Distillation of methanol-ethanol solutions in a small column containing hollow fibers is independent of whether the fibers are nanoporous or covered with a thin, highly permeable coating. The hollow fibers do not provide selectivity but serve as a form of structured packing, so that the fluid mechanics in the column is not constrained by loading and flooding. The overall mass transfer coefficient based on a vapor side driving force and measured across the fibers is around 0.03 cm/s, the result of roughly equal mass transfer resistances in the condensate, the membrane, and the vapor. Further improvements in this form of distillation will require significant changes in module design, which reduce each of these three resistances.
Bibliographical noteFunding Information:
This work was principally supported by the Petroleum Research Fund (grant 3653908328-AC9) and by the Department of Energy (grants CRADA LA01C10455 and FG07-02ER63509). Other support came from the US Air Force Office of Scientific Research (F49620-01-1-0333) and from the National Science Foundation (CTS 0322882). J.B.C. had a traveling fellowship from Postech, Pohang University of Science and Technology, South Korea.
- Fiber membranes
- Microporous and porous membranes
- Organic separations