Mass-Transfer Enhancement in Double-Pass Mass Exchangers with External Refluxes

The enhancement of mass transfer in double-pass countercurrent-flow parallel-plate mass exchangers with uniform wall concentration and external refluxes at the ends has been developed by either inserting an impermeable sheet or preferably inserting a permeable barrier. The analytical treatment was carried out by the orthogonal expansion technique with the assumptions of fully developed laminar flow and constant fluid properties. Considerable improvement in mass transfer is obtainable by employing double-pass devices with a permeable barrier instead of using double-pass devices with an impermeable sheet and single-pass devices. Analytical results also show that the reflux ratio and permeable-barrier (or impermeable-sheet) position are two important manipulated parameters resulting in substantial improvement of the mass-transfer efficiency compared with that in single-pass operations.