JPH05118777A - Structure of evaporating part of loop type heat pipe - Google Patents

Abstract

PURPOSE:To accelerate evaporation of working fluid in an evaporating tube. CONSTITUTION:A shaft-like filling material 24 is inserted into an evaporating pipe 23 provided vertically inside a heat reserving body 20 to define therein a space long vertically and small in cross-sectional passage area. As a result, the working fluid 31 is blown up by boiling reaching a greater height.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loop type heat pipe used for a heat storage type water heater and the like, and more particularly to the structure of its evaporation part.

[0002]

2. Description of the Related Art As an apparatus having a loop type heat pipe, the present applicants have already developed and proposed a heat storage type water heater. The basic structure is schematically shown in FIG. 14, in which the heat storage body 3 is provided in a portion of the loop-type heat pipe 1 which is to be the evaporation portion 2 and water is provided in the portion which is to be the condensation portion 4. A heat exchanger 5 for heating W is provided.
That is, the evaporation unit 2 includes a large number of evaporation pipes 8 arranged between the upper header pipe 6 and the lower header pipe 7, the heat storage body 3 is provided outside thereof, and the heater 9 for heating the heat storage body 3 is provided. It is a thing. The heat exchanger 5 has a structure in which, for example, water is flown around the outer circumference of the meandering pipe 10 to exchange heat, and the inlet of the meandering pipe 10 and the upper header pipe 6 are connected by a steam pipe 11. The outlet is connected to the lower header pipe 7 by a liquid return pipe 12.

Then, a non-condensable fluid such as air is exhausted into the inside of the closed pipe line formed by the evaporation section 2, the steam pipe 11, the heat exchanger 5 and the liquid return pipe 12 as described above. A condensable fluid is enclosed as a working fluid, and a loop heat pipe is formed therein.

[0004]

In the water heater having the structure shown in FIG. 14, the liquid return pipe 12 is connected to the evaporation pipe 8 in the evaporation unit 2.
It is operated by supplying a liquid-phase working fluid from the side,
The operation is stopped by stopping the supply of the working fluid. However, since the sensible heat storage body is used as the heat storage body, there is a problem as described below.

That is, when the working fluid is flown into the evaporation pipe 8, the inner wall surface of the evaporation pipe 8 is as hot as the heat storage body 3, so that the working liquid which comes into contact with the inner wall surface of the evaporation pipe 8 immediately. It boils and evaporates. Therefore, the liquid level inside the evaporation pipe 8 does not become high, and the entire inner surface of the evaporation pipe 8 cannot be effectively used as the evaporation surface of the working fluid, and heat is taken out only from the lower part of the heat storage body 3. However, there is a problem that the entire heat storage body 3 cannot be effectively utilized.

A part of the working liquid may be blown up as it is due to boiling of the working liquid, but most of the liquid drops inside the evaporation pipe 8 as it is, so the working liquid should be supplied to a higher position of the evaporation pipe 8. Was difficult.

On the other hand, the operation of the heat pipe 1 is stopped by stopping the inflow of the working liquid from the liquid return pipe 12 into the evaporation pipe 8. For this purpose, an opening / closing valve is provided in the liquid return pipe 12 to stop the operation. Even if the operation of the heat pipe 1 is stopped by closing, the heat pipe 1 continues to operate until the working liquid remains inside each evaporation pipe 8 and completely evaporates. In the container, there is a disadvantage that heat is unnecessarily taken out from the heat storage body 3 because the amount of the hydraulic fluid remaining in the evaporation pipe 8 at the time of stop is large.

Further, as the residual liquid evaporates, the heat pipe 1
There is a disadvantage that a special means for condensing the vapor of the residual working fluid is required in order to prevent such a situation because the inside of the cylinder becomes high pressure.

The loop type heat pipe is a development of the thermosyphon type heat pipe. Since the loop type heat pipe can evaporate the working fluid by boiling as described above, the heat flux can be increased. In some cases, it was difficult to supply the working liquid to the required and sufficient height of the evaporation portion, the heat transport amount at the time of starting was small, and it was necessary to improve the starting characteristics.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a structure of an evaporation portion of a loop heat pipe capable of promoting evaporation of a working fluid in an evaporation pipe. It is a thing.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention comprises an evaporating portion for evaporating a working fluid by heat input from the outside and a condensing portion for condensing a working fluid vapor by radiating heat. In a loop type heat pipe connected so as to form a circulation path as a whole, the evaporator is arranged vertically in the heat storage body, and a working fluid inlet is provided below the evaporator, and A filling material is provided inside the evaporation portion so that a working fluid flow path is formed along the inner wall surface of the evaporation portion.

[0012]

According to the present invention, the working fluid flowing from the lower portion of the evaporation portion is heated and evaporated in the evaporation portion, and the vapor flows to the condensation portion and then radiates heat to be condensed to generate heat as evaporation latent heat of the working fluid. To transport. The working fluid that has flowed into the evaporation section receives heat from the inner surface of the evaporation section and boils to generate bubbles, but since the working fluid channel is a narrow channel along the inner surface of the evaporation section, the working fluid is generated by the bubbles. Are conveyed to the upper side, and the width of the working fluid channel itself is narrow, so the height of the liquid surface is high, and therefore the area in which the working fluid comes into contact is widened, so that evaporation of the working fluid is promoted and the amount of heat transport is increased. Will increase.
Also, when the supply of hydraulic fluid is stopped, the amount of hydraulic fluid remaining inside the evaporation unit is small due to the narrow working fluid flow path, so the amount of heat extracted from the heat storage body can be reduced, and the supply of hydraulic fluid can be reduced. The amount of evaporation of the working fluid, that is, the amount of heat transfer, which occurs after stopping the operation is reduced.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which the present invention is applied to a loop type heat pipe of a heat storage type water heater will be described with reference to the drawings.

FIG. 1 is a schematic view showing the principle of the water heater, which is from a heat storage body 20 as a heat source to a heat exchanger 21 for hot water.
The loop type heat pipe 22 transfers heat. That is, the heat storage body 20 stores heat as sensible heat of a metal block, a heat storage brick, or the like, and an evaporation pipe 23 is formed in the inside thereof in the vertical direction, and further inside the evaporation pipe 23, As shown in FIG. 2, a solid shaft-shaped packing 24 is arranged substantially along the central axis of the evaporation pipe 23. The filling 24 is highly stable under high temperature, such as a metal rod, and has a smaller diameter than the evaporation pipe 23. By being arranged in the center of the evaporation pipe 23, the filling 24 is An annular space having a small flow passage cross-sectional area is formed. Further, the heat storage body 20 is provided with a heater 25 such as an electric heater.

On the other hand, in the hot water heat exchanger 21, for example, by flowing water W to the outside of the radiating pipe 26, heat is exchanged between the radiating pipe 26 and the water W to obtain hot water.

The upper outlet of the evaporation pipe 23 and the inlet of the heat radiation pipe 26 are connected by a steam pipe 27, and the outlet of the heat radiation pipe 26 and the lower inlet of the evaporation pipe 23 return to the liquid. It is connected by a pipe 28. A liquid reservoir 29 is provided in the liquid return pipe 28, and a control valve 30 is provided between the liquid reservoir 29 and the evaporation pipe 23.

Therefore, the evaporation pipe 23 and the radiation pipe 26 are
The steam pipe 27 and the liquid return pipe 28 are connected so as to form a circulation path as a whole, and a condensable fluid such as CFC is used as a working fluid 31 inside the circulation path in a state where a non-condensable gas is exhausted. Enclosed, it becomes a loop type heat pipe.

Next, the operation of the water heater described above will be described. First, heat is stored by operating the heater 25. In that case, the control valve 30 is closed to prevent the working fluid 31 from flowing into the evaporation pipe 23. Since the heat storage body 20 is made of a sensible heat storage material as described above, it stores a large amount of heat by being heated to a temperature as high as possible.

When hot water is supplied, the control valve 30 is first opened to allow the working fluid 31 to flow from the liquid reservoir 29 into the evaporation pipe 23 by a predetermined amount. The inside of the evaporation pipe 23 is the heat storage body 20.
Since the temperature is as high as
Immediately vigorously boils when flowing into the inside of the evaporation pipe 23, but since the axial filling 24 is inserted into the inside of the evaporation pipe 23 to form a space having a narrow annular cross section, the working fluid 3
With the boiling of 1, the droplet is blown up to a high position, and the droplet adheres to the inner surface of the evaporation pipe 23. As a result, the evaporation of the working fluid 31 occurs in a wide range of the inner wall surface of the evaporation pipe 23, and the heat is removed from the heat storage body 20.
The deviation is not particularly large at the upper and lower positions.

Working fluid 31 generated inside the evaporation pipe 23
Of the steam flows through the steam pipe 27 to the radiating pipe 26 in the heat exchanger 21 for hot water. Therefore, if the water W is flown on the outer peripheral side, the working fluid vapor flowing inside the radiating pipe 26 radiates heat to heat the water W to warm water of a predetermined temperature, and the working fluid 31 is condensed. Then, the liquefied working fluid 31 is returned to the liquid reservoir 29 via the liquid return pipe 28.

The hot water supply is stopped by stopping the supply of the water W to the hot water heat exchanger 21 and closing the control valve 30. In that case, the amount of the working fluid 31 remaining inside the evaporation pipe 23 when the control valve 30 is closed is determined by the evaporation pipe 2
Since the central portion of 3 is occupied by the axial filling 24, the amount is small, and therefore the amount of evaporation of the working fluid 31 generated after the control valve 30 is closed, that is, the amount of heat extracted from the heat storage body 20 is reduced. Accordingly, even if the heat exchanger 21 for hot water is provided with a heat storage function of depriving heat from the working fluid vapor generated in this way and condensing it, its capacity may be small, and therefore, the water heater as a whole is downsized. be able to.

FIG. 3 shows the result of an experiment conducted to confirm the effect of using the above-mentioned filling material 24. In the experiment, an evaporation tube with an outer diameter of 19 mm was installed inside the heat storage body, a wick made of a metal mesh was installed on the inner surface, and a shaft-shaped filling with an outer diameter of 8 mm was provided along the central axis of the evaporation tube. An object is arranged, the heat storage body is heated to about 500 degrees, and the working liquid is caused to flow into the evaporation pipe to start heat transfer, and the temperature change of the heat storage body at that time is measured at the upper portion and the lower portion. .. Further, as a comparative example, the same measurement was performed when the axial filler was not used. The solid line in FIG. 3 shows the result of this invention example, and the broken line shows the result of the comparative example. As is clear from these, when the axial packing is used, the temperature drop at the upper part of the heat storage body is fast. In addition, the temperature drop in the lower part was moderated accordingly, and it was confirmed that heat was taken out from the entire heat storage body. Therefore, when the axial filler is used, heat is efficiently extracted from a wide area of the heat storage body and the amount thereof is increased, so that the starting characteristics are improved.

By the way, as is known from the above-mentioned embodiment, the present invention operates at the time of starting by filling a so-called dead space on the center side, that is, a portion which does not contribute to the evaporation by arranging the filling inside the evaporation pipe 23. Since it promotes the evaporation of the fluid, the packing used is not limited to the one shown in the above embodiment, and the shape and structure of the evaporation pipe 23 are not limited to those shown in the above embodiment.
Examples of filling materials and evaporation tubes that can be used in the present invention are shown below.

The example shown in FIG. 4 is an example in which a supporting portion 24a is provided between the shaft-shaped filler 24 and the evaporation pipe 23. According to this structure, the shaft-shaped filler 24 can be reliably and easily fixed, and the gaps are evenly distributed, so that the heat flow is not biased and the thermal efficiency is improved.

In the example shown in FIGS. 5A and 5B, a pin fin is used as the supporting portion 24b for supporting the axial filling 24. That is, the support portion 2 which is a pin fin
4b are arranged substantially horizontally between the axial packing 24 and the evaporation pipe 23, and the respective support portions 24b are arranged alternately offset in the axial direction of the axial packing 24.
And the evaporation tube 23 are in heat contact with each other. By doing so, the heat transfer area is equivalently expanded, so that the heat transfer to the shaft-shaped filler 24 is improved.

The example shown in FIG. 6 is an example in which a spiral support portion 24c is used as a means for supporting the axial filling 24. Although the spiral support portion 24c is shown as being provided intermittently in FIG. 6, it may be continuous as a whole. In the example shown in FIG. 6, in addition to the expansion of the heat transfer area to the axial filling 24, the flow of the working fluid vapor becomes turbulent, so most of it comes into contact with the heat transfer surface, and Thermal efficiency is improved.

The examples shown in FIGS. 7 and 8 are examples in which a plurality of spheres 34 are used as the filling material. With such a filling material, the gap between the spheres 34 and the evaporation pipe 23 is the working fluid. It becomes a flow path, and it is possible to obtain the same actions and effects as those of the above-mentioned embodiment.

The example shown in FIG. 9 is an example in which the evaporation tube 23 is an elliptical tube. With such a structure, the spheres 34 can be easily filled, a working fluid channel can be sufficiently secured, and the structure is suitable for a thin heat storage body, and space efficiency is improved.

In the example shown in FIG. 10, a hollow shaft is used as the shaft-shaped packing 44, the hollow shaft is opened to the bottom side of the evaporation pipe 23, and the heat storage body 20 is further inserted therein. is there. With such a configuration, the outer surface of the shaft-shaped packing 44 also serves as the evaporation surface of the working fluid, so that the evaporation of the working fluid can be further promoted.

FIG. 11 shows an example in which the taper shaft 54 whose outer diameter on the upper side is gradually reduced is used as the filling material. With such a configuration, since the flow path width in the upper portion where the amount of the working fluid vapor is large becomes wide, the evaporation of the working fluid can be promoted and the flow resistance can be reduced.

FIG. 12 is constructed so as to obtain the same action and effect as the example shown in FIG. 11, and is an example in which the evaporation pipe 23 and the filling material 64 are tapered so that the diameter increases on the upper side. If these taper angles are equal, the flow passage width will not be wide, but the diameter of the flow passage will be larger at the upper side, so the cross-sectional area of the flow passage will be wider, and as a result, the evaporation of the working fluid will be accelerated and the flow resistance will increase. Can be reduced.

FIG. 13 shows an example in which the stranded wire 74 is used as a filling material. In this way, the working fluid is spread evenly,
Thermal efficiency is improved.

By the way, as used in the experiment performed to obtain the results shown in FIG. 3, a wick may be provided on the inner surface of the evaporation tube. As the wick, in addition to the metal mesh described above, an evaporation tube may be used. It may be a fine groove formed on the inner surface of the. The narrow groove may be along the axial direction, or may be spiral.

Further, a pipe having a fold along the axial direction may be used as an evaporation pipe, and the fold portion may be a narrow groove which acts as a wick.

[0035]

As is apparent from the above description, according to the present invention, since the space in the evaporation pipe has a vertically long narrow passage cross-sectional area, the working fluid blown up with the boiling of the working fluid is The arrival position becomes high, and as a result, the working fluid is distributed and supplied over a wide range above and below the evaporation pipe, so that the substantial evaporation area is widened and the working fluid is efficiently evaporated. be able to.

Further, since the amount of the working fluid remaining inside the evaporation pipe when the supply of the working fluid to the evaporation pipe is stopped can be reduced, unnecessary heat extraction after the supply of the working fluid is reduced, Furthermore, the means for temporarily storing the heat thus extracted can be miniaturized.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a water heater including an evaporation unit according to the present invention.

FIG. 2 is an enlarged cross-sectional view of an evaporation pipe in the evaporation unit shown in FIG.

FIG. 3 is a diagram showing experimental results.

FIG. 4 is a sectional view showing another example of the present invention.

FIG. 5 is a cross-sectional view showing an example using a support portion which is a pin fin.

FIG. 6 is a cross-sectional view showing an example using a spiral support portion.

FIG. 7 is a vertical cross-sectional view showing another example of the present invention in which a spherical body is used as the filling material.

FIG. 8 is a cross-sectional view thereof.

FIG. 9 is a cross-sectional view of an example in which an elliptic tube is used as an evaporation tube.

FIG. 10 is a vertical cross-sectional view showing an example in which a hollow shaft is used as a shaft-shaped packing.

FIG. 11 is a vertical cross-sectional view showing an example using a taper shaft-shaped filler.

FIG. 12 is a vertical cross-sectional view showing an example in which the packing and the evaporation tube are tapered.

FIG. 13 is a vertical cross-sectional view showing an example in which a twisted wire is used as a filler.

FIG. 14 is a system diagram showing a general structure of a water heater using a conventional loop heat pipe.

[Explanation of symbols]

20 ... Heat storage body, 22 ... Heat pipe, 23 ... Evaporation pipe, 24, 44 ... Axial packing, 31 ... Working fluid,
34 ... Sphere, 54 ... Tapered shaft, 64 ... Filling material, 7
4: Stranded wire.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshihide Sugita 1-3-3 Uchiyuki-cho, Chiyoda-ku, Tokyo Tokyo Electric Power Co., Inc. (72) Inventor Jun 1-3-1 Uchisai-cho, Chiyoda-ku, Tokyo East Within Kyoden Electric Co., Ltd. (72) Inventor Shotaro Yoshida 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Electric Line Co., Ltd. (72) Inventor Masataka Mochizuki 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Electric Line Co., Ltd. (72) Inventor Koichi Masuko 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Electric Line Co., Ltd.

Claims (1)

[Claims] 1. A loop-type heat pipe in which an evaporation part for evaporating a working fluid by heat input from the outside and a condensing part for condensing a working fluid vapor by radiating heat are connected to form a circulation path as a whole, The evaporation part is arranged in the heat storage body in the vertical direction, a working fluid inlet is provided in the lower part of the evaporation part, and the working fluid along the inner wall surface of the evaporation part is provided inside the evaporation part. A structure of an evaporation part of a loop heat pipe, wherein a filling material is provided so as to form a flow path.