The influence of interfacial transfer and film coupling in the modeling of distillation columns to separate nitrogen and oxygen mixtures

Abstract

Coupling between heat and mass transfer occurs across interfaces and in vapor and liquid films. In this work, we present the first rigorous investigation of the role of these physical phenomena in the mathematical modeling of distillation columns for a nitrogen–oxygen mixture. Coupling phenomena in the liquid film have a strong influence on the local behavior, where it can alter the direction of the measurable heat flux in that phase and change the nitrogen molar flux by 45% on average. However, we found that the steady-state temperature and concentration profiles inside an adiabatic distillation column for nitrogen–oxygen separation remain largely unchanged. This supports the common approach of neglecting these physical phenomena in such modeling. Since the values of the interface coefficients, estimated by kinetic theory, have unknown uncertainties, further work is needed to reveal the true magnitude and relevance of these parameters, either experimentally or by use of non-equilibrium molecular dynamics simulations.