Bulk and diffusional transport of gases at non-uniform pressures

Abstract

An analytical analysis is presented for bulk and diffusional transport in the continuum regime of a binary gas mixture under steady-state conditions. The analysis considers flow through a tube which is subjected to pressure and concentration gradients. This system is representative of most evaporation processes. The governing equations are solved with appropriate boundary conditions in order to determine an equation for the rate of transport of each component as well as the pressure and concentration distributions. The results of the analysis show that the pressure effect, which has hitherto been neglected, can be included with little additional mathematical complexity. The cases for which the pressure can be considered uniform are outlined and an important class of problems which manifest a non-uniform pressure are discussed.