The Experimental Studies of Heat Transfer and Friction Factor in a Roughened Solar Air Heater using Arc Rib Geometries

Solar air heater utilizes rib roughness to enhance heat transfer. Experimental investigation has been conducted to study heat transfer and efficiency improvement in solar air heater using the arc rib roughness. Rib roughness has relative roughness pitch of 10, rib height is 2 mm and mass flow rate varies from 4000-14000. Heat transfer and efficiency improvement have been compared with smooth plate operating under similar flow conditions. Maximum enhancement in Nusselt number is 2.06, 2.25, 2.40 and 2.57 over a smooth plate for continuous arc, gap in a continuous arc, staggered element in broken arc rib and for proposed new arc rib geometry namely multi staggered element in broken arc respectively. Maximum thermo-hydraulic parameter amongst all arc rib geometries studied is reported as 1.70 for proposed new arc rib geometry.