Computational And Experimental Investigation Of Soot Load And Regeneration Characteristics In Catalytic Diesel Particulate Filters

Nanoparticles in diesel exhaust can do great harm to human’s respiratory system. As an effective way of reducing the diesel particles, Diesel Particulate Filter (DPF) has already been developed and manufactured in North American market. In order to meet the emission regulations, diesel aftertreatment technology is developing rapidly in our country. This paper investigated the DPF soot loading and regeneration characteristics through numerical simulation and experimental validation. The research described the working process of DPF, which could provide theoretical guide for the optimal design and control of DPF. The main conclusions are:The pressure drop of DPF increased with the engine speed and exhaust flow rate. Engine bench test showed the measured pressure drop of DPF could fit the calculated one very well. When the flow rate equaled 0.04kg/s, CPSI was 100 and the initial specific particle mass was 6g/l, the pressure drop increased rapidly at the initial stage of soot loading and kept constant in the later. When the flow rate equaled 0.02kg/s, CPSI was 400 and the initial specific particle mass was 0g/l, the pressure drop increased slowly in the whole stage of soot loading.The inner flow speed showed higher in the center part and lower in the peripheral part of DPF; the flow speed decreased in the direction of inlet channel. The soot distributed more in the frontal and rear part of DPF and less in the middle part. The substrate temperature showed higher in the back center of DPF when the regeneration ended. The soot regeneration speeded up when the inlet flow temperature was 738K or more under steady operation state. When the slope of temperature curve k1 equaled 2, the soot regeneration happened in DPF quickly, however, the temperature of substrate also climbed rapidly. When the slope of inlet temperature curve k1 equaled 0.67, the soot particles were also burned quickly with slower temperature climbing. Specific cake particles burned rapidly at the initial stage of regeneration, while specific depth particles burned slowly during the whole stage of regeneration. After the first regeneration, soot load began from the cake filtration and the depth particle mass kept constant. When the oxygen concentration in diesel exhaust equaled 15%, soot particles were burned quickly in DPF, and the substrate temperature was also higher than the one with 5% and 10% oxygen concentration. DPF coated with catalysts could burn soot more rapidly than the one without catalysts while the substrate temperature showed smoothly increase. Catalytic DPF showed lower pressure drop legend and quicker soot burn-off speed compared with the O2 thermal regeneration and fuel additive regeneration.