Pressure Response during Filtration and Oxidation in Diesel Particulate Filter

Combustion-generated soot particles that arise from diesel vehicles are known to cause substantial damages to the environment as well as to human health. A diesel particulate filter (DPF) is needed to trap nanoparticles in the diesel exhaust aftertreatment. In the present study, using carbon particles as model soot, we evaluated the filtration and regeneration performances of diesel or gasoline soot in silicon carbide–DPF. Especially, particles with different size distributions were used. Results show that, independent of the particle size, the pressure drop raised by the particle deposition almost exhibits the same dependence on the deposited particle mass. When the volumetric flow rate is increased, the smaller particle can pass through the filter but the larger particle is trapped more efficiently. In the filter regeneration process, CO and CO₂ concentrations initially increase with the lapse of time, reach the maximum, and then decrease gradually. The decreasing rate in the pressure drop is the largest in case 3 of the smallest particle distribution, followed in order by cases 2 and 1. Since the particle density in case 3 is the lowest, it is derived that the sparse deposition layer composing of smaller particles is oxidized more easily, resulting in the shorter period of the filter regeneration. By comparing the variation of the pressure drop during the filtration and the regeneration, the dependence of the pressure drop on the deposited particle mass is different, showing the hysteresis in the transition of the pressure drop.