Abstract
We measured gas and water permeability in sets of nano-composite silica gels, (silica gel network withaerosil particles), which are highly porous but low permeability materials. Experimental results showedthat 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 waterpermeability. This difference was analysed in view of the gas slippage effect. To this end, we tested andcompared different correction factor models (Knudsen and Klinkenberg correction factors) proposed inthe literature. We showed that the Klinkenberg factor increases with porosity, and discuss the effect oftortuosity. Models that account for porosity and tortuosity improve the accuracy of the prediction. TheKnudsen correction increased the accuracy of the experimental data and made it possible to extrapolatethe intrinsic permeability from the gas permeability with quite reasonable accuracy.