Heat transfer characteristics of porous rocks: II. Thermal conductivities of unconsolidated particles with flowing fluids

Abstract

Abstract Experimental heat transfer studies were carried out in beds of unconsolidated glass beads and sand through which fluids were flowing. The scope of the measurements included four fluids, helium, air, carbon dioxide, and water liquid at atmospheric pressure in beds packed with four sizes of glass beads, 110, 370, 570, and 1,020 μ and with two sizes of sand, 110 and 240 μ. Flow rates ranged form 1 to 26 lb./(hr. sq.ft.) in a direction parallel and countercurrent to energy flow. The data were interpreted in terms of apparent, effective thermal conductivities of the bed. The values of k e increase significantly with mass velocity of fluid. By considering the mechanism of heat transfer in porous media a relationship was developed between k e and the heat transfer coefficient between fluid and particle. Treatment of the experimental data in this fashion, combined with available information for larger particles, results in a correlation of Nusselt and Reynolds numbers for air that covers the range N = 10 −1 to 10 4 .