JPH08219668A - Heat pipe - Google Patents

Abstract

PURPOSE: To provide a heat pipe which fails to drop even when a maximum heat transfer capacity is applied to unidirectional heating by changing the cross section shape of a wick for the generation of a capillary tube force in the peripheral direction of the tube. CONSTITUTION: This invention comprises a tightly closed tube 1, which is used as a heat pipe vessel and a porous material 2, which is used as a capillary force generation wick installed on the inner wall of the tube 1 and a working fluid 3, which is sealed inside the tube 1 and produces its phase changes. The thickness of the porous material 2 close to a heating board 6 is increased while the thickness of the porous material is reduced at a spot separated from the heating board 6 in the peripheral direction of the inner wall surface of the tube 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pipe for use in a space or ground heat exhaust device.

[0002]

2. Description of the Related Art FIG. 17 shows a conventional heat pipe.
Is a sectional view thereof. In the figure, 1 is a sealed tube that serves as a heat pipe container, and 2 is a porous material as a wick for generating a capillary force provided on the inner wall of the tube 1. Usually, a sintered metal or a foam metal is used. Reference numeral 3 denotes a working fluid which causes a phase change enclosed in the tube 1, 4 denotes a heating portion of a heat pipe, 5 denotes a cooling portion of the heat pipe, 6 denotes a heating plate provided on the outer surface of the heating portion 4 of the heat pipe, 7 Is a cooling plate provided on the outer surface of the cooling unit 5 of the heat pipe.

Next, the principle of operation when this heat pipe is used will be described. The heat applied from the heating plate 6 to the outer surface of the tube 1 is transferred to the working fluid 3 existing in the porous material 2 through the porous material 2 of the heating part 4 by heat conduction in the thickness direction of the tube 1. The working fluid 3 evaporates. The evaporated working fluid 3 flows in the pipe 1 in the direction of the cooling part 5 having a low saturated vapor pressure, is condensed in the porous material 2 of the cooling part 5, and releases latent heat. This heat is transferred to the outer surface of the tube 1 by heat conduction,
The heat is radiated to the cooling plate 7. The working fluid 3 condensed in the porous material 2 of the cooling part 5 is returned to the heating part 4 in the porous material 2 by the capillary force. Heat is transferred from the heating plate 6 to the cooling plate 7 by this cycle.

FIG. 19 is a cross-sectional view of an axial groove type heat pipe, which uses a porous heat pipe except that a plurality of axially extending fins 8 are provided on the inner wall surface of the pipe 1 as a wick. It is the same. Usually, the fin 8 is extruded integrally with the tube 1.

Next, the operating principle when this axial groove type heat pipe is used will be described. The heat applied from the heating plate 6 to the outer surface of the tube is transmitted to the fins 8 of the heating section 4 by heat conduction in the thickness direction of the tube 1. The heat transferred to the fins 8 is transferred to the working fluid 3 existing in the groove formed by the fins 8 and the inner wall surface of the tube 1, and the working fluid 3 is evaporated. The evaporated working fluid 3 flows in the pipe 1 toward the cooling unit 5 having a low saturated vapor pressure, is condensed by the fins 8 of the cooling unit 5, and releases latent heat. This heat is transferred to the outer surface of the tube 1 by heat conduction and radiated to the cooling plate 7. The working fluid 3 condensed by the fins 8 is returned to the heating unit 4 by the capillary force of the groove formed by the fins 8 and the inner wall surface of the pipe 1. Heat is transferred from the heating plate 6 to the cooling plate 7 by this cycle.

[0006]

The limit of the heat transport capacity of the heat pipe occurs when the pressure loss of the working fluid becomes larger than the maximum capillary pressure generated by the wick. When the heat transfer is limited due to this capillary force, the working fluid does not flow back to the end of the heating section, and the wick is dried up. FIG.
If the heating plate is evenly installed in the circumferential direction of the heating section as described above, the wick simultaneously dries up in the circumferential direction of the inner wall surface of the tube. This is because the thermal resistance from the heating plate to the working fluid that is steam is uniform in the circumferential direction of the inner wall surface of the tube, and the heat flux transmitted to the wick is also uniform in the circumferential direction.

However, as shown in FIG. 20, when the heating plate is installed only in a part of the heating portion and the heat pipe is heated only from one direction, the wick close to the heating plate having the largest heat flux to the wick is generated. First of all, the wick that dries up gradually expands in the circumferential direction of the inner wall surface of the pipe.
In this case, the one-way heating has a problem that the maximum heat transport amount is reduced by several tens of percent as compared with the uniform heating. This is because the heat applied from the heating plate is gradually transferred to the wick while flowing in the tube in the circumferential direction, but since the evaporation heat resistance of the wick is uniform in the circumferential direction of the inner wall surface of the tube, the wick far from the heating plate is used. This is because the thermal resistance in the pipe circumferential direction increases and the heat flux to the wick decreases.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a heat pipe in which the decrease in the maximum heat transfer capacity due to the capillary force is small even in the case of unidirectional heating.

[0009]

A heat pipe according to a first embodiment of the present invention is one in which the thickness of a porous material, which has been the same in the past, is changed in the circumferential direction of the inner wall surface of the tube.

In the axial groove type heat pipe according to the second embodiment of the present invention, the height of the fin, which has been the same in the prior art, is changed in the circumferential direction of the inner wall surface of the pipe.

In the axial groove type heat pipe according to the third embodiment of the present invention, the thickness of the fin, which has been the same in the past, is changed in the circumferential direction of the inner wall surface of the pipe.

In the axial groove type heat pipe according to the fourth embodiment of the present invention, the fin intervals, which were conventionally the same, are changed in the circumferential direction of the inner wall surface of the tube.

In the axial groove type heat pipe according to the fifth embodiment of the present invention, the height and thickness of the fin having the same shape in the prior art are changed in the circumferential direction of the inner wall surface of the pipe.

The axial groove type heat pipe according to the sixth embodiment of the present invention is such that the fin height and the fin interval are changed in the circumferential direction of the inner wall surface of the pipe.

In the axial groove type heat pipe according to the seventh embodiment of the present invention, the fin thickness and the fin interval are changed in the circumferential direction of the inner wall surface of the pipe.

[0016]

According to the first embodiment of the present invention, the thickness of the porous material is varied in the circumferential direction of the inner wall surface of the pipe so that the thickness of the porous material becomes the thickest in the vicinity of the heating plate. The evaporation heat resistance of the porous material changes in the circumferential direction of the inner wall surface of the pipe so that the evaporation heat resistance of the porous material is the largest in the vicinity of the heating plate and becomes smaller at the distance from the heating plate in the circumferential direction of the inner wall surface of the pipe To do.
This effect and the effect that the thermal resistance in the pipe circumferential direction increases as the distance from the heating plate is canceled out, and even in the case of unidirectional heating, the heat flux to the porous material is made uniform in the circumferential direction of the inner wall surface of the pipe, It is possible to reduce the decrease in the maximum heat transport capacity.
In addition, the flow passage cross-sectional area of the porous material near the heating plate becomes large,
The increase in the heat transport capacity of the porous material near the heating plate also has the effect of preventing the maximum heat transport capacity from decreasing.

According to the second embodiment of the present invention, the evaporation heat resistance is heated by changing the fin height in the circumferential direction of the inner wall surface of the tube so that the fin height becomes the highest near the heating plate. It is the largest in the vicinity of the plate, and becomes smaller at the position distant from the heating plate in the circumferential direction of the inner wall surface of the tube. This effect is offset by the effect that the thermal resistance in the circumferential direction of the pipe increases as it moves away from the heating plate, and even in the case of unidirectional heating, the heat flux to each groove is made uniform and the decrease in the maximum heat transfer capacity is reduced. be able to. Also, the flow passage cross-sectional area of the groove near the heating plate becomes large,
Even if the heat transport capacity of the groove near the heating plate is increased, the maximum heat transport capacity is prevented from being lowered.

According to the third embodiment of the present invention, the evaporation heat resistance is changed by changing the fin thickness in the circumferential direction of the inner wall surface of the tube so that the fin thickness becomes the thinnest in the vicinity of the heating plate. It is the largest in the vicinity of the heating plate and becomes smaller at the position farther from the heating plate in the circumferential direction of the inner wall surface of the tube. This effect is offset by the effect that the thermal resistance in the circumferential direction of the pipe increases as it moves away from the heating plate, and even in the case of unidirectional heating, the heat flux to each groove is made uniform and the decrease in the maximum heat transfer capacity is reduced. be able to.

According to the fourth embodiment of the present invention, the evaporation heat resistance is changed by changing the fin interval in the circumferential direction of the inner wall surface of the tube so that the fin interval is maximized near the heating plate. It is the largest in the vicinity and becomes smaller at the position farther from the heating plate in the circumferential direction of the inner wall surface of the tube. This effect is offset by the effect that the thermal resistance in the circumferential direction of the pipe increases as it moves away from the heating plate, and even in the case of unidirectional heating, the heat flux to each groove is made uniform and the decrease in the maximum heat transfer capacity is reduced. be able to.

According to the fifth embodiment of the present invention, the height and the thickness of the fins are arranged in the circumferential direction of the inner wall surface of the pipe so that the height of the fins is the highest and the thickness of the fins is the thinnest in the vicinity of the heating plate. The evaporation heat resistance is maximized in the vicinity of the heating plate and is decreased at a position distant from the heating plate in the circumferential direction of the inner wall surface of the tube by changing the value of. This effect is offset by the effect that the thermal resistance in the circumferential direction of the pipe increases as it moves away from the heating plate, and even in the case of unidirectional heating, the heat flux to each groove is made uniform and the decrease in the maximum heat transfer capacity is reduced. be able to. Further, there is also an effect of preventing a decrease in the maximum heat transporting ability by increasing the heat transporting ability of the groove near the heating plate.

According to the sixth embodiment of the present invention, the height and spacing of the fins are varied in the circumferential direction of the inner wall surface of the pipe so that the height of the fins is the highest and the spacing between the fins is the widest in the vicinity of the heating plate. By doing so, the evaporation heat resistance becomes maximum near the heating plate and becomes smaller at a position farther from the heating plate in the circumferential direction of the inner wall surface of the tube. This effect is offset by the effect that the thermal resistance in the pipe circumferential direction increases as the distance from the heating plate increases, and even in the case of unidirectional heating, the heat flux to each groove is made uniform and the decrease in maximum heat transfer capacity is reduced. You can Further, there is also an effect of preventing a decrease in the maximum heat transporting ability by increasing the heat transporting ability of the groove near the heating plate.

According to the seventh embodiment of the present invention, the thickness and spacing of the fins are changed in the circumferential direction of the inner wall surface of the tube so that the thickness of the fins is the smallest and the spacing between the fins is the widest in the vicinity of the heating plate. By doing so, the evaporation heat resistance becomes the largest in the vicinity of the heating plate and becomes smaller at the position farther from the heating plate in the circumferential direction of the inner wall surface of the tube. This effect is offset by the effect that the thermal resistance in the circumferential direction of the pipe increases as it moves away from the heating plate, and even in the case of unidirectional heating, the heat flux to each groove is made uniform and the decrease in the maximum heat transfer capacity is reduced. be able to.

[0023]

【Example】

Example 1. 1 is a view showing a heat pipe according to a first embodiment of the present invention, and FIG. 2 is a sectional view of FIG. In the figure, reference numeral 1 is a closed tube that serves as a heat pipe container, and 2 is a porous material provided on the inner wall of the tube 1 as a wick for generating a capillary force, and usually a sintered metal or a foam metal is used. Reference numeral 3 denotes a working fluid which causes a phase change enclosed in the tube 1, 4 denotes a heating portion of the heat pipe, 5 denotes a cooling portion of the heat pipe, 6 denotes a heating plate provided on the outer surface of the heating portion 4 of the heat pipe, Reference numeral 7 is a cooling plate provided on the outer surface of the cooling unit 5 of the heat pipe. Porous material 2
Is the thickest near the heating plate 6 and is continuously thin in the circumferential direction of the inner wall surface of the tube 1.

Next, the operating principle when this heat pipe is used will be described. The heat applied from the heating plate 6 to the outer surface of the tube 1 is transferred to the porous material 2 provided on the inner wall surface of the tube 1 by heat conduction in the thickness direction and the circumferential direction of the tube 1. The heat transmitted to the porous material 2 evaporates the working fluid 3 existing in the porous material 2. The evaporated working fluid 3 flows in the pipe 1 toward the cooling unit 5 having a low saturated vapor pressure, condenses in the porous material 2 inside the cooling unit 5 and releases latent heat. This heat is transferred to tube 1 by heat conduction.
And is radiated to the cooling plate 7. Porous material 2
The working fluid 3 condensed in 1 is returned to the heating unit 4 by the capillary force of the porous material 2. Heat is transferred from the heating plate 6 to the cooling plate 7 by this cycle.

In the porous material 2 near the heating plate 6, the heat resistance of the tube 1 is small, while the heat resistance of the porous material 2 is large, and conversely, the porous material 2 is separated from the heating plate 6 in the circumferential direction of the inner wall surface of the tube 1. In the quality material 2, the heat resistance of the tube 1 is high, while the heat resistance of the porous material 2 is low. Therefore, the heat flux to the porous material 2 is made uniform in the circumferential direction of the inner wall surface of the tube.

FIG. 3 shows a case where the thickness of the porous material is partially changed in the circumferential direction of the inner wall surface of the tube 1. In the figure, 2 is a porous material having a partially changed thickness, and only the thickness in the vicinity of the heating plate 6 is changed, but the thickness of a plurality of portions may be changed.

Example 2. FIG. 4 is a diagram showing an axial groove type heat pipe according to a second embodiment of the present invention, and FIG. 5 is a diagram in which the cross section of FIG. 4 is developed in the pipe circumferential direction. In the figure, the structure is the same as that of the first embodiment except that a plurality of fins 8 extending in the axial direction are provided on the inner wall surface of the tube 1 as a wick. Fin 8
Has the highest height near the heating plate 6 and continuously lowers in the circumferential direction.

Next, the operating principle when this axial groove type heat pipe is used will be described. The heat applied from the heating plate 6 to the outer surface of the tube 1 is transferred to the fins 8 of the heating section 4 by heat conduction in the wall thickness direction and the circumferential direction of the tube 1. The heat transferred to the fins 8 is transferred to the working fluid 3 existing in the groove formed by the fins 8 and the inner wall surface of the tube 1, and the working fluid 3 is evaporated.
The evaporated working fluid 3 flows in the pipe 1 toward the cooling unit 5 having a low saturated vapor pressure, is condensed by the fins 8 in the cooling unit 5, and releases latent heat. This heat is transferred to the outer surface of the tube 1 by heat conduction and radiated to the cooling plate 7. The working fluid 3 condensed by the fins 8 is returned to the heating unit 4 by the capillary force of the groove formed by the fins 8 and the inner wall surface of the pipe 1. Heat is transferred from the heating plate 6 to the cooling plate 7 by this cycle.

In the fins 8 near the heating plate 6, the heat resistance of the tube 1 is small, whereas the fins 8 have a large evaporation heat resistance, and conversely, in the fins 8 apart from the heating plate 6, the heat resistance of the tube 1 is large. Evaporation heat resistance of 8 parts is small. Therefore fin 8
The heat flux to is uniformed in the circumferential direction.

FIG. 6 is a sectional development view of an axial groove type heat pipe in which the fin height is partially changed in the circumferential direction of the inner wall surface of the tube 1. In the drawing, 8 is an example in which only the height in the vicinity of the heating plate 6a is changed by the fin whose height is partially changed, but the heights of a plurality of portions may be changed.

Example 3. FIG. 7 is a sectional development view of an axial groove type heat pipe according to a third embodiment of the present invention. In the figure, the configuration is the same as that of the second embodiment except that the fin 8 is thinnest in the vicinity of the heating plate 6 and is continuously thickened in the circumferential direction of the inner wall surface of the tube 1. The operating principle is the same as that of the second embodiment.

FIG. 8 is a sectional development view of an axial groove type heat pipe in which the thickness of the fin is partially changed in the circumferential direction of the inner wall surface of the tube 1. In the drawing, 8 is an example in which only the thickness in the vicinity of the heating plate 6 is changed by the fin whose thickness is partially changed, but the thickness of a plurality of portions may be changed.

Example 4. FIG. 9 is a sectional development view of the axial groove type heat pipe according to the fourth embodiment of the present invention. In the figure, the structure is the same as that of the second embodiment except that the fins 8 are widest in the vicinity of the heating plate 6 and are continuously narrowed in the circumferential direction of the inner wall surface of the tube 1. The operating principle is the same as that of the second embodiment.

FIG. 10 is a sectional development view of an axial groove type heat pipe in which the fin intervals are partially changed in the circumferential direction of the inner wall surface of the tube 1. In the figure, 8 is an example in which only the gap in the vicinity of the heating plate 6a is changed by the fin whose gap is partially changed, but the gap of a plurality of parts may be changed.

Example 5. FIG. 11 is a sectional development view of an axial groove type heat pipe according to a fifth embodiment of the present invention. In the figure, except that the fin 8 has the highest height and the smallest thickness near the heating plate 6, and the fin height is continuously low and the thickness is thick in the circumferential direction of the inner wall surface of the tube 1. Is the same as in Example 2. The reasoning principle is the same as that of the second embodiment.

FIG. 12 is a sectional development view of an axial groove type heat pipe in which the fin height and thickness are partially changed in the circumferential direction of the inner wall surface of the tube 1. In the figure, 8 is an example in which only the height and thickness in the vicinity of the heating plate 6 are changed by fins whose height and thickness are partially changed, but the height and thickness of a plurality of portions may be changed.

Example 6. FIG. 13 is a sectional development view of the axial groove type heat pipe according to the sixth embodiment of the present invention. In the drawing, the fins 8 have the highest height and the widest space near the heating plate 6, and the fin height is continuously low in the circumferential direction of the inner wall surface of the tube 1 and the space is narrow. Same as example 2. The operating principle is the same as that of the second embodiment.

FIG. 14 shows a sectional development view of an axial groove type heat pipe in which fin heights and intervals are partially changed in the circumferential direction of the inner wall surface of the tube 1. In the figure, 8 is an example in which only the height and the spacing in the vicinity of the heating plate 6 are changed by the fins whose height and spacing are partially changed, but the height and the spacing of a plurality of portions may be changed.

Example 7. FIG. 15 is a sectional development view of the axial groove type heat pipe according to the seventh embodiment of the present invention. In the embodiment, except that the fins 8 have the smallest thickness and the widest space in the vicinity of the heating plate 6 in the figure, and the thickness is continuously thick and the space is narrowed in the circumferential direction of the inner wall surface of the tube 1. Same as 2. The operating principle is the same as that of the second embodiment.

FIG. 16 is a sectional development view of an axial groove type heat pipe in which the fin thickness and interval are partially changed in the circumferential direction of the inner wall surface of the tube 1. In the figure, 8 is an example in which only the thickness and the spacing in the vicinity of the heating plate 6 are changed by the fin whose thickness and spacing are partially changed, but the thickness and the spacing of a plurality of portions may be changed.

[0041]

As described above, according to Embodiments 1 to 7 of the present invention, the evaporation heat resistance is increased near the heating plate of the heat pipe by changing the wick shape in the circumferential direction, and the inner wall surface of the pipe is removed from the heating plate. By reducing the distance in the circumferential direction, it is possible to suppress the decrease in the maximum heat transport capacity even in the case of unidirectional heating.

[Brief description of drawings]

FIG. 1 is a diagram showing a heat pipe according to a first embodiment of the present invention.

FIG. 2 A of a heat pipe according to Embodiment 1 of the present invention
It is the figure which showed the A line cross section.

FIG. 3 is a view showing a cross section of a heat pipe in which the thickness of the porous material is partially changed in Example 1 of the present invention.

FIG. 4 is a diagram showing an axial groove type heat pipe according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a cross section of an axial groove type heat pipe according to a second embodiment of the present invention, which is developed in a circumferential direction of the pipe.

FIG. 6 is a diagram in which a cross section of an axial groove type heat pipe in which the height of the fin is partially changed in the second embodiment of the present invention is developed in the circumferential direction of the pipe.

FIG. 7 is a diagram in which a cross section of an axial groove type heat pipe according to a third embodiment of the present invention is developed in a circumferential direction of the pipe.

FIG. 8 is a view in which a cross section of an axial groove type heat pipe in which a thickness of a fin is partially changed in a third embodiment of the present invention is developed in a circumferential direction of the pipe.

FIG. 9 is a sectional view of the axial groove type heat pipe according to the fourth embodiment of the present invention, which is developed in the circumferential direction of the pipe.

FIG. 10 is a diagram in which a cross section of an axial groove type heat pipe in which a gap between fins is partially changed in a fourth embodiment of the present invention is developed in a circumferential direction of the pipe.

FIG. 11 is a view in which a cross section of an axial groove type heat pipe according to a fifth embodiment of the present invention is developed in the circumferential direction of the pipe.

FIG. 12 is a view in which the cross section of an axial groove type heat pipe in which the height and thickness of the fin are partially changed in the fifth embodiment of the present invention is developed in the circumferential direction of the pipe.

FIG. 13 is a sectional view of an axial groove type heat pipe according to a sixth embodiment of the present invention, which is developed in the circumferential direction of the pipe.

FIG. 14 is a view in which a cross section of an axial groove type heat pipe in which the heights and intervals of fins are partially changed in the sixth embodiment of the present invention is developed in the circumferential direction of the pipe.

FIG. 15 is a view showing a cross section of an axial groove type heat pipe according to a seventh embodiment of the present invention, which is developed in a circumferential direction of the pipe.

FIG. 16 is a view in which a cross section of an axial groove type heat pipe in which the thickness and intervals of fins are partially changed in Example 7 of the present invention is developed in the circumferential direction of the pipe.

FIG. 17 is a diagram showing a case where a conventional heat pipe is uniformly heated in the circumferential direction of the pipe.

FIG. 18 is a view showing a cross section taken along line AA of a conventional heat pipe.

FIG. 19 is a view showing a cross section of a conventional axial groove type heat pipe.

FIG. 20 is a view showing a case where a conventional axial groove type heat pipe receives heating from one direction.

[Explanation of symbols]

1 tube, 2 porous material, 3 working fluid, 4 heating part,
5 cooling parts, 6 heating plates, 7 cooling plates, 8 fins.

Claims (7)

[Claims] 1. A heat pipe comprising a closed pipe to be a heat pipe container, a porous material provided on a management wall as a wick for generating a capillary force, and a working fluid enclosed in the pipe to cause a phase change. In the heat pipe, the thickness of the porous material is changed in the circumferential direction of the inner wall surface of the tube. 2. An axial groove type heat pipe comprising a plurality of fins extending in the longitudinal direction of the tube as an inner wall of the tube as the wick, wherein the height of the fin is changed in the circumferential direction of the inner wall surface of the tube. A heat pipe characterized by being present. 3. The heat pipe of the axial groove type, wherein the thickness of the fin is changed in the circumferential direction of the inner wall surface of the pipe. 4. The heat pipe of the axial groove type heat pipe, wherein the intervals of the fins are changed in the circumferential direction of the inner wall surface of the pipe. 5. The heat pipe of the axial groove type, wherein the height and thickness of the fins are changed in the circumferential direction of the inner wall surface of the pipe. 6. The heat pipe of the axial groove type, wherein the height of the fins and the distance between the fins are changed in the circumferential direction of the inner wall surface of the pipe. 7. The heat pipe of the axial groove type heat pipe, wherein the thickness of the fins and the distance between the fins are changed in the circumferential direction of the inner wall surface of the pipe.