Comparative Flux Measurement and Raytracing for the Characterization of the Focal Region of Solar Parabolic Trough Collectors

The focal region of parabolic trough collectors is extended over the whole length of the concentrator. This complicates the measurement of the flux distribution on the absorber of such solar collectors. However, in order to optimize the solar field output it is essential to study the effects of absorber geometry and concentrator precision on the optical performance of parabolic trough collectors. The intercept factor of radiation with the absorber is a significant measure for this. In this paper we present and compare three methods, a ray-tracing simulation model and two measurement systems, to assess the flux distribution in the focal region, from which the intercept factor can be calculated. Using real reflector surface data from photogrammetry, the ray-tracing results show very detailed flux maps that are in agreement with measured flux distribution in the focal area. Thus, collector optimization with ray tracing tools becomes an attractive option.