Diffusion of ideal gases in capillaries and porous solids

✍ Scribed by D. S. Scott; F. A. L. Dullien

• Publisher: American Institute of Chemical Engineers
• Year: 1962
• Tongue: English
• Weight: 614 KB
• Volume: 8
• Category: Article
• ISSN: 0001-1541
• DOI: 10.1002/aic.690080126

✦ Synopsis

The steady state diffusion of gases through capillaries or through the pores of a solid when fusion, bulk flow of the gases is free to the total pressure in the system is constant is considered. I t is shown that the ratio of the molar occur, but in the present situation diffusion rate of the lighter gas to that of the heavier gas must be equal to the square root such bulk flow is effectively prohibited by the mechanics of flow in the fine of the ratio of the molecular weight of the heavier to the lighter.

From simple momentum transfer considerations a diffusion equation is derived to describe the diffusion rate as the nature of the process changes from ordinary mutual diffusion to pores* Therefore the rates Knudsen diffusion. This equation is shown to give good agreement with experimental measure-Of diffusion Of the molecular ments of diffusion rates in porous solids. A structural parameter of the porous solid, the diffusion species may be different, and the