Effective Efficiency Distribution Characteristics for Different Configurations of Arc and V-Shape Ribs in Solar Air Channels

Abstract

The usefulness of conventional flat plate solar air collectors can be enhanced by utilizing different geometries of artificial roughness on absorber plate, especially of ribs. Various configurations of arc and V-shape ribs as turbulence promotors have been studied with solar air collectors. The geometrical parameters for arc and V-shape ribs are almost similar, but significant variations can be observed in their performance. The current chapter discusses the comparative study of effective efficiency distribution characteristics for continuous arc vs continuous V-shape, discrete arc vs discrete V-shape, multiple arc vs multiple V-shape, and discrete multiple arc vs discrete multiple V-shape ribs. The potential parameters utilized for effective efficiency characteristic assessment are the relative roughness width (W/w), relative roughness height (e/D h), relative gap position (d/w), angle of attack (α), relative roughness pitch (P/e), and relative gap width (g/e). At low (3000 ≤ Re ≤ 7000) and high Reynolds number range (25000 ≤ Re ≤ 32000), comparatively more effective efficiency was observed for V-shape and arc rib configurations, respectively. The optimum values of e/D h, g/e, and d/w have been found to be 0.045, 1, and 0.65 for selected arc and V-shape rib configurations at low and medium Reynolds number range. The optimum values of P/e for discrete arc and V-shape ribs are observed at 10 and 8, respectively. The optimum value of W/w for multiple arc and V-shape ribs have been observed at 5 and 6, respectively. Similar trends have been observed for discrete multiple arc and V-shape ribs. The effective efficiency for a medium range of Reynolds number is observed to be more for discrete multiple arc ribs than for discrete multiple V-shape ribs. The outcome of the present study urges to find the cause of such deviation in the performance of arc and V-shape rib configurations.