JP2663316B2 - Structure of evaporation part of loop type heat pipe - Google Patents

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 a structure of an evaporating section thereof.

[0002]

2. Description of the Related Art As a device having a loop-type heat pipe, the applicants have already developed heat storage water heaters, was proposed. FIG. 8 schematically shows the basic structure of the loop type heat pipe 1. A heat storage unit 3 is provided in a portion of the loop heat pipe 1 which is assumed to be an evaporator 2, and a water storage is provided in a portion which is assumed to be a condenser 4. A heat exchanger 5 for heating W is provided. That is, in the evaporating section 2, a number of evaporating tubes 8 are arranged between the upper header tube 6 and the lower header tube 7, and the heat storage 3 is provided outside thereof, and the heater 9 for heating the heat storage 3 is provided. It is a thing. The heat exchanger 5 has, for example, a structure in which water flows around 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.

[0003] A non-condensable fluid such as air is exhausted into a closed pipe formed by the evaporating section 2, the steam pipe 11, the heat exchanger 5, and the liquid return pipe 12 while exhausting a non-condensable fluid such as air. A condensable fluid is sealed as a working fluid, where a loop heat pipe is formed.

[0004]

In the water heater having the structure shown in FIG. 14, a liquid return pipe 12 is provided in the evaporator pipe 8 in the evaporator 2.
Operate by supplying working fluid in liquid phase from the side,
The operation is stopped by stopping the supply of the working fluid. However, the use of a sensible heat storage medium as the heat storage body has the following problems.

That is, when the working fluid flows into the evaporating tube 8, the working fluid that has contacted the inner wall surface of the evaporating tube 8 immediately Boils and evaporates. Therefore, the liquid level inside the evaporating tube 8 does not increase, so that the entire inner surface of the evaporating tube 8 cannot be effectively used as the evaporating surface of the working fluid, and heat is extracted 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 used effectively.

In some cases, the working fluid is boiled up in a liquid state due to the boiling of the working fluid. However, most of the fluid falls directly inside the evaporating pipe 8, so that the working fluid must be supplied to a high position of the evaporating pipe 8. Was difficult.

On the other hand, the operation of the heat pipe 1 is stopped by stopping the flow of the working fluid from the liquid return pipe 12 to the evaporating pipe 8. Even if the operation of the heat pipe 1 is stopped by closing, the heat pipe 1 continues to operate until the working fluid remains in each of the evaporating pipes 8 and completely evaporates. Since the amount of the working fluid remaining in the evaporator tube 8 at the time of shutdown is large, there is a disadvantage that heat is unnecessarily extracted from the heat storage body 3.

[0008] The heat pipe 1
Since the pressure inside the inside becomes high, there is a disadvantage that special means for condensing the vapor of the remaining working fluid is required to prevent such a situation.

The loop heat pipe is a development of the thermosiphon heat pipe. Since the working fluid can be evaporated by boiling as described above, the heat flux can be increased. In some cases, it is difficult to supply the working fluid to a necessary and sufficient height of the evaporator, so that the amount of heat transport at the time of starting is small, and it is necessary to improve the starting characteristics.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a structure of an evaporating section of a loop type heat pipe which can promote the evaporation of a working fluid in an evaporating pipe. Things.

[0011]

In order to achieve the above object, the present invention provides an evaporator for evaporating a working fluid by heat input from the outside, and a condensing part for condensing working fluid vapor by radiating heat. In a loop heat pipe connected so as to form a circulation path as a whole, while the evaporating section is disposed in the heat storage body in the vertical direction,
A working fluid inlet is provided below the evaporator , and
Side wall surface of the evaporator from above the bottom wall surface of the evaporator
Inclusions that have extended out of contact with the
This inclusion and the evaporator side
It is characterized in that a working fluid channel is formed between the wall and the wall .

[0012]

According to the present invention, the working fluid flowing from the lower portion of the evaporator is heated and evaporated in the evaporator, and the vapor flows to the condenser, and then radiates and condenses, thereby generating heat as the latent heat of evaporation of the working fluid. To transport. The working fluid that has flowed into the evaporator receives heat from the inner surface of the evaporator and boils to generate air bubbles.However, since the working fluid flow path is a narrow flow path along the inner surface of the evaporator, the hydraulic fluid is generated by the air bubbles. Carried up
It is. Width or hydraulic fluid channel itself from narrow Ikoto, liquid level
In terms of height is increased, the side wall surface of the evaporation portion by the inclusions
Large area of contact with hydraulic fluid
Thus, the evaporation of the working fluid is promoted. Therefore, the evaporator
Almost all of the side wall surface of the
As a result, the amount of heat transport increases. In addition, when the supply of the working fluid is stopped, the amount of the working fluid remaining inside the evaporating section becomes small due to the narrow working fluid flow path, so that the amount of heat extracted from the heat storage body can be reduced, and the supply of the working fluid can be reduced. The amount of evaporation of the working fluid, that is, the amount of heat transport generated after stopping the operation is reduced.

[0013]

Next, an example in which the present invention is applied to a loop heat pipe of a regenerative water heater will be described with reference to the drawings.

FIG. 1 is a schematic view showing the principle of the water heater, in which a hot water storage device 20 serving as a heat source is connected to a hot water heat exchanger 21.
The heat is transported by a loop-type heat pipe 22. 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 evaporating tube 23 is formed in the inside thereof in a vertical direction. As shown in FIG. 2, a solid shaft-shaped inclusion 24 is arranged substantially along the central axis of the evaporator tube 23 . That is, the axial inclusion 24
Is provided in a non-contact state with the side wall surface of the evaporation tube 23.
You. More specifically, this inclusion 24
High stability at high temperature such as a metal rod, and
The diameter of the evaporator tube 23 is smaller than that of the evaporator tube 23.
In the center of the bottom part while extending upward from the part
It is fixed by appropriate means. Therefore, this axial
An annular space with a small flow path cross-sectional area is provided on the outer peripheral side of the inclusion 24.
This annular space is compatible with the working fluid flow path.
Hit. Also the heat storage body 20, a heater 25 such as electric heater is provided.

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

The outlet of the evaporator tube 23 at the upper end and the inlet of the radiator tube 26 are connected by a steam tube 27, and the outlet of the radiator tube 26 and the inlet of the lower end of the evaporator tube 23 return to liquid. They are connected by a tube 28. A liquid reservoir 29 is interposed in the liquid return pipe 28, and a control valve 30 is interposed between the liquid reservoir 29 and the evaporating pipe 23.

Therefore, the evaporating tube 23 and the radiating tube 26 are
The steam pipe 27 and the liquid return pipe 28 are connected so as to form a circulation path as a whole. Inside the circulation path, a condensable fluid such as chlorofluorocarbon is discharged as a working fluid 31 in a state where non-condensable gas is exhausted. Enclosed to form a loop heat pipe.

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

When supplying hot water, the control valve 30 is first opened, and the working fluid 31 flows into the evaporating pipe 23 from the liquid reservoir 29 by a predetermined amount. The inside of the evaporator tube 23 is
The working fluid 31 in the liquid phase
Boils immediately after flowing into the inside of the evaporating tube 23, but a space with a narrow annular cross section is formed inside the evaporating tube 23.
Because they are, the droplets blown up between a high position with the boiling of the working fluid 31, yet the droplets evaporation pipe 2
3 adheres to the side wall surface. In that case, the axial inclusions 24
As the side wall surface of the evaporation tube 23 is not covered
Evaporation of the body 31 occurs in almost the entire area of the wide side wall surface, and heat is taken out of the heat storage body 20 at each of the upper and lower positions without particularly large deviation.

The working fluid 31 generated inside the evaporation tube 23
Flows through the steam pipe 27 to the radiator pipe 26 in the heat exchanger 21 for hot water. Therefore, if the water W is allowed to flow on the outer peripheral side, the working fluid vapor flowing inside the radiator tube 26 radiates heat to heat the water W to hot water of a predetermined temperature, and the working fluid 31 is condensed. Then, the liquefied working fluid 31 returns to the liquid reservoir 29 via the liquid return pipe 28.

The supply of hot water is stopped by closing the control valve 30 together with the supply of water W to the heat exchanger 21 for hot water. In this case, when the control valve 30 is closed, the amount of the working fluid 31 remaining inside the evaporator
3 is small because the central portion is occupied by the axial filling 24, and thus 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 a heat storage function for removing heat from the generated working fluid vapor and condensing it is given to the heat exchanger 21 for hot water, its capacity may be small, and therefore the water heater is downsized as a whole. be able to.

FIG. 3 shows the results of an experiment conducted to confirm the effect of using the above-described filler 24. In the experiment, an evaporator tube with an outer diameter of 19 mm was provided inside the heat storage body, a wick made of a metal mesh was provided on the inner surface, and an axial filling with an outer diameter of 8 mm was provided along the center axis of the evaporator tube. An object is placed, the heat storage body is heated to about 500 degrees, and the working fluid is caused to flow into the evaporator tube to start heat transport, and the temperature change of the heat storage body at that time is measured in the upper part and the lower part. . As a comparative example, the same measurement was performed for the case where no axial filler was used. The solid line in FIG. 3 shows the result of the present invention, and the broken line shows the result of the comparative example. As is clear from these, the temperature drop at the upper part of the heat storage body is faster if the axial filler is used. Accordingly, the temperature drop in the lower part was slightly alleviated, and it was recognized that heat was extracted from the entire heat storage body. Therefore, when the axial filling is used, heat is efficiently extracted from a wide range 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 arranging a filler inside the evaporating tube 23 to fill a so-called dead space on the center side, that is, a portion which does not contribute to evaporation. It promotes the evaporation of the fluid, and therefore, the packing used is not limited to the one shown in the above embodiment, and the shape and structure of the evaporating tube 23 are not limited to those shown in the above embodiment.
Hereinafter, examples of the packing and the evaporating tube which can be used in the present invention will be described.

[0024]

[0025]

[0026]

[0027]

[0028]

FIG . 4 shows an example in which a hollow shaft is used as the shaft-like inclusion 44, the hollow shaft is opened on the bottom side of the evaporating tube 23, and the heat storage body 20 is further inserted therein. is there. With such a configuration, the outer surface of the shaft-like inclusion 44 also serves as an evaporating surface of the working fluid, so that the evaporation of the working fluid can be further promoted.

FIG . 5 shows an example in which the tapered shaft 54 whose upper outer diameter is gradually reduced is used as an inclusion. With such a configuration, the flow path width at the upper portion where the amount of the working fluid vapor increases increases, so that the evaporation of the working fluid can be promoted and the flow resistance can be reduced.

FIG . 6 shows an example in which the same operation and effect as those of the example shown in FIG. 5 are obtained. In this example, the evaporating tube 23 and the inclusions 64 are tapered so that the diameter increases on the upper side. If these taper angles are equal, the width of the flow path does not increase, but since the diameter of the flow path increases on the upper side, the cross-sectional area of the flow path increases, thereby promoting the evaporation of the working fluid,
In addition, the flow resistance can be reduced.

FIG . 7 shows an example in which the stranded wire 74 is used as an interposition.
In this way, the working fluid is diffused on average, and the thermal efficiency is improved.

By the way, as used in the experiment conducted to obtain the results shown in FIG. 3, a wick may be provided on the inner surface of the evaporator tube. May be a narrow groove formed on the inner surface of the substrate. Note that the narrow groove may be along the axial direction, or may be spiral.

Alternatively, a pipe having folds formed along the axial direction may be used as the evaporating tube, and the folds may be formed as narrow grooves acting as wicks.

[0035]

According to apparent this invention from the above description, a narrow space formed in the evaporation section of the flow path cross-sectional area
Are in the order becomes circular in portrait, the arrival position of the working fluid to be blown up with the boiling of the working fluid is increased, as a result, the supply is working fluid distributed over the entire side wall surface of the evaporation portion Therefore, the substantial evaporation area is increased, and the working fluid can be efficiently evaporated.

Further, since the amount of the working fluid remaining inside the evaporating tube when the supply of the working fluid to the evaporating tube is stopped can be reduced, unnecessary heat extraction after stopping the supply of the working fluid can be reduced. Further, the means for temporarily storing the heat thus extracted can be reduced in size.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of a water heater including an evaporator according to the present invention.

FIG. 2 is an enlarged sectional view of an evaporator tube in the evaporator shown in FIG.

FIG. 3 is a diagram showing experimental results.

FIG. 4 is a longitudinal sectional view showing an example in which a hollow shaft is formed as a shaft-shaped inclusion.

FIG. 5 is a longitudinal sectional view showing an example using a tapered shaft-shaped inclusion.

FIG. 6 is a longitudinal sectional view showing an example in which inclusions and evaporating tubes are tapered.

FIG. 7 is a longitudinal sectional view showing an example in which a stranded wire is used as an inclusion.

FIG. 8 is a system diagram showing a general structure of a water heater using a conventional loop-type heat pipe.

[Explanation of symbols]

Reference numeral 20: heat storage element, 22: heat pipe, 23: evaporating pipe, 24, 44: axial inclusion, 31: working fluid,
34: spherical body, 54: tapered shaft, 64: inclusion, 7
4: Twisted wire.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshihide Sugita 1-3-1 Uchisaiwaicho, Chiyoda-ku, Tokyo Tokyo Electric Power Co., Inc. (72) Inventor Jun Okada 1-3-1 Uchisaiwaicho, Chiyoda-ku, Tokyo TEPCO (72) Inventor Shotaro Yoshida 1-5-1 Kiba, Koto-ku, Tokyo Fujikura Electric Wire Co., Ltd. (72) Inventor Masataka Mochizuki 1-5-1 Kiba, Koto-ku, Tokyo Fujikura Electric Wire Co., Ltd. ( 72) Inventor Koichi Mashiko 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Electric Wire Co., Ltd. (56) References JP-A-3-160274 (JP, A) JP-A-61-223493 (JP, A)

Claims (1)

(57) [Claims] 1. A loop heat pipe in which an evaporator for evaporating a working fluid by heat input from the outside and a condenser for condensing a working fluid vapor by radiating heat are connected so as to form a circulation path as a whole. The evaporating section is formed in the heat storage body in the vertical direction, a working fluid inlet is provided below the evaporating section, and the evaporating section extends upward from the bottom wall surface of the evaporating section.
Inclusions extending out of contact with the side wall surface of the
In addition to being provided integrally on the bottom wall,
A structure of an evaporator of a loop heat pipe , wherein a working fluid flow path is formed between the evaporator and a side wall surface of the evaporator.