The dispersion models developed by Turner and Aris for fluids flowing in packed beds of porous solids is here extended to packed beds of porous adsorbing solids. For the nonadsorbing systems it was found that molecular diffusion, convective flow in the bed channels, and holdup in pores are additive contributions to the overall dispersion coefficient. In adsorbing systems, however, it is here shown that pore holdup and adsorption are not simply additive contributions, but are combined in a complex fashion. The general expression for the adsorption coefficient, Eq. (33), is shown to reduce to the simpler equations for porous nonadsorptive systems and for nonporous adsorptive systems (chromatographic equations, ion exchange equations). EXTENSIVE work has been done in the last fifteen years to charactarize the flow pattern and residence time distribution of flowing fluids in porous and nonporous packed beds. The need for this information comes in the scale up of packed beds used as chromatographic, ion exchange and absorption columns as well as catalytic reactors, and review articles by Levenspiel and Bischoff [ 11, Hoelscher [2], and Bischoff and McCracken[3]
present the status of theory and experiment in this area.