Improvement of ceramic absorber material for open volumetric receivers

The air receiver technology, which is demonstrated at the solar tower of Jülich, uses ceramic honeycomb structures to absorb concentrated solar radiation and transfer the heat to an air flow. Therefore, the absorbers have to be highly porous to let the radiation penetrate deeply into the structure but must also feature a large internal heat transfer surface. The paper reveals the basic correlation between geometry and performance by means of a simplified mathematical model. New developments of honeycomb absorbers are presented and their thermal efficiency measured in a laboratory test is shown. The absorber development is accompanied by a thermal shock and cycle test program to assure sufficient mechanical stabilit