A study on the cell structure and the performances of wall-flow diesel particulate filter

As for the recent PM regulations, a diesel particulate filter (DPF) has been one of the important aftertreatment technologies. Although the square cell structure of DPF is a generally worldwide standard, several cell designs have been proposed to reduce the pressure loss due to the soot loading as well as the ash deposition in DPF. In this study, we focused on the cell geometry using a hexagonal cell DPF and a conventional square cell DPF. In the engine test bench under nearly real conditions, these DPF performances were evaluated. Results show that, in comparison with square cell DPF, the particle number concentration of the hexagonal cell DPF decreases more rapidly, and the filtration efficiency is higher. In addition, in DPF regeneration test, independent of the inlet temperature, the regeneration rate of the hexagonal cell DPF is higher. Between two DPFs, the aperture ratio of inlet/outlet cells is different. Thus, the superior DPF performance of the hexagonal cell DPF could be explained by the difference of exhaust gas flow and soot deposition region.

► Diesel Particulate Filters (DPF) were evaluated on the engine test bench.
► PM filtration efficiency with pressure drop and regeneration rate were investigated.
► The soot layer formation of the wall surface on the initial usage was observed by SEM.
► The hexagonal cell DPF indicates superior performances.
► The filtration mechanism and effects of cell geometry are discussed.