JPS5869355A - Solar heat collector - Google Patents

Abstract

PURPOSE:To improve the heat collecting efficiency and the durability of the titled heat collector and to reduce the manufacturing cost thereof by a method wherein a carbon fiber material of low elasticity made of petroleum or coal pitch is used as a heat collecting material. CONSTITUTION:The solar heat collector is formed of, for example, a heat collecting vessel 1, a reinforced glass plate 2 covering the upper opening of the vessel 1 and the heat collecting material 3 placed over the bottom surface of the vessel 1. Further, a heat insulating material 6 is interposed between an outer member 4 and an inner member 5 of the heat collecting vessel 1 and a water supply hole 7 and a water discharge hole 8 are provided in the side surfaces of the vessel 1, respectively. The heat collecting material 3 is made of the carbon fiber material, especially the non-elastic one made of petroleum or coal pitch. Such carbon fiber material is made in the form of a porous short fiber sheet by using an epoxy resin as a binder and is fixed to the bottom surface of the heat collecting vessel 1 with band-like pressing member 9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solar collector. Its purpose is to provide excellent heat collection efficiency and durability.1. Moreover, we propose a heat collector that is low cost.

Solar heat collectors usually pass a heat-absorbing medium such as water or air through a container or tube in which a heat-collecting material such as a heat-collecting plate is placed.
A type that uses a heat-absorbing medium to absorb solar heat collected by a heat-collecting material has been put into practical use.

The heat collection materials for these heat collectors must maintain high heat collection performance and durability, so they are made of expensive materials such as copper, aluminum, and stainless steel, treated with a special selective absorption film, and machined with presses, welding, etc. It required processing and was expensive.

These heat collecting materials are susceptible to damage such as corrosion and cracking from work-hardened parts and welded parts, and because they have a fixed shape, they are prone to accidents due to freezing in the winter.

In addition, there are heat collectors that use air as a heat absorbing medium and use a material such as butyl rubber as the heat absorbing material, but these have problems such as low heat resistance and easy deformation at high temperatures.

As described above, although conventional heat collecting materials satisfy all of the requirements of low cost, durability, and collection performance, they have not been found to be superior to others. .

This invention has been made in view of the above-mentioned problems.

The gist of the solar heat collector is that it is constructed using carbon fiber as a heat collecting material, and the carbon fiber is a low elastic modulus carbon fiber made from petroleum or coal pitch.

Carbon fiber is a black body with an extremely large surface area per unit volume, and has a high absorption rate of irradiated solar heat. Furthermore, it has a high emissivity and has an excellent heat exchange rate with heat-absorbing media such as water and air flowing in contact with it. In particular, low elastic modulus carbon fibers made from petroleum or coal pitch (usually elastic modulus 3. OOO~8
．． OOOK9/d) is a high elastic modulus carbon fiber (normally elastic modulus 20.000 to 3o, o o o Ky7,4) made from polyacrylonitrile etc. and fired at high temperature.
), the thermal conductivity is approximately three times higher, and the absorption rate of solar heat and the heat exchange rate to the heat absorbing medium are improved, making it possible to improve the performance of the solar heat collector.

Carbon fiber is also extremely stable thermally and chemically.
During use, there are few hardened and fixed parts, so there is no risk of damage due to thermal deformation, freeze-thaw, corrosion, etc., and the durability of the heat collector is improved. Moreover, since carbon fibers can be used in the form of tow, web, chopped, non-woven fabric, woven fabric, sheet, etc., unlike conventional heat collecting materials, there is no need for many complicated processes, and the processed surface Cost reduction can be achieved.

The low modulus carbon fiber made from petroleum or coal pitch as a raw material used in this invention is manufactured by refining petroleum or coal pitch, polymerizing it, spinning it, and subjecting it to infusibility treatment and carbonization treatment. The cost of this carbon fiber is significantly lower than that of high modulus materials made from materials such as polyacrylonitrile, and together with the low processing cost, it can significantly reduce the cost of heat absorbing materials. can.

The table below lists some of its typical physical properties.

(Physical properties of pitch-based carbon fiber) Density = 1.5-1.8 Thread diameter: 10-20μ Tensile strength = 50-100 Kf/-Modulus: 3
,000~8. OOOK9/- Electrical specific resistance: 5-1
5 x 10-3Ω・I thermal conductivity; 40~18w
/m-h-' (: Heat resistance: 310°C in air When carbon fiber is used as a heat collecting material, it is processed into tow, chopped, web, nonwoven, woven, sheet, etc. Attached to the heat collector.When processing carbon fiber into nonwoven fabric, web, or sheet form, the fibers may be intertwined using needle punching, papermaking, etc., or bound using a binder as necessary. Measures will be taken to

For example, carbon fiber short fibers with a fiber length of 0 to 30 m are formed with an epoxy resin as a binder and have a basis weight of 50 to 20.
A porous sheet-like material having a weight of 0 g/d is suitable because it has a three-dimensionally wide heat exchange surface, and has installation stability and durability.

This will be explained below with reference to the embodiments shown in the drawings.

The illustrated heat collector has a rectangular parallelepiped heat collection container 1. A tempered glass plate covering the top opening 2. It is composed of a heat collecting material of a porous sheet 3 laid on the bottom surface of the container 1. container 1
A heat insulating material 6 is interposed between an outer member 4 and an inner member 5, and a water supply hole 7 and a water discharge hole 8 are provided. The porous sheet 3 is made of short carbon fibers with a fiber length of 10 to 30 m using an epoxy resin binder and has a basis weight of 50 g/d. Two sheets are stacked on top of each other to a thickness of about 20 mm. be.

Incidentally, this porous sheet 3 is fixed to the bottom surface of the container with a band-shaped tie material 9.

In this heat collector, the water moving between the water supply hole 7 and the water discharge hole 8 contacts the fiber surface through the porous sheet 3 and three-dimensional fiber gaps, and the porous sheet 3 absorbs the solar heat collected. It heats up well.

For example, if the structure is similar to the drawing, the inside dimensions of the container are 500X3'.
When 0OX150iolI was installed on the ground facing south and tilted 20 degrees Celsius, it was possible to raise the temperature of 107 water to 50.5 degrees Celsius.

The heat collector of the present invention is not limited to the illustrated embodiment. In addition to regular heat collectors, it can be applied to a wide range of heat collectors, including roof-integrated type, wall-integrated type, solar heat collectors for agricultural greenhouses, solar heat collectors for drying and heating purposes in factory warehouses, etc. can.

It goes without saying that in addition to liquids such as water, gases such as air can be used as the heat absorbing medium.

When installing carbon fiber as a heat collecting material in a heat collector, a porous sheet should be installed on top of a net-like fence a few minutes away from the bottom to prevent the flow of heat-absorbing media such as water or air. Alternatively, cut a porous sheet into strips and arrange them in a wavy manner on the bottom of the heat collection container, or when using a gas such as air as the heat absorption medium, the surface of the heat collector may be covered with double glass to prevent heat loss. Various aspects can be taken depending on the conditions such as covering or the like.

The solar heat collector of this invention is as described above, and provides the following effects.

■ Improved heat collection efficiency.

■ Reduced damage and longer service life.

■ Cost reduction could not be achieved.

[Brief explanation of drawings]

The drawing is a partially cutaway perspective view of a heat collector according to an embodiment. DESCRIPTION OF SYMBOLS 1... Heat collection container, 2... Tempered glass plate, 3... Porous sheet, 4... Outer material, 5... Inner material, 6...
...Insulation material, 7. Water supply hole, 8. Log hole, 9. Band-shaped spruce material.

Claims (2)

[Claims] (1) A solar heat collector comprising carbon fiber as a heat collecting material, wherein the carbon fiber is a low elastic modulus carbon fiber made from petroleum or coal pitch. (2) The solar heat collector according to claim 1, wherein the carbon fibers are made of epoxy resin as a binder and short carbon fibers as a porous sheet-like material.・