Analysis Of Thermal Performance And Heat Transfer Characteristics Of Discrete W-Shaped Ribs In A Double Pass Solar Air Heater

This paper presents the effect of discrete w-shaped ribs as artificial roughness over the absorber plate in a double/two pass solar air heater. For the experimentation, a duct rectangular in shape has been fabricated. Various parameters were taken for the analysis. Duct's aspect ratio (W/H) is taken as 10. The relative roughness pitch (p/e) is taken as 5, 10 and 20. The Reynolds No. for the experiment varies between 4500 to 12000. Analysis is done for single relative roughness height (e/D-h) of 0.044 and for single angle of attack (alpha) of 45 degrees with relative gap width(g/e) taken as constant at 2.0. From the experiment it has been observed that the Thermal performance and heat transfer characteristics get to its maximum at p/e of 10. This paper presents the variation of various parameters like Nusselt No., Friction factor, Thermal efficiency and Thermohydraulic efficiency with Reynold's no. at angle of attack (a) of 45 degrees in discrete w-shaped ribs placed over the absorber plate on both of its side.