Heat Transfer Coefficient for a Glazed Transpired Solar Collector in Natural Convection Mode

Abstract

A glazed transpired solar collector (GTC) was set up to operate in natural convection mode. Collector air temperature and velocity were measured at specific points in the collector. Solar radiation, ambient temperature, collector cover glass and absorber temperature were also measured. Using dimensional analysis and the measured data, a heat transfer correlation was obtained for the collector which will enable the heat transfer coefficient to be determined. The GTC heat transfer correlation based on influence of pitch is .  The GTC absorber plate hole diameter was 3.0 mm and the pitches ranged from 15 mm to 35 mm. The Nusselt number correlation for influence of pitch, P for  predicted all Nusselt numbers well with maximum error of 5.2%. The predicted Nusselt numbers using the correlation of this work were found to be in close agreement with a similar model which was developed based on the influence of absorber hole diameter. Furthermore, the correlation of this work is valuable for future studies on optimization of pitch for a given hole size in the application of the GTC for air heating and crop drying.