Studies on effective thermal conductivities in packed beds

Applying both their own assumptions and the mechanism of lateral mixing proposed by Ranz ( 20 ), the authors obtained theoretical formulas for effective thermal conductivities k e in packed beds. Previously reported experimental data were analyzed with these equations, and the usable data for predicition of k e were shown. In order to see the influence of both packing characteristics and temperature on the effective thermal conductivities, experimental data were obtained with air for beds with various kinds of packing, i.e., iron spheres, porcelain packings, cement clinker, insulating fire brick, and Raschig rings. Correlation of these data with Equation (15) showed that this equation adequately expressed the heat transfer mechanisms in packed beds with motionless gases, especially at hight temperatures.