NUMERICAL STUDIES ON CAPABILITY TO FOCUS SOLAR RADIATION WITH MIRRORS OF DIFFERENT CURVATURES

The article presents the methodology and results of a parametric analysis performed to investigate the effects of changes in the curvature of the solar concentrator mirror on its ability to focus the radiation. Working conditions of the concentrator, i. e. possible values of radiation intensity, were adopted according to irradiance typical for Poland, and, therefore, similar to the conditions in many European countries. The curvatures of examined mirrors were obtained by modification of a parabolic curve. The calculations were conducted for two cases: when the Sun radiation falls completely directly and when it's half diffuse. The 2-D simulations were conducted in ANSYS FLUENT 18.2 software. Discrete ordinates model was employed to simulate radiation phenomenon. Also, a sensitivity analysis was carried on discrete ordinates model parameters and density of the computational mesh. The results allow stating that some of the new curvatures provide only slightly worse focus than the classical parabolic shape, but also show greater insensitivity to the increasing share of diffusive part of radiation. The presented model is a quick and proven tool for testing new curvatures of solar concentrator mirrors.