Solar Radiation Conversion

This chapter covers the use of cellular materials as absorbers in volumetric solar receivers. A receiver is a central element of the so-called solar tower technology which converts concentrated solar radiation into high temperature heat. In the case of a volumetric absorber cellular material is employed to absorb concentrated solar radiation and to transfer the energy to a fluid flowing through its open cells. The concentrated radiation is generated by a large number of controlled mirrors (heliostats), each of which redirects the solar radiation onto the receiver as a common target on the top of a tower. An overview on the ceramic materials used is given as well as the most important thermophysical and fluid dynamic properties and how to determine them. Finally physical restrictions and problems occurring when using volumetric absorbers are presented