Thermo-Mechanical Analysis of a Silicon Carbide Honeycomb Component Applied as an Absorber for Concentrated Solar Radiation

Abstract

The study focuses on a numerical model describing the thermo-mechanical processes in an open volumetric solar absorber. In this application thermal loads of up to 850 kW/m² induce mechanical stresses inside the volume of the component. The objective of the study is to identify critical thermal load cases which may especially occur during start-up or shut down cases as well as during the transition of clouds. The study can be subdivided into three major parts. In a first step, the mechanical strength of the investigated materials has been determined in double-ring, three or four-point bending tests. In a subsequent numerical stress analysis the maximum stresses in the walls of the honeycomb structure at fracture load have been determined. The results of this combined experimental/numerical approach have been compared with the strength properties of dense materials. In a second step various transient and stationary load cases were considered and the corresponding temperature distributions were calculated. Thirdly, the thermo-mechanical model was used to determine the stress distributions which have been induced. Special attention was paid on the influence of the macro geometry and cell-density. The results of the study allow important conclusions for the operation of the receiver.