A Review on Comparative Study of Thermal Performance of Artificially Roughened Solar Air Heaters

Provision of artificial roughness is made to enhance the heat transfer rate in solar air heaters. Information regarding different configurations and geometries of roughness elements producing different quality and quantity of heat transfer is available in literature. This paper reviews the comparative rate of heat transfer quantitatively and qualitatively in artificially roughened solar air heaters of various configurations. Analytical and experimental result as well as worked out values of result with respect to heat transfer data in terms of Nusselt number, utilizing the equations or correlations developed by various researchers and investigators have been represented with respect to the roughness and flow parameters (p/e, e/D and Re), for the comparison of rate of heat transfer. The experimental values of average Nusselt number for multi V-roughness has been found to be the highest. However, the analytical values of average Nusselt number in the end of side roughened solar air heaters are the maximum.