Coupled optical and thermal analysis of large aperture parabolic trough solar collector

Large-aperture parabolic trough solar collector (PTSC) has the potential to improve the performance of the solar field and also to reduce the capital cost of the power plant. In the present study, coupled flux distribution and thermal analysis of large aperture PTSC are presented by incorporating the limb darkening effect. MATLAB tool is used to develop the in-house model to obtain the circumferential flux distribution on the absorber surface. The analyses are performed for different Sun shape models, the number of rays, aperture, rim angle, slope error, and receiver displacement on the flux distribution. The flux distribution for large aperture PTSC such as 7, 8, 9, and 10 m has also been studied with an available absorber diameter of 70, 80, 90 and 110 mm. Better manufacturing standards need to be incorporated to improve the performance of the large aperture PTSC with available receiver sizes. There is no significant effect on the intercept factor for the upward and downward displacement of larger aperture PTSC receiver, but the downward displacement of the conventional PTSC receiver drastically decreases the intercept factor. Based on the flux distribution analysis, a collector geometry having an aperture of 9 m with an absorber diameter of 110 mm has been considered for the thermal analysis. The effect of variation of the mass flow rate, aperture, and various heat transfer fluids are studied on the PTSC thermal performance. Liquid sodium offers the least thermal gradient around the absorber circumference, which leads to less deformation of the receiver from the focal length.

Automated summary

The study presents the coupled flux distribution and thermal analysis of large aperture PTSC incorporating limb darkening effect. Various parameters affecting flux distribution are analyzed, and the need for improved manufacturing standards to enhance the performance of large aperture PTSC is highlighted.