Diffusion of gases in porous solids: Simulations and measurements
Abstract
The diffusion of a gas in a porous solid is analogous to two other classical problems: the conduction of heat in a two phase medium, one phase being insulating, and the conduction of electricity in a two phase medium one phase of which does not conduct. An example of the latter would be the problem of predicting the resistance of an electrolyte containing gas bubbles given the resistivity of the electrolyte alone and information on the gas bubbles. This problem was examined theoretically by both Maxwell and Bruggeman who provided equations that predict the variation of the effective resistivity (or its inverse, the effective conductivity) versus the volume fraction of bubbles. This analogy appears to have been left unrecognized and unexploited by investigators concerned with predicting diffusion rates in porous solids. It enables the prediction to be made using the Maxwell or Bruggeman equations. Conversely the Monte Carlo simulations of gaseous diffusion in porous solids being carried out at Berkeley should yield predictions of the effective conductivity of electrolytes containing gas bubbles. Some results from the new algorithm for predicting gaseous diffusion rates are compared to the predictions of the Bruggeman and Maxwell equations.
 Publication:

California Univ., Berkeley Report
 Pub Date:
 April 1984
 Bibcode:
 1984ucb..rept.....E
 Keywords:

 Gaseous Diffusion;
 Porous Materials;
 Solids;
 Algorithms;
 Bubbles;
 Gases;
 Monte Carlo Method;
 Predictions;
 Rates (Per Time);
 Simulation;
 Fluid Mechanics and Heat Transfer