Effect of physiognomic behaviour of symmetrical arc rib roughness having gaps and staggered rib on the thermal performance of solar air heater

Abstract

ABSTRACT This article pertains to physiognomic behavior of flowing air underneath the absorber plate using artificial roughness to enrich heat transfer coefficient (h) between the absorber plate and the flowing fluid by penetrating the boundary sub-laminar layer developed underside of the SAH duct absorber plate. This article reveals the effect of relative gap width (g/e) on thermal performance of roughened SAH duct using symmetrical arc rib roughness having gaps and staggered rib. The present novel arc rib geometry is obtained by providing additional gap in considerably long continuous arc segment of existing best arc rib geometry so as to break the boundary layer reformation along it. To determine the improvement in the proposed work, experimental results are compared with smooth SAH duct. The investigating parameters for proposed geometry are Re as 3000–16000, p/e as 10, α of 30°, p’/p of 0.4, Ng as 4, ng as 4, g/e as 2–5, e/Dh as 0.043, d/w as 0.65, g’/e as 1 and g/e as 2–5. Optimal escalation is perceived in Nu and f at g/e as 4 and 3, respectively. Maximum THPP is attained at g/e as 4. Under different operating circumstances, correlation development and economic evaluation have been conducted.