Low cost transpired solar collector

Abstract

A low cost solar collector, or collector system, that employs opposing plate members separated by spiral coils over which a transpired material is interwoven in an alternating or zigzag manner, and further including side closures to form a fluid flow path between the plates. With a transparent or translucent top plate, sun light entering the collector will heat the spiral coils and the transpired material so that fluid flowing through the coils and transpired material will be heated.

Description

TECHNICAL FIELD OF THE INVENTION [0001] This invention relates to an apparatus for collecting radiant solar energy and more particularly to a low cost, modular, adjustable solar energy heater which can be mounted on any surface exposed to the sun and which provides enhanced solar energy collection for surfaces which receive sun at low angles. BACKGROUND OF THE INVENTION [0002] In the United States, nearly two thirds of the energy used in buildings and facilities is to provide heating for interior spaces, water, and various other residential, commercial, and industrial heating needs. Typically, the heat provided is derived from natural gas, fuel oil, propane, and electricity. These energy sources are sold to customers at commodity rates. [0003] A known but less developed source of energy for heating is solar energy. To be cost competitive with the typical energy sources, solar collectors must deliver heat for the same or lower cost as the other sources. To be competitive in performan...

AI Technical Summary

Benefits of technology

[0022] In accordance with the present invention, a solar energy receiving surface is a collector of transpired material, for example in the form of a fabric, interwoven between parallel spiral support coils. The transpired material and coils are arranged between and in contact with each of two glazing plates. Fluid, to be heated, flows through the opening formed between the two plates, through the transpired material and through the spiral support coils. The upper plate is transparent or translucent and allows sunlight to pass through to the transpired material and spiral coils. The transpired material and spiral coils form the solar energy absorbing surface of the collector and become heated in the presence of sunlight. The transpired material is alternately draped or lightly stretched over, then under, the adjacent spiral coils, forming a series of alternating peaks and valleys in the transpired material. The coils provide the structure to support the transpired material as well as the strength to support and position the upper plate at a set distance above the lower plate

[0037] Where the large areas of collector are required, it may be necessary to combine individual collectors. To do this, the fluid inlet opening from one collector could be inserted into the fluid outlet opening of an adjacent collector. Where corrugated plates are used, the inserted opening should end with a peak corrugation that fits into another peak corrugation. In this manner, any rain that falls will run into the next valley of the inserted plate and drain off the bottom of the plate before entering the fluid flow space. When collectors are combined transversely, as mentioned above, the added number of passes of fluid through the transpired material and spiral coils will further raise the outlet temperature compared to fluid passing though a single collector. Similarly, collectors can be combined vertically by inserting the top of the lower collector with closure channel removed, into the bottom of the upper collector.

Problems solved by technology

In many cases, this is because the collectors themselves have been too complicated, too expensive and the delivered cost of solar energy (including the amortized capital cost) has been higher than traditional gas, oil, and electricity costs.

In many cases, the systems have been complex and, as a result, expensive to assemble and install.

The addition of mounting hardware is one of the items raising the cost of these collectors.

When glass panels are used, the frame must be quite rigid and heavy relative to the active absorber and solar heat transfer fluid.

The rigid frame adds considerable expense to the cost of the collector.

These traditional methods of supporting the transpired absorber add considerable expense to the collector.

Copper wire gauze is an expensive absorber material currently selling for over $3 per square foot compared to a more modern material, such as polymer fabric, which is lower cost, at about $0.20 per square foot, and which provides similar absorption of solar energy, but does not have the stiffness of the gauze.

However, in winds of 7 miles per hour, it can loose as much as 25% of its productive capacity when operating at high outlet temperatures.

The disadvantage of such a system is that the fibrous material on the bottom of the tubular passage receives much less sunlight than the fibers nearest the top of the tube.

For that reason, the system can not achieve as high a temperature rise as a system that uses a thin fabric evenly exposed to the rays of the sun as they first enter the collector.

Thus, these regions of the absorber will operate at higher temperatures and have higher heat loses than the regions near the holes.

Unglazed collectors, however, are not practical in most environments and in colder weather will exhibit major heat losses to the environment.

Traditional methods of assembling the solar collector system components, either on buildings or at ground level, have also increased the cost of the solar hardware to the point that the cost of the system often exceeds the value of the energy it can deliver.

Images