JP2003161534A - Glazing collector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the disadvantages of a solar heat collector by prior art such as the inadequateness to the use in a cold district because of large heat loss, the insufficient heat transfer performance between a pipe and a heat medium, the increase in manufacturing cost including material cost, and the increase in transportation cost or the like by increase in weight. <P>SOLUTION: This mass-producible thin and lightweight glazing collector with high performance has a structure in which all elements related to a solar heat collection such as a reflector having a high condensing ratio, a heat collecting pipe provided with a turbulence promoter, and a heat insulating material, are put in a thin glazing vacuumed or sealedly filled with an inert gas having low thermal conductivity. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of hot water and high-temperature heat medium using solar energy.

[0002]

2. Description of the Related Art A flat plate collector is often used in a conventional solar collector (hereinafter referred to as a solar collector) for heating hot water for heating houses and high-temperature heat medium. FIG. 9 shows an example of a flat plate type collector.
The outline is shown in. A typical flat plate collector is composed of aluminum fins 14 and copper heat collecting tubes 4, a heat medium is circulated inside the heat collecting tubes 4, and the back surface is insulated by a heat insulating material 6. These are usually housed in an outer box having a transmissive body on the upper surface, and the transmissive body 5 is usually made of tempered or semi-reinforced single glass.

However, according to the above conventional techniques,
The heat loss increases due to the convection and heat conduction phenomenon of the air inside the collector, and the sunlight is not collected (concentration ratio is almost 1).
And the poor heat transfer between the heat collection tube and the heat medium, etc., are effective in collecting heat during weak sunlight, high temperature heat collection, and use in cold regions (60 ℃ to 70 ℃ heat collection). There is a disadvantage that the thermal efficiency is significantly reduced.

In the prior art, in order to improve the heat loss of the device, a pair glass structure may be used for the transmissive body to improve the heat insulating performance. In this case, the inside of the pair of glasses may be evacuated or filled with air or an inert gas such as krypton gas having a low thermal conductivity. A vacuum tube type collector in which the heat collecting tube is covered with a glass tube and the inside of the glass tube is evacuated has also been proposed.

However, according to the prior art, although the heat loss from the upper surface of the transparent body is improved, the heat loss from the side surface and the back surface of the device is not improved at all, and the convection and the internal convection
Since the heat conduction phenomenon is not essentially improved, it is difficult to significantly improve the heat collection efficiency. Further, the paired glass is very heavy, the device itself is thick and bulky, and the manufacturing cost is high. Further, the vacuum tube type collector has a high manufacturing cost although the heat collection efficiency per effective area is low, and there is a risk that the glass tube evacuated will burst.

[0006]

The first problem to be solved is that the prior art collectors have too much heat loss that they are almost impossible to use in cold climates. Secondly, the weight and manufacturing cost of the collector increase, and thirdly, the heat transfer performance between the piping and the heat medium is insufficient. By improving the above problems, the present glazing collector is a useful invention that can realize a performance of about 3 to several times that of a flat plate type collector and is excellent in cost performance.

[0007]

In order to solve the above three problems, a thin glazing layer filled with an inert gas such as krypton having a low thermal conductivity or having a small thermal conductivity is formed in a fine and fine structure. A collector with a three-dimensional or two-dimensional CPC type reflector with a large light collection ratio, a heat collecting tube with a turbulence promoting body such as a fin structure inside the tube, and a high-performance heat insulating material. Invented
By including all the elements inside the thin glazing layer, the heat loss from the device can be drastically improved. In addition, by using a fine CPC type reflecting mirror, it is possible to suppress the natural convection phenomenon inside the reflecting mirror (called a cavity) and to suppress the convective heat loss. Furthermore, the heat transfer to the heat medium is significantly improved by the turbulent flow accelerators such as fins and helical ribbons in the heat collecting tube.

[0008]

1 shows an embodiment of a glazing collector of the present invention. 2 (a) and (b)
2 is a cross-sectional shape around the reflecting mirror and the heat collecting tube of the glazing collector of the present invention. As shown in Figs. 1 and 2, one unit of the glazing collector is an anti-reflective treatment (Anti-Re
A thin glazing layer (usually 10-20) consisting of a single piece of tempered glass with a flection coating and an outer box.
mm or less), a two-dimensional or three-dimensional shape CPC-type reflecting mirror with a relatively high light collection ratio (light collection ratio of about 3 to 8), a heat collecting part, a heat collecting tube with a turbulence promoter, And the structure will contain heat insulating material. The entire inside of the glazing layer is filled with krypton gas (inert gas) whose thermal conductivity is about 1/3 or less of that of air. The gas is also enclosed so that it can sufficiently permeate around the rear heat insulating material. By using a reflecting mirror that is as fine as possible, the natural convection phenomenon inside the cavity can be suppressed and the loss due to convective heat transfer can be almost eliminated. The heat collecting part 2 has a structure integrally bonded to the heat collecting tube 4 or in close contact with the heat collecting tube 4, and circulates the heat medium 3 in the heat collecting tube 4 to obtain a high temperature medium. Further, the heat collecting portion 2 is thermally insulated from the reflecting mirror 1, and has a structure for suppressing heat loss due to the fin effect of the reflecting mirror 1. In the collector having the CPC type reflecting mirror, all the sunlight rays 10 incident at the sunlight incident angle 20 smaller than the allowable deviation angle 7 are incident on the heat collecting section 2. The heat collecting tube has selective absorption by black chrome plating. For the heat insulating material on the back surface of the heat collecting tube, ultrafine silica heat insulating material or the like having excellent high temperature heat insulating property is used.

In the embodiment shown in FIG. 1, reflecting mirrors 1 such as a bowl-shaped three-dimensional CPC type having a circular opening are arranged, but if the opening of the reflecting mirror 1 remains circular, A gap is generated between the reflecting mirrors, and the effective area with respect to the effective area is reduced. In order to solve this, a structure of a three-dimensional reflecting mirror whose opening is a regular hexagon as shown in FIG. 3 is given. In this case, only the opening has a regular hexagonal shape, and under the opening, it has a CPC type shape.

FIGS. 4A and 4B show the internal structure of the heat collecting tube. Due to the recent technological advances, it is possible to process the fins in the tube as shown in the figure, and the heat transfer promotion effect can be expected. Although FIG. 4 (a) shows an example of a spiral internal fin, a method of inserting a twisted plate (helical ribbon) as shown in FIG. 4 (b) into a straight pipe may be considered.

One module as shown in FIG. 1 is formed by connecting a plurality of units in parallel or in series according to the scale of heat collection, and this module serves as a unit as an apparatus. Note that FIG. 1 shows an embodiment in which the CPC type reflecting mirror has a three-dimensional shape obtained by rotating the cross section of FIG. 2 around the axis, that is, a bowl shape.

[0012]

EXAMPLE As another example, there is a glazing collector constituted by a two-dimensional CPC type reflector as shown in FIG. This cross-sectional shape is the same as that of the three-dimensional shape in Fig. 1, but the reflector such as the CPC type of the three-dimensional shape has a flat bottom like a bowl, while this is shown in Fig. 2. It is a gutter-shaped reflector with the cross-sectional shape shown in. 2 for 3D shape
It is suitable for high-temperature heat collection and steam production because the light collection ratio is larger than the three-dimensional shape, but the two-dimensional shape is suitable for heat collection at a relatively lower temperature than the three-dimensional shape. It is desirable to use them properly.

As another embodiment, inside the glazing layer
It is also possible to insert a conventional flat plate type heat collecting fin without using the CPC type reflecting mirror. This is effective when it is not necessary to collect much light.

As another embodiment, as shown in FIG. 6, a grating-like absorber having a size of submicron to 2 to 3 μm is formed in place of the reflecting mirror to bring the wavelength closer to the wavelength of light, thereby suppressing the reflectance. Included structures.

As another embodiment, as shown in FIG. 7, by attaching a solar cell 13 to the heat collecting portion 2 of the glazing collector having a three-dimensional shape and a two-dimensional shape,
In addition to the heat collector, it can be used as a composite solar power generator. In addition, this can significantly reduce the area of the solar cell. In this case, since the solar cell 13 can be cooled by flowing the heat medium through the heat collecting tube 4 and the efficiency can be improved, which leads to the improvement of the power generation efficiency, the CP
Highly efficient solar power generation is possible in combination with the condensing action of C-type reflectors.

[0016]

As described above, the glazing collector of the present invention has a much higher heat collecting performance in cold regions and high temperature heat collection than conventional flat plate type collectors, vacuum tube type collectors, etc. in comparison of heat collecting efficiency. Exert. FIG. 8 shows the heat collection efficiency of the glazing collector of the invention.
The comparison with the heat collection efficiency of the vacuum tube type and flat plate type collectors is shown. Furthermore, due to the reduction of manufacturing costs such as material costs, it can be expected to be a thin mass-produced collector that has never been seen before. In addition, it can be expected to have a wide range of applications of more than 20 types, from the production of hot water for heating and hot water supply to general households to the high heat source of absorption heat and chemical heat pumps using hydrogen storage alloys.

In warm regions such as Kyushu and Shikoku, solar water heaters have a high penetration rate of around 50%, but in Aomori and other regions it is low at around 2% due to low heat collection efficiency. The efficiency is about three times higher than that of the conventional one, which is extremely effective. Furthermore, the steam turbine can be driven by producing hot water of 130 to 200 ° C, and it can be used as so-called steam power generation (Thermal electric). By combining this with hot water supply and heating, total efficiency can be increased. It can be expected to open up a new way of utilizing solar energy in the future, because it can be improved to about 6 times that of solar cells.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of a glazing collector.

FIG. 2 is a schematic view around a reflecting mirror and a heat collecting tube as an embodiment of a glazing collector.

FIG. 3 is a schematic view of a reflector having a regular hexagonal opening as an embodiment of a glazing collector.

FIG. 4 is a schematic diagram of a heat collecting tube internal structure as an embodiment of a glazing collector.

FIG. 5 is a schematic view showing another embodiment 1 of the glazing collector.

FIG. 6 is a schematic view showing another embodiment 2 of the glazing collector.

FIG. 7 is a schematic view showing another embodiment 3 of the glazing collector.

FIG. 8 is a diagram comparing heat collection efficiency of glazing collectors.

FIG. 9 is a schematic view of a flat plate type collector showing a conventional technique.

[Explanation of symbols]

1 reflector 2 Heat collecting part 3 heat medium 4 heat collecting tubes 5 Transmitter 6 insulation 7 Allowable declination 8 opening length 9 Sunlight incident angle 10 sun rays 11 internal fins 12 Helical Ribbon 13 solar cells 14 Heat collecting fins

Claims (5)

[Claims] 1. A thin glazing layer (Gl) filled with an inert gas such as krypton having a low vacuum or a low thermal conductivity.
azing Layer), a thin solar heat collecting device (hereinafter referred to as a glazing collector) that contains all the elements necessary for solar heat collection such as a heat collecting tube, a reflecting mirror, and a heat insulating material. 2. A compound parabolic concentrator (hereinafter C) having a fine three-dimensional or two-dimensional shape.
The glazing collector according to claim 1, wherein the glazing collector has a reflecting mirror of PC type or the like and is capable of achieving a large light collection ratio. 3. The glazing collector according to claim 1, wherein the glazing collector has a structure in which fins or a turbulence promoting body is inserted in the heat collecting tube to promote heat transfer in the tube. 4. The glazing collector according to claim 1, which can be used in combination with solar power generation by attaching a solar cell to the heat collecting portion. 5. The glazing according to claim 1, which has a structure in which the reflectance is suppressed by forming a lattice-like absorber having a size of submicron to 2 to 3 μm instead of the reflecting mirror to bring it closer to the wavelength of light. collector.