Hydrodynamic Enhancement of Direct Contact Membrane Distillation Using a Corrugated Feed Channel: A Numerical Study

Abstract

A numerical simulation of a direct contact membrane distillation (DCMD) cell that had rectangular corrugations placed in the feed channel was studied in this research to explore the benefits of hydrodynamic mixing and an increase in the rate of permeate flux. The coupling of flow and mass transfer in channel geometries, both in conventional and modified geometries, was simulated in a two-dimensional steady-state model to simultaneously describe the mass transfer and flow. The effect of different rib height, breadth, and pitch on pressure drop and permeate flow was investigated in a systematic fashion. Findings also indicated that rib geometry is a critical factor in determining mass transfer effectiveness and flow patterns. Specifically, raising rib height by 1mm to 3mm resulted in a significant reduction in permeate flux, mainly due to the growth of a greater number of layers of obstruction to the flow and the formation of concentration layers. On the same note, permeate flux gradually reduced with an increase in rib breadth. On the other hand, an increase in rib pitch 5mm by 15mm provided a small improvement in flux enhancement by removing excessive blockage of flows while also keeping mixing levels satisfactory. The pressure-drop analysis has shown that smaller rib pitches increased hydraulic resistance, which points to the fact that there is a trade-off between increased mass transfer and decreased flow losses. In general, the best setup was achieved with low rib height, intermediate width, and increased pitch, which optimally balanced the augmentation of flux and minimum pressure loss. The results are useful in designing more effective membrane modules since it was established that a small change in the geometry of the channels can have immense effects on DCMD performance.