NATURAL-CONVECTION HEAT-TRANSFER AROUND HEATED CYLINDERS INSIDE A CAVITY WITH CONDUCTING WALLS

A numerical study has been conducted for natural convection heat transfer for air around two vertically separated horizontal heated cylinders placed inside a rectangular enclosure having finite wall conductances. The interaction between convection in the fluid-filled cavity and conduction in the walls surrounding the cavity is investigated. Results have been obtained for Rayleigh numbers Ra between 10(3) and 10(6), dimensionless wad-fluid thermal conductivity ratio ($) over bar alpha between 0.2 and 1000.0, and different thermal boundary conditions. The results indicate that wall heat conduction reduces the average temperature differences across the cavity, partially stabilizes the flow, and decreases natural convection heat transfer around the cylinders. Heat removal through the vertical wad is significant even when its outer surface is insulated. The overall heat transfer coefficient for both cylinders is correlated with C Ra-n for different ($) over bar alpha and thermal boundary conditions.