Gas and liquid permeability in nano composites gels: Comparison of Knudsen and Klinkenberg correction factors
Résumé
We measured gas and water permeability in sets of nano-composite silica gels, (silica gel network with
aerosil particles), which are highly porous but low permeability materials. Experimental results showed
that gas and liquid permeability increased with aerosil content, allowing control of transport properties.
Our results also showed that gas permeability was more than one order of magnitude higher than water
permeability. This difference was analysed in view of the gas slippage effect. To this end, we tested and
compared different correction factor models (Knudsen and Klinkenberg correction factors) proposed in
the literature. We showed that the Klinkenberg factor increases with porosity, and discuss the effect of
tortuosity. Models that account for porosity and tortuosity improve the accuracy of the prediction. The
Knudsen correction increased the accuracy of the experimental data and made it possible to extrapolate
the intrinsic permeability from the gas permeability with quite reasonable accuracy.