Direct Visualization of Soot and Ash Transport in Diesel Particulate Filters during Active Regeneration Process 2019-01-2287
This study employed a diesel particulate generator (DPG), with an installed engine oil injector for soot and ash accumulation in a diesel particulate filter (DPF). Ash was generated by engine oil injection into the diesel burner flame. The amount of soot accumulation per loading varied from 0.5 g/L to 8 g/L while ash accumulation amount per loading was maintained at 0.5 g/L.
Initially, ash accumulation distribution in the DPF was visualized using X-ray computed tomography (CT). It was revealed that the form of ash accumulation changed depending on the amount of soot accumulation before active regeneration, i.e., a large amount of soot accumulation resulted in plug ash, whereas a small amount of soot accumulation resulted in wall ash.
To clarify ash accumulation mechanisms, soot and ash transport behavior in DPF during active regeneration process was directly observed using a high-speed camera through an optically accessible D-shaped cut DPF covered with a quartz glass plate.
From the results, it was found that for larger amounts of soot accumulation, the lump of soot in the soot cake layer was transported toward the end plug of the DPF. On the other hand, for smaller amounts of soot accumulation, the lump of soot was not formed in the soot cake layer. Soot was oxidized on the spot and gradually disappeared. In addition, it was found that once the wall ash was formed, the lump of soot could be transported easily, even with a lower amount of soot accumulation.