High levels of fine particulate matter pollution in metropolitan areas such as Stuttgart or Munich are currently the focus of media attention and are known nationwide. Fine particles with more than fifty percent having an aerodynamic diameter less than 2.5µm (PM2.5) pose a particulary high health risk as they can penetrate into the alveoli of the lungs by inhalation.
Cabin air filters are applied to protect vehicle passengers from this particulate matter by preventing dust, pollen and other particles from entering the interior. In order to meet the high requirements on filter performance, the so-called electret effect is used. Thereby, the known mechanical collection mechanisms are supplemented by additional electrostatic filtration effects. This allows for high collection efficiencies combined with high dust holding capacitiy and low pressure drop at the same time. However, the mechanisms of electrostatic separation are not yet fundamentally understood. By means of digital technologies sound knowledge about the particle behaviour on the microscale level can be aquired. Computer-aided simulation tools enable a virtual separation of the different collection mechanisms in order to make them individually and specifically analyzable.
The aim of the research project is to carry out the influence of electrostatic charges on filtration performance and thus decisively advance the microstructure simulation of cabin air filter media. Two different simulation approaches are considered. On the one hand, a well-established approach regarding filtration is used, which is based on xCT images of real filter media. The simulation process of the filtration process is then carried out on the digitized structures based on continuum mechanics. However, the unidirectional coupling between fluid flow and particles completely neglects particle-particle interactions. Therefore, a second approach is considered to be a fully coupled system in order to model the underlying physical procedures more precisely. This approach takes into account the mutual influence between fluid and particles as well as the interaction between individual electrostatically charged particles.
Funded by MANN+HUMMEL in the Graduate School of Excellence advanced Manufacturing Engineering (GSaME)
- Miriam Mehl
- Carolin Schober
- Manfred Piesche, Martin Lehmann (MANN+HUMMEL)