Numerical assessment of thermal performance of heated air duct with novel arc profile ribs in non-interrupted arrangement

Abstract

The use of roughness elements in the form of recurring ribs have been established to be a proficient technique of improving the thermal performance of the heated air ducts. In the present research work, the numerical assessment of the thermal performance of arc profile ribs arranged in a non-interrupted arrangement under forced convection has been presented. The ribs are attached to the bottom side of the heated air duct. The key geometrical parameters examined are a ratio of pitch of the rib to the height (p/y = 4–9), a ratio of the height of the rib to arc radius of the rib (y/r = 0.75–1), a ratio of the height of rib to the height of the duct (y/Y = 0.06–0.1) and Reynold’s numbers (Re) in between 12,270 and 36,810. It is revealed from the numerical evaluation that the novel arc profile ribs placed on the plate aids to encourage the level of turbulence which consequences in the improvement of the heat transfer. The thermal performance indicative parameters such as heat transfer improvement factor (HTIF), friction factor ratio (FFR), and overall thermal performance (OTP) are studied against variation of Reynold number and key geometrical parameters. The Nusselt number, friction factor for the ribbed plate represent an improvement of about 45%, 41% respectively as compared to the plain plate. The findings from the present work are compared with earlier published work for the same range of Re. The magnitude of OTP reported in the present work is higher than unity. Therefore this can be considered as one of the effective techniques for improvement of thermal performance of heated duct under forced convection.