Exergetic Optimization and Optimum Operation of a Solar Dish Collector with a Cylindrical Receiver

Abstract

An exergy and energy analysis on a solar parabolic dish collector (PDC) is carried out. In the experimental conditions the destructed exergy due to solar energy absorption by receiver and heat losses from the receiver end up being approximately 60% waste of total exergy in some cases. The maximum exergy efficiency in the experiments is less than 10%. An objective function for maximizing the exergy efficiency is developed mainly based on heat transfer fluid (HTF) inlet temperature and mass flow rate. Optimization results indicate that the HTF outlet temperature as design parameter can be specified based on the given system application. At optimum values of operating parameters, the maximum destructed exergy due to solar absorption and heat losses from the receiver are less than 45 and 15%, respectively. A parametric study based on the developed objective function shows that exergy efficiency greater than 20% is attainable. In this condition an optimum HTF inlet temperature to the receiver is found to be approximately 310 K. The intensity of solar irradiation has significant effect on the optimum HTF mass flow rate. To achieve the maximum exergy efficiency, depending on solar intensity, the optimum HTF mass flow rate must be selected from optimization results.