Gas relative permeability in the capillary-network model

Abstract

A theory for the permeability to a gaseous phase of a network of capillaries containing a second adsorbate phase is derived in terms of equations previously developed for the flow of gas in regular capillary networks with radii randomly selected from a distribution. The role of blind, as well as through, pores is considered. Numerical calculations, using a matrix-inversion method, are used to evaluate the theory. Excellent agreement is found at low volume fractions V_s of the adsorbate, but divergence becomes marked as V_s→ 1. This can be attributed to the inability of the theory to account for the non-regular nature of a random network in which some capillaries are filled by condensed adsorbate.