Binary gas diffusion of methane-nitrogen through porous solids

Abstract

Diffusion rates of nitrogen and methane have been measured across ten porous solids at 35°C and 1 atm by a steady state flow method. The porous plugs used were cylindrical in shape, with diffusion occurring in the direction of the axis. Diffusion data were taken with porous cores either dry or saturated with liquids. Water and n -heptane were used as saturating liquids. The rather complex internal structure of porous solids were indirectly characterized through some auxiliary measurements. These included porosity, permeability, and electrical resistivity factor (yet another indirect measurement of tortuosity). The effective diffusion coefficients were correlated for the gas phase diffusion as a function of porosity. The ratio of effective diffusion coefficient to the open space diffusion coefficient ( De / Do ) was correlated for dry cores using the properties approximately characterizing the pore structure.