Optical modelling and performance analysis of a solar LFR receiver system with parabolic and involute secondary reflectors

In this paper, a pilot scale solar Linear Fresnel Reflector of 154 m2 is designed and optically analyzed with two different profiles for the secondary concentrator. Compounded profiles of parabolic (PB) and involute (IN) shapes are compared for the secondary reflector geometry. Non-uniform intensity distribution of the solar disc with the flux transmission by the Monte Carlo Ray tracing method is used. Analyses are carried out with a 3D optical model and the combined optical performance of the Linear Fresnel Reflector (LFR) system with the parabolic secondary reflector is compared with that of the involute secondary reflector. The effects of truncating the secondary reflectors, optimizing the focusing distance of the absorber and the gap between the absorber and the secondary reflector, are investigated. Also the effects of errors caused by sun-tracking and contour of the mirror surface are studied. The efficiency of the Linear Fresnel Reflector system with the two models of secondary concentrators at different incidence angles of the solar beam are evaluated with Incidence Angle Modifier. Optical performance at different Direct Normal Irradiance (DNI) conditions is also performed. It is found that the Linear Fresnel Reflector system with Parabolic secondary reflector provides a higher optical efficiency of 62.3% with secondary efficiency of 83.3%. The Involute secondary on the other hand, provides an optical efficiency of 59.5% and secondary efficiency of 78.33%.