Properties of an optical fluid filter: Theoretical evaluations and measurement results

The DLR solar furnace in Cologne has been working successfully since 1994 t o allow high flux tests in the field of solar chemistry and materials resea rch. Sophisticated measurement technique like the Flux and Temperature Meas urement System (FATMES) and the High Flux Spectrometer (HIS) support the ev aluation of measurement results. The efficiency of the DLR measurement equi pment is demonstrated by means of determination optical properties of a flu id filter. Additionally obtained measurement results are compared with theo retical calculations. The fluid filter was designed, constructed and tested to absorb undesired radiation before entering photochemical reactors. As a first application the filter was filled with water to absorb the IR pan of the solar spectrum. Due to the changes in the spectral content of the conc entrated radiation the flux measurement system had to be calibrated especia lly for the employment of the water filter. Each filler thickness requires its own calibration. This lead to an intensive measurement campaign to dete rmine the optical properties of the fluid filter and the efficiency of the measurement equipment.