Russia: Collectors with a Convex Polycarbonate Casing
A Russian solar thermal pioneer: Boris Kazandzhan, President of Holding Alten, has over 25 years of practical expertise in the solar energy sector. He has now developed a new generation of collectors with a multi-layer polycarbonate casing. Serial production is planned for the first half of 2010.
Photo: Bärbel Epp
The brand mark of the Russian company Holding Alten, which is located near Moscow, is a collector panel with a convex form: The collector manufacturer developed a collector model with a double-layer, cellular polycarbonate cover, which surrounds the absorber entirely. “This curvature of the transparent enclosure better withstands external overload and allows us to use curved absorbers, which collect more energy during a day than the ones with a flat form,” Boris Kazandzhan explains. He is professor at the Moscow Power Engineering Institute (Technical University) and President of Holding Alten.
“The small space between the two polycarbonate layers prevents convection of air and therefore decreases heat losses to the environment,” adds the professor. “Cellular polycarbonate is a very fitting material for transparent covers of collectors. Although the temperature is much lower in practice, it can be used even at 130 °C. It has a good transparency value (82 %) and resistance to UV radiation.” The absorber consists of separate and slightly bent extruded aluminium sheets, with special indentations at its back, in order to press in copper tubes. The selective coating on the absorber surface consists of titanium carbide. Mineral wool was chosen for the heat insulation between the back wall of the transparent enclosure and the back side of the absorber. The manifolds are leaving the collector casing at the top and the bottom.
Holding Alten is made up of two companies, one for research, called Scientific-Production Company (SPC) Alten, and one for producing the collectors, called Alten. Kazandzhan heads both companies and wants to start serial production of the new collector type in the first half of 2010. The production line is about to be set up already.
The polycarbonate enclosure of one collector module is 2.1 m long and 1 m wide. The company uses a special procedure to achieve the curving with a 4 cm radius at both sides. Alten collectors are lighter than flat plate collectors with a metal frame and a glass cover.
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