Determination of Pore Size Distribution in Porous Media

2 Determination of Pore Size Distribution in Porous Media 

The pore size distribution in a porous medium is determined by measuring the counterdiffusion rates of two gases across the medium in a Wicke-Kallenbach experiment (Brown and Travis, 1983). The experiments are carried out without a temperature or pressure gradient across the pellet. 

The thickness of the porous medium is L. The mole fractions of a gaseous species A at the near face and a distant face at L are denoted by y Q and y, respectively. Define a as a function of molecular weights of the gases A and B as follows  

For diffusion through a cylindrical pore, an equation describing the dependence of diffusion rate on the porosity (e), temperature (T), pressure (P), and pore size (r) is given as 

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