JPS5939570Y2 - solar heat collector - Google Patents

Description

[Detailed description of the invention] This invention relates to a solar heat collector, and its purpose is to cause the transparent plastic film that covers the heat collector plate with a space between it to sag when it thermally expands and stretches due to a rise in temperature. The object of the present invention is to provide a solar heat collector that can reliably prevent this.

In general, the thermal output of a solar collector is expressed as the amount of incident solar energy minus the heat loss of the collector plate, and the efficiency of the collector is calculated by dividing the thermal output by the amount of solar energy incident on the opening area of the collector. It is expressed as the quotient divided by energy.

Heat loss from the heat collector plate consists of radiation loss, convection loss, and conduction loss, and among these, convection loss mainly occurs in the space between the transparent cover and the heat collector plate.

The temperature of the heat collector increases when it absorbs incident solar energy, but since the transparent cover located above it is in contact with the outside air, the temperature of the transparent cover is much lower than that of the heat collector, and the heat collector The heated air rises and reaches the low-temperature inner surface of the transparent cover, where it is cooled and returns to the heat collecting plate.

In order to suppress heat loss due to convection in the space between the heat collecting plate and the transparent cover, conventionally a transparent partition plate is inserted into this space to divide the space into two or several layers (top and bottom). Something was being done.

As the material for the inserted partition plate, a thin transparent plastic film was used because it was desirable to have a moderate transmittance to solar radiation.

However, this thin transparent plastic film has a large linear expansion coefficient of 8.3 to 10.5 x 10', so this transparent plastic film stretches as the temperature of the heat collecting plate increases, and hangs down on the heat collecting plate and comes into contact with it. If this happens, the effect of preventing convective heat loss in the air layer will no longer be obtained, resulting in a significant drop in performance.

Therefore, in the past, support metal fittings were installed on the heat collecting plate to prevent the transparent plastic film from sagging even when it expanded.
Alternatively, in order to prevent the transparent plastic film from sagging when it stretches due to temperature rise, tension was applied to the transparent plastic film in advance to make it stick evenly, but it is extremely difficult to stick it while applying tension evenly. At the same time, a special frame for this purpose had to be manufactured, a transparent plastic film was pasted on the frame, and then it had to be installed in the space between the heat collector plate and the transparent cover, which required a considerable amount of effort. However, it also had disadvantages such as high processing costs.

The present invention eliminates the above-mentioned conventional drawbacks by simplifying the structure, and the present invention will be explained below based on the drawings showing the embodiments thereof.

In Figures 1 and 2, 1 is a box-shaped container, 2 is a heat collecting plate that receives sunlight and converts the solar energy into heat energy, and this heat collecting plate 2 is It is housed in the container 1.

4 is a side insulation material, 5 is a transparent plastic film that covers the heat collecting plate 2 with a space in between, and 6 is a transparent cover that covers the transparent plastic film 5 with a space in between.
is attached to the top flange 14 of the container 1 by a presser metal fitting 7.

Reference numeral 8 denotes a fixture fixed to the side wall of the container 1. One end of the transparent plastic film 5 is placed on the fixture 8, and a presser 9 is disposed on top of the fixture 8 to hold the transparent plastic film 5. One end is clamped and fixed.

10 is a convex metal fitting fixed to the side wall of the container 1. The other end of the transparent plastic film 5 is placed on this convex metal fitting 10 as shown in the enlarged view of FIG. Cover the shaped metal fitting 11, extend the other end of the transparent plastic film 5 by the covering depth d, and in this state, use the screw 13 through the washer 12 to tighten the three parts, that is, the concave metal fitting 11. Transparent plastic film5. The convex metal fittings 10 are fastened together.

With such a fixing structure, the transparent plastic film 5 is stretched by the covering depth d, so that a uniform tension is applied to the transparent plastic film 5.

Since the length of extension of the transparent plastic film 5 is determined from the room temperature at the time of assembling the heat collector and the maximum operating temperature of the heat collector, once the covering depth d of the convex metal fittings 10 and the concave metal fittings 11 is determined, You can easily obtain uniform tension.

The following table shows the linear expansion coefficient α of typical transparent plastic films.

Figure 3 shows the length J of the transparent plastic film based on the value of /(Horizontal axis)
The elongation length of the transparent plastic film relative to the covering depth d) (vertical axis) is expressed.

Generally, the size of most solar heat collectors is 2mXim, and in this case the length of the transparent plastic film is l.
The elongation length is about 8 to 14, but in the future it will be 3 to 14.
Even if a large heat collector of 4 m appears, the covering depth d is about 13 to 21 mm, so it can be adequately accommodated.

As described above, according to the present invention, when fixing a transparent plastic film disposed between a transparent cover and a heat collecting plate, one end thereof is fixed to a metal fitting fixed to a container, and the other end is fixed to a metal fitting fixed to a container. The transparent plastic film is placed on a convex metal fitting fixed to the container, and a concave metal fitting is placed on top of the concave metal fitting to push the transparent plastic film by the covering depth. Even if thermal expansion occurs, the thermal expansion can be absorbed by the tension of the transparent plastic film, and as a result, the transparent plastic film will not hang down and come into contact with the heat collecting plate. It is possible to effectively suppress convective heat loss from.

Since the structure is extremely simple, it is possible to provide a high-performance solar heat collector at a low cost.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a solar heat collector showing an embodiment of the present invention, Figure 2 is an enlarged view of part A in Figure 1, and Figure 3 is the elongation of the transparent plastic film relative to its length. This is a graph showing the length and depth of cover. 1... Container, 2... Heat collection plate, 3...
...insulation material, 5...transparent plastic film, 6...transparent cover, 8...fixing metal fittings, 9...pressing metal fittings, 10... ... Convex metal fitting, 11... Concave metal fitting.

Claims (1)

[Scope of utility model registration request] a heat collecting plate that receives sunlight and converts the solar energy into heat and energy; a transparent plastic film that covers the heat collecting plate with a space between them; a transparent cover that covers the transparent plastic film with a space between them; The transparent plastic film has one end fixed to a metal fitting fixed to the container; A solar heat collector characterized in that the other end is placed on a convex metal fitting fixed to the container, and a concave metal fitting is covered from the top of the concave metal fitting, and the transparent plastic film is stretched by the covering depth. vessel.