Numerical simulation of flow and mass transfer in profiled membrane channels for reverse electrodialysis

Abstract

Profiled membranes, the membranes with microstructures on one side or two sides, are expected to be a viable alternative to the spacers and enhance the power output of the reverse electrodialysis (RED) process. However, there are some problems for the present single-sided profiled membranes such as flow stagnating and insufficient fluid mixing. As for double-sided profiled membranes, the membrane preparation and exact stack assembling are still difficult. With respect to these problems, a single-sided wave-profiled membrane with wavy sub-corrugations as additional mixing promoters is proposed in this study. Based on the Computational Fluid Dynamics method, the flow and mass transfer characteristics in the wave-profiled membrane channel and several other channels (for purposes of comparison) are simulated. Results show that the single-sided wave-profiled membrane channel has more advantages than the single-sided pillar-profiled membrane channels especially at low Reynolds numbers typically used in RED applications, although its performance is still inferior to that of the double-sided chevron-profiled membrane channel and woven spacer channel. Furthermore, it can be proved that the wavy sub-corrugations can enhance the mass transfer and reduce the concentration polarization, while they have a better influence on the surface where the sub-corrugations are located.