Visualizing and simulating composite filtration mats : a study using X-ray microscopy and fluid flow simulations

Abstract

Our research focuses on verifying the design of efficient composite filtration mats using simulations based on XRM volumetric data. Three filter mats were prepared with different amounts of PET microfibers and electrospun PAN nanofibers, with and without a diblock copolymer. The structure of the PET-PAN mats was characterized by SEM and XRM. Three-dimensional XRM images were used in fluid flow simulations and the filtration properties were evaluated by standard methods. Incorporating 5-µm PET fibers with 1 wt% PAN nanofibers and a diblock copolymer doubled efficiency in single-pass filtration test at a small pressure drop. Raising PAN to 2 wt% increased efficiency to 72 % but also increased the pressure drop. Simulated permeabilities from XRM volumes follow the same order and lie within experimental uncertainties. Streamlines illustrate fluid flow paths within the simulated environment, showing locations where fiber bundles create straight-through pores. XRM simulations showed flow paths, confirmed permeability trends, and can guide the optimization of fiber dispersion. Discrepancies between XRM volumes and bulk tests show that microscale heterogeneity dominates resistance. Larger volumes are needed for accurate prediction. Streamline-guided rules can shorten development cycles by indicating where to adjust fiber orientation, nanofiber amounts and copolymer amounts.