Analysis of mass transfer in parallel-flow dialyzer with internal recycle for improved performance

•Mass transfer for dialysis can be improved by applying the reflux effect.•Theoretical analysis of mass transfer in the dialyzer is analogous to heat transfer in heat exchangers.•Mass transfer resistance is reduced with the increase of fluid velocity by recycling.•Considerable improvement in mass transfer is achieved, especially for large flow rate and high reflux ratio.

The internal reflux effect on dialysis through the retentate phase of a parallel-flow rectangular module is investigated. Theoretical analysis of mass transfer in the membrane devices with or without recycling is analogous to heat transfer in heat exchangers. In contrast to a device without reflux, considerable mass transfer is achievable if parallel-flow dialyzers are operated with reflux, which provides an increase in fluid velocity, resulting in a reduction in mass-transfer resistance. It is concluded that reflux can enhance mass transfer, especially for large flow rate and feed-concentration operated under high reflux ratio.