A NEW CONCEPT OF A SELECTIVE SOLAR RECEIVER FOR HIGH-TEMPERATURE APPLICATIONS

A new volumetric solar receiver concept for central receiver systems is presented. It consists of a ceramic foil receiver, which is covered by a matrix of square channels of quartz glass. ambient air, used as heat transfer medium, is driven through the whole structure by a fan. The foil receiver is assembled of SiSiC ceramic and consists of square ducts with a cross section of 3 mm. The quartz glass matrix structure is made of square glass channels with a cross section of 15 mm which are melted together at the edges. The material is highly transparent to the solar radiation but partly absorbs thermal radiation emitted by the ceramic part of the receiver. For this reason it is possible to reduce the emissive losses of the receiver. The absorbed radiation in the quartz glass section can be regained as utilizable heat, as the matrix is cooled by the same air flow. A one-channel receiver model is presented to qualify the potential for energy conversion efficiency. It indicates that gas outlet temperatures up to 1000-degrees-C and efficiency improvements up to 10%, in comparison to a foil receiver without quartz glass structure, are possible. This effect can be proved in a wide range of parameter variations. A sensitivity analysis of the dependence of optical and thermal properties of the material on the coefficient of performance (COP) and a variation of the geometrical parameters are discussed.