In order to comply with increasingly stringent emission regulations and ensure
clean air, wall-flow particulate filters are predominantly used in exhaust gas
aftertreatment systems of combustion engines to remove reactive soot and inert
ash particles from exhaust gases. These filters consist of parallel porous
channels with alternately closed ends, effectively separating particles by
forming a layer on the filter surface. However, the accumulated particulate
layer increases the pressure drop across the filter, requiring periodic filter
regeneration. During regeneration, soot oxidation breaks up the particulate
layer, while resuspension and transport of individual agglomerates can occur.
These phenomena are influenced by gas temperature and velocity, as well as by
the dispersity and reactivity of the soot particles. Renewable and biomass based
fuels can produce different types of soot with different reactivities and
dispersities. Therefore, this study focuses on the influences of soot dispersity
and reactivity by varying the reactive particle system. A model wall-flow filter
channel is used for the investigation, enabling the observation of the layer
break-up and detachment of particle structures from the filter surface over the
entire channel length using a high-speed camera operating at 1000 fps.
Recordings reveal significant differences in the behavior of the different soot
types. Image analysis provides insights into the visual layer break-up,
evolution of structure sizes, detachment dynamics, agglomerate velocities, and
the spatial and temporal distribution of detachment events. General parameters,
such as regeneration time and pressure drop, further characterize the
regeneration process. The results provide insights into the detachment and
rearrangement behavior of reactive particle structures with varying dispersities
and reactivities in wall-flow filters, demonstrating that these characteristics
can significantly influence the regeneration process.