The Changing Landscape of Vehicle PM: GDI Soot Oxidation Kinetics on Particulate Filters

Melanie  DeBusk, Oak Ridge National Laboratory

The automotive industry’s quest for improving fuel efficiency to meet new standards and regulations is resulting in an evolution of the gasoline engine. It has been consistently shown that the switch from port fuel injection (PFI) to gasoline direct injection (GDI) increases both number and concentration of particulate matter (PM).  New market penetration of GDI vehicles is projected to be greater than 50% of the gasoline fleet by 2017.  Furthermore, the adoption of lean-GDI operation for improved fuel efficiency may lead to even greater PM emissions.  Future mobile source regulations will restrict PM emissions by 70% in 2020 and potentially by 90% in 2025.  The trend of increasing gasoline PM emissions and decreasing PM limits raises the potential that particulate filters (PF) will be needed on gasoline vehicles.  An understanding of the oxidation kinetics of GDI-PM on PFs can assist in developing PM control strategies.  Uncoated cordierite PF mini-cores (1” X 3” ) were exposed to exhaust from a light-duty GDI engine operating on both gasoline (E0) and a 30% blend of ethanol in gasoline (E30).  These cores were used in pulsed oxidation studies to explore the oxidation kinetics of the PM throughout a staged-regeneration.  These results suggest that the reactivity of GDI-PM on the PF cores is sensitive to both its environmental history as well as the type of fuel being used.