Active DPF Regeneration for 2007 Diesel Engines

A Diesel Particulate Filter (DPF) is needed to meet the Particulate Matter (PM) requirements of US EPA 2007 regulations for diesel engines. A catalyzed diesel particulate filter (cDPF or CSF) in combination with a diesel oxidation catalyst (DOC) is effective if the DOC has achieved light-off. However, for some applications, exhaust temperature will be too low to achieve DOC light-off. Therefore a reliable active regeneration means will be required. This paper presents a diesel-fired filter regenerator that works with an uncoated DPF. During regeneration, the thermal regenerator raises the exhaust temperature to 650 °C at the filter face at any engine condition, including idle. The thermal regenerator was tested on a cordierite filter placed on a heavy-duty diesel engine with cooled-EGR (2007 calibrations). THC, CO and NOx emissions, as well as opacity, in the tailpipe were measured at both steady state and transient engine conditions. In addition, the temperatures inside the filter during regeneration at various engine conditions were measured. Finally, a vehicle installation was performed, and the system was shown to achieve good regeneration in on-vehicle conditions. The test data show that this active DPF regeneration technology is a viable PM solution for 2007 diesel engines under any operating duty cycle.