ALTERNATING FLOW MODEL FOR MASS AND HEAT DISPERSION IN PACKED-BEDS

The alternating flow model (AFM) views dispersion in packed beds as a sequence of streamline plugs that must repeatedly split and merge as the bulk fluid traverses the vessel. Thus, the flow in the AFM is ordered, as opposed to the random flow implied by the Fickian analogy. For mass dispersion only, model parameters arise from a priori considerations of packing geometry. Steady state and transient data (5. 6 less than D//t/d//p=21 54. 4, 100 less than Re//p less than 1000, gases and liquids) show the AFM to surpass the Fickian analogy (based on correlations for dispersion coefficients) in most cases.