US EPA

4961666 

Journal Article 

EFFECTIVE DIFFUSIVITY AND TORTUOSITY IN WICKE-KALLENBACH EXPERIMENTS - DIRECT INTERPRETATION USING STOCHASTIC PORE NETWORKS 

Patwardhan, AV; Mann, R 

1991 

Yes 

Chemical Engineering Research and Design
ISSN: 0263-8762
EISSN: 1744-3563 

69 

3 

205-207 

WOS:A1991FY64100011 

Stochastic pore networks, previously developed to interpret mercury porosimetry and low temperature adsorption isotherms, have been applied to simulate diffusion in the classic Wicke-Kallenbach experiment as used to measure the effective diffusivity of a porous material. Solution of the overall flux across a network of size n x n requires the solution of n2 linear equations. Stochastic networks exhibit a distribution of individual pore segment fluxes, such that some large pores show low fluxes and vice versa. The overall flux provides a direct interpretation of tortuosity. A single pore size exhibited a tortuosity of 2.5. A uniform pore size distribution with pores up to 2000 angstrom gave a value of 3.36. Bimodal pore sizes gave anomolously high tortuosity beyond the percolation threshold for the large pores.