JPS5819017B2 - solar collector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solar collector used in solar water heaters, solar heating and cooling systems, etc.

FIG. 1 is an explanatory diagram showing a solar collector 1 according to Conventional Example I.

This solar collector 1 includes a heat collecting plate 2 that converts sunlight into one thermal energy and transmits it to a heat medium such as water, and a heat collecting plate 2f that serves as a path for the heat medium. a transparent plate 4 made of glass or the like that transmits sunlight, prevents convective heat loss from the heat collecting plate 2, and protects the heat collecting plate 2 from dirt from the outside. , a heat insulating material 5 that prevents heat loss to the back side, and a transparent plate 4 including the entire heat collector.
Tomo 1 heat collecting plate 2. It consists of an outer box 6 that protects a heat insulating material 5.

The performance of such solar collectors depends on the convection of absorbed energy,
How to suppress heat loss due to radiation and conduction1
It is determined accordingly.

Conventionally, as a method of suppressing such heat loss, the surface of the heat collecting plate 2 is subjected to selective absorption surface treatment to suppress this radiation loss.

A convection prevention structure for suppressing convection loss, such as a honeycomb transparent body, is provided between the heat collecting plate 2 and the transparent plate 4.

Vacuum insulation methods are used to suppress conduction loss and convection loss.

By the way, although the conventional method of suppressing one heat loss in one solar collector is effective in suppressing one heat loss, it is effective in suppressing three heat losses consisting of convection, radiation, and conduction. Suppressing one of these forms will increase heat loss through the other forms.

There is also a causal relationship in that if the loss due to two of these forms is suppressed, the heat loss due to the remaining form increases.

For example, in the solar collector 1 shown in FIG. 1, if one surface of the heat collector plate 2 is selectively treated with an absorbing surface, the amount of heat radiated from the heat collector plate 2 to the transparent plate 4 will decrease. However,
As a result, the temperature of the transparent plate 4 decreases, and the amount of convective heat transfer from the heat collecting plate 2 to the transparent plate 4 increases.

In addition, in the conventional vacuum cylindrical solar collector 1A1 as shown in FIGS. 2A and B1, the surface of the heat collecting plate T is a selective absorption surface, and the heat collecting plate T and the transparent cover are When vacuum insulating the insulation layer 9 between the
Although the heat loss caused by the shape tube is suppressed, the vacuum enclosure part 1
Heat loss due to conduction from zero increases significantly.

In other words, as shown in the above two examples, although the conventional method of suppressing heat loss in a single solar collector is somewhat effective, the problem is that it is not possible to simultaneously suppress three forms of heat loss. There is a point.

The present invention was devised in view of the above-mentioned conventional problems, and it is possible to simultaneously suppress heat loss in the three forms of convection, radiation, and conduction, without reducing incident solar energy, and to achieve high thermal efficiency. The purpose is to provide a heat collector.

In order to achieve the above object, the present invention provides a solar collector having a heat collecting plate housed inside a box provided with a transparent plate on one surface, the surface of the heat collecting plate being movable. A V formed from a fluorinated ethylene resin film (Element C) having a film thickness of 10-1 μm (Element B) is subjected to selective absorption surface treatment (Element A), and one space between the transparent plate and the heat collecting plate is formed. A grooved transmitting body (element D) is arranged.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is an explanatory diagram showing a solar heat collector 11 as an embodiment of the present invention. 12. A heat medium flow path 13 forming a part of the heat collecting plate 12 and forming a heat medium path. A transparent plate 14 made of glass or the like is used to transmit sunlight and prevent convection heat loss from the heat collecting plate 12. Insulating material to prevent heat loss to the back side 15. An outer box 16 that houses the entire heat collector is provided, and the surface of the heat collector plate 12 is subjected to selective absorption surface treatment, and the heat collector plate 12 and a transparent plate are provided.

14 A transparent V-groove transmitting film formed from a fluorinated ethylene resin film with a thickness of 100 to 1 μm has an approximately V-groove shape in cross section as shown in FIG. A body 1γ is arranged.

Here, examples of the fluorinated ethylene resin film used as the constituent material of the V-groove transmitting body 11 include FEP, a copolymer of 4-fluorinated ethylene and 67-fluorinated propylene, and copolymer of 4-fluorinated ethylene and perfluoroalkyl vinyl ether. Preferred examples include copolymer PFA, copolymer ETFB of tetrafluoroethylene and ethylene, and the like.

Next, the heat collection characteristics of the solar collector 11 according to the above embodiment will be explained based on the effects of each element A to D.

The element of selectively applying absorption surface treatment to one surface of the heat collecting plate 12 has been proposed in the past.
radiation loss.

(2) Element B is that a thin film with a film thickness of 100 to 1 μm is used as the groove transmitting body 17.

If the transmittance is good and the transmitted solar energy is not attenuated, as will be described later, the emissivity for infrared and ray f is small, so the effect of suppressing radiation loss is ensured based on element A1. do.

According to the element Ct, a fluoroethylene resin film is used as a constituent material of the V-groove transmitting body 1γ.

The manufacturability and heat resistance required for the transparent body are improved.

That is, in order to use glass as a transmitting body and to ensure the effect of suppressing radiation loss caused by elements, the thickness of the glass must be extremely thin, on the order of several μm.

Difficult to manufacture.

In addition, when using general transparent plastics such as polycarbonate, acrylic, and vinyl fluoride as the transparent material, 1
This makes it impossible to ensure the heat resistance required in a heat collector whose temperature reaches as low as 200 to 250° C. when fired dry.

By making the cross-sectional shape of the V-groove transmitter 1T into a V-groove shape, element Df can suppress a decrease in transmittance and suppress convective heat loss. The area becomes smaller and heat loss due to conduction is suppressed.

That is, if we compare the effects of the grooved transmitting body 1γ and the honeycomb transmitting body conventionally used for convection prevention, we can see that the transmittance of solar energy is The number of chambers 1A to 7Af partitioned by the V-groove transmissive body 11#c with the same pitch so as not to reduce the number of chambers 1A to 7Af
-! , the number of chambers partitioned by the honeycomb transparent body 11A# is greater than the number of chambers IB to 4B, and it is recognized that the convection suppressing effect becomes greater.

In addition, the transmittance of the groove transmitting body 1T is similar to that of the honeycomb transmitting body 17kf, where the reflected light Q of the incident light P is directed toward the heat collecting plate 12, It is considered to have the same permeability as the body 11A.

In contrast, the honeycomb transparent body 17A must be manufactured using an adhesive method, whereas the V-groove transparent body 17 made of fluoroethylene resin can be manufactured using a mass-producible manufacturing method such as vacuum forming. It is possible.

an element A that selectively performs absorption surface treatment on the surface of the heat collecting plate 12;
According to element B, which sets the film thickness of the V-groove transmitter 1γ to 100 to 1 μm, the effect of suppressing radiant heat loss by element A is ensured by element B, which reduces the emissivity to infrared rays. .

That is, the temperature distribution of the V-groove transmitter 1γ when the outside temperature is 20°C, the heat collecting plate temperature is 100°C, and the transparent plate temperature is 30°C is as shown in Fig. 6. , conduction occurs from the heat collecting plate 12 to the transparent plate 14 , and the interior 1 partitioned by the V-groove transmitting body 11
This generates a small convection M (this convection M has almost no ability to transport heat compared to the convection f that would occur in the case where the V-groove transmitting body 11 is not provided).

Therefore, when the emissivity of the V-groove transmitter 1T is high, the flea causes radiation as shown by the arrow N from the surface of the V-groove transmitter 17 to be generated on the transparent plate 14f.

In order to suppress such heat radiation N from the V-groove transmitter 17, it is necessary to use a material that has a small emissivity for cutting off infrared rays, that is, does not emit heat radiation, as the V-groove transmitter 1γ.

The V-groove transmitting body 11 made of a woven ethylene-based resin having a film thickness of 100 to 1 μm has a property that its emissivity with respect to infrared rays is one point smaller as shown in FIG.

That is, the glass L1. Fluorinated ethylene resin (FEP) L2. with a film thickness of 1 mm. Film thickness 1
00 μm fluoroethylene resin (FEP) L3 and 1 μm film thickness fluoroethylene resin (FEP)
According to Figure 1, which shows the relationship between the wavelength of L4 and the monochromatic emissivity, the emissivity for one infrared ray in a thin fluorinated ethylene resin film L3 or L4 + film with a film thickness of 100 μm or 1 μm is qualitatively It is recognized that there is a tendency for f to be 1 smaller.

In conventional solar collectors, a transparent material with high emissivity for infrared rays is used as a transmitting material in order to improve thermal efficiency due to the greenhouse effect. This is effective only when the plate surface is a non-selective absorbing surface.
Furthermore, it is effective to use a fluorinated ethylene resin film which has a low emissivity with respect to infrared rays and has a thickness of 100 to 1 μm as described above.

Therefore, according to the above embodiment, it is possible to simultaneously suppress three types of heat loss and not to reduce incident solar energy.

That is, elements B, C, and D do not reduce the incident solar energy, and the combination of elements A, B, and C suppresses radiation loss well, and the combination of elements C and D1 reduces heat. By using hub plastic with poor conductivity and by reducing the contact area with the heat collecting plate or transparent plate1, conduction loss can be suppressed, and the 9-element Df can be compared to the conventional transparent body with a honeycomb structure. This makes it possible to suppress convection loss, and by combining these elements, it is possible to simultaneously suppress three forms of heat loss: convection, radiation, and conduction, and obtain high heat collection efficiency. becomes.

As described above, the present invention provides a solar collector 1 in which a heat collecting plate is housed in a box provided with one transparent plate on one surface, and one surface of the heat collecting plate is selectively treated with an absorbing surface. The thickness of the film between the transparent plate and the heat collecting plate is 100 to 1 μm.
The V-groove transmitting body molded from a fluorinated ethylene-based resin film is arranged in such a way that heat loss in the three forms of convection, radiation, and conduction is simultaneously suppressed, ensuring high heat collection efficiency. It has the effect of being able to.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a solar collector according to conventional example 1. FIG. 2A is a sectional view showing a solar collector according to Conventional Example 1. Fig. 2B is a sectional view taken along JIB-11B line 1 in Fig. 2A, Fig. 3 is a sectional view showing an embodiment of the solar collector according to the present invention 1, and Fig. 4 is a sectional view of the same embodiment. ■A perspective view showing the grooved transparent body enlarged, Fig. 5A is a sectional view showing the main part of Fig. 3, Fig. 5B is a sectional view showing the honeycomb transparent body in the conventional example, Fig. 6 FIG. 3 is a sectional view showing the state of heat transfer in 1, and FIG. 7 is a diagram showing the emissivity characteristic for one wavelength. 11... Solar heat collector, 12... Heat collecting plate, 14... Transparent plate, 1γ... V-groove transmitting body.

Claims (1)

[Claims] 1 A solar collector comprising a heat collecting plate housed inside a box provided with a transparent plate on the surface 1 and 2 on the surface 1 of the heat collecting plate.
This is subjected to selective absorption surface treatment, and between the transparent plate and the heat collecting plate, a fluorinated ethylene resin film with a film thickness of 100 to 1 μm is molded into a shape with a roughly V-shaped groove in cross section and repeated once. A solar heat collector characterized in that a V-groove transparent body is provided.