Numerical Investigation of Solar Flux Homogeneity and Intensity of a Parabolic Trough Receiver with Various Secondary Reflectors

The geometry and configuration of the secondary reflector affects the optical efficiency of parabolic trough collector. Therefore, the configuration and most appropriate shape of the secondary reflector need to be investigated. In this study, a solar parabolic trough is optically analyzed with four different profiles of secondary reflectors including parabolic, triangular, flat–parabolic segmented, and parabolic–parabolic segmented. A ray-tracing software SolTrace was used to calculate the uniformity and solar flux intensity on the absorber tube. Different configurations were numerically simulated to analyze its effect on the flux uniformity and flux intensity to obtain the optimized geometry of secondary reflector. The results concluded that parabolic reflector increases the solar flux up to 37% with high uniformity. Triangular reflectors enhance solar flux up to 28% while having a weak flux distribution over the receiver. Moreover, high slope angle and small sides’ triangular reflector have better flux homogeneity. The flat–parabolic reflector is the second best option after the parabolic reflector since it improves the flux by up to 32% with a sigma flux value of 19.4%, indicating improved solar flux uniformity. Flat–parabolic segmented solar radiations are restricted by the curved parabolic segments. Finally, the parabolic–parabolic segmented reflector has a significant non-uniformity with sigma flux value up to 49.4% and the lowest efficiency of 64% because of the divergence of its distinct parabolic segment focal points.