JP2005114179A - Heat pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce an area of liquid slag formed in a condensation part of a heat pipe, and to increase an effective length of the condensation part performing a condensation function. <P>SOLUTION: In this heat pipe, the inner circumferential wall face of a longitudinally extending sealed vessel is provided with a first capillary body, and an operating fluid is sealed such that the operating fluid fills the inside of the capillary body. The vessel is divided in an evaporation part applied with heat, the condensation part cooling vapor of the operating fluid to return it to liquid, and a heat insulation part provided between the evaporation part and the condensation part, and is used. The heat pipe has a second capillary body. The second capillary body has one end positioned in an end part of the condensation part formed with the liquid slag such that the end sucks the liquid slag, and the other end supported such that the other end extends to a longitudinal-direction hollow of the vessel and is opened, and has an effective pore radius and a length for adjusting a volume of the liquid slag remaining in the condensation part to a prescribed range. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heat pipe that is used in a space-free space such as an artificial satellite and is used for cooling an onboard electronic device.

  In a conventional heat pipe, a capillary body called a wick having fine grooves cut in the axial direction is formed on the inner peripheral wall surface of a vacuum-sealed cylindrical container made of copper or aluminum, and the capillary body fills the inside of the capillary body. Thus, it has a configuration in which an appropriate amount of ammonia is sealed as a working fluid (see, for example, Non-Patent Document 1). Referring to FIG. 1 of the present invention, one end of the heat pipe 100 is positioned on the side of an electronic device mounted on, for example, an artificial satellite, and forms an evaporation unit 103 that is heated by the heat. . The other end forms a condensing part 105 which is cooled by being positioned on the outer space side, and an intermediate part forms a heat insulating part 104 placed in a heat insulating state. In the evaporating unit 103, the heated working fluid evaporates to become a vapor, and when the vapor pressure increases, the force moves through the heat pipe 100 toward the condensing unit 105 at a speed close to the speed of sound. The vapor that has entered the condensing unit 105 is cooled and condensed to become a liquid. The working fluid that has returned to the liquid is transmitted through the capillary body 102 by the capillary action of the capillary body 102 applied to the inner peripheral wall surface of the cylindrical container 101, returns to the evaporation section 103 through the heat insulating section 105, and evaporates again by heating. To do. By such a circulating motion of the working fluid, the heat of vaporization is transported from the evaporator 103 to the condenser 105 with a low temperature difference, and the evaporator 103 can be effectively cooled.

“Theory and Application of Heat Pipe” W. Translated by Chi, translated by Koichi Oshima, Tadashi Matsushita, Masahide Murakami, Jateku Publishing, published June 23, 1978

  Since the conventional heat pipe is configured as described above, it has the following problems. The ambient temperature of the heat pipe mounted on the artificial satellite changes due to the influence of solar heat while the artificial satellite makes one round of the earth. Along with this, the operating temperature of the heat pipe also fluctuates. When the operating temperature of the heat pipe varies, the temperature of the working fluid also changes, and accordingly, the volume of the liquid phase portion of the working fluid varies. For this reason, the amount of the working fluid is set so that the liquid is filled in the capillary body under any conditions. Thus, there will be a surplus of working fluid liquid remaining inside the capillary body under any environmental conditions. This surplus liquid flows by being pushed by the vapor flow and accumulates at the end of the condensing part to form a liquid slag (corresponding to 107 in FIG. 1). Since there is no vapor space in the portion where the liquid slag exists, the vapor of the working fluid cannot be condensed. That is, the liquid slag portion does not contribute to heat dissipation, does not become a portion where the heat pipe acts effectively, and reduces the effective length of the condensing portion. As a result, the cooling effect of the evaporation part by the heat pipe is reduced.

  The present invention has been made to solve the above problems, and an object of the present invention is to obtain a heat pipe having a structure in which the area of liquid slag formed in the condensing part is reduced and the effective length of the condensing part is increased.

  In the heat pipe according to the present invention, a first capillary body is provided on an inner peripheral wall surface of a sealed container extending in a longitudinal direction, a working fluid is sealed so as to fill the inside of the capillary body, and the cylindrical container is sealed. The heat pipe is divided into a heat-applied evaporation part, a condenser part for cooling the working fluid vapor to return it to a liquid, and a heat insulating part provided between the evaporation part and the condensation part. The liquid slag is located at the end of the condensing part where the liquid slag is formed so as to suck in the slag, the other end is supported so as to open in the longitudinal hollow of the cylindrical container, and remains in the condensing part. A second capillary body having an effective pore radius and length for adjusting the volume within a predetermined range is provided.

  According to this invention, since the liquid slag is sucked by the second capillary body, the volume occupied by the liquid slag formed in the condensing part can be reduced to a predetermined range. As a result, the condensing part of the heat pipe There is an effect of increasing the effective length.

Embodiment 1 FIG.
1 is a cross-sectional view showing a configuration of a heat pipe according to Embodiment 1 of the present invention, and FIG. 2 is a cross-sectional view showing a configuration of a condensing unit. In the figure, a heat pipe 100 is provided with a capillary body 102 on an inner peripheral wall surface of a sealed container (here, a cylindrical container, but not limited to a cylinder) 101 extending in the longitudinal direction. The working fluid is sealed so as to fill the gas. The cylindrical container 101 is divided into an evaporating unit 103 to which heat is applied, a condensing unit 105 that cools the vapor of the working fluid and returns it to a liquid, and a heat insulating unit 104 provided between the evaporating unit 103 and the condensing unit 105. The working fluid is used for cooling by performing a circulating motion. In the first embodiment, when the capillary body 102 is the first capillary body, the second capillary body 1 is provided in the center.

  The capillary material of the second capillary body 1 is made of a metal porous body, for example, made of aluminum or nickel-based foam metal, and is a porous material having a high porosity and connecting pores, and Celmet (Sumitomo Electric). It is commercialized under a name such as Kogyo Co., Ltd. Since the second capillary body 1 made of a metal porous body has elasticity, it is supported by press-fitting one end into a recess 108 provided at the end of the condensing unit 105, and sucks the liquid slug 107. It is positioned. The second capillary body 1 is supported so that the other end extends in the longitudinal direction of the cylindrical container 101 and is opened, and the volume of the remaining liquid slug 107 formed at the end of the condensing unit 105 is set to a predetermined level. It has an effective pore radius and length that adjusts to the range.

Next, the effective pore radius given to the second capillary body 1 will be described. The effective pore radius (pore radius) can be obtained from equations (1) to (3) using the capillary pressure difference and the surface tension. In the equations (1) to (3), σ represents the surface tension.
The capillary pressure difference ΔP _cp possessed by the second capillary body 1 is expressed by equation (1).
ΔP _cp = 2σ / r _p (1)
Here, r _p is the effective pore radius having a second capillary body 1. Further, as shown in FIG. 2, when the pore radius of the liquid slag 107 is r _s , the capillary pressure difference ΔP _s possessed by the liquid slag 107 is expressed by Expression (2).
ΔP _cs = 2σ / r _s (2)
Similarly, when the effective pore radius having a first capillary 102 and r _g, the capillary pressure difference [Delta] P _g with the first capillary 102 is represented by the formula (3).
ΔP _cg = 2σ / r _g (3)

In order for the working fluid liquid sealed in the heat pipe 100 to permeate the first capillary body 102 first and then the remaining liquid slug 107 be absorbed by the second capillary body 1, the condition of equation (4) must be satisfied. It is necessary to satisfy.
ΔP _cg > ΔP _cp > ΔP _cs (4)
Accordingly, the effective pore radius r _p of the second capillary element 1 is required to be selected to satisfy equation (5).
r _g <r _p <r _s (5)
That is, the condensing unit and the second effective pore radius r _p of the capillary body 1, greater than the effective pore radius r _g of the first capillary element 102, and the mutual positional relationship of the first capillary body and the second capillary element set to be smaller than the pore radius r _s which is formed in 105 vapor space.
As a result, the liquid slag 107 generated at the end of the condensing unit 105 is effectively sucked into the second capillary body 1 and the volume of the remaining liquid slag 107 is reduced. As a result, a vapor space is formed in the portion after the liquid slag 107 is absorbed, and the vapor of the working fluid occupying the portion can be condensed. Therefore, heat can be dissipated by using most of the entire length of the condensing unit 105, thereby increasing the cooling effect of the evaporating unit 103.

  As described above, according to the first embodiment, the second capillary body 1 is provided, and one end is located at the end of the condensing unit 105 where the liquid slag is formed so as to suck the liquid slag 107, and the other Since the end is supported so as to open in the longitudinal hollow of the cylindrical container 101 and has an effective pore radius and length that adjusts the volume of the liquid slag remaining in the condensing part to a predetermined range, The volume occupied by the liquid slag formed in the liquid slag forming part of the condensing part can be reduced, and the effect of increasing the effective length for performing the condensation function of the heat pipe can be obtained. Moreover, since the 2nd capillary body 1 is the elasticity which consists of a metal porous body, the effect that it can fix-support easily by pressing in the recessed part provided in the edge part of a condensation part is also acquired.

Embodiment 2. FIG.
FIG. 3 is a sectional view showing the structure of the condensing part of the heat pipe according to Embodiment 2 of the present invention. In the figure, the same parts as those in FIG. Here, the capillary 2 is used as the second capillary body. The narrow tube 2 is formed of a circular tube whose inner diameter is adjusted so as to satisfy the formula (5). One end is close to the end of the condensing unit 105 so as to suck the liquid slug 107, and the other end is a cylinder. The container 101 is supported using appropriate support pillars 3a and 3b so as to extend in the longitudinal direction of the container 101 and be opened.

  By configuring the condensing unit 105 as described above, the liquid slag 107 generated at the end of the condensing unit 105 is absorbed by the thin tube 2 and the volume occupied by the remaining liquid slag 107 is reduced. As a result, a vapor space is formed in the portion after the liquid slag 107 is absorbed, and the vapor of the working fluid occupying the volume can be condensed. Therefore, heat can be radiated using most of the entire length of the condensing unit 105, and the cooling effect of the evaporating unit 103 is increased. In addition, since a circular tube having a simple structure is used as the second capillary body, an effect of being inexpensively manufactured can be obtained.

Embodiment 3 FIG.
FIG. 4 is a cross-sectional view showing the configuration of the condensing part of the heat pipe according to Embodiment 3 of the present invention. In the figure, the same parts as those in FIG. Here, a parallel plate 4 is used as the second capillary body. The parallel plate 4 has a gap width adjusted between the two plates so as to satisfy the formula (5). One end of the parallel plate 4 is fixed to the end of the condensing unit 105 so as to suck the liquid slug 107, and the other end is cylindrical. The container 101 is supported so as to extend in the longitudinal direction and open.

  By configuring the condensing unit 105 as described above, the liquid slag 107 generated at the end of the condensing unit 105 is absorbed by the parallel plate 4 and the volume of the remaining liquid slag 107 is reduced. As a result, a vapor space is formed in the portion after the liquid slag 107 is absorbed, and the vapor of the working fluid occupying the portion can be condensed. Therefore, heat can be radiated using most of the entire length of the condensing unit 105, and the cooling effect of the evaporating unit 103 is increased. In this case, since the parallel plate 4 having a simple structure is used as the second capillary body, an effect that can be manufactured at low cost is obtained.

Embodiment 4 FIG.
FIG. 5 is a sectional view showing the structure of the condensing part of the heat pipe according to Embodiment 4 of the present invention. In the figure, the same parts as those in FIG. Here, a grooved plate 5 provided with a plurality of grooves extending in the longitudinal direction on both sides is used as the second capillary body. The grooved plate 5 has a groove width adjusted so as to satisfy the formula (5). One end of the grooved plate 5 is fixed to the end of the condensing unit 105 so as to suck the liquid slug 107, and the other end of the cylindrical plate 101 It is supported so that it may extend in the longitudinal direction and open.

  By configuring the condensing unit 105 as described above, the liquid slag 107 generated at the end of the condensing unit 105 is absorbed by the grooved plate 5 and the volume of the remaining liquid slag 107 is reduced. As a result, a vapor space is formed in the portion after the liquid slag 107 is absorbed, and the vapor of the working fluid occupying the portion can be condensed. Therefore, heat can be radiated using most of the entire length of the condensing unit 105, and the cooling effect of the evaporating unit 103 is increased. In this case, since the grooved plate 5 having a simple structure is used as the second capillary body, an effect that can be manufactured at low cost is obtained.

Embodiment 5 FIG.
6 is a sectional view showing the structure of a heat pipe according to Embodiment 5 of the present invention. In the figure, parts that are the same as or correspond to those in FIG. Here, the heat pipe 100 is configured so as to include the evaporation units 103 at both ends of the cylindrical container 101, and the condensing unit 105 is located at the center of the cylindrical container 101. As the second capillary body, the metal porous body described in Embodiment 1, the porous body made of Teflon (registered trademark) or ceramic is used. The second capillary body is supported so as to extend in the longitudinal direction of the cylindrical container 101 and be opened so that both ends reach the evaporation section 103 through the heat insulating section 104 through the central section of the condensing section 105. In this case also effective pore radius r _p of the second capillary member 1 is selected so as to satisfy the equation (5).

  In this case, the liquid slag 107 tends to be formed at the center of the condensing unit 105, but the liquid slag 107 is absorbed by the second capillary body 1. Even in the configuration in which the condensing unit 105 is located at the center of the heat pipe, the volume of the liquid slug 107 generated at the center is reduced. As a result, a vapor space is formed in the portion after the liquid slag 107 is absorbed, and the vapor of the working fluid occupying the portion can be condensed. Therefore, since the two evaporation parts 103 are also provided and the condensation part 105 can radiate heat using most of the entire length, an effect of increasing the cooling effect can be obtained.

It is sectional drawing which shows the structure of the heat pipe by Embodiment 1 of this invention. It is sectional drawing which shows the structure of the condensation part which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the structure of the condensation part which concerns on Embodiment 2 of this invention. It is sectional drawing which shows the structure of the condensation part which concerns on Embodiment 3 of this invention. It is sectional drawing which shows the structure of the condensation part which concerns on Embodiment 4 of this invention. It is sectional drawing which shows the structure of the condensation part which concerns on Embodiment 5 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 2nd capillary body, 2 capillary, 3a, 3b support | pillar, 4 parallel plate, 5 grooved plate, 100 heat pipe, 101 cylindrical container, 102 capillary body (1st capillary body), 103 evaporation part, 104 heat insulation part , 105 condensing part, 107 liquid slag.

Claims (8)

  A first capillary body is provided on the inner peripheral wall surface of the sealed container that extends in the longitudinal direction, the working fluid is sealed so as to fill the inside of the capillary body, and the container is heated by an evaporation unit, In a heat pipe that is used separately for a condensing unit that cools the working fluid vapor and returns it to a liquid, and a heat insulating unit provided between the evaporating unit and the condensing unit, one end of the liquid is sucked into the liquid slag. It is located at the end of the condensing part where slag is formed, the other end is supported so as to open in the longitudinal direction of the container, and the volume of liquid slag remaining in the condensing part is within a predetermined range. A heat pipe comprising a second capillary body having an effective pore radius and a length to be adjusted.   The pores formed in the vapor space of the condensing portion by the effective pore radius of the second capillary body being larger than the effective pore radius of the first capillary body and the mutual positional relationship between the first capillary body and the second capillary body The heat pipe according to claim 1, wherein the heat pipe is smaller than a radius.   The second capillary body is formed of a capillary material having elasticity, and one end thereof is supported by being press-fitted into a concave portion formed at an end portion of the condensing portion. Item 3. The heat pipe according to Item 2.   The heat pipe according to any one of claims 1 to 3, wherein the second capillary body is formed of a metal porous body.   The heat pipe according to claim 1 or 2, wherein the second capillary body is formed of a circular thin tube.   The heat pipe according to claim 1 or 2, wherein the second capillary body is formed of a parallel plate.   The heat pipe according to claim 1 or 2, wherein the second capillary body is formed of a grooved plate provided with a plurality of grooves extending in the longitudinal direction.   A first capillary body is provided on the inner peripheral wall surface of the sealed container that extends in the longitudinal direction, the working fluid is sealed so as to fill the inside of the capillary body, and the container is heated by an evaporation unit, In a heat pipe that is used separately for a condenser that cools the working fluid vapor and returns it to a liquid, and a heat insulating part provided between the evaporator and the condenser, the condenser is provided at the center of the container. A heat insulating part and an evaporation part are provided on both sides of the condensing part, both ends of the condensing part are supported by the condensing part in which the liquid slag is formed so as to extend and open in the longitudinal direction of the container, and the condensing part A heat pipe comprising a second capillary body made of a porous body having an effective pore radius and length for adjusting the volume of the liquid slag remaining in a predetermined range.

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