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T. Loimer, P. Uchytil:
"Influence of the flow direction on the mass transport of vapors through membranes consisting of several layers";
Talk: HTFFM-V, Marseille; 2014-04-23 - 2014-04-25; in: "Proceedings of the 5th International Conference on Heat Transfer and Fluid Flow in Microscale", L. Tadrist, I. Graur (ed.); (2014).

The flow of isobutane through a porous ceramic membrane consisting of three different layers is theoretically investigated. The individual layers have different thicknesses with pore sizes of 10 nm for the separation layer, 100 nm for the middle layer and 6 μm for the support layer. The mass flow is calculated for values of the upstream relative pressure, i.e., the ratio of the upstream pressure to the upstream saturation pressure, varying between 0.7 and 1. For small relative upstream pressures, the fluid does not condense within the porous membrane, and the mass flux is a few percent larger for the flow direction from the support to the separation layer than for the other flow direction. For larger relative upstream pressures, the fluid may condense and liquid or a two-phase mixture may be transported through parts of the membrane. The mass flow can become about 7 times larger for one flow direction than for the opposite flow direction. The flow is modeled accounting for capillary condensation, for the transport of energy, and for the temperature variation due to the Joule-Thomson effect.

http://publik.tuwien.ac.at/files/PubDat_234139.pdf