JP2001108306A - Solar heat water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar heat water heater, hard to see fur produced, light in weight and excellent in heat exchanging property. SOLUTION: A hydrophilic semi-conductor, such as titanium oxide or the like which coats the inner wall of a container for heat exchange is irradiated with strong beams of an ultraviolet ray spectrum whereby super-hydrophilic effect is developed and a solar heat water heater is constituted so that water is spread on the inner wall of the container without any limit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improving the efficiency of a solar water heater.

[0002]

2. Description of the Related Art As is well known, a conventional solar water heater fills a panel-shaped heat exchange container with water, heats the water by solar heat, converts the water into hot water, and supplies it to a hot water storage tank or a water heater. I have. In such a solar water heater, the heat exchange efficiency is low in spite of its heavy weight, and the heat exchange efficiency is further reduced due to the adhesion of water scale and the like during long-term use. As a countermeasure, a device using a heat collector using a thermosiphon heat transfer pipe as a medium has been proposed. At the same time, it was expensive, and the efficiency was greatly affected by the installation inclination.

[0003]

As described above, in a solar water heater in which the entire inside of a panel-shaped heat exchange container is filled with water, the heat exchange efficiency is low in spite of its heavy weight, and it can be used for a long time. The heat exchange efficiency was further reduced due to the adhesion of water scale and the like. In addition, the thermosiphon solar water heater is expensive, and has a problem that the efficiency is greatly affected by the installation inclination and there is no flexibility.

[0004] In view of the above problems, an object of the present invention is to provide a solar water heater that is light in weight and has good heat exchange properties with less formation of scale.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems by irradiating a hydrophilic semiconductor such as titanium oxide coated on the inner wall of a heat exchange container with a light beam having a strong ultraviolet spectrum of a heat source such as sunlight. The problem is solved by utilizing the super-hydrophilic effect and spreading the water to the inner wall of the container without limit.

More specifically, in a solar water heater having a heat exchange container having an upper surface and a lower surface and hermetically sealing the inside, at least one surface of the upper surface and the lower surface is made of a light transmitting material, A main portion of the inner surface of the container is coated with a hydrophilic material, and a heat exchange container is inclinedly installed so that the surface made of the light transmitting material is easily received by sunlight. A solar water heater characterized in that water is supplied so that a water film spreads on a surface on which material coating is applied.

[0007] The supply amount of the water may be controlled by the amount of water stored in the lower bottom portion of the heat exchange container or the temperature or amount of the hot water stored in the hot water storage portion of the heat exchange container. Further, a process or a material which promotes the capillary phenomenon may be provided inside the lower surface of the heat exchange container, or at least the inside of the lower surface of the heat exchange container may be black.

[0008]

FIG. 1 is a perspective view of a heat exchange container of a solar water heater according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line AA in FIG. is there.

In FIG. 1 and FIG.
Has a panel shape composed of a plurality of cells 1 combined according to a required heat exchange capacity. The upper surface 2 of the heat exchange container 30 exposed to sunlight is coated with a hydrophilic titanium oxide 20 on the inner surface. The lower surface 3 is made of a weather-resistant metal such as stainless steel coated with a hydrophilic titanium oxide 20 on a black coating made of an inorganic material mainly composed of alumina or silica. It is configured.

A semicircular hot water reservoir 4 is formed at one end of the lower surface 3 of the heat exchange container 30, and a part of the inner space of the hot water reservoir 4 has a double pipe structure. The partition plate 5 is provided so as to form a double pipe bottom 6 at the bottom of the space formed by the partition plate 5.
A water pipe 7 for inputting tap water or the like is attached near the double pipe bottom 6, and further near the bottom of the hot water reservoir 4 and outside the double pipe bottom 6. In the space, a hot water pipe 8 serving as an output section of hot water after heat exchange is attached, and a lower bottom 9 serving as the other end of the lower surface 3 of the heat exchange container 30 is provided with a regular cleaning and freezing prevention. Drain pipe 10 is attached.

The hot water pipe 8 is connected to a hot water storage tank (not shown) or a water heater for additional heating, and a check valve is attached to each pipe as appropriate. Further, the coating of the hydrophilic titanium oxide 20 is made by spray coating in which particles having a particle size of 10 nm or less are dispersed, and does not hinder the transparency of the glass on the upper surface 2.

With respect to the heat exchange container 30 having the above structure, the principle of hydrophilizing a photocatalyst by titanium oxide, which is well known in the self-cleaning technology for tiles and the like, will be briefly described with reference to FIG.
2) On the surface, as shown in FIG. 3 (a), oxygen is crosslinked between Ti and Ti and stabilized, and in this state, the surface shows hydrophobicity, and water on the surface repels in a polka dot. When this surface is irradiated with ultraviolet rays, as shown in FIG. 3 (b), a part of the cross-linking oxygen is dropped and oxygen defects are generated.

The moisture in the air is dissociated and adsorbed on the oxygen vacancies, and the surface hydroxyl groups (chemically adsorbed water) shown in FIG. Further, as shown in FIG. 3 (d), moisture in the air is adsorbed on the surface hydroxyl groups, and a physical adsorption layer is formed by hydrogen bonding, whereby the hydrophilicity is enhanced.

As a result, a hydrophilic domain is generated in the hydrophobic surface, and water is absorbed by the hydrophilic portion by a two-dimensional capillary phenomenon on the surface structure. Spreads wet on the surface.

When the irradiation of ultraviolet rays is stopped, the surface hydroxyl groups are replaced with oxygen again to return to the hydrophobic state shown in FIG. 3 (a). However, by adding silica-silicone-based aqueous substances to titanium oxide, The hydrophilicity can be increased to maintain the superhydrophilicity for a long time.

Next, the operation of the embodiment of the present invention will be described. For convenience of explanation, it is assumed that sunlight is sufficiently applied from above the heat exchange container 30. When the water is supplied from the water pipe 7, water is supplied into the heat exchange container 30 along the space between the hot water reservoir 4 on the lower surface 3 of the heat exchange container 30 and the double pipe structure partition plate 5, and the partition plate 5 End 1 of
Due to the narrowing of the outlet of 1, the supplied water is:
At the same time as the water flows down along the inner surface of the upper surface 2 formed of transparent glass, it flows down while thinning due to the photocatalytic hydrophilicity of the titanium oxide 20 coated on the upper surface 2. , A portion of the thinned water evaporates in a blink of an eye to become a vapor, moves upward inside the heat exchange container 30, and is cooled by water supplied from the outside. When it hits the plate 5, it condenses and becomes hot water and starts to accumulate at the bottom of the hot water reservoir 4.

If the supply water from the water pipe 7 further increases, the evaporation area of the upper surface 2 cannot sufficiently evaporate and starts to accumulate in the lower bottom portion 9 of the container. Due to the photocatalytic hydrophilization of titanium, the water film spreads above the inside of the lower surface 3 of the heat exchange container, evaporates by solar heat to become steam, and becomes hot water stored at the bottom of the hot water reservoir 4 according to the above principle.

Here, the heat exchange efficiency depends on the heat exchange container 30.
Is determined by the size of the surface area of the upper surface 2 and the lower surface 3 and the thickness of the supplied water film. In order to maintain a high heat exchange efficiency, the water is newly supplied from the water pipe 7 by the evaporation amount of water. It is necessary to control the amount of water that is generated. In this case, although not shown, the level of water accumulated at the bottom 9 of the heat exchange container,
Alternatively, it can be controlled by installing a sensor for measuring the temperature or level of hot water.

The reason why the inside of the lower surface 3 of the heat exchange container 30 is blackened is to improve the absorption of heat rays. Efficiency can be improved by roughening the inner wall of No. 3 or installing a member that promotes the capillary phenomenon such as a glass braided wire.

In order to maintain hydrophilicity when sunlight is shaded, silica may be added to titanium oxide, or ZnO or Ni-K4Nb may be used as a photohydrophilic material instead of titanium oxide.
It goes without saying that various known materials such as 6O17 can be used.

In the embodiment shown in FIGS. 1 and 2, the hydrophilic coating is applied to both the inner surface of the upper surface 2 and the lower surface 3 of the heat exchange container 30. However, only the lower surface 3 is coated to inject the injected water. The outlet 11 of the partition plate 5, which is a supply port of the above, may be installed along the lower surface 3 so that a water film due to hydrophilicity is formed only on the lower surface 3 of the container. By providing the heat exchange container 30 having a mixed combined cell structure different from that of the embodiment in each case, an excellent system having advantages of each other can be obtained.

It is needless to say that a hydrophilic coating for self-cleaning can be appropriately formed on the outer surface of the upper surface 2 made of the light transmitting material of the heat exchange container 30. In addition, the warm water reservoir 4 in the above embodiment has a semicircular bulging shape, but a liquid serving as warm water accumulates.
Any other shape may be used as long as the required amount of hot water can be stored, and the shape of the heat exchange container is not limited to the panel shape shown in the above embodiment, but may be, for example, a cylindrical shape. And other shapes.

[0023]

As described in detail above, according to the present invention, the combination characteristics of a photo-excited hydrophilic material that positively utilizes ultraviolet rays of sunlight, which is also a heat source, and water, which is a heat exchange target, can be obtained. By configuring inside the replacement container, it is possible to obtain a high-efficiency solar water heater that is lightweight, has good responsiveness like an instantaneous water heater, and is extremely resistant to water scale over a long period of time. As a result, the well-known disinfecting effect of titanium oxide can also perform a disinfecting action on water that accumulates in the lower bottom portion and the hot water reservoir.

[Brief description of the drawings]

FIG. 1 shows a perspective view of a solar water heater according to an embodiment of the present invention.

FIG. 2 shows a sectional view of FIG.

FIG. 3 shows the flow of the principle of hydrophilization of a photocatalyst by titanium oxide.

[Explanation of symbols]

 In the drawings, the same reference numerals indicate the same or corresponding parts. DESCRIPTION OF SYMBOLS 1 Cell 2 Upper surface 3 Lower surface 4 Hot water pool part 5 Partition plate 6 Double pipe bottom part 7 Water pipe 8 Hot water pipe 9 Lower bottom part 10 Water distribution pipe 11 End part 20 Hydrophilic titanium oxide 30 Heat exchange container

Claims (5)

[Claims] 1. A solar water heater comprising a heat exchange container having an upper surface and a lower surface and hermetically sealing the inside thereof, wherein at least one surface of the upper surface and the lower surface is made of a light transmitting material, and the inner surface of the heat exchange container is provided. A main part is coated with a hydrophilic material, and a heat exchange container is inclinedly installed so that a surface made of the light transmitting material is easily received by sunlight, and the hydrophilic material coating is applied from above the inside of the heat exchange container. A solar water heater characterized in that water is supplied so that a water film spreads on the surface on which the water is applied. 2. The solar water heater according to claim 1, wherein the amount of water supplied is controlled by the amount of water accumulated at the lower bottom of the heat exchange container. 3. The solar water heater according to claim 1, wherein the amount of supplied water is controlled by the temperature or amount of the hot water stored in the hot water storage section of the heat exchange container. 4. The solar water heater according to claim 1, wherein a process or a material for promoting a capillary phenomenon is provided inside the lower surface of the heat exchange container. 5. The solar water heater according to claim 1, wherein at least the inside of the lower surface of the heat exchange container is black.