FLAT-PLATE COLLECTORS

A flat-plate collector consists of an absorber, a transparent cover, a frame, and insulation. Usually an iron-poor solar safety glass is used as a transparent cover, as it transmits a great amount of the short-wave light spectrum.

Simultaneously, only very little of the heat emitted by the absorber escapes the cover (greenhouse effect). In addition, the transparent cover prevents wind and breezes from carrying the collected heat away (convection). Together with the frame, the cover protects the absorber from adverse weather conditions. Typical frame materials include aluminum and galvanized steel; sometimes fiberglass-reinforced plastic is used. The insulation on the back of the absorber and on the side walls lessens the heat loss through conduction. Insulation is usually of polyurethane foam or mineral wool, though sometimes mineral fiber insulating materials like glass wool, rock wool, glass fiber or fiberglass are used. Flat collectors demonstrate a good price-performance ratio, as well as a broad range of mounting possibilities (on the roof, in the roof itself, or unattached). In order to reduce heat loss within the frame by convection, the air can be pumped out of the collector tubes. Such collectors then can be called evacuated-tube collectors. They must be re-evacuated once every one to three years.

EVACUATED-TUBE COLLECTORS

In this type of vacuum collector, the absorber strip is located in an evacuated and pressure proof glass tube. The heat transfer fluid flows through the absorber directly in a U-tube or in countercurrent in a tube-in-tube system. Several single tubes, serially interconnected, or tubes connected to each other via manifold, make up the solar collector. A heat pipe collector incorporates a special fluid which begins to vaporize even at low temperatures. The steam rises in the individual heat pipes and warms up the carrier fluid in the main pipe by means of a heat exchanger. The condensed liquid then flows back into the base of the heat pipe.

The pipes must be angled at a specific degree above horizontal so that the process of vaporizing and condensing functions. There are two types of collector connection to the solar circulation system.

Either the heat exchanger extends directly into the manifold ("wet connection") or it is connected to the manifold by a heat-conducting material ("dry connection"). A "dry connection" allows to exchange individual tubes without emptying the entire system of its fluid. Evacuted tubes offer the advantage that they work efficiently with high absorber temperatures and with low radiation. Higher temperatures also may be obtained for applications such as hot water heating, steam production, and air conditioning.

COLLECTORS WITHOUT GLASSES

Tthey are a kind widely diffused and asserted on the market as far as it uses it ages them, mainly heating of the discovered swimming pool water, heating of the water for the showers of bathing establishments, you camp, you lodge ages them etc. In these collectors the absorbent body is constituted from with of obtainable tubes for plastic material particular extrusion (polypropylene, neoprene or PVC), to the inside of which slides the termovettore liquid. These tubes in kind are produced in make us modular of the width of a meter and variable length and are connect you to the extremities from two tubes of the same material that have function of tubes collectors. The collector is composed only from the absorbent slab.

 

COLLETTORS WITH INTEGRATED TANK

This are a kind not too much diffused although opportune conditions of exercise offer of the certain advantages regarding the collectors plans. In these collectors, the black body sanitary napkin is constituted from or more tanks (to the cylindrical shape or of parallelepipedo) to whose inside slides the water that will come then used.

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