CFD analysis of heat and mass transfer in hollow fiber DCMD enhanced by metal foam

This study introduces a novel approach to enhance hollow-fiber direct contact membrane distillation (DCMD) by integrating copper metal foam, a configuration unexplored in prior DCMD research, which typically focused on membrane modifications or geometric optimizations. Using a comprehensive three-dimensional computational fluid dynamics (CFD) model, we investigate four DCMD configurations: without metal foam (Model 1), with metal foam on the tube side (Model 2), shell side (Model 3), and both sides (Model 4). The high thermal conductivity (38 W/m.K) and porosity (0.9) of copper foam disrupt thermal and hydrodynamic boundary layers, significantly reducing temperature polarization and increasing water vapor flux by up to 32% and Sherwood number by 48% in Model 4 compared to the baseline. These improvements stem from enhanced convective heat transfer and flow uniformity, which boost the vapor pressure gradient across the membrane. However, the incorporation of metal foam increases friction factors, leading to higher pressure drops, though these remain low (386 Pa tube-side, 150 Pa shell-side) and compatible with standard pumping systems. This work demonstrates the potential of metal foam-enhanced DCMD for scalable, energy-efficient desalination, offering a promising solution for sustainable water treatment. Limitations include the need for experimental validation and optimization of foam properties to minimize energy costs, paving the way for future research to refine this innovative approach.