Solar blind pyrometric temperature measurement on pressurized volumetric power tower receivers

The measurement in solar blind spectral regions of atmospheric absorption bands offers one possible solution of filtering the solar radiance from the measurement signal. Along with the intensity of the incoming solar radiation and the absorber emittance, the bi-directional reflection properties and the temperature of the object determine for the required selectivity of the spectral filter. Due to the solar blind selection of the measurement range, the influence of the atmospheric absorption on the measurement signal cannot be neglected even for small path length. The paper describes the methods of solar blind pyrometric temperature measurement on solar thermal high temperature receivers and shows the possibilities and limitations of accounting for the atmospheric absorption with models based on radiation transfer calculations. Finally, experimental results recorded with an infrared mirror scanner especially designed for the measurement on a pressurized volumetric receiver are presented and compared to thermocouple readings and results of thermodynamic models of the receiver