The application of thermal, catalytic and non-thermal plasma oxidation processes to enhance NO-NO\(_2\)oxidation in the engine exhaust and improve DPF regeneration at lower temperatures

Diesel Particulate Filter (DPF) is believed to be one of the most effective methods and provides an efficient system that traps more than 90% of PM. However, the soot accumulated within the filter requires a regeneration process to recover its performance. Thus, the high oxidation ability of NO-NO\\(_2\\) increases the interest of applying it in the low temperature regeneration process. \n \nThe intention of this thesis is to investigate several possibilities of on-board NO-NO\\(_2\\) oxidation methods for increasing the NO\\(_2\\)/NO\\(_X\\) ratio in the exhaust gas. \n \nThese possible oxidation routes incorporate the in-cylinder to the exhaust gas treatment processes. A wide range of operated temperatures are managed by the application of the non-thermal plasma oxidation (NTP) for low temperatures, catalytic oxidation for moderated temperatures and thermal oxidation for high temperatures studied. \n \nThe in-cylinder NO oxidation was significantly improved by adding H\\(_2\\) or the reformed EGR (REGR) to the combustion. The remaining H\\(_2\\) after the combustion also contributes to the downstream HC-SCR which in turn promotes the NO oxidation. \n \nThe thermal and NTP methods in the exhaust treatment cannot adequately achieve a satisfactory NO oxidation result under a single occupied condition. The propane (C\\(_3\\)H\\(_8\\)) addition may potentially create useful radicals (HO\\(_2\\), RO\\(_2\\)) within the system and convert a large portion of NO into NO\\(_2\\).