COUPLING OF WALL CONDUCTION WITH NATURAL CONVECTION FROM HEATED CYLINDERS IN A RECTANGULAR ENCLOSURE

摘要

A numerical study has been conducted for natural convection heat transfer for air from two vertically separated horizontal heated cylinders confined to a rectangular enclosure having vertical walls of finite conductances and horizontal walls at the heat sink temperature. The interaction between convection in the fluid filled cavity and conduction in the vertical walls is investigated, Results have been obtained for Rayleigh numbers, Ra, between 10(3) and 10(6), dimensionless wall-fluid thermal conductivity ratio <(alpha)over bar> between 0.2 and 1000.0 and dimensionless wall thickness (W) over bar between 0.25 and 1.375. Results indicate that the Nusselt number along the vertical wall-fluid interface is a complex function of both Ra and <(alpha)over bar>. In general, the relative heat removal contribution by conduction in the wall through the top horizontal surface eta(N) decreases with Ra while that for the bottom surface eta(S) increases. For 0.2 less than or equal to <(alpha)over bar> less than or equal to 5.0, eta(S) is nearly independent of Ra. Moreover, for Ra greater than or equal to 10(5), 0.2 < <(alpha)over bar> less than or equal to 5.0 and 0.25 less than or equal to (W) over bar less than or equal to 1.375, eta(S), is independent of <(alpha)over bar> while eta(N) Lends to zero with increasing <(alpha)over bar>. [References: 7]