Heatable Optical Analyse System for High Temperature Absorbers
Abstract
Solar thermal power plants concentrate sunlight onto special absorbers that convert the radiation into thermal energy. The used ceramic absorbers in the solar tower power plant of Juelich are designed for thermal stability and high absorption. The surface properties should be optimized in different ways to increase the efficiency further. A new setup allows measurements of different optical and thermal quantities. The ceramic absorber cups can be heated in an oven element more than 800 °C, the front surface remains freely accessible for optical measurements. So the absorption and reflection as a function of temperature can be determined. For reflection measurements, the absorber is illuminated with a parallel source of radiation from a range of directions. With an integrated spectrometer connected to a measuring collimating lens the spectral reflectance is determined from different view angles. The spectral radiation factor is determined by comparing the reflection of a white standard with the reflection of the test surface.