Abstract
Studies were made of axial dispersion in packed beds at low Reynolds numbers (0.01 to 1) using imperfect pulse chromatography. Three types of experiments were used to measure dispersion. One set was done with non-porous particles, another with non-porous particles coated with a thin liquid film to which mass transfer occurred, and a third set was done with porous particles in which there was internal diffusion.
Measurements confirmed the presence of a maximum Peclet number in the low Reynolds number region, as was previously identified by other workers. At the lowest Reynolds number used, the Peclet number approaches a limit imposed by molecular diffusion.
Different values of the axial dispersion coefficient were obtained in the presence of mass transport and internal diffusion. This disturbing result calls into question the validity of the commonly accepted dispersion-fluid particle transport model of packed beds in the region of low Reynolds numbers.
