Thermal performance analysis of parabolic trough solar collectors equipped with elliptical absorber tubes

The current study consist of a three-dimensional numerical simulation for steady state and turbulent flow conditions on the thermal performances of a parabolic trough solar collector (PTC) equipped with an elliptical absorber tube. The variation of the absorber tube's aspect ratio (a/b) on heat transfer, thermal efficiency, and exergetic efficiency was investigated under the effect of a non-uniform heat flux condition. ANSYS Fluent was utilized to simulate turbulent fluid flow and convective heat transfer inside the absorber tube, using Therminol VP-1 as the working fluid. The results show that the elliptical absorber tubes having smaller aspect ratios significantly raise the outlet fluid temperature and overall thermal efficiency, yielding improvements of up to 2.3 % in thermal efficiency and 7.78 % in exergetic efficiency. However, the use of an elliptical cross-sectional shape lead only to a marginal reduction in thermal losses. In conclusion, the use of elliptical absorbers in PTC systems show a good potential for the enhancement of the performances, particularly in low aspect ratio configurations, providing insights for future optimization of concentrated solar power systems.