(227a) Understanding Membrane Separation of Gases in the Transition Flow Region Through Comsol Multiphysics Modeling

The pore sizes of many membranes presently being studied for separating the components in gas mixtures are on the scale of nanometers. Depending on the specific gases and pressures being used, this scale will put the flow either in the Knudsen flow regime or in the transition regime. The differential flow of the individual gas components gives the relative transport of the gases through the membrane. The solubility of the gases into and out of the membrane provides another mechanism of separation. The solubility can be enhanced through facilitated transport using carriers which react reversibly and selectively leading to improved permeate selectivity. However, before vesting resources in experimental programs, it is critical to develop a model to enable screening of viable solutions and avoid resource redundancy.  These models need to consider the impact of the different mechanisms on separation and predict the membrane selectivity and yield for facilitated transport in different Knudsen number regimes. In this work, we investigate methods of combining the different mechanism with a multiphysics model to understand the resultant separation. In particular, we look at implementations of some different transition flow models in this framework.