Modeling of dilute ethanol-water mixture separation by membrane distillation

The effect of membrane distillation process parameters on ethanol-water separation has been investigated using a comprehensive mathematical model. Three mass transfer solutions are considered in the model, namely: the exact solution of the Stefan-Maxwell equations developed by Krishna and Standart; the approximate solution of the Stefan-Maxwell equations suggested by Krishna and Wesselingh; and the binary Fickian solution. Temperature and concentration variation along the flow and diffusion paths are accounted for in the model. Though the exact and approximate solutions of the Stefan-Maxwell equations are coincident with each other, some differences are noticed between them and the Fickian-based solution. The difference between the three mass transfer-based solutions, as well as the process performance under several process parameters, are discussed.