Radial effective thermal conductivity in packed beds with cocurrent gas-liquid downflow

Radial effective thermal conductivity and apparent wall heat transfer coefficient were measured from temperature profiles in cocurrent air-water downflow through beds packed with glass spheres of 3 different sizes (0.12-0.43 cm). This paper concerns the effective thermal conductivity. In the range of low liquid flow rate, a stagnant effective thermal conductivity, which was independent of gas and liquid flows, was predominant. In the range of high liquid flow rate, heat transfer by lateral mixing of liquid predominated. Effect of gas flow on the effective thermal conductivity appeared only for the conditions of low liquid flow rate and high gas flow rate. The effective thermal conductivity was correlated by employing a heat transfer model which took into account stagnant effective thermal conductivity and heat transfer by lateral mixing of gas and liquid, as in the following equation: (Formula present) where (αβ)g was expressed as a function of particle diameter alone, and (αβ)i as a function of particle diameter and gas Reynolds number based on the superficial velocity. © 1979, Society of Chemical Engineers, Japan. All rights reserved.