Spatial distribution of microstructure of solar receivers exposed to high solar fluxes

摘要

The tube type receivers of point focus systems are exposed to complex radiation and temperature distributions. In these conditions, long term aging can modify the material microstructure and also its spatial distribution around and along the tube as a consequence of the temperature gradients. In this work the microstructure spatial distribution of a receiver tube that has been in operation for more than 1000 hours is studied. The bulk microstructure examination along the tube and in the circumferential direction has revealed a complex precipitates distribution. These precipitates can modify the mechanical properties of the alloy. Therefore, it can seriously affect to the receivers reliability, and must be consider during the design phase. Moreover radiation seems to enhance the oxidation rate which can seriously affect the durability of the receiver.