JPS6245474B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat pipe, and particularly to a heat pipe of a type in which a liquid-phase working fluid is forcibly returned to an evaporation section by mechanical force.

As is well known, in a heat pipe, a liquid-phase working fluid receives heat and evaporates, thereby transporting heat as its latent heat.The heat pipe also transports heat by radiating heat, condensing and liquefying the working fluid, and returning it to the evaporator. It can be used continuously without applying external energy, and its apparent thermal conductivity is tens to hundreds of times higher than that of copper. It is used in various fields such as equipment, and recently it has also been used for indirect cooling of power cables.

By the way, when indirectly cooling a power cable with a heat pipe, the power cable generates heat over its entire length, so a fairly long heat pipe is laid along the power cable to be cooled, and the power cable is Therefore, the heat pipe for indirect cooling of power cables is required to have a high pressure in order to return the gas-phase working fluid to the evaporation section.

However, in conventional heat pipes, the liquid-phase working fluid is returned to the evaporation section by capillary pressure generated in a pipe made of metal nets, grooves, etc., so the evaporation section (heating section) is connected to the condensation section (cooling section). )
If the location is higher and the height difference is large, or if the distance between the evaporation section and the condensation section is long and the pressure loss of the liquid phase working fluid between them is large,
In some cases, the capillary pressure generated by the heat pipe is insufficient and the liquid-phase working fluid cannot be returned to the evaporator. Therefore, in conventional heat pipes, there is a difference in height and a long distance for the liquid-phase working fluid to be returned to the indirect power cable. It was difficult to perform cooling.

In order to eliminate such inconveniences, for example, as shown in FIG. 1, a plurality of heat pipes 1 and 2 are arranged on the same axis and connected to each other, and an uneven part 3 is provided at the connection part to transmit heat. It is conceivable to widen the thermal area and make the length over which the liquid-phase working fluid should be refluxed shorter than the overall length, that is, the length that can transport heat, but in such a configuration, the uneven portion 3
The reflux of the liquid-phase working fluid to the heat pipes does not necessarily occur smoothly, and the substantial length of each heat pipe 1, 2 is L as shown in FIG. In the case of the so-called top heat mode, there was a problem that the reflux of the liquid phase working fluid was insufficient and the heat transport ability was poor.

Conventionally, the first heat pipe 4 is formed into a hollow cylinder shape as shown in FIG. 2, and the second heat pipes 5, 6 are inserted into the hollow part from both sides. A configuration has been proposed that connects and integrates the
However, in such a configuration, the adhesion between the hollow cylindrical heat pipe 4 and the second heat pipes 5 and 6 is poor, and an air layer may be formed between them. Between the working fluid in the heat pipe 4 and the working fluid in the second heat pipes 5 and 6, there are
8, 9 and the peripheral walls of the containers 10, 11, 12, therefore, the heat transfer resistance (total thermal resistance) between the first heat pipe 4 and the second heat pipe 5, 6 is As a result, heat transfer between the second heat pipes 5 and 6 via the first top pipe 4 is poor, and in the case of the top heat mode, for example, even if sufficient reflux of the liquid phase working fluid occurs, the heat transfer is poor. Transportation could not be carried out satisfactorily, and in the end, even the configuration shown in FIG. 2 was unsuitable for indirect cooling of power cables.

On the other hand, as a method for refluxing a liquid-phase working fluid, methods using centrifugal force, electrostatic force, electromagnetic force, osmotic pressure, etc., in addition to capillary action, have conventionally been considered. According to this method,
It may be possible to circulate the liquid phase working fluid to a considerable height or over a considerable distance, but if the centrifugal force uses electrostatic or electromagnetic force, the mechanical energy or electrical energy must be given,
The characteristic of heat pipes, that is, the ability to transport heat without applying external energy, is lost. In addition, when using electrostatic force, electromagnetic force, or osmotic pressure,
There is a problem in that the working fluid that can be used is limited.

This invention was made in view of the above circumstances, and it is possible to forcibly return a liquid phase working fluid to the evaporation section by mechanical force, that is, pump pressure, without applying energy from the outside. To provide a heat pipe capable of sufficiently transporting heat even when there is a large height difference between an evaporating part and a condensing part and a long return distance of a liquid-phase working fluid, as in the case of indirectly cooling a power cable. The purpose is to

Embodiments of the present invention will be described below with reference to FIGS. 3 to 6.

FIG. 3 is a schematic diagram showing the overall structure of an embodiment of the present invention, and a heat pipe 20 shown here has a liquid pumping drive section 2 between an evaporating section 21 and a condensing section 22.
The configuration includes 3.

The evaporation section 21 is a section that receives heat from the outside to evaporate the liquid phase working fluid, and as shown in FIG.
Therefore, it is formed to be quite long to match a heat generating element (not shown) such as a power cable, and is sloped so that the tip end side (the left end side in FIG. 3) is higher. Since the liquid-phase working fluid is forcibly refluxed in the evaporator 21 as described later, there is basically no need to provide a wick, but the evaporator 21
In order to ensure that the liquid-phase working fluid spreads over the entire inner circumferential surface of the metal tube 24, the inner circumferential surface of the metal tube 24 is coated with a wick, especially a flexible wick such as a metal net. It is preferable to provide 25. Note that depending on the environment of the location where the cable is to be laid, it is preferable to provide the anti-corrosion layer 26 on the outer peripheral surface of the metal pipe 24.

On the other hand, the condensing section 22 is located at a lower position than the evaporating section 21 and is exposed to a cooling fluid (not shown) such as air or cold water, and removes heat by the cooling fluid. It is adapted to condense and liquefy the phase working fluid. Note that a wick is provided on the inner circumferential surface of the metal tube 27 constituting the condensing section 22,
Further, an anticorrosion layer may be provided on the outer peripheral surface of the metal tube 27 as appropriate.

Further, as shown in FIGS. 3 and 4, a liquid that causes the working fluid condensed and liquefied in the condensing section 22 to flow into a portion of the housing 28 constituting the liquid pumping drive section 23 near the condensing section 22 is provided. A reservoir 29 is formed, and a pump 30 is disposed within the reservoir 29. The pump 30 has a liquid reservoir 2
The pump 30 is for refluxing the liquid-phase working fluid 31 in the evaporator 21 to the evaporator 21, and the reflux conditions require a small capacity and a high head. Therefore, the pump 30 is preferably a displacement pump such as a gear pump. Furthermore, a turbine 32 is arranged at a location on the evaporation section 21 side within the liquid pumping drive section 23. The turbine 32 is rotated by the gas-phase working fluid flowing from the evaporator 21 to the condenser 22, and its rotational force drives the pump 30. It is preferable to use an axial flow turbine as the turbine 32 because the pressure difference between the turbine 22 and the turbine 22 is small and the flow rate of the gas phase working fluid is large. Further, in order to increase the gas phase working fluid flow rate to the turbine 32, for example, a fifth
As shown in the figure, it is preferable to provide a throttle 33 on the front side of the turbine 32.

The rotating shaft 34 of the turbine 32 is a hollow tube, and the rotating shaft 34 is supported by a bearing 35 so as to be parallel to the flow direction of the gas-phase working fluid, that is, along the central axis of the liquid pumping drive section 23. It is rotatably supported, and its rotating shaft 34 and the pump 3
0 input shaft 36 is connected via a gear reduction gear 37. An example of the gear reducer 37 is shown in FIGS. 4 and 6. That is, a bevel gear 38 is attached to the end of the rotating shaft 34 on the liquid reservoir 29 side, the bevel gear 39 is attached to a worm shaft 40, and a worm 41 integrated with the worm shaft 40 is attached to a worm wheel 42. A spur gear 43 provided coaxially with the worm wheel 42 meshes with a spur gear 44 attached to the input shaft 36 of the pump 30. Note that this gear reducer 37 is preferably small, lightweight, and has a small moment of inertia in order to reduce transmission force loss due to frictional resistance and the like, and to reduce acceleration energy.

Further, a liquid supply pipe 45 is provided at the discharge port of the pump 30.
is connected to the turbine 3, and the liquid feeding pipe 45 is connected to the turbine 3.
It extends into the evaporation section 21 by penetrating the inner circumference of the rotating shaft 34 of No. 2, and a large number of micropores 46 are formed in the peripheral wall inside the evaporation section 21. The micropores 46 are for distributing and supplying the liquid-phase working fluid to the inner circumferential surface of the evaporation section 21, and are used as the liquid-feeding pipe 45.
Prevents the pressure drop of the liquid phase working fluid on the tip side of the
In order to distribute and supply the liquid-phase working fluid to the inner peripheral surface of the evaporator 21 as evenly as possible, the diameter of the micropores 46 is made larger toward the distal end of the liquid sending tube 45, or the distance between the micropores 46 ( Pitch) P is made narrower toward the distal end of the liquid feeding pipe 45.

Next, the heat pipe 20 configured as above
The effect of this will be explained.

Heat Q is applied to the evaporator 21 by attaching the evaporator 21 to a power cable, for example, and when heat Q is removed from the condenser 22 by exposing the condenser 22 to a cooling fluid, the evaporator 21 The liquid phase working fluid is evaporated in the condensing section 22, and the gas phase working fluid is condensed and liquefied in the condensing section 22.
A pressure difference is generated between the evaporating section 21 and the condensing section 22, so that the gas phase working fluid flows from the evaporating section 21 to the condensing section 22. In that case, if the flow velocity of the gas-phase working fluid exceeds the sound velocity,
Since this is no longer a normal operating condition, operating conditions such as heat flux are set so that the flow velocity of the gas-phase working fluid is below the sonic velocity. The gas-phase working fluid flowing from the evaporator section 21 toward the condensing section 22 passes through the turbine 32, causing the turbine 32 to rotate, and as a result, the pump 30 is rotated by the turbine 32 via the gear reduction gear 37. The liquid-phase working fluid 31 in the liquid reservoir 29 is pumped up by the pump 30.
The liquid-phase working fluid 31 pumped up by the pump 30 is sent to the evaporator 21 side by a liquid feed pipe 45, and is distributed and supplied to the inner peripheral surface of the evaporator 21 through the micropores 46 thereof. In that case, the opening diameter of the micropores 46 is small or the pitch of the micropores 46 is large on the base end side of the liquid sending pipe 45, so that the liquid phase working fluid 31 does not flow out from each micropore 46. , is suppressed at the proximal end side of the liquid sending pipe 45 where the pressure is high and promoted at the distal end side where the pressure is low. It is evened out throughout, preventing partial dryout and the resulting decrease in heat transport efficiency.
On the other hand, the gas-phase working fluid that has reached the condensing section 22 is deprived of heat and condenses into a liquid, and the resulting liquid-phase working fluid flows into the liquid reservoir section 29 .

Therefore, in the heat pipe 20 described above, since the liquid-phase working fluid is refluxed to the evaporator 21 by the pump 30, a considerably higher reflux pressure can be obtained than by the wick in a conventional general heat pipe. Therefore, according to the heat pipe 20, even in the so-called top heat mode where the evaporating section 21 is located at a considerably higher position than the condensing section 22, or when the distance between the evaporating section 21 and the condensing section 22 is considerably long. Also, the liquid phase working fluid can be reliably refluxed to the evaporator 21, and sufficient heat transport can be carried out. Further, the heat pipe 20 is powered by a pump 3 by a turbine 32 which is rotated by a gas-phase working fluid.
Since the pump 30 is configured to drive the pump 30 by using a portion of the heat to be transported, in other words, the pump 30 can be operated normally without particularly supplying energy from the outside.

As is clear from the above description, according to the heat pipe of the present invention, a turbine rotated by gas-phase working fluid is provided between the evaporating section and the condensing section, and the liquid-phase working fluid is pumped up and evaporated. Since the pump to be sent to the heat pump of the present invention is configured to be driven by the turbine, a high reflux pressure can be obtained by using the heat energy that is originally to be transported without applying any particular energy from the outside. According to the pipe, the liquid-phase working fluid can be reliably returned to the evaporator section even when there is a heat source such as a heating element to be cooled in a high position or when the distance between the heat source and the cooling section is quite long. This allows for sufficient heat transport. In addition, in this invention, the opening diameter or pitch of the micropores formed in the liquid sending pipe to allow liquid-phase working fluid to flow out to the evaporator section is changed depending on the distance from the pump, that is, the degree of pressure loss. The supply amount of the phase working fluid is equalized over the entire evaporation section, thereby preventing partial dryout in the evaporation section and an accompanying decrease in heat transport efficiency. Note that the heat pipe of this invention uses a portion of the applied heat to drive the turbine, so it is difficult to extract all of the applied heat in the condensing section. This is particularly effective when it is necessary to simply cool the heating element by removing its heat.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing an example of a conventional heat pipe, FIG. 2 is a schematic cross-sectional view showing another example of a conventional heat pipe, and FIG. 3 is a schematic cross-sectional view showing the overall configuration of an embodiment of the present invention. 4 is a detailed view of the liquid pumping drive section, FIG. 5 is a schematic view showing an example of a throttle section for the turbine, and FIG. 6 is a view taken along the line - - in FIG. 4. 20... Heat pipe, 21... Evaporation section, 22
... Condensation section, 29 ... Liquid reservoir section, 30 ... Pump, 31 ... Liquid phase working fluid, 32 ... Turbine,
33... throttle section, 37... gear reducer, 45...
Liquid feeding pipe, 46...microhole.

Claims (1)

[Claims] 1. A turbine rotated by the gas-phase working fluid flowing from the evaporator section to the condensation section is disposed between the evaporator section where the liquid-phase differential fluid evaporates and the condensation section where the gas-phase working fluid condenses. , a liquid reservoir for storing a liquid-phase working fluid is formed in the condensing section, a pump driven by the turbine is provided in communication with the liquid reservoir, and one end is communicated with the pump. A tube is housed and arranged in the evaporation section, and a large number of micropores are arranged in the axial direction on the peripheral wall of the liquid transfer tube. A self-driven forced reflux heat pipe characterized by reducing the opening diameter or increasing the pitch of the micropores to equalize the amount of liquid-phase working fluid flowing out from the micropores over the entire length of the liquid pipe. .