Comparison of different mass transfer models for direct contact membrane distillation flux evaluation

The discrepancies between mass flux prediction models is a major issue in membrane distillation (MD) literature. Computational fluid dynamics model was used to capture the driving pressure gradient across the membrane using a range of inlet feed temperatures and flow velocities. Hence, a comparison between the most pronounced prediction models is presented. Validation and error estimation of those models is done using recent literature experimental work. Results revealed that all current models follow and reserve the same trend of actual mass flux. Nevertheless, actual mass flux merges to a higher estimated model when flow velocity increased, which as a result decreased the error estimate of that model from 0.90 at low flow velocity to 0.03 at high flow velocity. Results also show the inapplicability of some models as the dusty gas model and Multi-pore size model in MD, while the precision of the others. This work also eliminates the doubts of Poiseuille flow as it clearly showed its significance in mass flux prediction. Current models are acceptable for the time being the stage of MD and are useful tools for sensitivity studies.