PERMEABILITY OF PACKED-BEDS FILLED WITH POLYDISPERSE SPHERICAL-PARTICLES

The effective medium approximation (EMA) has been applied for the pred iction of the permeability of packed beds filled with polydisperse sph eres. The EMA assumes a model system in which a packing particle is su rrounded by a fluid envelope and an effective medium beyond the envelo pe. This model provides an analytical expression for the permeability of the packed bed as a function of the packing size distribution and t he porosity. Unlike the present model, most existing models utilize an average packing size for the permeability prediction as they are not capable of fully incorporating the packing size distribution. The perm eability prediction of the present model has been compared with those of recent numerical calculations, the semiempirical Kozeny-Carman corr elation, and experimental data that are available. The Kozeny-Carman c orrelation, which is widely accepted in industrial applications, uses a mean particle size to account for the packing size distribution. Bot h the present model and the Kozeny-Carman correlation show a good agre ement with the numerical results for packed beds of monodisperse parti cles and experimental data for packed beds of bidisperse particles. Wh ile the prediction of the present model agrees well with the Kozeny-Ca rman correlation when the packing size distribution is narrow, a signi ficant deviation is noted as the size distribution becomes broader.