Performance study of solar air heater duct with gap in V-rib with symmetrical gap and staggered ribs

Experimental study of SAH duct having absorber plate roughened with gap in V-rib with symmetrical gap and staggered ribs is carried out and effect on Nusselt number (Nu) and friction factor (f) is investigated. Range of parameters for the present study are Reynolds number (Re) of 4000–14,000, ratio of rib pitch to height (P/e) of 12, ratio of rib height to hydraulic diameter (e/Dh) of 0.043, flow angle of attack (α) of 60o, ratio of staggered rib position to pitch (P’/P) of 0.65, ratio of gap width to rib height (g/e) of 4, ratio of staggered rib size to rib height (r/e) of 4, relative gap position of gap in each of symmetrical rib elements (d/w) of 0.65, relative gap width of additional gap in each of symmetrical rib elements (g’/e) of 1 and number of gaps (Ng) of 1, 2, 3 and 4. Maximum augmentation in Nu and f is 2.05 and 3.39 times the smooth plate respectively corresponding to number of gaps (Ng) of 3. Thermo-hydraulic performance parameter (THPP) is also obtained maximum for number of gaps (Ng) of 3. Correlations for heat transfer and friction factor have also been developed. Experimental data is used for validation of mathematical model and is used for prediction of performance of SAH under different operating condition for the roughness considered.