Study of the aging of a solar absorber material following the evolution of its thermoradiative and thermophysical properties
Antoine Boubault, Bernard Claudet, Oliver Faugeroux, Nathan Guerin and Gabriel Olalde
Absorber materials used in concentrating solar power systems are subjected to extreme conditions such as high irradiation, high temperature and strong thermal shocks. These factors accelerate aging mechanisms that are responsible for the decrease of the material’s thermal performance. To evaluate the service lifetime of solar absorber materials, some thermoradiative and thermophysical properties need to be monitored. Our study focuses on a two-layer material (metal + black paint) that is commonly used in solar power tower receivers. Two devices are described: a solar optical fiber reflectometer allows estimating the normal solar absorptance of the paint coating; an impulse photothermal method coupled with an inverse method algorithm allows estimating the thermal diffusivity, effusivity, and conductivity of the coating, as well as the thermal contact resistance between the paint coating and the metal substrate. Some unexposed and aged material samples are characterized. Both devices enable us to estimate the properties accurately..
Keywords: CSP, solar, durability, aging, receiver, absorber, coating, paint, absorptance, diffusivity, effusivity, thermal contact resistance.