Numerical validation of the dusty-gas model for binary diffusion in low aspect ratio capillaries

Abstract

The dusty-gas model is an empirical formulation commonly used to describe gas flows in porous media. While experiments have validated the model for pores with high aspect ratios, a validation for near-unity aspect ratios is lacking. We used direct simulation Monte Carlo to evaluate the accuracy of the dusty-gas model for binary diffusion in low aspect ratio capillaries. Our results suggest that the dusty-gas model deviates from the Monte Carlo simulations by less than 3% for aspect ratios ! 1, thus supporting its suitability as a phenomenological model for transport in nanoporous structures in various applications such as heat transfer, catalysis, and water purification.

Toward a universal framework for evaluating transport resistances and driving forces in membrane-based desalination processes

“…Analyzing mass transport in air-filled membranes involves the use of the Dusty-Gas Model and Stefan-Maxwell equation with the following assumptions: The air gap contains a binary mixture of air and water vapor, air is stagnant inside of the pores, flow is one-dimensional, and contributions from viscous flow can be neglected. The Dusty-Gas Model has been applied to transport through porous media and is a well-established model for gas transport ( 68 – 70 ). In addition, the assumptions made here have been applied in previous work to accurately simplify the expression for vapor permeability in air-filled membranes ( 17 , 25 ).…”

The Steady State Characteristics of Multicomponent Diffusion in Micro- and Mesoporous Media for Adsorbable and Nonadsorbable Species

“…Today, the dusty gas model [ 16 , 17 , 18 ] is usually used for quantitative description of diffusion in the pores of solids, while the generalized Maxwell–Stefan formalism [ 19 , 20 , 21 , 22 , 23 ] is most commonly used to model multicomponent mass transport by surface diffusion. It can be observed that both in the literature cited here and in other works where such complex diffusion is discussed, models describing simultaneous pore and surface diffusion are presented in such a way that only the total molar flux densities N tot can be calculated [ 21 , 24 , 25 , 26 ].…”