New low-cost medium-temperature solar collectors
Solar collectors are devices that concentrate sunlight onto a specially designed collector tube that converts that sunlight energy into heat. However, the tubes currently used at medium temperatures (between 100 and 300 °C) are rather complex and expensive to manufacture. The project SOLEGLASS (All glass mid temperature direct flow thermal solar vacuum tube) provided a route around this barrier by designing innovative solutions that improve vacuum retention. The main advancement the developed technology lies in is the replacement of glass-metal seals and joints with an all-glass system to compensate for the tube expansion and contraction. Researchers successfully developed solar collectors for compound parabolic concentrators (CPCs) and a concentrated solar power plant. Regarding the CPC collector, two modules were developed with seven tubes each. Simulation work focusing on the hydrodynamic, thermal and structural properties helped to find the best module design. The bellow-shaped ending on both sides of the tube is what reduces thermal losses. Prior to constructing the solar thermal collectors, team members successfully tested the structural behaviour of the glass bellow tubes under static and dynamic loads as well as high thermal and pressure conditions. Results from experimental tests and numerical simulations were compared. Based on these results, they adjusted and calibrated the models and designs. With minimised maintenance costs, SOLEGLASS solar thermal collectors provide a truly green, renewable energy solution for industrial and residential heating and cooling applications. Given that glass decreases material cost of solar tubes, SOLEGLASS technology will have a far-reaching impact on sustainable energy production.
Keywords
All-glass tubes, thermal solar collectors, heating, cooling, SOLEGLASS