Design and principle of operation of non-pressure solar collector
Design:
The solar collector consists of vacuum tubes made of borosilicate glass. High operational safety of borosilicate glass has been achieved thanks to the use of an appropriate mix of SiO2 and B2O3 oxides, which results that the product has high chemical resistance as well as extraordinary purity and uniformity. Borosilicate glass is environment-friendly and can be recycled many times. The process of thermal annealing (hardening) was also used. Together with the low thermal expansion typical for borosilicate glass gives it a particularly high resistance to changes of temperature in comparison to standard glass. Tubes are resistant to hail size up to 25 mm. The use of tubes with a diameter of 47 mm and 58 mm allows concentric placement of one inside the other. The air between the pipes is pumped out, and the pipes are welded together.
Solar radiation on the absorber on the inner tube is converted into thermal energy and causes heating of the interior of the tube. The vacuum between the tubes is an excellent insulator and prevents heat loss. The collector manifold/bus bar is made of SUS 304-2B stainless steel and is insulated with polyurethane foam.
Principle of operation:
There is water in both in the tank and the tubes. Under the influence of sunlight, the water in the tubes heats up. Thanks to convective movements, it goes up to the tank. Water circulates continuously between the tank with water and the vacuum tubes, which causes a constant increase of temperature. of water. High efficiency of the collector results from the ability to absorb diffused radiation (for example, on cloudy days) and maximum reduction of heat loss.
Advantages:
- The higher efficiency of the vacuum collector in comparison to a standard, flat collector.
- Simple design, low failure rate - service life of tubes over 15 years.
- Easy servicing and self installation possible.