Experimental study of free convection in compound parabolic concentrator (CPC) cavities

Abstract

An experimental study of the free convection heat transfer between the cylindrical absorber and the flat top of a compound parabolic concentrator (CPC) is described. Results are obtained for a range of absorber temperatures and four CPC cavity heights. For similar conditions of operating temperature, the heat transfer from a cylinder in free air is about 30 to 50 percent higher than in a CPC cavity. Two correlations for Nusselt and Grashof numbers have been obtained using the equivalent length and the cavity height as the characteristic length of the system.