A Numerical Study of the Natural Convection in CPC Solar Collector Cavities with Tubular Absorbers

Abstract

The laminar free convection in a compound parabolic concentrator (CPC) solar collector cavity is numerically simulated using the finite element method. Results are presented for representative CPC collectors with tubular absorbers of concentration ratio 2. The effect of Grashof number, truncation and tilt angle were investigated. Generally, higher rates of heat transfer between the tubular absorber and the flat cover plate of the cavity are associated with larger Grashof numbers and shallower cavities. The maximum heat transfer rates occur when the tilt angle is about 60 deg. Contour plots are obtained for the field variables and these provide an insight into the spatial characteristics of the convective mechanisms within the cavity.