JP2600117B2 - Temperature stable type selective radiation material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for utilizing environmental energy, and more particularly to a selective radiation material for radiation cooling using a high-rise atmosphere or outer space as a heat source.

[0002]

2. Description of the Related Art It is well known that radiant heat rays are emitted from all objects having an absolute temperature of zero degree or higher. As an example of the heat radiation phenomenon, there is a radiation cooling phenomenon in which the ground surface or an object on the ground surface cools down at night when the weather is fine.
Atmospheric spectral characteristics are deeply involved in this phenomenon,
There is a region with a very high transmittance in the wavelength range of m, which is called an “atmospheric window”. Since the heat radiation from the ground surface and near the ground surface having a temperature of about the air temperature is large in the above wavelength range, the radiant heat dose exiting the object will be the radiant heat dose coming from another incoming object or the lower atmosphere. Exceeds
The object will be cooled. Attempts to use such a principle of radiative cooling to artificially control and use it for cooling etc. have the special effect of not requiring the supply of energy such as electric power, and various studies have been made in recent years. I have.

[0003] Of the radiation cooling materials utilizing the "atmospheric window", a material having wavelength selectivity and capable of obtaining a lower temperature than a non-selective material is called a selective radiation material. In addition, various materials (CG Granqvist, Applied Optics, 20, 260) can be used in which a dielectric film or polymer film having an appropriate thickness is formed on a metal substrate, or a gas having an appropriate optical path.
6 (1981), Morihiro Matsuda, Shigeo Terada, Hiroshi Ito, Solar Energy, 10, 33 (1984)). Among them, a material in which a dielectric film (inorganic film) is formed on a metal substrate is expected to be particularly promising in view of ease of handling and excellent environmental resistance. Then, a material in which a silicon monoxide film or a mixed film of silicon monoxide and silicon nitride is formed on a metal substrate has been prototyped. (TS Eriksson, S. -J. Jian
g, CGGranqvist, Solar Energy Materials, 12, 319
(1985), TS Eriksson, CGGranqvist, Applied O
ptics, 22, 3204 (1983)).

[0004]

However, the performance of the conventional selective radiation material is a dielectric film (inorganic film).
Since the thickness depends on the thickness of the film, the thickness of the film cannot be made sufficiently uniform by a method such as a sputtering method which is usually used for forming a thin film. In addition, the degree of the temperature drop varies greatly depending on the amount of the heat insulating material used around the selective radiation material and the amount of the refrigerant for transporting the low temperature to another place, which also causes a failure to obtain a constant temperature drop. . Therefore, there has been a demand for a selective radiating material that reduces the sensitive film thickness dependency of the selective radiating material and realizes a certain and stable temperature reduction.

[0005]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above, and comprises forming a vanadium dioxide film to which tungsten is added on a black substrate, and further forming a silicon monoxide film on the upper surface thereof. And a temperature-stable selective radiation material for radiation cooling.

The black substrate may be made of any material as long as it has a high absorptance in the infrared region, and its shape and dimensions are not particularly limited. Further, a sputtering method and other known methods can be used as a forming method, but are not particularly limited.

The tungsten-added vanadium dioxide film may be made of any material as long as it has a thermochromic property showing a metal-semiconductor transition, and may be formed by a sputtering method or another known method. Can be used, but there is no particular limitation.

[0008]

【Example】

Example 1 As a selective radiation material of Example 1 shown in FIG. 1, an aluminum plate coated with black paint was used as a black substrate 1, and a vanadium dioxide film 2 to which tungsten having a phase transition temperature of 12 ° C. was added was provided on the upper surface thereof. And a structure in which a silicon monoxide film 3 is further formed on the upper surface thereof. The thickness of the vanadium dioxide film 2 to which tungsten is added is 0.1 μm, and the thickness of the silicon monoxide film 3 is 1 μm. The thickness of the substrate 1 coated with black paint is not particularly limited as long as it is impermeable to infrared light.

Using the theory of multilayer thin film (edited by Shiro Fujiwara, 2nd edition of optical thin film, published by Kyoritsu Shuppan, 1986) in the above configuration, the temperature drop of the case where insulation is ideal is calculated. Even when heat of about 11 W / m ² flows in from, even when about 4 W / m ² of heat is excessively discharged to the outside, the temperature reached an equilibrium at 12 ° C. and was constant.

The optical constants of silicon monoxide are described in the literature (ed. By ED Palik, Handbook of Optical Constant).
s of Solids, Academic Press, 765 (1985)), and the optical constant of the vanadium dioxide film doped with tungsten used the value obtained by measuring the reflectance and transmittance of the sample prepared by the sputtering method. . The optical characteristics of the black substrate were those of a black body. The calculation of the drop temperature is described in the literature (Morihiro Matsuda, Shigeo Terada, Hiroshi Ito, Solar Energy, 10,
33 (1984), Masato Tazawa, Kazuki Yoshimura, Ken Miki, Sakae Tanemura, Solar Energy, 19, 39 (1993))
This was done by calculating the dependence of radiative cooling capacity on sample temperature.

Embodiment 2 As a selective radiation material of Embodiment 2 shown in FIG. 2, an aluminum plate coated with black paint is used as a black substrate 1, and a vanadium dioxide film 2 to which tungsten having a transition temperature of 14 ° C. is added on its upper surface. And a silicon monoxide film 3 is formed on the upper surface thereof. The thickness of the vanadium dioxide film 2 to which tungsten is added is 0.1 μm, and the thickness of the silicon monoxide film 3 is 1 μm.

As a result of performing the same calculation as in Example 1 for the selective radiating material of Example 2, the temperature of the selective radiating material is about 9 W even if heat of about 3 W / m ² flows in from the outside. / m ²
The equilibrium was reached at 14 ° C. and remained constant even if the heat of the sample was excessively exhausted.

Comparative Example 1 A similar calculation was performed for a selective radiation material having a silicon monoxide film having a thickness of 1 μm formed on an aluminum substrate, and Comparative Example 1 was obtained. The temperature of the selective radiating material of Comparative Example 1 reached an equilibrium at about 0.4 ° C. when there was no release of heat inflow with the outside, but when about 4 W / m ² of heat flowed in from the outside, About 4
When about 2.5 W / m ² of heat was excessively exhausted to the outside at ° C., an equilibrium was reached at about −2 ° C.

Although the present invention has been described based on the embodiments, the present invention is not limited to the above-described embodiments, and can be implemented in any manner unless the configuration described in the claims is changed. Can be.

[0015]

As described above, the selective radiating material of the present invention stably reduces the temperature of the selective radiating material by inserting vanadium dioxide to which tungsten is added between the black substrate and the silicon monoxide film. Will do. Therefore, it is easy to obtain a low temperature with a stable temperature, and it is expected to be used for container wall materials and the like, for example, for chemicals that need to be stored at a constant temperature.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically illustrating a configuration of a selective radiation material according to one embodiment.

FIG. 2 is a cross-sectional view schematically illustrating a configuration of a selective radiation material according to another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Black substrate 2, 2 'Vanadium dioxide film which added tungsten 3 Silicon monoxide film

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References Proceedings of the 1993 Joint Research Meeting of the Japan Solar Energy Society and the Japan Wind Energy Association, (Heisei 5-12-9), p. 245-248 Sunshine Journal 11-1! (1990), (Heisei 2-3-3-25), p. 25- 33

Claims (1)

(57) [Claims] 1. A selective radiation material for radiation cooling, comprising: forming a vanadium dioxide film to which tungsten is added on a black substrate, and further forming a silicon monoxide film on an upper surface thereof.