Application of Transport Equations for Heat and Mass Transfer to Distillation of Ethanol and Water

摘要

The purpose of this work is to apply equations for heat and mass transport that are derived from irreversible thermodynamics to distillation. They contain six resistances based on experimental data, correlations, and kinetic theory. Data from an experimental rectifying column that separated ethanol from water were used. Overall resistances were obtained by fitting theoretical expressions for forces and resistances to the experimental entropy production rates. The entropy production in the interface was negligible with resistances from kinetic theory. In this case, we can therefore assume that there is local equilibrium across the interface. In our formulation the resistances have a contribution up to 11 % from the coupling between heat and mass transport in the liquid phase, i.e. thermal diffusion. In contrast to normal practise, this coupling effect can thus not be neglected.