Enhancement of Convective Heat Transfer Coefficient in Solar Air Heater of Roughened Absorber Plate

This paper presents an experimental investigation of thermal performance of solar air heater with roughened absorber plate. Solar air heater for high air velocity, flow becomes turbulent. Turbulent boundary layer with small laminar sub-layer is formed on the absorber plate. Experimentally it has been found that laminar sublayer is formed on the absorber plate. Experimentally it has been found that laminar sub-layer offers very high resistance to heat flow. By breaking this layer or creating turbulent in this region, we can improve the heat transfer between absorber plate and air steam. Under the influence of artificial roughness on heat and flow characteristics, showed an important improvement in the thermal performance. The use of artificial roughness is found to be affective method to enhance the heat transfer coefficient.