Experimental study of thermal augmentation in solar air heater roughened with aligned gaps in V-rib roughness with staggered element geometry

The most suitable approach to augment convective heat release rate is to fabricate the roughness underside of solar air heater (SAH) duct. This paper reveals an experimental effort made to augment the thermal performance of aligned gaps along with staggered element on SAH with minimum frictional consequence. The V-rib roughness namely aligned gaps in V-rib with staggered element roughness is evaluated with investigated range of parameters as relative rib height (e/Dh) 0.043, number of gaps (Ng) 2–5, relative gap breadth (g/e) 2–5, relative rib pitch (P/e) 10, relative staggered roughness pitch (P’/P) 0.4 and relative staggered rib length (r/g) 1. As per the selected mass flow rate Reynolds number varied from 4000 to 14,000. The result shows the augmentation in Nusselt number (Nu) value and friction factor (f) which is recorded as 2.16 times and 2.73 times respectively compared to flat plate surface. Performance of aligned gaps in V-rib with staggered element corresponding to studied geometrical parameters of roughness is compared with contemporary better performing V- rib geometry has also been done.