Experimental investigation of free convection in roof solar collector

A test set-Lip was developed for determining the internal convective heat transfer coefficient and the induced air flowrate of a roof solar collector. The set-up was composed of an open-ended inclined rectangular channel. The tilt angle and air gap of channel were fixed at 30degrees and 140 mm, respectively. The inner channel width and length were 680 and 1360 mm, respectively. The upper plate was maintained at a uniform temperature and tests were carried out for a wide range of temperature varying between 40degreesC and 75 degreesC. Data analysis were made to develop Nusselt and Reynolds number correlations as a function of Rayleigh number and aspect ratio (gap/length). The equations could be used for deter-mining the mean convection heat transfer coefficient and the induced air flowrate of the roof solar collectors and a wide range of convective heat exchangers of similar geometry as well. (C) 2002 Elsevier Science Ltd. All rights reserved.