DISPERSION IN THE INTERSTITIAL SPACE OF PACKED-COLUMNS

In order to study the dispersion mechanism occurring in the interstitial space of a porous medium, a column was packed with large (210 μm) impenetrable particles by a special dry-packing procedure, designed to obtain a permeable bed that is as uniform as possible. The experimental conditions are selected so as to eliminated as far as possible any other source of dispersion and focus essentially on that arising in the moving fluid. A linear regression analysis of the dispersion data for non-retained solutes shows that the Huber and the Horváth and Lin models fail to describe correctly the experimental results whereas the Giddings model provides a good fit to the data. The reduced plate height becomes constant and equal to 2 at high reduced velocities. It reaches a minimum value of 1 at a reduced velocity of about 3. The models and some previously published experimental data are discussed at the light of these results. © 1990.