Numerical and experimental investigation of different rib roughness in a solar air heater

A numerical study is aimed at comparing dissimilar types of repeated-rib roughness: arc-shape with gap and V-shape with gap on the absorber plate of the solar air heater having similar shape and size working under identical boundary conditions. Relative gap width (g/e) of 1, relative roughness height of 0.04, the relative roughness pitch of 10, p/P = 0.65, d/W = 0.69, No. of gaps = 1, attack angle alpha = 60 degrees of the rib, heat flux 1000 W/m(2), etc. are kept constant and variation in range of Reynolds number is 3000-15000. Numerical simulations are conducted with the help of ANSYS CFD tool, and results have been validated with the experimental studies. The V-shape ribs have maximum frictional loss penalty of 4.05 and Nusselt number enhancement of 3.4 at Re 3000. The arc-shape ribs have maximum frictional loss penalty of 3.94 and Nusselt number enhancement of 2.4 for Re 15000. The maximum THPP for the V-shape ribs and arc shape ribs are 2.21 and 1.5 respectively at Re 3000.