Heat transfer from a cylinder in a porous medium subjected to axial flows.

Abstract

Heat transfer from an isothermal cylinder placed in a porous medium and subjected to natural or forced flows in the axial direction has been studied experimentally. It is shown in a preliminary analysis that both natural and forced convective-heat transfer from the cylinder may be described as a perturbed case from a flat-plate problem. ξ=L/a√(Ra) and ζ=L/a√(Pe), each representing the curvature effect, serve as the parameters for natural and forced flow, respectively. The departure of the heat transfer rate relative to a flat-plate case is described as a function of ξ or ζ. Using a porous layer of glass beads and water, heat transfer rates from the cylinder are measured for three different sizes of bead diameters. The experimental results agree well with the theoretical predictions; the Nusselt numbers divided by √(Ra) or √(Pe), in general, increase as ξ or ζ increases.