Study on solar photo-thermal conversion efficiency of a solar parabolic dish system

The solar parabolic dish system is an effective means to concentrate and convert solar energy into usable forms. Systematical investigation on the photo-thermal conversion efficiency is important to improve the cost effectiveness of the system. In this article, Monte-Carlo ray-tracing method is used to calculate the radiation flux distribution of the receiver, and then Fluent with User Defined Functions is used for radiation and convection heat transfer problems; lastly the energy efficiency of the system has been investigated by experimental method. During the period of the simulation and experiment, various direct normal irradiations were considered in this article. Model of the energy efficiency of the system has been established based on the first law of thermodynamics. The results show that outlet water temperature and energy input linearly increase with increasing direct normal irradiations, but energy output non-linearly increases with increasing direct normal irradiation. The results also show that the maximum energy efficiency is 52.12% when the direct normal irradiation is 80 W/m², whereas it has a minimum of 40.51% when the direct normal irradiation is 570 W/m².