Airflow and particle transport simulations for predicting permeability and aerosol filtration efficiency in fibrous media

- Synchrotron X-ray microtomography is used to produce images of fibrous filter media.
- Representative domains are created using Matlab®.
- Flow and efficiency simulations are carried out thanks to GeoDict®.
- Good agreement is found between experimental and simulated values of permeability.
- Simulated values of efficiency give a good approximation of experiments.

In this work, synchrotron X-ray microtomography was used to produce high spatial resolution images of two kinds of binderless and monodisperse fibrous filter media, made of fiberglass and sintered stainless steel respectively. Representative computational domains were created based on these images. Both flow and collection efficiency simulations were then carried out using the flow and particle transport modules of the GeoDict® code. An image analysis program based on Matlab® was used to determine the structural properties of the computational domain, namely the thickness, the solid volume fraction and the fiber size distribution. In parallel, permeability and collection efficiency measurements were performed on the same media, to provide an experimental comparison. Very good agreement was found between the experimental and the simulated permeability values. We showed that, in order to compare collection efficiency from experiments with those simulated with GeoDict®, it was necessary to take into account the difference between the thickness of the fibrous structures that were used to create the calculation domain, and the averaged experimental thickness characterized by SEM. Using this way of comparison, we obtained the first experimental validation of the GeoDict® code on both permeability and efficiency aspects for aerosols filtration.