vehicle body weight. In addition, the heat exchanger 1 of the boiling cooling device of this embodiment
In manufacturing 0, the inner fin 140 was inserted.
If not, the tube 102 is thin
Warp easily occurs and the corrugated fin 101 and the chew
Brazing with the bush 102 may not be performed well. Only
Then, insert the inner fin 140 as in this embodiment.
If so, the tube 102 is less likely to warp.
Wax of corrugated fin 101 and tube 102
It has the effect of easy attachment. In addition, when the device is
Even in the event of pressure fluctuations, the
The inner fin 140 plays the role of a reinforcing material, and the pressure resistance is
It also has the effect of improving.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takashi Furukawa 1-1, Showa-cho, Kariya city, Aichi Prefecture, Nihon Denso Co., Ltd. (72) Inventor Masahiko Suzuki, 1-1, Showa-cho, Kariya city, Aichi prefecture Within the corporation

Claims (11)

[Claims] 1. A heating element that is used in an electric circuit or the like to generate extra heat when driven, a refrigerant that absorbs the heat generated by the heating element and is vaporized by the heat, and a cooling tank that contains the refrigerant. And, while one opening surface is attached to the cooling tank,
The other opening surface is attached in a hermetically sealed manner, and is formed in contact with a cylindrical heat radiating portion that liquefies the liquefied and rising refrigerant into a cooling liquefaction and returns it to the cooling tank. A boiling cooling device, comprising: a condensation promoting unit that enhances heat radiation to a heat radiation unit. 2. The condensation promoting means has a structure for increasing an inner area of the heat radiating portion so as to easily absorb heat from the refrigerant that has been vaporized by boiling and rising.
The boiling cooling device described. 3. The boiling cooling apparatus according to claim 1, wherein the condensation promoting means is a fin. 4. The boiling cooling apparatus according to claim 1, wherein the condensation promoting means is divided into a plurality of upper and lower portions. 5. The boiling cooling device according to claim 1, wherein the condensation promoting means is composed of a corrugated member. 6. The boiling cooling device according to claim 5, wherein the concave-convex groove portion of the corrugated member extends in the tubular longitudinal direction of the heat radiating portion. 7. The condensation promoting means is composed of a corrugated member, and the peaks and valleys of the divided corrugated member are offset from the peaks and troughs of the other corrugated members that meet next to each other. The boiling cooling apparatus according to claim 4, wherein the boiling cooling apparatus is arranged. 8. The condensation promoting means has a structure in which a part of a lower end portion is lower than other portions, and the refrigerant adhering to the inside of the heat radiating portion is easily returned to the cooling tank. The boiling cooling device according to any one of claims 1 to 7. 9. The boiling cooling apparatus according to claim 1, wherein the condensation promoting means is provided with a louver portion formed by cutting and raising. 10. The condensation promoting means has a structure in which a louver portion formed by cutting and raising is provided and an open end side of the louver portion is lower than the other end side, and the refrigerant adhering to the inside of the heat radiating portion is removed. The boiling cooling device according to claim 1, which has a structure that facilitates returning to the cooling tank. 11. The boiling cooling device according to claim 1, wherein the condensation promoting means has a hole formed therein.