Diesel urban buses and refuse trucks are part of the particulate emissions sources that affect city air quality. In order to reduce particulate pollutant emissions, a development program has been carried out based on a Euro 4 engine with a DPF technology.
Currently, for Euro 4 compliance, SCR is the favoured technology. To avoid a completely new development, the Exoclean™ DPF system was located after the SCR. Catalyst. The severe operating conditions and the location of the DPF necessitated the development of an active system based on the association of a DPF and a Fuel-Borne Catalyst. A Renault Trucks MD9 engine was used. This work was funded by ADEME (French Agency for Environment and Energy Management).
Due to severe stop and go duty cycles and the interest to fit the DPF downstream of the SCR, this study shows the benefit of using an active DPF with an FBC to ensure full regeneration even at low temperatures.
This study started with the optimization of the oxidation catalysts and fuel injection efficiency in order to get a sufficiently high exotherms in front of the DPF to trigger regeneration.
In a second step, the impact of the FBC was investigated at different DPF inlet temperatures. This paper shows the advantages of using an FBC in combination with a DPF system allowing fast regeneration (1 minute) and high regeneration rates of more than 95% at low temperatures, thus limiting fuel consumption.
Finally, in a future study the system will be fitted to a refuse truck for assessment under real world driving conditions over a 12 months demonstration program.