HYDRODYNAMICS AND HEAT-TRANSFER IN PACKED-BED WITH COCURRENT UPFLOW

The authors investigate radial heat transfer in packed columns with cocurrent upflow of gas and liquid. The experiments are performed in a packed bed electrically heated through its wall, with flow of water and saturated nitrogen. The packing diameter has been varied from 1 to 6 mm, and the reactor inner diameter is either 50 or 100mm. Radial and axial temperature profiles are measured inside the packed bed. The heat transfer parameters of the packed bed are obtained by fitting the parameters of a two-dimensional, homogeneous model to the measured profiles: the radial effective thermal conductivity of the packed bed (LAMBDA(r)), and the wall heat transfer coefficient (alpha(w)). The liquid holdup is measured by conductimetric probes, using a salt tracer technique. The heat transfer in the packed bed strongly depends on the flow regimes. A discussion on the flow regimes and on liquid holdup estimation is first presented and then heat transfer results and correlations are proposed for each flow regime : separated flow, bubble flow and pulsed flow.