A detailed parameter study on the comprehensive characteristics and performance of a parabolic trough solar collector system

This paper presents the theoretical analysis results of the relations between the geometric parameters of the reflector of a parabolic trough collector (PTC) system and the focal shape formed by the defocusing phenomenon of the non-parallel solar beam firstly. Then the effects of these designed parameters and the defocusing phenomenon on the comprehensive characteristics and performance of the whole process of the photo-thermal conversion in the PTC system were numerically studied and optimized, using a proposed three-dimensional integrated model combined the Finite Volume Method (FVM) with the Monte Carlo Ray-Trace (MCRT) method. It is revealed that the numerical results can be well explained by the theoretical analysis results, proving that the model and method used in the present study is feasible and reliable. It is also found that the comprehensive characteristics and performance are very different from some critical points determined by the defocusing phenomenon of the non-parallel solar beam. From these critical points, the optional ranges of the geometric parameters of the reflector are determined to collect the entire reflected beam from the reflector, with relative optimized performance. In addition, an improved description for the characteristics of the solar flux density distributions on the absorber tube is further presented. -- Highlights: • It is to present an analytical method or reference for designing more effective PTC. • Relations between the focal shape and the geometric parameters were analyzed. • Effects of the geometric parameters were studied by the FVM combined with the MCRT. • The comprehensive performance is mainly determined by the defocusing phenomenon. • Optional ranges of geometric parameters with optimized performance can be determined