High performance selective solar absorber stable in air for high temperature applications

A new selective solar absorber stable in air based on a novel multilayer configuration is designed for CSP applications with operating temperatures up to 550 degrees C. This configuration satisfies the higher operating temperature requirements of next-generation CSPs and prevents the current high-temperature failures due to oxidation. This material is made of six layers (SiO2/PtAl2O3/Pt/PtAl2O3/CuCoMnOx/SiO2), deposited on stainless steel and quartz by the cost-effective dip-coating methodology. A solar absorptance of 0.957 and a thermal emittance of 0.10 at 500 degrees C are achieved for the optimised material prepared on stainless steel 316L. The work presents the optimisation and characterisation of the solar absorber developed in stainless steel and its durability study with respect to thermal and constant condensation conditions on both stainless steel and quartz substrates. XRD analysis indicates the high crystallinity of each constituting layer except SiO2 (amorphous) and the depth profile by XPS confirms the sequence of the six layers that comprise the absorber. The multilayer stack shows outstanding thermal stability withstanding perfectly 3072 h at 500 degrees C in an open air atmosphere (PC < 0.01), independently of the substrate. The resistance to condensation test is directly dependent on the substrate. The designed CuCoMnOx-based selective absorber confirms its ability to be used in solar thermal systems. The material presented can be used in parabolic trough receivers with the advantage of maintaining its performance in case of vacuum loss. Moreover, its stability under condensation conditions directs a future line of research aimed at its application in solar tower receivers (Inconnel/AISI 347).