Effect of pore structure and macroscopic non-homogeneity on the relative gas permeability of porous solids

Abstract

The effect of pore structure on the relative gas permeability, P_R, of a mesoporous solid containing a low volume fraction, V_s, of sorbed vapour has been examined by means of simple capillary models consisting of parallel or serial arrays of capillaries of varying radius. These simple models represent the limiting behaviour of a more realistic network model at high or low connectivity, respectively. Certain general results, as well as detailed information about the effect of the shape and width of the radius-distribution function, on the initial slope and shape of the P_R(V_s) curve are reported and conclusions are drawn about important aspects of the relative permeability behaviour of random and non-random networks. The effect of macroscopic non-homogeneity of the porous solid, in the form of axially or radially non-uniform porosity, on the initial slope of P_R(V_s) curves has also been investigated and shown to be an important factor to be considered in practice.