JPH07127982A - Heat transfer pipe - Google Patents

Abstract

PURPOSE:To provide a heat transfer pipe in which a boiling pressure is high, and correspondingly a pressure for circulating fluid is high and no check valve is installed. CONSTITUTION:A heat generating part 4 is integrated with a fine tube 3. A cooling part 2 is contacted with the fine tube 3. A reservoir 5 is fixed near the heat generating part 4 of the fine tube 3 and working liquid condensed at the cooling part 2 is stored there, and then the liquid is returned back to the heat generating part 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat transfer device for controlling heat, and more particularly to a heat transfer pipe having a loop type heat pipe structure used for cooling a heating element.

[0002]

2. Description of the Related Art FIG. 8 is a sectional view of a conventional example of this type of heat transport pipe, and FIG. 9 is a sectional view of a check valve 14 in FIG.

The thin tube 13 has an annular shape, and a fixed amount of condensable hydraulic fluid is enclosed therein. A check valve 14 for determining the circulation direction of the condensable hydraulic fluid is attached inside the thin tube 3. The heating element 11 is an object that is to be thermally controlled and has a large amount of heat generation, and is attached so as to come into contact with the thin tube 13. The cooling fin 12 is a cooling unit for releasing heat from the heating element 11, is attached in contact with the thin tube 11, and has an area such that the heating element 11 has a predetermined temperature. The check valve 14 includes a small ball 15, a throat 16 and a stopper 17, as shown in FIG. In the check valve 14, when the hydraulic fluid comes from the direction of the throat 16, the ball 15 is caught by the stopper 17, the hydraulic fluid flows out from the gap between the ball 15 and the stopper 17, and conversely, the hydraulic fluid is discharged from the stopper 17. When flowing, the sphere 15 flows toward the throat 16 and the sphere 1
5 is closely attached to the throat 16 to stop the flow.

Next, the principle of cooling of the heating element 11 in the heat transport pipe shown in FIG. 8 will be described. The heat generated from the heating element 11 conducts heat to the wall of the thin tube 13 to boil the condensable working liquid enclosed therein. When the condensable working liquid boils and evaporates, it is taken into the vapor as evaporation latent heat and flows to the cooling unit 12, where it is condensed as a liquid and released as condensation heat to the outside of the thin tube 13. By the boiling pressure in the thin tube 13 which is in contact with the heating element 11,
The fluid is pushed out to the cooling unit 12, and the action of the check valve 14 present in the thin tube 13 determines the circulation direction of the condensable hydraulic fluid. When the heating element 11 is not generating heat, the condensable hydraulic fluid is collected at the bottom of the thin tube 13 and there is a space at the top, but when boiling begins, the space formed at the top is vaporized. Passes through. Then, since the thin tube 13 is thin, the working liquid swells due to the steam flowing to the liquid surface, and when the steam velocity is high, the wave becomes large and the tube cross section is closed. The working fluid that has blocked the cross section of the pipe becomes a liquid pool having a certain length. That is, the flow flows to the cooling unit 12 in a state of slag flow in which steam and hydraulic fluid alternate. When the condensable hydraulic fluid is returned from the cooling unit 12 to the heat generating unit 11, the liquid condensed in the cooling unit 12 is accumulated, and the liquid curved surface formed at the liquid pool end and the liquid formed near the evaporation unit 11 are collected. It is caused by the capillary pressure difference caused by the difference in the curved surface and the effect of the check valve 14. FIG. 10 is a diagram for explaining the capillary pressure difference caused by the difference in the liquid curved surface, where 18 is the liquid curved surface near the heat generating portion 11, 19 is the liquid curved surface near the cooling portion 12, and 20 is the radius of curvature at the liquid curved surface. Show. The difference between the vapor pressure and the liquid pressure is inversely proportional to the radius of curvature, and the gas-liquid pressure difference becomes large in the heat generating portion 11. Comparing the radii of curvature of the liquid when the heat generating part and the cooling part are close to each other as shown in FIG. 10, the radius of the heat generating part is smaller than the radius of the cooling part. When there is a space in the upper part of the pipe, steam easily moves to the cooling part, so that the steam pressure is almost equal between the heat generating part and the cooling part. Therefore, the liquid pressure in the cooling unit 12 becomes larger than that in the heat generating unit 11, and the condensable hydraulic fluid returns to the heat generating unit 11.

However, when the pipe is thick, it is difficult to form a slug flow that blocks the cross section of the pipe when the working liquid swells, and the condensable working liquid collects in the lower part by gravity and forms in the upper part. Since the steam passes through the space and moves to the cooling unit, the fluid is divided into two phases and flows. In this flowing state, the temperature of the condensable hydraulic fluid accumulated in the lower portion is low, so the vapor passing therethrough is condensed into the fluid and the vapor pressure drops.
Then, the force for returning the liquid pool in the cooling unit to the evaporation unit becomes small, and since the pipe diameter is large, the capillary pressure becomes weak and the amount of liquid that can be returned becomes small. That is, it becomes difficult to transport a large amount of heat.

[0006]

In the heat transport pipe of FIG. 8, the thermal conductivity is determined by the circulation speed of the fluid, and when the circulation speed is slow, the temperature difference between the heating element and the cooling unit 12 becomes large. Therefore, effective cooling effect cannot be obtained. The circulation speed depends on the boiling pressure, and when there is a large amount of liquid boiling, the circulation speed also increases. However, since the diameter of the thin tube 13 that is in contact with the heating element is small, the amount of liquid existing inside is small and it is not possible to obtain a pressure sufficient to circulate the fluid. In the case of FIG. 8, the boiling pressure is obtained by arranging a plurality of thin tubes 13 in parallel from the heating element to the cooling section 12. But,
When the area of the heating element is extremely larger than that of the thin tubes 13 or when the heat generation is large, it is necessary to increase the number of turns of the thin tubes to be contacted to remove heat, and thus the number of thin tubes to be arranged in parallel increases. The size becomes large. Moreover, even if the number of check valves is increased by increasing the number of turns, the flow becomes complicated and the flow direction cannot be controlled, so that the fluid cannot always circulate. Furthermore, a high level of processing technology is required when installing the check valve. For example, inserting a sphere with a diameter of 1 mm into a thin tube with an inner diameter of 3 mm or 2 mm and attaching a stopper or throat requires precision processing, which complicates the manufacturing process and makes the check valves annular. Attaching to a thin tube increases the number of welding points, and reduces reliability when the heat transport pipe is used for a long period of time.

An object of the present invention is to provide a heat transport pipe having a large boiling pressure and no check valve.

[0008]

A heat-transporting pipe of the present invention has a heat-generating portion, a cooling portion, an annular thin tube connecting the heat-generating portion and the cooling portion, and a heat-sealing pipe enclosed in the thin tube. The condensable working fluid and a reservoir for storing the working fluid, which is provided in the vicinity of the heat generating section in the middle of the thin tube, include a heat generating section and the thin tube.

[0009]

[Function] By connecting the thin tube integrally with the box-shaped heat generating portion for attaching the heat generating element,
The heat generating part can be adjusted to the size of the heat generating element, the inner volume of the heat generating part can be changed in the thickness direction (the cross-sectional direction of the thin tube), and the working fluid amount can be adjusted to a liquid amount according to the heat generating amount. . When arranging multiple thin tubes in parallel with a large amount of waste heat,
By connecting a plurality of thin tubes to one heat generating part, it becomes easy to install the heat generating element in the heat generating part, and since there is only one boiling space, it becomes easy to determine the size of the heat generating part. As a result, the boiling pressure is increased and a large driving amount for circulating the hydraulic fluid can be obtained. Further, by mounting the reservoir near the heat generating portion, the working fluid from the heat generating portion is stored in the reservoir through the cooling portion. Since the working fluid is always present in the reservoir, the working fluid can be easily sent to the heat generating portion. In this way, the circulation direction of the hydraulic fluid is determined, and the check valve is unnecessary.

Further, the cooling effect of the heating element becomes greater as the thermal resistance between the heating element and the cooling section becomes smaller. If a condensable liquid with a low dielectric constant can be used as the working fluid, the heating element can be installed in the heating section and the heating element can be brought into direct contact with the working fluid, and the heat from the heating element can be piped into the heating section. The hydraulic fluid can be evaporated without going through the wall. That is, the thermal resistance between the condensable hydraulic fluid and the heating element can be reduced. Therefore, the thermal resistance from the heating element to the cooling portion is reduced by the amount obtained by removing the thermal resistance between the heating element tube wall and the heating element tube wall and the working fluid, and the cooling effect is also increased.

Further, when the amount of heat generated from the heating element is large, the inner diameter is small when only one thin tube connects the heating element and the cooling section, and the liquid flow rate returning to the heating section is limited.
Therefore, when the calorific value is large, by connecting a plurality of thin tubes between the reservoir and the heat generating portion, the flow rate at which the condensable hydraulic fluid returns can be increased. In order to facilitate the return of the hydraulic fluid between the reservoir and the heat generating portion, the inner diameter of the thin tube is reduced to increase the capillary pressure. In addition, since the capillary pressure effect between the heat generating part and the cooling part and between the cooling part and the reservoir is not as important as that between the reservoir and the heat generating part, the capillary has an inner diameter enough to block the working fluid inside the pipe. Good. By arranging a plurality of those having the inner diameter in parallel, the flow rates of the steam and the working liquid can be increased, so that the cooling effect can be increased even for a heating element having a large heating value.

[0012]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a plan view of a heat transport pipe according to a first embodiment of the present invention, and FIG. 2 is a perspective view thereof. In addition, in FIGS. 2A and 2B, a part is broken. Heating part 4
Is manufactured integrally with the thin tube 3, and has a size capable of installing the heating element 1. The cooling part 2 is in contact with the thin tube 3, and its size can be determined by the amount of heat generated and the heat transport capacity. A reservoir 5 is attached to the thin tube 3 in the vicinity of the heat generating portion 4, and the working liquid condensed in the cooling portion 2 can be stored therein.

Since the reservoir 5 holding the working fluid is present in the vicinity of the heat generating portion 4, the vapor generated from the heat generating portion 4 flows from the direction without the reservoir 5 to the cooling portion 2, and the working fluid is condensed in the cooling portion 2. To be done. The condensed working fluid flows to the reservoir 5 by the action of propagating the capillary pressure and the boiling pressure, and in order to supplement the vapor generated in the heat generating section 4, the working fluid in the thin tube 3 ′ near the reservoir 5 and the heat generating section 4 is The hydraulic fluid flows from the reservoir 5 to the heat generating portion 4 due to the capillary pressure difference caused by the curvature.

In the present embodiment, since the heat generating portion 4 is integrally connected to the thin tube 3, the heat generating portion 4 can be manufactured in accordance with the size of the heat generating body 1, and the amount of the working fluid filled can be determined by the thickness. Therefore, the boiling pressure is increased and a large driving force for driving the hydraulic fluid is obtained.

FIG. 3 is a plan view of the heat transport pipe of the second embodiment of the present invention. In this embodiment, steam is delivered,
The heat generating part 4 and the reservoir 5 are connected by two thin tubes 3, and the working fluid is returned to the heat generating part 4. The reservoir 5 and the heat generating part 4 are connected by three thin tubes 3'having an inner diameter smaller than that of the thin tube 3. It was done. Since the capillary pressure acting on the inside of the tube increases as the inside diameter of the tube decreases, the working fluid is accumulated in the reservoir 5, and the working fluid flows into the heating portion 4 at the connection between the thin tube 3 ′ and the heating portion 4, A liquid surface shape having a certain curvature in the thin tube 3 ′ there is formed. Since the capillary pressure is inversely proportional to this radius of curvature, the capillary pressure difference between the reservoir 5 and the heat generating part 4 becomes large by reducing the inner diameter of the capillary 3, and the return of the hydraulic fluid from the reservoir 5 to the heat generating part 4 is easy. Is. Also, since the number of thin tubes 3 and 3'is large, the amount of liquid to be returned is large. Therefore, the cooling effect is increased.

FIG. 4 is a plan view of a heat transport pipe according to a third embodiment of the present invention, and FIG. 5 is a perspective view thereof. Note that FIG.
A part is broken in (2) and (3). In this embodiment, as shown in FIG. 5 (2), the heating element 1 is mounted inside the heating portion 4, and is an example for controlling the heat of the heating element 1 which generates a large amount of heat in a small area. When the heating element 1 is attached to the outside of the heating portion 4, the thermal resistance of contact exists between them, and this value is large, and the temperature difference between the heating element 1 and the heating portion 4 becomes significant. Even if the heating element 1 has a certain size, it can be mounted inside by providing the heating portion 4. In this embodiment, since the heating element 1 is in direct contact with the working fluid, the thermal resistance between the working fluid and the heating element 1 is small, the thermal resistance between the heating element 1 and the cooling unit 2 is also small, and the cooling effect is large. Become.

FIG. 6 and FIG. 7 are views for explaining the internal structure of the reservoir 5 and a part thereof is shown broken away.
For example, a mesh 6 is attached to the inner surface of the reservoir 5 so that the hydraulic fluid can be held by the capillary pressure (FIG. 6),
By arranging the thin plates 7 inside the reservoir 5 (FIG. 7), the capillary pressure can be increased and the working fluid can easily flow from the cooling unit 2 to the reservoir 5 so that the working fluid can be always retained in the reservoir 5.

[0019]

As described above, the present invention has the following effects. (1) The invention of claim 1 By integrally connecting the heat-generating part and the thin tube, the heat-generating part can be manufactured in accordance with the size of the heat-generating body, and the amount of condensable hydraulic fluid enclosed is determined by the thickness of the heat-generating part. it can. As a result, a large driving force for increasing the boiling pressure and circulating the fluid can be obtained. Also, by disposing the reservoir in the vicinity of the heat generating portion, the direction of fluid flow can be regulated, and a circulation type heat transport pipe without a check valve can be realized. (2) Invention of Claim 2 By directly contacting the heating element with the condensable hydraulic fluid,
Since the thermal resistance between the heating fluid and the heating element is reduced by removing the thermal resistance between the heating element tube wall and the heating element, the thermal resistance between the heating element and the cooling section is also reduced and the cooling effect is increased. (3) Invention of Claim 3 When the calorific value is large, the inner diameter and the number of the thin tubes for returning the working fluid between the reservoir and the heat generating portion are set to be larger than the inner diameter of the thin tube for sending vapor between the heat generating portion and the reservoir. The flow rate of the condensable hydraulic fluid returned can be increased by reducing the number, increasing the number, and increasing the capillary pressure by narrowing the capillaries. Also, by arranging multiple thin tubes with an inner diameter that block the inside of the working fluid in parallel between the heat generating part and the cooling part, and between the cooling part and the reservoir, the flow rate of steam and working fluid can be increased, so the cooling effect Can be increased.

[Brief description of drawings]

FIG. 1 is a plan view of a heat transport pipe according to a first embodiment of the present invention.

FIG. 2 is a heat transport pipe of the first embodiment (FIG. 2 (1)),
A perspective view in which a part of the heat generating portion 4 and the reservoir 5 is cut away (see FIG.
(2) and (3)).

FIG. 3 is a plan view of a heat transport pipe according to a second embodiment of the present invention.

FIG. 4 is a plan view of a heat transport pipe according to a third embodiment of the present invention.

FIG. 5 is a heat transport pipe of the third embodiment (FIG. 5 (1)),
A perspective view in which a part of the heat generating portion 4 and the reservoir 5 is cut away (see FIG.
(2) and (3)).

6 is a perspective view showing an example of the internal structure of the reservoir 5. FIG.

7 is a perspective view showing another example of the internal structure of the reservoir 5. FIG.

FIG. 8 is a plan view of a conventional example of a heat transport pipe.

9 is a cross-sectional view of the check valve 14 in FIG.

FIG. 10 is a diagram for explaining the principle of the liquid returning from the condensing part to the heat generating part in the conventional heat transport pipe.

[Explanation of symbols]

 1,11 Heating element 2,12 Cooling part 3,3 ', 13 Capillary tube 4 Heating part 5 Reservoir 6 Mesh 7 Thin plate 14 Check valve 15 Ball 16 Throat 17 Stopper 18 Liquid curved surface in the vicinity of the heating part 19 In the vicinity of the cooling part Liquid surface 20 Radius of curvature on liquid surface

Claims (3)

[Claims] 1. A heat-generating part, a cooling part, an annular thin tube connecting the heat-generating part and the cooling part, a condensable hydraulic fluid enclosed in the thin tube, and an intermediate part of the thin tube. A heat transport pipe provided in the vicinity of the heat generating portion, including a reservoir for storing the working fluid, wherein the heat generating portion and the thin tube are integrated. 2. The heat transport pipe according to claim 1, wherein a heating element is installed in the heating section and is in contact with the working fluid. 3. A thin tube which is connected between the heat generating part and the reservoir, and which has the inner diameter and the number of thin tubes for returning the hydraulic fluid to the heat generating part, is connected between the reservoir and the heat generating part and which sends out vapor. The heat transport pipe according to claim 1 or 2, wherein the heat transport pipe is smaller than the inner diameter and larger than the number.