Spectral characterisation of high temperature solar absorber coating

Abstract

In the course of the Raiselife project, four solar absorber coatings are to be evaluated after thermal cycling at a dish facility. One key parameter is the thermal emittance. Optical measurements carried out at PSA show a deviation between two complementary spectrophotometers. Different approaches for the mismatch correction are applied. After the successful correction, a new measurement routine following DIN EN ISO 22795-3 is defined and the corrected values are evaluated with a round robin campaign. The standard deviation of thermal emittance values determined by different participating laboratories can be reduced by implementing a common processing of spectral data. The postprocessed DLR/CIEMAT value deviates around 2.1 % from the mean value determined within the round robin campaign. A new calibrated reference standard promises a further reduction of the deviation and hence an improvement in the absorber coatings’ thermal efficiency characterisation.