JPS58203345A - Solar heat collector - Google Patents

Abstract

PURPOSE:To prevent the overheating of the solar heat collector accurately by a method wherein a heat collecting pipe capable of contacting with, and separating from, a heat collecting pipe, a heat collecting member comprising a pair of bimetallic heat collecting plates and a tray-like reflecting mirror are mounted in a high temperature closed pipe so that when a predetermined temperature is reached, the heat collecting plates separate from the heat collecting pipe. CONSTITUTION:The heat collecting member 8 has is upper end fixed to a support member 13 comprising a wire press-fitted in a proper part of the inner surface of the closed outer pipe 6 due to its resiliency. The pair of right and left bimetallic heat collecting plates 8b forming the heat collecting member 8 are coated with black heat discharge films of carbon black or the like on the inner surfaces thereof and each of them has a height suitable for covering the displacement of a black point on the reflecting mirror 11 adopted to follow the displacement of the sun. Further, the inner surfaces of the bimetallic heat collecting plates 8b are usually in contact with the heat collecting plate 8a in a heat conductive manner and the coefficient of thermal expansion of the bimetal of which they are made is so determined that when the heat collecting plate 8a reaches a desired temperature, for example, 200 deg.C, the heat collecting plates separate from the heat collecting pipe 8a.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solar heat collector in which a reflective mirror is installed in a transparent sealed outer tube. Since the hot water used in ordinary households is mainly for hot water supply, low temperature heat collection of 100°C or less is sufficient, so the heat collection efficiency was not an issue. However, in industry, there are few applications below 100℃;
It is said that there are many applications for medium-temperature heat collection from ℃ to 200℃, which covers about 30% of the residual heat energy. As a means of collecting medium-temperature heat, a heat collector may be constantly tracked toward the axis of sunlight according to the displacement of incident sunlight. However, as a tracking means, it requires a tracking mechanism that moves the mirror, lens, or heat collecting plate, energy for that purpose, and a structure to support it, so the cost of acquiring energy is high, so it is only used experimentally. Not done.

The present invention uses dilute solar thermal energy without tracking it.

Focus the light with a reflective mirror and heat the heat collecting member to 100℃
The purpose is to extract thermal energy at ~200°C.

As shown in Figure 1, a conventional example of a heat collector is a transparent glass vacuum outer tube (2) whose opening is sealed with a sealing plate (1).
A heat collecting tube (3) inside and a gutter-shaped reflective mirror (4) for reflecting sunlight onto the heat collecting tube (3) are installed in the axial direction of the outer tube (2). This heat collecting pipe (3) is installed completely through the sealing plate (1), and is connected to the heat exchanger (5) by welding the joint part, and is completely evacuated inside and changes into gas-liquid two-phase, such as fluorocarbon. It is designed to operate as a new heat pipe by filling it with a working fluid. This heat exchanger has a heat medium pipe (5) through which a heat medium such as water flows, and is heated by the latent heat of the working fluid.

In the conventional structure, the temperature of the heat collecting pipe (3) may exceed the expected temperature in some cases, such as during midsummer, and the temperature of the heat collecting pipe (3) may exceed the expected temperature.
3) The pressure of the working fluid inside increases, causing a so-called excessive heat collection phenomenon that may lead to an explosion. In order to prevent this, a dry firing sensor and associated circuits are required, and software improvements have been made, but this poses problems in terms of cost and reliability.

The present invention is suitable for node improvement of the heat collector itself, and easily and reliably prevents over-collection of heat.The present invention has a structure in which a heat collecting tube and the heat collecting tube are placed inside a translucent sealed outer tube. A heat collection member consisting of a pair of bimetal heat collection plates that can be freely brought into contact with and separated from the heat pipe and a gutter-like reflection mirror are installed, and the bimetal heat collection plate usually comes into contact with the heat collection pipe to surround and collect the limbs. It senses the predetermined temperature of the heat tube and thermally expands to separate from the heat collection tube. When the heat collection tube reaches a certain temperature, the heat collection plate separates and it is not heated any further, so the working fluid inside the heat collection tube It is possible to reliably prevent excessive heat collection without causing the pressure to rise and cause an explosion.

An embodiment of the present invention will be described below with reference to FIGS. 2 to 4.

(6) is a translucent sealed outer tube made of glass whose opening at one end is sealed with a metal sealing plate (7)K, and the inside thereof is evacuated. (8h) is a heat collecting member (8) that penetrates the connecting pipe (9) attached to the sealing plate (7), welds the penetrating part, and is installed in the outer pipe (6) in the axial direction. In one heat exchanger (10), the part of the heat collecting tube protruding from the outer tube (6) is communicated with the outer tube (10a) of the heat exchanger (10) consisting of a double inner and outer tube. The outer tube (log) and the heat collecting tube (8a) are evacuated and filled with a working fluid that changes into gas-liquid two-phase, such as fluorocarbon, to operate as a heat pipe. The inner pipe (lob) of the heat exchanger (10) is communicated with a hot water storage tank or the like, and a heat medium such as water circulates therethrough, so that the inner pipe (lob) of the heat exchanger (10) is heated by the latent heat of the working fluid.

(11) Fi: A gutter-shaped reflective mirror supported by a support leg (12) hanging from the lower part of the heat collecting pipe (8a), which irradiates the heat collecting plate (8b) to be described later with reflected light that collects sunlight. It is supposed to be done. (8b) is a supporting member (1) made of a wire crimped to a suitable position on the inner surface of the outer tube (6) by its elastic force.
3) A pair of left and right bimetal heat collecting plates that serve as heat collecting members (8) whose upper ends are fixed to 3), each having a black heat dissipation film such as carbon black on the inner surface and a selective absorption film made of chromium oxide, triiron tetroxide, etc. on the outer surface. The given height H) is sufficient to cover the displacement of the sunspot that tracks the solar displacement of the reflecting mirror (11). And the bimetal heat collecting plate (8b)
Normally, the inner surface of the heat collecting pipe (8a) contacts the heat collecting pipe (8a) in a thermal transfer manner, and the temperature of the heat collecting pipe (8a) is lower than the expected temperature, for example, 200°C.
When the temperature reaches ℃, it senses the heat and thermally expands to form a heat collecting tube (8a).
The coefficient of thermal expansion of the bimetal is selected so that it is spaced from .

The bimetal heat collector plate (8b) is heated by the reflected light from the reflective mirror (11), and the heat is transferred to the heat collector tube (8a).
), which heats and evaporates the internal working fluid. The steam is transferred to the heat exchanger (lO) which becomes the condensation part, where it is condensed and released into a heat medium such as water, and the steam itself is liquefied and transferred by its own weight to the outer tube (6) which becomes the heat supply part. Heat collecting pipe located inside (8a
), where it is heated again by the reflected light from the reflection mirror (11) and evaporated, repeating the cycle fi/ to heat the heat medium.

When the temperature of the heat collecting pipe (8a) exceeds the expected temperature, the bimetal heat collecting plate (8b) thermally expands as shown by the dotted line in Figure 4, and the heat of the heat collecting plate (8b) is transferred to the heat collecting pipe (8a). Therefore, there is no further temperature rise and there is no risk of pressure increase of the working fluid. Furthermore, since a heat dissipation film is provided on the inner surface of the heat collection plate (8b), heat dissipation from the heat collection plate is promoted.

As described above, the present invention prevents excessive heat collection and prevents VC.
It was possible to prevent explosions, and it was possible to solve this problem only from the hardware side without considering the costly software side.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a conventional heat collector, FIG. 2 is a perspective view of the heat collector of the present invention, FIG. 3 is a cross-sectional view, and FIG. 4 is a longitudinal sectional view of the main parts. (6)...Outside☆, (8)...Heat collecting member, (
8a)... Heat collection tube, (8b)... Bimetal heat collection plate, (11)... Gutter-shaped reflective mirror. 7-

Claims (3)

[Claims] (1) A heat collecting member and a trough-like reflector that reflects sunlight on the heat collecting member are installed in the axial direction of the outer pipe in a translucent sealed outer pipe, and the heat collecting member is attached to the heat collecting pipe. and a pair of bimetal heat collection plates that can be moved into and out of the heat collection tube and have one end fixed to a supporting member. A solar heat collector characterized in that it is configured to detect a predetermined temperature of a heat pipe, thermally expand, and separate from the heat collecting pipe. (2) A solar heat collector according to claim 1, which is formed by providing a selective absorption film on the outer surface of a bimetal heat collecting plate! vessel. (3) A solar heat collector according to claim 1 or 2, which comprises a bimetal heat collector plate with a heat dissipating film provided on the inner surface thereof.