Using Diesel Aftertreatment Models to Guide System Design for Tier II Emission Standards

Ford Motor Company is participating in the Department of Energy's (DOE) Ultra-Clean Transportation Fuels Program with the goal to explore the development of innovative emission control systems for advanced compression-ignition direct-injection (CIDI) transportation engines. CIDI (or diesel) engines have the advantages of a potential 40% fuel economy improvement and 20% less CO₂ emissions than current gasoline counterparts. To support this goal, Ford plans to demonstrate an exhaust emission control system that provides high efficiency particulate matter (PM) and NOx reduction. Very low sulfur diesel fuel will be used to enable low PM emissions, reduce the fuel economy penalty associated with the emission control system, and increase the long-term durability of the system. The end result will allow vehicles with CIDI engines to be Tier II emissions certified at a minimum cost to the consumer.

Proper system integration of the PM filter and NOx control device is critical to successful implementation of these technologies on a vehicle. Ford proprietary computer simulation tools were used together with data from a laboratory catalyst evaluation to guide the initial aftertreatment system design and highlight key areas requiring further development. This paper describes the modeling tools, laboratory reactor tests and analyses that were conducted to aid with the initial system design.