Experimental investigation of free convection in roof solar collector

A test set-up 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 30° 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 40°C and 75°C. 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 determining 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.