Transient energy and exergy analysis of parabolic trough solar collector with an application to Sahel climate

The purpose of the present work is to investigate transient behaviour of a parabolic trough solar collector in the climate conditions of Sahel through the energetic and exergetic analysis. An unsteady state approach of the first and second law of thermodynamic is applied on the heat collector element. The Finite Volume and Gauss quadrature methods, and Tri-Dimensional Matrix Algorithm were used as computational methods. Synthetic oil was considered as thermal fluid. The incident solar radiation and solar radiation availability were estimated respectively by Capderou and Petela models for different tracking modes. Furthermore, the optical, thermal and exergetic fluxes and efficiencies were computed. Based on numerical results, it was concluded that, by realising 14.04 GJ/m(2), 71.62%, 71.47% and 9.08%, respectively the annual solar irradiance, optical, thermal and exergetic efficiencies, the polar East-West is the suitable one axis tracking mode. The decrease of the collector's thermal efficiency is monotonous with inlet temperature of fluid, while his transient exergetic efficiency varies toward an optimum point over the year,, corresponding to 150 degrees C.