Impact of pleating on the filtration performance of fibrous air filters

Pleated fibrous air filters are widely used for aerosol filtration but the impact of pleating on its filtration performance is still lacking detailed analysis. Pleating results in changes in thickness of the filter media (indentation or bulge zone) and it is generally difficult to simulate the particle filtration process of a pleat due to large difference in scale between that of the pleat and fiber. To address this problem, a dual-scale simulation method is developed in this study by combining the fiber-scale and pleat-scale models. This is achieved by incorporating the simulation results of fiber-scale models into the pleat-scale models, using the permeability coefficient and particle capture function of the porous media in the pleat model. From the fiber-scale model, it is found that the bulge zone is beneficial to improving quality factor as it could lead to a lower pressure drop. However, for the pleat-scale model, the indentation zone has a lower pressure drop than the bulge zone, resulting in a higher quality factor. This contradicts the findings of the fiber-scale model. For real applications, it has been found that pleating with indentation is more beneficial for filter performance compared to pleating with bulges. These findings help us better understand the pleating effect on filter performance and provide guidance on optimal pleating approaches.