Dimensionless heat transfer correlations for estimating edge heat loss in a flat plate absorber

Abstract

Data obtained from heat transfer relations discretized with the finite element method were used in developing dimensionless correlations, which led to determining prediction equations for the average edge temperature of a flat plate absorber. For a prescribed flux, if parameters like the incident radiation intensity, edge insulation thermal conductivity and ambient temperature are known, the value of the edge temperature variable is immediately determined. A range of edge-to-absorptive area ratios is considered, as well as the effects of the edge insulation on enhancing thermal performance. Notably, the edge loss is high in absorbers with high edge-to-absorptive area ratios and ambient conditions with low ha and Ta. In extreme operating conditions, however, the loss can be employed of a high proportion. As a result, prediction equations are obtained, which can be employed in design and simulation so as to minimize useful energy losses and thereby improve efficiency