Diesel particulate filters are effective devices to remove particulate matter from the diesel exhaust and to fulfill emission standards. However, the operating behavior is crucially influenced by the characteristics of the deposited and accumulated soot and ash, which is affected by different diesel engine operating parameters. This is especially relevant for the thermal control of the regeneration process that poses a challenge resulting from the lack of knowledge concerning the operation behavior of the filter.
Within this study, the regeneration behavior of diesel particulate filters with several age-related states is compared. For that purpose, filters were aged with an accelerated method. These filters were loaded with different steady state conditions at the engine test bench. The subsequent regeneration was applied via post-injection. Therefore, it was possible to investigate the influence of different ash levels on the regeneration behavior of the filter.
The results reveal significant differences concerning regeneration behavior of uncoated filters with several ash levels. Characteristic values were used for the evaluation of the regeneration process. The most relevant differences were visible when the filters were loaded with engine operating conditions with small particle agglomerates. These differences particularly include the duration, the temperature levels and temperature gradients inside the filter during the regeneration. Furthermore, the ash level influences the soot distribution and thus, the start of the soot oxidation and the temperature levels. In addition, the mass flow during the loading of the filter plays a significant role for the distribution of the soot and therefore for the regeneration process.