A REVIEW REPORT FOR HEAT TRANSFER AND FLUID FLOW CHARECTRISTICS
Keywords:
Relative roughness pitch, (p/e); Relative roughness height, (e/D); Flow Reynolds number, (Re); Nusselt number, (Abstract
Solar air heaters are one of the simplest and cost effective solar energy utilization systems for various drying applications. The thermal efficiency of solar air heaters is found to be low due to low heat transfer coefficient on the air side. Attempts have been made to enhance the heat transfer rate from the absorber plate to air by using different roughness elements. Enhancement of heat transfer coefficient is achieved by providing artificial roughness, always goes with an increment of pressure drop and more pumping power is required. So, there is a need to optimize the system parameters to maximize heat transfer, while keeping the friction losses as low as possible. In the present paper the effect of artificial roughness of various geometries and glass cover on the performance of solar air heaters, investigated and analyzed by different investigators, has been mentioned. Also the results due these roughness and glass covers have been illustrated.
