Mathematical Modeling of a Hollow Fiber Membrane Module-Performance in Direct Contact Membrane Distillation

Using a multi-physics modelling approach, we investigate the effect of significant physical parameters involved in the direct contact membrane distillation process (DCMD) for hollow fiber membrane modules. A three-dimensional model was constructed to study the effect of operating conditions, and physical and geometrical parameters of the system on permeate flux. The normalized permeate flux was calculated for different module arrangements, fiber length, membrane structural parameters—tortuosity, porosity, external radius, and thickness—as well as operating conditions such as feed temperature, and flow configuration and velocities. The results indicate that the permeate flux decreases when fiber length, external radius, and tortuosity increase. Nevertheless, increasing feed temperature, fiber porosity and thickness, and velocity of permeate result in increased permeate flux. We found that the normalized permeate flux significantly dropped once the interspacing parameter of fibers—the ratio of external radius of fibers to the center-to-center distance between neighboring fibers—approached 0.47. Among all physical parameters, the importance of fiber length, membrane tortuosity and wall thickness were found to be most pronounced.