Heat transfer and fluid flow investigation in dimple roughened solar duct arranged in multiple arc pattern
Ahmad Kamal Hassan, Mohammad M. Hasan, Mohammad Emran Khan
Abstract
This paper deals with the effects of roughness parameters on Nusselt number (Nur) and friction factor (fr) for dimple roughened solar duct arranged in multiple arc pattern tested under actual outdoor condition. Maximum rise in Nur is seen at Reynolds number (Re) 17,984, roughness relative width (W/w) of 4, relative roughness height (e/Dh) 0.036, relative roughness pitch (p/e) 12 and arc inclination (α) 60˚ while maximum fr is observed at Re 2200, W/w 5, e/Dh 0.045, p/e 4 and α/90 of 0.667. Maximum augmentation in ‘Nur’ & ‘fr’ for varying ‘p/e’, ‘e/Dh’, ‘W/w’ and ‘α’ was, respectively, found as 3.19–5.56 times, 2.87–5.61 time 3.29–5.16 times and 2.74–5.18 times for ‘Nur’ and 1.14–1.62 times, 1.36–2.27 times, 1.88–2.15 times and 1.01–2.16 times for ‘fr’ compared to non-roughened duct.