Cabin air filters in different states - new, used in cars and artificially aged with silicon dioxide, diesel exhaust gas and ambient air - were subjected to breakthrough tests with NO2 as the adsorptive gas. As expected, cabin air filters already used in cars exhibit a lower adsorption capacity for nitrogen oxides and with it a clearly higher breakthrough compared to new filters. At the same time the amount of NO2 which is catalytically transformed to NO on the activated carbon decreases. The filter performance of used cabin air filters varies considerably, which is plausible when considering different ambient conditions while driving, loading histories and changing intervals. Further tests are planned to investigate a correlation between the pressure drop over the used filter and filter deterioration, which the completed tests indicate. The simulation of cabin air filter ageing in cars with silicon dioxide, diesel exhaust gas and ambient air showed the influence of fine particles on the separation process of nitrogen oxide. While the filter loading with silicon dioxide particles in the micrometer range does not impair the NOx separation, the loading with diesel exhaust gas and ambient air containing fine particles in the nanometer range clearly deteriorates the filter performance. The breakthrough of NOx increases considerably and the catalytic conversion of NO2 to NO decreases. If the particle fraction of the diesel exhaust gas or the ambient air is almost removed, then the effects of the respective loading are reduced. These findings suggest that there is an important role for the fine particle fraction on the filter ageing process, in addition to the adsorptive loading with gaseous compounds. Currently, the activated carbon pellets of the filters loaded with diesel exhaust gas or ambient air are being microscopically investigated in order to locate the places of deposition for the aerosol particles. Furthermore, the loading of cabin air filters with an aerosol (air/graphite) with a mean diameter in the nanometer range is in preparation. In summary, it is possible to simulate the ageing process of cabin air filters during their life cycles with regard to NO2 separation capacity, by using diesel exhaust gas or ambient air as the loading aerosol. Artificial ageing with untreated diesel exhaust gas leads to a limited filter performance with regard to NO2 separation.
Adsorption performance of a cabin air filter during a life cycle
Filtration and Separation ; 49 , 4 ; 38-41
2012
4 Seiten, 7 Bilder, 9 Quellen
Aufsatz (Zeitschrift)
Englisch
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