Modeling of dilute ethanol-water mixture separation by membrane distillation

The effect of membrane distillation process parameters on ethanol-water sep aration has been investigated using a comprehensive mathematical model. Thr ee mass transfer solutions are considered in the model, namely: the exact s olution of the Stefan-Maxwell equations developed by Krishna and Standart; the approximate solution of the Stefan-Maxwell equations suggested by Krish na and Wesselingh; and the binary Fickian solution. Temperature and concent ration variation along the how and diffusion paths are accounted for in the model. Though the exact and approximate solutions of the Stefan-Maxwell eq uations are coincident with each other, some differences are noticed betwee n them and the Fickian-based solution. The difference between the three mas s transfer-based solutions, as well as the process performance under severa l process parameters, are discussed. (C) 1999 Elsevier Science B.V. All rig hts reserved.