Heat and mass transfer in packed beds

Abstract

Abstract Eddy mass diffusivities, effective thermal conductivities, and wall heat transfer coefficients were measured in an 8‐in. tube packed with 1/2‐ and 3/4‐in. glass spheres. Superficial mass velocities ranged from 110 to 1,640 Ib./(hr.) (sq. ft.), corresponding to modified Reynolds numbers of 100 to 2,000. Air was the main stream fluid in all cases. The modified Peclet group (D p V/E* td ) was found to be constant at a value of about 12 in the region of fully developed turbulence. At lower Reynolds numbers this group varied with the flow rate. Effective thermal conductivities were correlated by an equation. Modified Peclet numbers for heat transfer were about 25% less than those for mass transfer. The wall heat transfer coefficient varied with the superficial mass velocity as h w = 0.090 ( G o 0.75 ). An explanation is suggested for the similarity in velocity dependence between these values and those for turbulent flow in an empty tube, based on channeling at the wall.