AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
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Modeling and Simulation of Electrostatically Charged Particle Dynamics in the Inflow and Transition Area of Cabin Air Filter Media
CAROLIN SCHOBER, David Keerl, Martin Lehmann, Miriam Mehl, MANN+HUMMEL GmbH
Abstract Number: 541 Working Group: Aerosol Physics
Abstract Cabin air filters are applied to prevent small particles such as pollen, fine dust and soot amongst others from being transferred into the interior (cabin) of a vehicle. The filter media often make use of the so called electret effect as means for achieving high filtration efficiency at low pressure drop. Thereby, electrostatic filtration effects are supplemented to the well-known mechanical collision mechanisms (such as inertia, diffusion, etc.). Besides the interference of several fiber-particle interactions (Coulombic attraction/repulsion, induced forces, etc.) particle-particle interactions potentially play an important role. However, this effect is completely neglected in previous research studies due to the high degree of complexity. The objective of this study is to determine the effect of particle-particle forces and whether a simplified approach is justifiable.
In this work, we present a detailed investigation of particle motion in the inflow and transition area of the filter media. For a precise description of the underlying physical procedures, the simulation is based on a fully coupled system. This approach takes into account the reciprocal influence between fluid flow and particle motion as well as the interactions between single electrostatically charged particles. The software package ESPResSo [1] provides a powerful tool for this four-way coupling. Based on a molecular dynamic approach the software offers the advantage of applying efficient algorithms for the modeling of long-ranged electrostatic interactions. In order to emulate the air flow, the molecular dynamic simulation is coupled with a Lattice-Boltzmann fluid. For comparison with testing results a wired mesh is used instead of the filter media which allows for excluding the electrostatic charges by grounding and focusing on the particle-particle interactions. Despite the simplification the scenario includes all modeling requirements as necessary for the complex filter media structure. The simulation results show significant deviations of particle trajectories for charged and uncharged particles, respectively.
[1] Arnold A., Lenz O., Kesselheim S., Weeber R., Fahrenberger F., Roehm D., Košovan P., Holm C., “ESPResSo 3.1: Molecular Dynamics Software for Coarse-Grained Models”, Lecture Notes in Computational Science and Engineering (2013).