Modeling of mass transfer in multi-pass mass exchangers with external recycle

The mass transfer in a multi-pass mass exchanger with external recycle has been investigated theoretically. The analytical solutions were obtained by using the orthogonal expansion technique associated with the eigenfunction expanding in terms of an extended power series. The influences of the subchannel thickness ratio beta, recycle ratio R, and the parameter of permeable barrier gamma on the outlet concentration and mass transfer efficiency were discussed and represented graphically in the present study. The mass transfer efficiency improvement by employing the multi-pass mass exchangers with recycle was defined as the percentage increase in mass-transfer rate, based on that of a single-pass device with same working dimensions and without external recycle and any permeable barrier inserting. Considering both mass transfer efficiency improvement and power consumption increment, an optimal device performance of multi-pass mass exchangers can be obtained with the suitable adjustment of the permeable barrier locations.