Modeling Solar Cavity Receivers: A Review and Comparison of Natural Convection Heat Loss Correlations

As the main difficulty of modeling cavity receivers is determining natural convection heat losses, this paper presents a survey of the different natural convection correlations developed by several authors to model natural convective heat losses from cavity receivers of solar thermal power tower plants. The different correlations studied for modeling convective heat losses are later compared by performing simulations on an implemented cavity receiver. For this work a model of a PS10-like cavity receiver, using Solar Salt as the heat transfer fluid, is implemented in Modelica. The simulations have shown how the results of four out of the five studied correlations do agree, while one of the analyzed correlations clearly overestimates convective heat losses for the simulations performed.