Simulation of Nonporous Polymeric Membranes Using CFD for Bioethanol Purification

A mechanistic model is developed to simulate ethanol purification using membrane technology. In the considered process, a feed solution containing 10 wt% water + 90 wt% ethanol is contacted with a polymeric dense membrane in a pervaporation system. The membrane selectively separates water from solution in order to purify the ethanol. In the development of the model, it is assumed that the water is the main penetrant through the membrane due to the hydrophilicity of membrane material. The mass fraction of water molecules in the feed solution, as well as membrane, is estimated using Maxwell-Stefan approach. The governing equations are then solved using finite element method in order to predict mass fraction, mass transfer flux, and velocity of the solution in the membrane module. The results indicate that the model can predict the formation of concentration and velocity boundary layer in the feed solution near the membrane/feed interface. Moreover, the developed model is robust and reliable in the understanding of membrane separation processes applicable for dehydration of alcohols.