JPS63263393A - thermal diode - Google Patents

Abstract

PURPOSE:To make it possible to easily form the title equipment and to facilitate the effective use of heat, by a method wherein a liquid with a low boiling point is sealed in a closed container whose upper and lower surfaces are formed by using a material superior in thermal conductivity and whose side surfaces are also formed by using a material inferior in thermal conductivity, and then the upper and lower surfaces thereof are made to adhere closely to heat sources having a temperature difference. CONSTITUTION:By using a metallic material superior in thermal conductivity for the upper surface 2 and the lower surface 3 of a thermal diode 1 and also by using a synthetic resin or the like superior in solvent resistance but inferior in thermal conductivity for the side surfaces thereof, a container is formed to constitute the thermal diode 1 in such a manner that fluorocarbon or the like is sealed in said container with a space left therein. For example, Cu is used for the upper and lower surfaces of the thermal diode while stainless steel is used for the side surfaces thereof and, after decompression and exhaust have been conducted, fluorocarbon is sealed in the container up to the level of its one half height. Then, a water tank (heat storage tank) 5 covered with an adiabatic material 4 is made to adhere closely to the upper surface of the thermal diode 1, except the lower surface thereof, by using a bonding agent with thermal conductivity, and a condenser 6 is set underneath the thermal diode 1, condenses the rays 7 of the sun and irradiates the lower surface of the thermal diode to obtain boiling water.

Description

[Detailed Description of the Invention] [Summary] As a structure of a thermal conductor whose thermal conductivity differs significantly in the vertical direction, a material with excellent thermal conductivity is used for the upper and lower surfaces, and a material with poor thermal conductivity is used for the upper and lower surfaces. A thermal diode that is used by sealing a low-boiling-point liquid in a sealed container with side surfaces formed by the heat source, and placing the top and bottom surfaces of the sealed container in close contact with a heat source with a temperature difference.

[Industrial application field]

The present invention relates to the construction of thermal diodes.

Heat is often consumed without being fully utilized, not only in factories but also in homes.

For example, in the case of factory wastewater, although it is sufficiently heated, it cannot be reused because it is contaminated and is often discarded.

However, in such cases, it is desirable to recover as much thermal energy as possible, store it, and reuse it.

However, in this case, the heat source does not always have a higher temperature than the heat storage part, and the opposite may be the case.

That is, this is the case when the operation of the heating source is stopped, otherwise the heat in the heat storage section will be transferred to the heating source and cooled.

Therefore, it is necessary to interpose a device that has a rectifying effect on the heat flow between the heating source and the heat storage section.

The present invention relates to thermal diodes for use in such applications.

[Conventional technology and problems]

A thermal diode is a device whose thermal conductivity shows directionality.
Such equipment has not yet been put into practical use.

Here, the requirements for the thermal diode are: ■ High rectification ratio, ■ Simple configuration; ■ Low cost; etc.

[Means for solving problems]

The above problem can be solved by using materials with excellent thermal conductivity to
Another solution is to use thermal diodes, which are used by sealing a low boiling point liquid in a sealed container whose sides are made of a material with poor thermal conductivity, and by placing the top and bottom surfaces of this sealed container in close contact with a heat source with a temperature difference. can do.

[Effect]

The present invention is applicable to cases where a high heat source is placed in contact with the lower side of a container filled with a liquid with a low boiling point, and a low heat source is placed in contact with the upper side of the container.
Heat from a high heat source below boils a liquid with a low boiling point, and when the boiling vapor touches the top of the container and liquefies, it utilizes upward heat conduction that occurs by releasing latent heat.

On the other hand, if there is a high heat source in contact with the top of the container and a low heat source in contact with the bottom of the container, the pressure of the steam increases and pressurizes the liquid level, and as a result, vaporization of the liquid is suppressed and the upward flow is suppressed. Heat conduction will no longer take place.

Therefore, the thermal conductivity of liquids and their gaseous forms is much lower than that of metals.

For example, the thermal conductivity at room temperature (25℃) is acetone
...213 xto-n W/a+ -k
Ethanol...147 Xl0-' W/
Copper (Cu) in m-398Gl/m-
Aluminum (AJ)...237 W/
++ - Stainless steel (SIJS 24)...1
7 W/s -k The heat transfer may then be performed only by the latent heat released by the boiling steam as it liquefies when the high heat source is below and the low heat source is above.

FIG. 1 is a cross-sectional view showing the structure of a thermal diode according to the present invention, in which the upper surface 2 and lower surface 3 of the thermal diode 1 are made of a metal material with excellent thermal conductivity, such as Cu, and the side surfaces are made of a metal material with excellent thermal conductivity, such as Cu. The container is made of synthetic resin or stainless steel, which has excellent solvent resistance and low thermal conductivity.

Then, a considerable amount of voids are left in this and a low boiling point solution such as fluorocarbon (CJtm) with a boiling point of 56°C or a boiling point of 6°C is added.
A thermal diode 1 is constructed by sealing and enlarging Freon or the like at 0°C.

Here, it is preferable to provide the upper surface 2, which is made of a metal material with good thermal conductivity, with serrated irregularities in order to increase the surface area and to improve the dripping of the liquefied solution, and the lower surface to prevent the boiling of the liquid. It is effective to provide small protrusions in order to make the surface uniform.

By adopting such a configuration, effective heat rectification can be performed.

〔Example〕

Using Cu for the top and bottom surfaces and stainless steel for the sides,
30 (width) x 100 (length) x 3 (height) cmO
After making a thermal diode and depressurizing the air, fluorocarbon (C?Hr s
O) was enclosed.

Here, the thickness of the Cu plate constituting the upper surface and the lower surface was set to 5 mm.

The thermal conductivity of a thermal diode with the above configuration is 1.2 W/c+*'C from the bottom to the top, and 2 xto-' from the top to the bottom? J/cm” ”
It is C.

A water tank (thermal storage tank) 5 coated with a heat insulating agent 4 was adhered onto the thermal diode 1 except for the lower surface using a thermally conductive adhesive.

Next, a condenser 6 made of a concave mirror was installed below the thermal diode 1 to collect sunlight 7 and illuminate the lower surface of the thermal diode.

If a solar water heater with such a configuration is used, boiling water can be obtained in about an hour even in the middle of winter.

Conversely, if there is no sunlight and the external temperature is 0°C,
Even after 12 hours had passed, the water, which was initially 100°C, had only cooled to 70°C.

〔Effect of the invention〕

As described above, the thermal diode according to the present invention has a simple structure, so it can be easily formed, and by using it, it is possible to easily utilize heat effectively.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the configuration of a thermal diode according to the present invention, and FIG. 2 is a configuration diagram of a solar water heater to which the present invention is applied. In the figure, 1 is a thermal diode, 2 is a top surface, and 3 is a bottom surface. The cross section of the thermal diode according to the present invention shows the redundancy of the thermal diode.
[! l No. 21!1

Claims (1)

[Claims] A liquid with a low boiling point is sealed in a sealed container whose top and bottom surfaces are made of a material with excellent thermal conductivity, and whose side surfaces are formed with a material with poor thermal conductivity, and the top and bottom surfaces of the sealed container are kept at a temperature. A thermal diode characterized by its use in close contact with different heat sources.