Mass-transfer enhancement in double-pass mass exchangers with external refluxes

lThe enhancement of mass transfer in double-pass countercurrent-flow parall el-plate mass exchangers with uniform wall concentration and external reflu xes 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 f ully developed laminar flow and constant fluid properties. Considerable imp rovement in mass transfer is obtainable by employing double-pass devices wi th a permeable barrier instead of using double-pass devices with an imperme able sheet and single-pass devices. Analytical results also show that the r eflux ratio and permeable-barrier (or impermeable-sheet) position are two i mportant manipulated parameters resulting in substantial improvement of the mass-transfer efficiency compared with that in single-pass operations.