Studies on axial effective thermal conductivities in packed beds

The axial effective thermal conductivities of packed beds were determined by measuring the axial temperature gradients at steady state, the heat being conducted in the direction opposite to that of air. The present experiments were carried out with the beds of glass beads, metallic balls, broken pieces of limestone, and Raschig rings, taken in separate experiments. It was found that the axial effective thermal conductivity increases more with the increase of air flow than it does in the case of radial conductivity. The axial effective thermal conductivity coincides with the radial conductivity when N Re → 0.