JP2001116368A - Solar water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar water heater that can furthermore increase the temperature of hot water without losing the advantages of a conventional storage type solar water heater where a configuration is simple and price is low. SOLUTION: In the solar water heater, anodized aluminum where a black oxidation covering is formed at a base that is made of aluminum or the like is set to an absorption member of solar energy, and the absorption member is arranged in an inner box along the width direction of the deep part in the depth direction of the inner box of a double box consisting of the inner box and an outer box, and the inner and outer boxes are integrated with a gap by including a heat-insulating member between the inner and outer boxes whose sectional shape is rectangular in the double box.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0101]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar water heater for increasing water temperature by absorbing solar energy consisting of solar heat and sunlight.

[0092]

2. Description of the Related Art As one of conventional solar water heaters according to the prior art, one having a construction shown in FIG. 3, that is, a plurality of pipes 11 having an appropriate diameter commonly called a pumping type is closely arranged in parallel. The pipes 11 include a structure in which the pipes 11 are housed in a box 13 having a lid 12 made of a transparent plate, and a structure in which the pipes 11 are water-injected and interconnected. Here, the pipe 11 functions as a heat collector.

[0093]

In recent years, environmental problems such as global warming due to an increase in carbon dioxide and health damage to the human body due to depletion of the ozone layer have come to the fore. Attention has been focused on solar water heaters that use inexhaustible and harmless solar energy.
Although the solar water heater according to the prior art is simple in construction and inexpensive, the hot water temperature is 5 in summer.
The limit is 0 ° C. and 20 ° C. in winter, which is insufficient as a practically sufficient hot water temperature. Also, in winter, drainage is indispensable to prevent pipe breakage due to freezing of water in the pipe. It is an object of the present invention to provide a solar water heater in which the temperature of the hot water can be further increased without impairing the advantage that the configuration of the pumping-type solar water heater has a simple configuration and is inexpensive.

[0093]

The means and the like will be described below with reference to FIGS. 1 and 2. The solar water heater according to the present invention has a structure in which alumite in which a black oxide film is formed on a base material made of aluminum or an aluminum alloy containing at least 3% by weight of silicon is used as the absorbing member 4 for absorbing solar heat and sunlight and the absorption. The structure in which the member 4 is arranged in the inner box along the width direction in the depth direction of the inner box 2 in which the member 4 is formed by the double box 1 of the inner box 3 and the outer box 2, A heat insulating member 5 is provided between the rectangular inner box 3 and the outer box 2 so as to be separated from each other, and a gap is provided to integrate the inner box and the outer box.

[0056]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The absorbing member 4 for absorbing solar energy 7 consisting of solar heat and sunlight used in the solar water heater of the present invention is made of aluminum or at least silicon 3.
Alumite is obtained by forming a black oxide film by anodic oxidation treatment on a substrate made of an aluminum alloy containing a weight percent, and the alumite is preferably an anodized infrared ray. This is because it has a higher absorption rate of the solar energy 7 required for the absorbing member 4.

The absorbing member 4 is not limited to a flat plate, but may be a corrugated plate, a mesh, a flat plate having a large number of apertures, or any other suitable shape. In particular, in order to increase the amount of solar energy absorbed in a limited narrow space, it is essential to increase the surface area of the absorbing member 4. For this purpose, a corrugated plate, a laminated mesh, or a large number of openings are used instead of a flat plate. It is effective to use a flat plate having holes, and it is desirable that the water absorbing member disposed in the inner box along the wide direction is disposed on the entire inner box.

The double box 1, which is one of the components of the solar water heater according to the present invention, is made up of an inner box 3 and an outer box 2 each having a rectangular cross section. The two boxes are integrated with the heat insulating member 5 interposed therebetween with a space therebetween. The reason why the gap is provided is to prevent the absorbed solar energy 7 from being radiated to the outside through an air layer having a low thermal conductivity. Here, at least one surface of the inner box 3 and the outer box 2 constituting the double box 1 is aligned to be a transparent body of either glass or synthetic resin (hereinafter, this transparent body is referred to as a sunlight transmitting window 6). This is to allow transmission of sunlight to the absorbing member. The heat insulating member 5 is made of an elongated rectangular bar, square piece or disk made of at least one of synthetic resin, rubber, glass and ceramics.

The double box 1 is made up of an inner box 3 and an outer box 2 each having a rectangular cross section. Here, the reason why the cross-sectional shapes are each rectangular is to obtain hotter water having a higher temperature. That is, the solar water heater of the present invention fills the inner box 3 with water (including a state close to being full) by injecting water from the water supply port 9 to absorb the water.
Is immersed in water to absorb the solar energy 7, so that the length of the inner box 3 in the depth direction (referred to as the XX 'direction shown in FIG. 2) can be increased to increase the distance from the absorbing member 4. This is because the heat capacity of the water is larger than the amount of the absorbed heat released, and high-temperature hot water that can be practically used cannot be obtained. Since the outer box 2 has a uniform space between the inner box 3 and the inner box 3 and is integrated with the inner box 3 via the heat insulating member 5, if the cross-sectional shape of the inner box 3 is rectangular, the cross-sectional shape of the outer box 2 is also From the standpoint of miniaturization of the outer box, it is desirable to have a cross-sectional shape similar to the inner box 3. However, it is not necessarily restricted to a similar cross-sectional shape.

In the present invention, the length of the inner box 3 in the depth direction is 40 mm or more in harmony between the amount of water injected into the inner box 3 and the hot water temperature.
0 mm or less. In other words, when the temperature is 40 mm or less, the temperature of the hot water can be 70 ° C. or higher, but the amount of water injected is not sufficient, and the water heater must be enlarged to secure a sufficient amount of water injection.
On the other hand, when the length is 80 mm or more, even though the amount of water injected is sufficient, the temperature of the hot water is only 50 ° C. even in summer, which is insufficient as a practically usable hot water temperature. The value of 40 mm or more and 80 mm or less is a value obtained by changing the length of the inner box in the depth direction in order to obtain a hot water temperature of 65 to 70 ° C. For example, the length in the depth direction of the inner box 3 is appropriately set by setting the length to be close to 40 mm, and if it is sufficient at about 65 ° C., to be close to 80 mm.

Next, if the gap between the inner box 3 and the outer box 2 via the heat insulating member 5 is made extremely small, the effect of preventing heat dissipation from the inner box 3 is lacked. Even if the effect of preventing heat dissipation is sufficient, the size of the water heater is increased, and harmony between the effect of preventing heat dissipation from the inner box 3 and the size of the water heater is required. In the solar water heater of the present invention, the gap between the inner box 3 and the outer box 2 is preferably 5 mm or more and 10 mm or less.

The absorbing member 4 is provided on the entire inner box 3 along the width direction of the inner box 3. This is in order to absorb more solar energy. Here, it is desirable to dispose the absorbing member 4 in the inner box 3 in the depth direction of the inner box 3. This is because in the solar water heater of the present invention in which the inner box 3 is filled with water (including a state close to full water) and the absorbing member 4 is immersed in water to absorb solar energy 7, the absorbing member 4 which is a heating source of hot water is used. This is because, if the above arrangement is adopted, the temperature of the warm water is made uniform by natural circulation by the convection of the warm water, thereby enabling the smooth circulation of the warm water. Here, the inner box 2 is filled with water and opened (not shown) to take out hot water from the water outlet 10. In an appropriate place.

[0122]

The solar energy 7 consisting of sunlight and solar heat transmitted through the sunlight transmitting window 6 of the outer box 2 and the inner box 3 constituting the double box 1 and the water of the inner box 3 is absorbed by the absorbing member 4 and then. The solar energy 7 absorbed by the absorbing member 4 is converted into heat energy, and is radiated toward water in the inner box that is in direct contact with the absorbing member 4. Here, the heat-dissipated water causes a rise in water temperature, which causes a volume expansion and a decrease in density. However, since the absorbing member 4 is arranged at the depth of the inner box 3 in the depth direction, the water whose temperature has risen moves to the upper part of the inner box by convection, and instead, low-temperature water flows from the upper part to the lower part. The convection moving toward is repeated.
This convection state is shown below with reference to FIG.
Usually, the solar water heater is installed at an angle with the sunlight transmission windows 6 of the outer box 2 and the inner box 3 constituting the double box oriented in the direction of sunlight irradiation in order to absorb more solar energy. . When the solar water heater is installed in such an inclined state, the solar water transmitting window 6 is in the upper position and the absorbing member 4 is in the lower position. 6 will rise. Due to the natural circulation of water in the inner box due to the repetition of the convection, the temperature of the water in the inner box gradually rises. Thereafter, the water is opened from the water outlet 10 by opening the plug (not shown) as necessary.

When the solar energy 7 is absorbed by the absorbing member 4 in the solar water heater of the present invention, the inside of the inner box is filled with water (including a state close to being full) and absorbed through the filled water. When an air layer exists between the sunlight transmitting window 6 of the inner box 3 and water in the inner box, and the solar energy is absorbed by the absorbing member 4 through the air layer, water vapor generated from the water surface due to a rise in water temperature is generated. As water droplets, they adhere to the inner surface of the sunlight transmitting window 6 of the inner box 3 and not only make the sunlight transmitting window 6 of the inner box 3 cloudy but also scatter sunlight, thereby reducing the amount of transmitted solar energy 7. This is to prevent that.

As the temperature of water in the inner box 3 increases due to the absorption of solar energy by the absorbing member 4, heat is emitted outward from the surface of the inner box. However, the solar water heater of the present invention has an inner box 3
Since an air layer having a low thermal conductivity is interposed between the outer box 2 and the outer box 2, heat release from the inner box surface is greatly suppressed by the air layer. Therefore, even if the sunshine to the solar water heater stops, the temperature of the hot water in the inner box 3 decreases only slowly. The drop in the temperature of the hot water can be made more slowly if the components of the inner box 3 are made of synthetic resin, ceramic, glass, stainless steel, or the like having a low thermal conductivity.

[0151]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the solar water heater according to the present invention is a structure in which a corrugated plate having a pitch of 10 mm and a plate thickness of 1 mm is used as an absorbing member 4, and an inner box 3 and an outer box 2 are connected to a solar transmission window 6. A structure in which a portion excluding a glass plate having a thickness of 5 mm and a sunlight transmitting window 6 is made of a synthetic resin polycarbonate plate or an acrylic plate, a configuration in which the length of the inner box 3 in the depth direction is 50 mm, an inner box 3 and an outer box 2 Of synthetic resin polycarbonate or acrylic to make the gap of 5 mm A solar water heater having a configuration in which a long rectangular bar is interposed between the inner box 3 and the outer box 2 as the heat insulating member 5 and the two boxes are integrated, and the inner box 3 is filled with water. Table 1 shows changes in air temperature and water temperature at each time when installed at an angle of ° and facing sunlight. According to this table, the water temperature initially rises by 44.5 ° C. from 23 ° C. (7:30), reaches 67.5 ° C. at 14:00, and is maintained at this temperature for 1 hour,
The water temperature began to drop from 5 o'clock and maintained at a water temperature of 60 ° C or higher, which could be put to practical use even at 17:00 in the evening. The solar energy conversion efficiency under the above conditions is determined by the solar radiation intensity 1 kw / m.
^When calculated as ² (= 〜1.43 cal / cm ² min), it is 69%.

[0162]

A first effect of the present invention is that the solar energy conversion efficiency is as high as ~ 70% while its structure is simple. In general, for a solar water heater to be accepted in the market, three factors must be balanced: performance, price and durability. Therefore, even if the performance is excellent like a heat pipe type water heater, if the configuration becomes complicated, the price will be reduced and sufficient demand cannot be obtained. In this regard, the solar water heater of the present invention has a simple configuration, so that the price can be kept low and the solar energy conversion efficiency, that is, the performance is high in proportion to the price. In addition, it can be said that the three factors of performance, price and durability are harmonized, taking into account the fact that the natural circulation by the convection of water is used and there is no failure factor and the durability is excellent.

A second effect of the present invention is that the temperature unevenness of the hot water in the inner box is as small as 1 ° C. or less. This effect is achieved by arranging the absorbing member 4 at the depth of the inner box 3 in the depth direction and bringing water into direct contact with the absorbing member 4 to continuously perform natural circulation by convection of water. A third effect of the present invention is that it is not necessary to drain water from the water heater even in winter. That is, in winter, even if the water in the inner box 3 expands due to freezing, the water in the inner box 3 is released to the outside through the air flow pipe 8 before the water is frozen, and the stress on the inner box 3 due to the freezing of the water. This is because the addition is not large enough to damage the inner box 3.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a solar water heater according to the present invention.

FIG. 2 is a cross-sectional view of the solar water heater according to the present invention.

FIG. 3 is an external view of a conventional pump-type solar water heater.

[Explanation of symbols]

 1. Double box 2. Outer box 3. Inner box 4. Absorbing member 5. Insulation member 6. 6. Sunlight transmitting window Solar energy 8. Air circulation pipe 9. Water inlet 10. Outlet

Claims (3)

[Claims] 1. A structure in which an alumite in which a black oxide film is formed on a substrate made of aluminum or an aluminum alloy containing at least 3% by weight of silicon is used as an absorbing member, and the absorbing member is a double box of an inner box and an outer box. A configuration in which the inner box is arranged in the inner box along the width direction at the depth in the depth direction of the inner box, and the heat insulating member is separated between the inner box and the outer box, each of which has a rectangular cross section. A solar water heater consisting of an inner box and an outer box that are integrated with a gap between them. 2. The solar water heater according to claim 1, wherein the absorbing member is made of one of a corrugated plate, a mesh, and a flat plate having a large number of openings. 3. The length of the inner box in the depth direction is 40 mm or more.
The solar water heater according to claim 1, wherein the thickness is 0 mm or less.