Mathematical model for the study and design of a solar dish collector with cavity receiver for its application in Stirling engines

This paper presents a mathematical model that allows representing the optical behavior of a solar parabolic dish concentrator and the thermal performance of a cavity receiver. A procedure and a graphical method for the design of dish/cavity systems are proposed. A parametric study of the main geometric variables is performed and the influence of climate variables on the thermal behavior of the system coupled to a Stirling engine is analyzed. The model considers errors of solar collector, intercept factor, reflected and emitted radiation, conduction, and convection heat losses. For the validation of the model, the results obtained were compared with theoretical and experimental results reported in the literature. The calculation of the radiation losses, emitted and reflected from the receiver presented errors of up to 14%, and the average error for the rest of the thermal losses, interception factor and the absorber's temperature, was less than 3%. These results show that the proposed model can be used with sufficient certainty to design and optimize solar dish collectors with cavity receivers.