An Experimental Analysis for Thermal and Thermohydraulic Performance of Double Pass Solar Air Heater having W-shaped Artificial Roughness on Absorber Plate

Abstract

This paper represents the enhancement in thermal and thermohydraulic performance of double pass solar air heater by employing W-shaped artificial roughness on both sides of absorber plate. An experimental investigation carried out on double pass solar air having rectangular duct of aspect ratio (W/H) 10. Artificial roughness in the form of W-shaped attached on both sides of absorber plate at 450 inclination angle (α). The relative roughness height (e/Dh) is fixed as 0.044 and relative roughness pitch (p/e) is varies from 5 to 20. Reynolds number for experiment varies from 6900 to 14000. It has been observed that artificially roughened solar air heater is more efficient than smooth one. At relative roughness pitch (p/e) of 10 maximum thermal and thermohydraulic efficiency occurs that is 1.45 and 1.4 times respectively of the smooth plate.