JPH0547967Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a heat pipe having a double tube structure that is disposed in a high-temperature fluid and mediates heat exchange between the high-temperature fluid and the low-temperature fluid.

BACKGROUND TECHNOLOGY As is well known, in a heat pipe, a working fluid sealed inside the pipe is evaporated by heat input from the outside.
It is a heat transfer element that transports heat as latent heat of the working fluid as the working fluid vapor flows toward the low temperature side, and exhibits extremely high thermal conductivity. Therefore, if placed between a low-temperature fluid and a high-temperature fluid flowing at locations separated from each other, the fluids can be separated as if they were one.
Heat exchange can be performed in the same way as when two partition walls are placed in contact with each other. In other words, heat pipes have the characteristic of being able to efficiently exchange heat between high-temperature fluid and low-temperature fluid while keeping both fluids isolated. It is considered to be used as an intermediate heat exchanger. An example of this is shown in FIGS. 2 and 3 in principle.

That is, in the heat pipe 1, an outer tube 3 is airtightly attached to the outer periphery of an inner tube 2 to form a double tube, and after the space between the inner tube 2 and the outer tube 3 is vacuum degassed, mercury etc. A condensable fluid that evaporates and condenses in the desired temperature range is sealed in the space as a working fluid 4. and heat exchanger H
The plurality of heat pipes 1 are installed through the high-temperature container 5 so that their axes face in the vertical direction, and a low-temperature fluid 6 such as water is allowed to flow through each inner pipe 2, while a low-temperature fluid 6 such as water is allowed to flow from the lower inlet 7 of the high-temperature container 5. It is configured to flow a high temperature fluid 9 such as liquid sodium toward an upper outlet 8 . Therefore, inside each heat pipe 1, the working fluid 4 evaporates due to the heat applied from the outside of the outer tube 3, while the working fluid vapor comes into contact with the outer peripheral surface of the inner tube 2 and evaporates inside. Heat is applied to the flowing low-temperature fluid 6 to condense it, and as a result, heat exchange between the high-temperature fluid 9 flowing around the outer circumference of the outer tube 3 and the low-temperature fluid 6 flowing inside the inner tube 2 is performed by the working fluid 4 of the heat pipe 1. mediates.

Problems to be Solved by the Invention However, in the heat pipe in the heat exchanger described above, almost the entire inner circumferential surface of the outer tube 3 is covered with the working fluid 4.
Although almost the entire outer circumferential surface of the inner tube 2 serves as a condensation surface on which the working fluid vapor condenses, there is a means for dispersing the liquid-phase working fluid 4 over the entire inner circumferential surface of the outer tube 3. Since the working fluid 4 is not particularly provided, the working fluid 4 tends to accumulate in the lower part due to the influence of gravity, and the liquid film tends to become thinner toward the upper part. As a result, in the heat pipe described above, the liquid phase working fluid 4 becomes insufficient on the upper end side of the outer tube 3, resulting in dryout, which reduces the effective area of the evaporation section.
There was a problem that the heat exchange capacity of the heat exchanger as a whole decreased.

This idea was made in view of the above circumstances, and the purpose is to provide a heat pipe for a heat exchanger that can improve heat exchange efficiency by promoting dispersion of liquid-phase working fluid over the entire evaporation surface. It is something to do.

Means for Solving the Problems In order to achieve the above object, this invention is configured to guide the working fluid condensed on the outer circumferential surface of the inner tube to the inner surface of the outer tube, and more specifically, This idea involves airtightly attaching an outer tube with an inner diameter larger than the outer diameter of the inner tube so that a predetermined space exists on the outer circumference of the inner tube, which is arranged so that its axis faces in the vertical direction. to form a double pipe, and after the space is vacuum degassed, a condensable fluid is sealed in the space as a working fluid, a low temperature fluid is allowed to flow inside the inner pipe, and the outer pipe is exposed to the high temperature fluid. The double tube type heat pipe is characterized in that an upper end portion of the inner tube inside the outer tube is curved so as to partially contact the inner surface of the outer tube.

Function: In the heat pipe of this invention, the outer tube is exposed to high-temperature fluid, whereas low-temperature fluid flows inside the inner tube, so the inner surface of the outer tube becomes an evaporation part and the working fluid evaporates. Further, the outer circumferential surface of the inner tube serves as a condensing portion, and the working fluid vapor condenses. As a result, the heat of the high-temperature fluid is transferred to the low-temperature fluid, and heat exchange occurs between the two. The working fluid condensed on the upper end side of the outer pipe inside the inner pipe flows down the outer surface of the inner pipe, but the upper end of the inner pipe curves inside the outer pipe and a part of the working fluid condenses on the outer surface of the inner pipe. is in contact with the inner surface of the outer tube, so the condensed working fluid is guided by the inner tube to the inner surface of the outer tube, which is the evaporation surface. Therefore, the liquid phase working fluid is actively supplied to the upper part of the inner surface of the outer tube where the liquid film tends to become thinner, and as a result, dryout is prevented and heat exchange ability is maintained well.

Embodiment Next, an embodiment of this invention will be described with reference to the drawings.

FIG. 1 shows a heat pipe 10 that can be used as an intermediate heat exchanger in the fast breeder reactor described above. A working fluid 14 is sealed in a portion 13. In other words, the inner tube 11 has a low-temperature fluid such as water 1 inside it.
5 is disposed so that its axis is directed substantially in the vertical direction, and a portion of the upper portion thereof is curved in a spiral shape to form a spiral portion 11a. On the other hand, the outer tube 12 is a pipe having an inner diameter approximately equal to the outer diameter of the spiral portion 11a of the inner tube 11, and accommodates the spiral portion 11a.
It is attached to the outer periphery of the inner tube 11 in an airtight manner so that the portion 1a is located at the upper part. Therefore, a space 13 having a sealed structure is formed between the outer circumferential surface of the inner tube 11 and the inner circumferential surface of the outer tube 12, and the spiral portion 11a is almost in contact with the inner circumferential surface of the outer tube 12. There is. Inside the space 13, a working fluid 14 such as mercury that condenses and evaporates in a target temperature range is sealed after being vacuum degassed.

As in the heat exchanger described above, the heat pipe 10 configured as described above is installed inside a high-temperature container through which a high-temperature fluid such as liquid sodium flows, so that the axis thereof faces in the vertical direction, and in this state, the inner pipe 1
1 is used by flowing a low-temperature fluid such as water inside it. Therefore, the entire inner circumferential surface of the outer tube 12 serves as an evaporation area for the working fluid 14, and the entire outer circumferential surface of the inner tube 11 serves as a condensation area for the working fluid vapor, so that the low-temperature fluid flowing inside the inner tube 11 Heat is applied to the tube 15 from the high temperature fluid outside the outer tube 13. The working fluid 14 that has been condensed by applying heat to the low-temperature fluid 15 on the outer circumferential surface of the inner tube 11 flows down the outer circumferential surface of the inner tube 11. Since the spiral portions 11a are in contact, a portion of the condensed working fluid 14 is guided to the inner peripheral surface of the outer tube 12 by the spiral portions 11a. That is, a part of the condensed working fluid 14
The upper part of the outer tube 12 is selected where the liquid film tends to become thinner.
Therefore, in the heat pipe 10 shown in FIG.
The amount of working fluid 14 is ensured in the upper portion of the inner circumferential surface of outer tube 12, and sufficient heat transport occurs in that portion as well. That is, since the working fluid 14 is distributed over the entire area in the vertical direction, uniform heat transport, ie, heat exchange, occurs throughout, resulting in good heat exchange efficiency.

Note that this invention is not limited to the above-mentioned embodiments, and the upper part of the inner tube may be curved into a shape other than the spiral shape shown in the above-mentioned embodiments.

Effects of the invention As is clear from the above explanation, according to the heat pipe of this invention, the upper part of the inner pipe is curved and brought into contact with the inner peripheral surface of the outer pipe, which serves as the evaporation section, so that the liquid film of the working fluid is thin. A sufficient amount of working fluid can be supplied even to the upper part, which tends to be damaged, and as a result, the working fluid is distributed almost uniformly over the entire length, making it possible to improve heat exchange efficiency.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing one embodiment of the present invention, FIG. 2 is a schematic diagram showing an example of a conventional heat pipe type heat exchanger, and FIG. 3 is a schematic cross-sectional view showing one of the heat pipes. 10... heat pipe, 11... inner tube, 11a
. . . spiral portion, 12 . . . outer tube, 13 . . . space portion,
14...working fluid, 15...water.

Claims (1)

[Claims for Utility Model Registration] An outer tube having an inner diameter larger than the outer diameter of the inner tube so that a predetermined space exists on the outer circumference side of the inner tube, which is arranged so that its axis faces in the vertical direction. The tube is installed in an airtight manner to form a double tube, and after the space is vacuum degassed, a condensable fluid is sealed in the space as a working fluid, a low-temperature fluid is flowed inside the inner tube, and the outer tube is closed. A double-tube heat pipe exposed to a high-temperature fluid, wherein an upper end portion of the inner tube inside the outer tube is curved so as to partially contact an inner surface of the outer tube. Double tube heat pipe.