Filtration is an important technology for nanoparticle control and reduction of human exposure to nanoparticles. Filtration by non-circular fibers is gaining more attention in search for better filter quality; elliptical fibers have extra significance because they may be used in simple models of dust loading. We carry out numerical simulation to investigate filtration by fibers with elliptical cross-sections. The drag force on individual fibers is in good agreement with analytical solutions for elliptical fibers obtained from the cell model. Our simulation covers mechanisms for particle capture due to interception, inertial impaction, and diffusion. Single-fiber efficiencies of different elliptical fibers are computed. The figure of merit, which is an indicator of the ratio of the collection efficiency to the pressure drop, is used to evaluate the performance of different elliptical fibers. It is found that blunt and close to circular fibers perform better for particles dominated by the effects of interception and inertial impaction, whereas long and slim fibers perform better for particles dominated by the diffusion effect. For very small nanoparticles, the diffusion effect is important and long and slim elliptical fibers may improve the filter performance.
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Acknowledgments The authors thank the support of members of the Center for Filtration Research: 3M Corporation, Cummins Filtration Inc., Donaldson Company, Inc., E. I. du Pont de Nemours and Company, Samsung Semiconductor Inc., Shigematsu Works CO., LTD, TSI Inc., and W. L. Gore & Associates and the affiliate member National Institute for Occupational Safety and Health (NIOSH). Support of University of Minnesota Supercomputing Institute (MSI) is also acknowledged.
- Elliptical fibers
- Figure of merit
- Single-fiber efficiency