Direct Observation of Fluid Mass Transfer Resistance in Porous Media by NMR Spectroscopy

Abstract

The kinetics of diffusion-controlled mass transfer between a fluid percolating through a bed of porous particles and the stagnant fluid in the pores of the particles (see drawing on the right) controls the rate of many important processes. The pulsed field gradient NMR method allows the rapid identification of the fraction of fluid exchanged between the stream and the pores during a given period of time. From this data the mass transfer kinetic coefficient, the porosity, the intraparticle diffusivity, and the tortuosity of the porous medium can be determined.