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.

The present work deals with the performance assessment of the finite volume method (FVM) and discrete transfer method (DTM) in term of their abilities to accurately satisfy conservation of both scattered energy and asymmetry factor of the scattering phase function, after angular discretization and their computational time to calculate the scattering phase function, in radiative transfer problems. Studies are carried out for many representative benchmark problems dealing with one-dimensional steady state radiative heat transfer through participating gray media under diffuse incident irradiation. For problems considered, tests were performed for a wide range of optical thickness, angular resolution, and anisotropic scattering phase function approximation. The results from both DTM and FVM formulations are presented and compared with available analytical and numerical literature solutions. While the two methods were found to give practically the same results, the DTM was found to be much computationally economical than the FVM, to evaluate the scattering phase function.

This chapter deals with the comparison of four heat transfer fluids (HTFs) for enhanced performance in heat transfer rates on the Sandia experimental LS-2 collector in Sahelian climate. The tested HTFs are dry air, liquid water, Therminol VP-1^, and Syltherm 800. In the literature, the thermal modeling of the parabolic trough solar collectors (PTSCs) is done by assuming: the steady-state or quasi-steady-state regime, the constant properties of HTFs, and others. These assumptions underestimate the transient heat transfer through the HTF flow. Moreover, the best theoretical performance of PTSCs evaluated in terms of idealized processes has not been developed satisfactorily yet. Subsequently, none effective assessment method of the PTSC has been experienced to investigate its transient thermal and thermodynamic sensitivity to (1) the collector, (2) operational, and (3) meteorological parameters. The implemented numerical approach here follows the transient analysis on the first and second laws of thermodynamics published recently. The physical model of a tubular receiver comprised an outer glass envelop, absorber pipe, and heat transfer fluid. Their respective heat rate balance equations were reliably established, discretized by the finite volume method, and efficiently computed. Then, a transient exergy-degradation analysis is conducted and validated using the available experimental results.