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Summary of In-use NOx Emissions from Heavy-Duty Diesel Engines

Journal Article
ISSN: 1946-391X, e-ISSN: 1946-3928
Published April 14, 2008 by SAE International in United States
Summary of In-use NOx Emissions from Heavy-Duty Diesel Engines
Citation: Thompson, G., Carder, D., Clark, N., and Gautam, M., "Summary of In-use NOx Emissions from Heavy-Duty Diesel Engines," SAE Int. J. Commer. Veh. 1(1):162-184, 2009,
Language: English


As part of the 1998 Consent Decrees concerning alternative ignition strategies between the six settling heavy-duty diesel engine manufacturers and the United States government, the engine manufacturers agreed to perform in-use emissions measurements of their engines. As part of the Consent Decrees, pre- (Phase III, pre-2000 engines) and post- (Phase IV, 2001 to 2003 engines) Consent Decree engines used in over-the-road vehicles were tested to examine the emissions of oxides of nitrogen (NOx) and carbon dioxide (CO2). A summary of the emissions of NOx and CO2 and fuel consumption from the Phase III and Phase IV engines are presented for 30 second “Not-to-Exceed” (NTE) window brake-specific values. There were approximately 700 Phase III tests and 850 Phase IV tests evaluated in this study, incorporating over 170 different heavy duty diesel engines spanning 1994 to 2003 model years. Test vehicles were operated over city, suburban, and highway routes. The results show that the post Consent Decree engines' 30 second NTE brake-specific NOx values were below the NOx NTE allowance limit.