Effects of fins geometries, arrangements, dimensions and numbers on natural convection heat transfer characteristics in finned-horizontal annulus

Abstract

Natural convection heat transfer in closed enclosure exists in a wide range of engineering applications. Although huge researches were conducted for natural convection in non-circular enclosures, researches for annular enclosures are very limited, especially finned enclosures. In the present results natural convection air flow and heat transfer characteristics in un-finned and finned annulus enclosed between two concentric horizontal cylinders are numerically investigated. The effects of the Rayleigh numbers, annulus width, fins geometrical dimensions, fins numbers, fins shapes and fins arrangements on the heat transfer, fluid flow and effective thermal conductivity of the annulus were investigated. The results show the increase of the heat transfer and the effective thermal conductivity of the annulus with the increase of the annulus thickness, Rayleigh number, number of fins and the fins width. For the same fins areas, the longitudinal fins showed more heat transfer rate and effective thermal conductivities enhancements compared to the annular fins.