Passive Regeneration Characteristics of a DOC/Asymmetric-CDPF System for Heavy-Duty Diesel Engines

Abstract

In this study, the properties of diesel particulate filter (DPF) structures were analyzed in terms of the particulate matter (PM) regeneration of the catalyzed DPF (cDPF) and the exhaust gas reduction efficiency. The performance of the cDPF in combination with a diesel oxidation catalyst was verified by measuring the balance point temperature (BPT) and by conducting world harmonized transient cycle (WHTC)/world harmonized stationary cycle (WHSC)-mode testing using a heavy-duty diesel engine bench. The BPT measurement results (238 degrees C) showed that, compared with the symmetric cDPF, the asymmetric cDPF exhibited better PM regeneration properties. Additionally, it demonstrated excellent performance in terms of fuel efficiency and reduction efficiency for the total hydrocarbons, carbon monoxide, and PM in exhaust gases. The NO, NO2, and NOx concentrations were analyzed in real time on stream during the cold-WHTC, hot-WHTC, and WHSC mode tests, and the NO2/NOx ratio was confirmed according to the cDPF structure. This study indicates the possibility of developing a stable diesel exhaust after-treatment system via passive regeneration by improving the BPT performance, exhaust gas reduction efficiency, and NO2/NOx ratio according to the structure of the cDPF.