JPH09145166A - Solar heat collecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar heat collecting device having a wide light receiving area, a thin thickness, a light weight and a high efficiency by a method wherein a heat absorbing plate for changing solar heat into a heat energy is arranged at an intermediate part of a flat space formed by a lid and a case and then many columns are arranged substantially in a uniform manner between the lid and the heat absorbing plate, and between the heat absorbing plate and a bottom part of the case. SOLUTION: A case 2 is formed into a flat box shape, wherein a lid 3 is arranged to cover its upper opening port. This lid 3 is formed by transparent material into a flat surface in such a way that solar light may pass through it. A closed space is formed by the case 2 and the lid 3, its inner area is kept in vacuum condition and a heat absorbing plate 4 for use in converting a solar light into heat energy is arranged at its intermediate part. This heat absorbing plate 4 is held by many columns 5. That is, the column 5 is divided into two segments, the heat absorbing plate 4 is held between the two segments so as to support the heat absorbing plate 4 in such a way that it may be directly contacted with either the lid 3 or the case 2. With such an arrangement as above, since the inner area is kept in vacuum condition, the case 2 and the lid 3 receiving atmospheric pressure from above and below them are prevented from being crushed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar heat collecting apparatus for converting sunlight energy into heat energy and utilizing the sunlight in the form of heat energy.

[0002]

2. Description of the Related Art Many conventional solar heat collectors do not evacuate the periphery of the heat absorbing plate that receives sunlight from the inside to convert it into heat. In such a solar heat collecting device, the heat absorbing plate is collected. Since the heat escapes to the outside by the convection and heat transfer of the air in the solar heat collector, the temperature of the heat absorbing plate does not rise.If the temperature does not rise, the heat received by the heat absorbing plate is transferred to the outside by a heat medium such as oil. The efficiency was poor when transported and used.

Therefore, in general, the heat absorbing plate is generally used as a part of a container for water, and the solar heat is used as a solar water heater for transmitting the heat received by the heat absorbing plate to water on the spot. However, in this way, the weight of the entire device was reduced because it contained water, and it was almost impossible to use solar heat for purposes other than heating the water. On the other hand, when the inside has a vacuum, the heat absorbing plate does not have a flat shape, and has a spherical shape or a round bar shape, and the light receiving area is smaller than the occupied area.

[0004]

In order to avoid these drawbacks, if the inside is evacuated and the window and the heat absorbing plate are made flat, the flat portion of the window which transmits sunlight receives a large atmospheric pressure. . For example, it receives an atmospheric pressure of 10 tons per 1 m ² . Therefore, if some measures are not taken, the members forming these must be made strong in order to withstand atmospheric pressure, which causes a drawback that the device becomes large and heavy.

[0005]

The present invention solves the above problems and provides a highly efficient solar heat collecting device which is light, has a wide light receiving area, and is thin, and has a flat transparent lid. And a housing having a flat bottom located parallel to the lid, and an endothermic plate that converts sunlight into heat energy in the middle of the space formed between the lid and the housing. Also, a large number of columns are arranged substantially evenly between the heat absorbing plate and the bottom of the housing so as to hold the heat absorbing plate and keep the space at a vacuum.

[0006]

1 is a sectional view of a solar heat collecting apparatus according to an embodiment of the present invention, in which (a) is a vertical sectional view and (b) is a horizontal sectional view taken along the line AB in FIG. It is a figure. In FIG. 1, 1 is the entire solar heat collecting apparatus, 2 is a housing, 3 is a transparent lid that covers the housing, 4 is a heat absorbing plate that absorbs solar heat, and 5 is between the housing 2 and the lid 3 and supports the heat absorbing plate 4. The column, 6 is a pipe that is in close contact with the heat absorbing plate 4, and 7 is a pipe that allows the heat medium to flow in and out of the pipe 6.

The housing 2 is shaped like a flat box-like container, and is configured so that a transparent lid is placed on the upper portion thereof, and a flat bottom portion is formed to be just parallel to the above-mentioned lid. ing.

The lid 3 is made of a transparent material such as glass that allows sunlight to pass therethrough, and is formed in a flat shape. A space enclosed by the housing 2 and the lid 3 is formed, the inside of which is kept in a vacuum, and an intermediate portion thereof is provided with a heat absorbing plate 4 which receives sunlight and converts it into heat energy.

The heat absorbing plate 4 is made of a material having a good thermal conductivity, for example, a material such as an aluminum plate or a copper plate which absorbs sunlight well on the surface,
For example, it is formed in a flat shape by being covered with a selective absorption film, and a pipe 6 through which a heat medium that absorbs the heat of the heat absorbing plate 4 and becomes high in temperature flows is attached to the front surface or the back surface. The heat absorbing plate 4 is held by a large number of columns 5 arranged between the lid 3 and the heat absorbing plate 4 and between the heat absorbing plate 4 and the bottom of the housing 2. That is, the pillar 5 is divided into upper and lower parts, and the heat absorbing plate 4 is interposed between them.
Are sandwiched and supported so that the heat absorbing plate 4 does not directly touch the lid 3 or the housing 2.

The pillars 5 are arranged almost evenly in the area for receiving sunlight, and because of the vacuum inside, the casing 2 and the lid 3 which are receiving atmospheric pressure from above and below in FIG. 1 (a) are crushed. To prevent it. The column 5 balances and disperses the pressure of the atmosphere having the same size but opposite directions applied to the housing 2 and the lid 3, and supports the housing 2 and the lid 3 via the heat absorbing plate 4. The height of the pillar 5 is substantially constant regardless of the area of the lid 3,
It is selected in the range of a few millimeters to a dozen millimeters.

The vacuum inside the solar heat collector is
This is to prevent the heat absorbed by the heat absorbing plate 4 from escaping to the outside by conduction and convection of the air if there is air inside. By making a vacuum, the heat that escapes from the heat absorbing plate 4 to the outside is only due to radiation, and a very efficient solar heat collecting device can be obtained. Since the heat loss from the heat absorbing plate 4 is only due to radiation, the surface of the heat absorbing plate 4 absorbs sunlight well, but the far infrared radiation from the surface of the heat absorbing plate 4 whose temperature has risen is suppressed. Covering with a selective absorption film can effectively collect solar heat and reduce radiation loss.

FIG. 2 is a perspective view of the plate lattice, and 21 is the plate lattice. In the plate grid 21, the grid is formed in a rectangular shape.
The columns 5 in FIG. 1 are independent columns, and columns such as columns, prisms, and polygonal columns are used. In this case, the stress due to atmospheric pressure is concentrated around the pillar. In order to withstand the stress, the diameter of the column must be increased or the thickness of the lid 3 must be increased. In order to eliminate such a defect, as shown in FIG. 2, the pillar 5 is a plate lattice 21 formed by a plate in a lattice shape. In this way, the load is distributed more widely than in the case of a cylinder. In other words, since all the parts of the lid 3 are closer to the pillars than in the case of a cylinder or the like, a relatively thin lid 3 can be used. The material that can be used for the lid 3, which must be transparent, is limited, so a structure that reduces stress as much as possible is desirable.

FIG. 3 is a plan view of another plate lattice, and 31 is a plate lattice. In the plate lattice 31, the lattice is formed in a honeycomb shape. 3 is superior to the plate lattice 21 of FIG.
It is a plate lattice 31 of. The plate lattice 31 uses a honeycomb-shaped lattice having a honeycomb-like shape instead of the rectangular lattice.
A plate lattice using a honeycomb type lattice is known to be able to support a large load with a lighter column, as is used in aircraft structures, and for the supported lid 3, the lid 3 is Since each part is closer to the pillar, a thinner material can be used for the lid 3 than a square grid. That is, the entire device becomes lighter.

FIG. 4 shows a path of rays of light when the sunlight obliquely incident through the transparent lid 3 reaches the heat absorbing plate 4. 41 is sunlight. The sunlight 41 does not always enter the solar heat collecting apparatus 1 at a right angle, and if there is no sunlight tracking apparatus, the sunlight enters obliquely for a considerably long time of the day. Therefore, it is necessary to allow the obliquely incident light to reach the heat absorbing plate with a small loss. When the pillar 5 is a cylinder, the shadow of the pillar 5 is small when the sunlight enters obliquely, but the shadow is large in the case of the plate gratings 21 and 31. Therefore, of course, in the case of the pillar 5, especially in the case of the plate gratings 21 and 31, the pillar itself is made transparent or its surface is covered with a light reflecting film.

According to the science chronological table, the spectral reflectance of a metal surface is 90% over a wide range from the ultraviolet region to the far infrared region of a vapor deposited film of a metal such as aluminum, silver or gold.
The above-mentioned favorable reflectance is shown. Particularly in the case of silver, the reflectance is about 98% over almost the entire range of sunlight except the ultraviolet region. If the plate of the plate grating 21 or 31 is covered with a reflective film having such a good reflection as described above, even if the plate is opaque, the obliquely incident sunlight 41 directly absorbs heat as shown in FIG. It reaches the plate 4, or is reflected by the plate gratings 21 and 31 one or more times and efficiently reaches the heat absorbing plate 4.

The plate lattice 21 or 31 is made of a heat insulator such as paper or plastic so that the heat does not escape from the heat absorbing plate 4 to the outside due to its own heat conduction, and its surface is made of a metal vapor deposition film. Try to cover.

FIG. 5 is a vertical cross-sectional view of another embodiment in which a filter is installed, in which sunlight passes, but infrared rays having a long wavelength emitted from the heat-absorbing plate 4 whose temperature has risen are reflected to improve the heat absorption efficiency. The place where the selective permeation filter is installed for raising is shown. The filter 51 is provided inside the lid 3 and may be formed in a film shape in the vicinity of the lid 3, but the lid 3 may be made of glass and the filter 51 may be formed on the surface of the glass by a known technique. .

A filter 51 is used to prevent the heat absorbed by the heat absorbing plate 4 from escaping to the outside due to radiation. The filter 51 has a characteristic of transmitting most of light having a short wavelength of 2 microns or less where most of the energy of sunlight exists and reflecting most of radiation having a long wavelength of 2 microns or more emitted from the heat absorbing plate 4. Use what you have.
The filter 51 can reduce the loss due to the radiation of infrared rays having a long wavelength from the heat absorbing plate 4 without hindering the reception of sunlight energy.

The filter 51 does not transmit all the energy of sunlight, but absorbs part of it. Therefore, the filter 51 is effective when it is used in a place where the temperature of the heat absorbing plate 4 rises and the amount of far infrared rays emitted therefrom increases. Since far-infrared rays are not emitted where the temperature of the heat absorbing plate 4 is low, the filter 51 may be omitted in such a place so as not to obstruct the passage of sunlight without using the filter 51. The filter 51 is effective when the temperature of the heat absorbing plate 4 is high, that is, at the final stage where the heat medium exits from the heat absorbing plate 4. For example, when a large number of the solar heat collectors 1 shown in FIG. 1 are connected in cascade, the filter 51 is used only for the solar heat collectors 1 at the final position where the temperature becomes high.

The heat of the sunlight absorbed by the heat absorbing plate 4 with high efficiency is transferred to the heat medium passing through the inside of the pipe 6 shown in FIG. 1, and the heat medium warmed by the solar heat is passed through the pipe 7 to the outside. Carried. As the heat medium, oil that does not deteriorate at high temperature and does not have high vapor pressure is used.

In the present invention, the upper and lower atmospheric pressures received by the lid 3 and the housing 2 are balanced and distributed over a large number of columns to reduce the load received by one column, and the load is received by a thin column. Enable Further, by doing so, it is possible to remove the limitation on the area of one lid 2. For example, 50 for the lid 2 of 5m x 10m
Even with respect to the atmospheric pressure of 0 tons, it is possible to balance the same atmospheric pressure of 500 tons applied to the housing 3 and to receive the load in a distributed manner. Can be realized. In this case, the thickness of the lid 2 and the housing 3 can be the same regardless of the area. This is because the pillars are evenly arranged, so that the load per unit area is equal regardless of the overall size of the lid 2 and the housing 3.

Of course, the atmospheric pressure applied to the side surface of the housing 3 must be taken into consideration, but the height of the side surface is at most several centimeters to several tens of centimeters, and the side plate is the bottom of the housing 3 and the lid. Since it is supported by 2, there is not much problem in terms of strength.

Another advantage is that by making the pillar thin, the ratio of the area of the pillar to the light receiving surface that receives sunlight can be reduced.

By forming the columns into a continuous plate lattice, it is possible to disperse more widely than in the case where the lid 3 and the flat plate at the bottom of the housing 2 and the contact portions of the columns are discontinuously arranged. Therefore, it is possible to receive the load due to the atmospheric pressure on the upper and lower flat plates forming the vacuum in a more dispersed manner than in the case of a cylinder or the like, so that the thickness of the flat plate can be further reduced.

Further, by making the shape of the lattice forming the pillars a honeycomb type, it is possible to receive the atmospheric pressure in a more dispersed manner than the plate lattice formed of a square lattice, so that the thickness of the flat plate Can be made even thinner. Moreover, since a large load can be supported with a column area smaller than that of the square grid, the entire device can be lightened.

[0026]

According to the present invention, it is possible to obtain a lightweight and highly efficient solar heat collector having a wide light receiving area and a small thickness. Therefore, when it is attached to the roof of a general house, the load on the roof can be made smaller than that of the conventional solar water heater. In addition, the solar heat collecting apparatus of the present invention is very efficient,
Since it is possible to obtain a high-temperature heat medium far exceeding 0 ° C, not only is it used for obtaining hot water, but it is also possible to evaporate seawater to obtain fresh water, cool it with an absorption-type air conditioner, or use it as a sun in the desert region. Where the light is strong, as a heat source of the steam engine,
It can also be used to generate electricity, energy problems,
It is very useful for solving environmental problems.

[Brief description of the drawings]

1A is a longitudinal sectional view showing an embodiment of the present invention, and FIG.

FIG. 2 is a perspective view of a plate lattice.

FIG. 3 is a plan view of another plate lattice.

[Fig. 4] Diagram showing the passage of sunlight

FIG. 5 is a vertical sectional view of an embodiment in which a filter is installed.

[Explanation of symbols]

 1 Solar Heat Collecting Device 2 Housing 3 Lid 4 Endothermic Plate 5 Pillar 21 Plate Lattice 31 Honeycomb-like Plate Lattice 51 Filter

Claims (7)

[Claims] 1. A flat transparent lid, a housing having a flat bottom located in parallel with the lid, and an intermediate portion of a space formed by the lid and the housing receiving sunlight. A heat absorbing plate that converts into heat energy is provided, and a large number of columns are arranged substantially evenly between the lid and the heat absorbing plate and between the heat absorbing plate and the bottom of the housing to hold the heat absorbing plate. A solar heat collecting device, characterized in that the space is kept in a vacuum. 2. The solar heat collecting apparatus according to claim 1, wherein the pillar is formed into an independent pillar. 3. The solar heat collecting apparatus according to claim 1, wherein the pillars are continuous pillars in a plate grid shape in which plates are formed in a grid shape. 4. The solar heat collecting apparatus according to claim 3, wherein the plate lattice has a honeycomb shape. 5. The solar heat collecting apparatus according to claim 1, wherein the pillar is made of a transparent material. 6. The outer surface of the column and the inner surface of the housing are covered with a light reflector.
The solar heat collecting device according to any one of 1. 7. The solar heat collecting apparatus according to claim 1, further comprising a filter that transmits sunlight and reflects infrared radiation having a long wavelength inside the lid. .