Optical performance enhancement of solar flux distribution uniformity of solar parabolic dish cavity system

Abstract

The design of the cavity receiver plays a crucial role in the conversion from solar to thermal energy that is absorbed in the cavity receiver to the heat transfer fluid. Nonuniform heat flux at the surface of cavities generates structural failure due to thermal unbalance. This research focuses on the optimization of cavity design based on position, aperture diameter, and eccentricities of elliptical-shaped cavity to enhance the uniformity of solar flux distribution on the cavity walls. The optical analysis is performed using Monte Carlo ray tracing using COMSOL Multiphysics on conical, cylindrical, rectangular, spherical, and elliptical shapes to determine the solar heat flux distribution. The validation of the computational model is performed through published experimental and analytical data. The flux distribution is more dispersed in spherical and elliptical-shaped cavities when positioned above the focal plane. The flux distribution uniformity increases when the cavities are positioned at a higher distance from the focal plane whereas the larger aperture opening eases the absorption of radiation flux on the surface. Partial obstruction of incoming rays starts to occur when positioning the cavity at a higher distance as well as in smaller aperture openings. The optimum configuration of the elliptical cavity is with 30% eccentricity, 100 mm above the focal plane, and 250 mm opening, providing a solar flux distribution uniformity factor of 0.585.