JP4415115B2 - Heat transfer device - Google Patents

Description

  The present invention relates to a heat transfer device, and more particularly to a heat pipe.

  In semiconductor devices used in personal computer CPUs, inverters, thyristors, etc., so-called power electronics, the removal of generated heat is an extremely important technical issue, and heat pipes are generally used.

As for the heat pipe, a wick for maintaining the capillary phenomenon is usually processed or arranged inside the container. However, in recent years, a heat transfer device that does not require a wick has been invented (see Patent Document 1). In particular, it is expected to be applied in a zero-gravity environment including space.
Japanese Patent No. 3416731

  Heat pipes are widely used in microelectronics, civil engineering, and space because of their simple structure and good apparent heat conduction. On the other hand, a copper pipe having good thermal conductivity is usually used for the container, and a wick structure is provided inside, so that no particular improvement has been made in terms of weight.

  Sure, as shown in Patent Document 1, in recent years, a heat pipe that does not require a wick has been invented, but the long container serving as a heat pipe body is formed of a rigid body, and has a large weight. In addition, there is a problem that handling during transportation is inconvenient, and space is increased in storage and installation on equipment.

  If compact storage can be achieved by drastically reducing weight, folding, etc., the application field will be greatly improved by adding the added value of mobilization to the conventional concept in the consumer field, including application to space thermal control. There is a possibility of spreading to.

  The present invention aims to solve the above-mentioned problems of the conventional heat pipe, and in particular, achieves a heat pipe that can be transported and accommodated in a compact state while achieving a significant weight reduction in terms of weight. The objective is to ensure that compact heat pipes meet the needs of essential application fields and application fields that require functions.

In order to solve the above-described problems, the present invention accommodates a solid or fluid serving as a heat transfer medium in a shrinkable and expandable container formed of a flexible material, and contains a curing agent in the flexible material. When the heat transfer medium is heated and the container expands once, a heat pipe is provided that maintains the expanded shape of the container .

  The container is a pipe having a flat cross section that can be wound or folded in a spiral shape when not in use.

  The container can be expanded and contracted in a bellows shape.

  The container is characterized by expanding when the vapor pressure of the heat transfer medium rises due to the temperature rise of the heat transfer medium in the container.

The heat transfer medium, when a fluid is characterized in that an aqueous solution of alcohol 10 from 4 carbon atoms.

  When the container material is composed of polyimide having excellent radiation resistance, a metal thin film having excellent heat conductivity, etc., the weight is at most 1/10 of the conventional copper heat pipe having the same heat removal capability. I was able to. Moreover, although it changed with the methods of accommodation about volume, it was able to be about 1/5 of the conventional copper heat pipe similarly.

  An embodiment of a heat pipe according to the present invention will be described below with reference to the drawings based on examples.

  First, the outline of the configuration of the present invention will be described. In the present invention, the container constituting the heat pipe body has a so-called inflatable structure such as a thin film so that it can be accommodated in a very compact manner when not in use (before operation), and the heat transfer medium during use (in operation). This is a configuration in which it is expanded by the vapor pressure and becomes a normal heat pipe shape.

  As described above, the present invention enhances heat conduction by using a heat pipe container as a thin film material, can be reduced in weight, and can be rounded (convolved), folded, shrunk, etc., and transported and stored compactly. A possible configuration is a feature of the present invention.

  And the wick on the inner wall of the container is a heat pipe that is used in a zero gravity environment in outer space, as long as the wettability of the inner wall of the container and the heat transfer medium is secured, there is no wick due to the Marangoni effect by the aqueous alcohol solution. It can fully function as a heat pipe (see Japanese Patent No. 3416731). In addition, a wick is usually required in a gravitational environment, but is not necessary for a heat pipe that is arranged vertically and used as a thermosiphon.

  Note that the heat pipe of the present invention maintains this shape after expansion and may take measures to prevent re-shrinkage due to a decrease in temperature, or when the operation is not necessary, the temperature of the heat transfer medium is decreased and used again. You may return to the previous compact state.

  FIG. 1 is a diagram illustrating a heat pipe according to the first embodiment. The heat pipe 1 of the first embodiment is a so-called “wickless heat pipe” in which no wick is provided. The heat pipe 1 has a container 2 as its main body.

  The container 2 is formed in a pipe shape from a flexible material such as a polyimide thin film having excellent radiation resistance or a metal thin film having excellent heat conductivity. The container 2 is filled with a fluid (which may be a solid) serving as a heat transfer medium. A portion on one end side of the container 2 functions as an evaporation portion (high temperature portion) 3, a middle portion as a heat insulation portion 4, and the other end as a condensation portion (low temperature portion) 5.

  The inner surface of the container 2 is hydrophilically treated so as to ensure wettability to the heat transfer medium. For example, the hydrophilic coating layer 2 ′ is formed by fluorinating the inner surface of the container or coating with a hydrophilic substance such as a silicon organic substance. In particular, if the evaporating part 3 whose wettability decreases at a high temperature is subjected to a hydrophilic treatment, the wettability with water can be improved and normal evaporation in the evaporating part 3 can be ensured.

  The degree of hydrophilicity in the hydrophilic treatment is adjusted by changing the thickness of the silicon organic material coating layer or by changing the density of the hydrophilic material such as fluorine or silicon organic material in the coating layer.

  As the heat transfer medium, a non-azeotropic composition of a polyhydric alcohol aqueous solution containing 4 or more carbon atoms including butanol and pentanol is used.

  This heat pipe container 2 has a pipe-like configuration in which the vapor pressure of the heat transfer medium is low in a non-use state (depressurized state) and has a flattened cross-section as shown in the left diagram of FIG. It is. However, in use, when the evaporation section 3 is heated with a heat source, the container 2 expands (expands) as the vapor pressure of the heat transfer medium filled therein increases, as shown in the right diagram of FIG. A pipe-like configuration (circular tube) having a circular cross section is obtained.

  In addition, the polyimide which is a flexible material for forming the container 2 is heated to contain a thermosetting material for curing after expansion, thereby expanding once into a pipe shape having a circular cross section. It is also possible for the container to maintain its shape.

(Function)
When the evaporation unit 3 is heated by the heat source, the heat transfer medium heated by the evaporation unit 3 is shown in FIG. 1B due to the temperature difference between the evaporation unit 3 and the condensation unit 5 in the container 2 and the concentration difference of the heat transfer medium. As shown, it moves from the evaporation unit 3 through the heat insulating unit 4 to the condensing unit 5, and heat is transferred to the heated object in the condensing unit 5.

  In short, heat is absorbed from the heat source in the evaporating unit 3 and exhausted in the condensing unit 5, whereby the heat of the heat source is transferred to the heated object (not shown) by the heat pipe 1. Then, the heat transfer medium flows back from the condensing unit 5 to the evaporation unit 3 along the inner surface of the container 2 by surface tension.

  By the way, when a non-azeotropic composition of a polyhydric alcohol aqueous solution having 4 or more carbon atoms is used as a heat transfer medium, the surface tension of the aqueous solution increases with increasing temperature at a certain temperature (20 to 70 degrees Celsius) or higher. , Rise significantly. Therefore, the temperature difference Marangoni effect and the concentration difference Marangoni effect act in the same direction, which further promotes the circulation of the liquid from the condensing unit 5 to the evaporation unit 3 (details of this point are disclosed in Japanese Patent No. 3416731). See the official gazette).

  In Example 1, the heat pipe 1 is composed of a pipe-shaped container 2 made of a flexible material such as polyimide having excellent radiation resistance and a metal thin film having excellent heat conductivity. At the time of use, the container 2 is in a decompressed state as shown in FIG. 1 (a), and the container 2 is contracted to have a flat cross section, so that if necessary, the container 2 is rounded into a spiral shape as shown in FIG. 1 (c). Can do. Thereby, since the container 1 becomes compact when not in use, it is very easy to handle in transportation and storage.

  FIG. 2 is a diagram illustrating the second embodiment. The heat pipe 6 of the second embodiment has substantially the same configuration as the heat pipe 1 of the first embodiment, but the container 7 of the heat pipe 2 is not used as a foldable configuration as shown in the left diagram of FIG. It is characterized in that it can be folded and transported and stored. At the time of use, the vapor pressure of the heat transfer medium increases and expands in the same manner as in Example 1, and the container 7 has a pipe shape as shown in the right figure of FIG.

  As a configuration in which the container 7 is foldable, it may be flexible as in the first embodiment. However, a configuration in which the outer surface of the folding portion is previously folded so that the strength of the container is not impaired. Also good. For example, as a fold, there is a configuration in which the thickness of the fold line portion 8 is made thinner than other portions along the dotted line or along the entire line to such an extent that the strength of the container is not impaired.

  FIG. 3 is a diagram for explaining the third embodiment. The heat pipe 9 of the third embodiment has almost the same configuration as the heat pipe 1 of the first embodiment, but the container 10 of the heat pipe 9 has a bellows-like configuration that can expand and contract as shown in the left diagram of FIG. As a feature, it is configured such that it can be shrunk and transported, stored, etc. when not in use. At the time of use, the vapor pressure of the heat transfer medium increases and expands itself as in the first embodiment, and the container 10 has a pipe shape as shown in the right diagram of FIG.

  FIG. 4 is a diagram for explaining the fourth embodiment. The heat pipe 11 of the fourth embodiment has substantially the same configuration as the heat pipe 1 of the first embodiment. However, as shown in the left diagram of FIG. Adhering to and attaching to a flat structure, the structure can be contracted and expanded in a flat shape.

  According to the fourth embodiment, when not in use, since it contracts and does not expand outward from the substrate 13, it can be transported, stored, etc. by stacking a plurality of substrates 13 together. At the time of use, the vapor pressure of the heat transfer medium increases and expands in the same manner as in Example 1, and the container 12 becomes a semi-circular pipe-shaped pipe shape as shown in the right diagram of FIG.

  As described above, in Examples 1 to 4, wickless heat pipes (heat pipes without wicks) have been described. However, heat pipes having wicks are the same as in Example 1. That is, the container which is the main body of the heat pipe is made of a flexible material and rolled up into a spiral shape like in Examples 1 to 4, and can be folded or stretched, and the wick provided on the inner surface of the container is What is necessary is just to comprise from a very fine and flexible line | wire.

  The best mode for carrying out the heat pipe according to the present invention has been described based on the embodiments. However, the present invention is not limited to such embodiments, and the technical scope described in the claims is not limited thereto. It goes without saying that there are various embodiments within the scope of the matter.

  Since the present invention is configured as described above, the present invention can be applied to industrial fields that require general heat transfer operations, and particularly to equipment that uses heat pipes for exhaust heat, such as personal computers and power electronics. Can be applied promptly.

  The field where the effect of the present invention is most remarkably exhibited is a field that requires heat transfer operation in a weightless environment such as a spacecraft. In other words, in the space utilization field, exhaust heat generated from each part of the satellite in the weightless state is transported to the radiator by a heat pipe and dissipated to the deep space, but the heat pipe is usually made of strong metal, and the structure is compared. Although it can be applied when it is folded at a large size, it is difficult to apply when it is expanded from a roll state or when it is expanded into a complicated shape due to lack of flexibility.

  Under such requirements, development of flexible heat pipes has been energetically performed, but the present invention has excellent heat transfer characteristics by making the heat pipe structure itself an inflatable structure. Weight reduction is achieved and the structure is rich in flexibility, and by using a unique heat transfer medium that has already been devised by the inventor, a configuration that does not require a wick structure inside can be realized.

  In addition, the present invention can be used in any posture on the ground as long as it has a wick structure inside rather than a zero-gravity environment, and if there is no wick structure, it can be used as a thermosiphon in a vertical arrangement. Can

It is a figure explaining Example 1 of the heat pipe which concerns on this invention. It is a figure explaining Example 2 of the heat pipe which concerns on this invention. It is a figure explaining Example 3 of the heat pipe which concerns on this invention. It is a figure explaining Example 4 of the heat pipe which concerns on this invention.

Explanation of symbols

1 Heat pipe of Example 1
2 containers
2 'hydrophilic coating layer
3 Evaporating part (high temperature part)
4 Insulation is in the middle
5 The other end is the condensation part (low temperature part)
6 Heat pipe of Example 2
7 containers
8 Folding line
9 Heat pipe of Example 3
10 containers
11 Heat pipe of Example 4
12 containers
13 Substrate

Claims (6)

A shrinkable and inflatable container formed of a flexible material contains a solid or fluid serving as a heat transfer medium, and the flexible material contains a curing agent, and the heat transfer medium is heated to A heat pipe that maintains the expanded shape of the container once the container is expanded .   The heat pipe according to claim 1, wherein the container is a pipe having a flat cross section that can be wound or folded in a spiral shape when not in use.   The heat pipe according to claim 1, wherein the container can be expanded and contracted in a bellows shape.   The heat pipe according to any one of claims 1 to 3, wherein the container expands when a vapor pressure of the heat transfer medium rises due to a temperature rise of the heat transfer medium in the container. The heat pipe according to any one of claims 1 to 4, wherein, when the heat transfer medium is a fluid, the heat transfer medium is an aqueous solution of an alcohol having 4 to 10 carbon atoms. The heat pipe according to claim 1, wherein a hydrophilic coating layer is formed on the inner surface of the container.