The prediction of transport properties of porous media using fractal models and NMR experimental techniques

A model has been constructed to determine the transport properties of porou s media where the total tortuosity associated with the void space of a part icular porous medium has independent contributions fi:om the structural fea tures of the material over Various lengthscales. CCA fractal model structur es have been used to represent the structural characteristics of real pelle ts over micro/mesoscopic (up to similar to 10 mu m) and macroscopic(>10 mu m) lengthscales that are probed by NMR experimental techniques sensitive to these lengthscales. NMR relaxometry and mercury porosimetry have been used to study the micro/mesoscopic scale and Magnetic Resonance Imaging (MRI) h as been used to study the macroscopic scale. In combination with simulation s of molecular diffusion using a finite difference algorithm, a model struc ture consisting of a hierarchical combination of micro/mesoscopic and macro scopic lengthscale models has been shown to give excellent predictions of t he total tortuosity of real pellets determined by MRI methods. (C) 1999 Els evier Science Ltd. All rights reserved.