title: Regulated and unregulated emissions from highway heavy-duty diesel engines complying with U.S. Environmental Protection Agency 2007 emissions standards.
abstract: As part of the Advanced Collaborative Emissions Study (ACES), regulated and unregulated exhaust emissions from four different 2007 model year U.S. Environmental Protection Agency (EPA)-compliant heavy-duty highway diesel engines were measured on an engine dynamometer. The engines were equipped with exhaust high-efficiency catalyzed diesel particle filters (C-DPFs) that are actively regenerated or cleaned using the engine control module. Regulated emissions of carbon monoxide, nonmethane hydrocarbons, and particulate matter (PM) were on average 97, 89, and 86% lower than the 2007 EPA standard, respectively, and oxides of nitrogen (NOx) were on average 9% lower. Unregulated exhaust emissions of nitrogen dioxide (NO2) emissions were on, average 1.3 and 2.8 times higher than the NO, emissions reported in previous work using 1998- and 2004-technology engines, respectively. However, compared with other work performed on 1994- to 2004-technology engines, average emission reductions in the range of 71-99% were observed for a very comprehensive list of unregulated engine exhaust pollutants and air toxic contaminants that included metals and other elements, elemental carbon (EC), inorganic ions, and gas- and particle-phase volatile and semi-volatile organic carbon (OC) compounds. The low PM mass emitted from the 2007 technology ACES engines was composed mainly of sulfate (53%) and OC (30%), with a small fraction of EC (13%) and metals and other elements (4%). The fraction of EC is expected to remain small, regardless of engine operation, because of the presence of the high-efficiency C-DPF in the exhaust. This is different from typical PM composition of pre-2007 engines with EC in the range of 10-90%, depending on engine operation. Most of the particles emitted from the 2007 engines were mainly volatile nuclei mode in the sub-30-nm size range. An increase in volatile nanoparticles was observed during C-DPF active regeneration, during which the observed particle number was similar to that observed in emissions of pre-2007 engines. However, on average, when combining engine operation with and without active regeneration events, particle number emissions with the 2007 engines were 90% lower than the particle number emitted from a 2004-technology engine tested in an earlier program.
authors.affiliation: Department of Emissions R&D, Southwest Research Institute, San Antonio, TX 78238, USA. lkhalek@swri.org
authors.forename: Imad A
authors.initials: IA
authors.lastname: Khalek
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Bougher
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Merritt
authors.forename: Barbara
authors.initials: B
authors.lastname: Zielinska
mesh_terms: D000397:Air Pollution / Q000032:analysis / Q000331:legislation & jurisprudence; D002248:Carbon Monoxide / Q000032:analysis; D005742:Gasoline / Q000592:standards; D008153:Lubrication; D009585:Nitrogen Dioxide / Q000032:analysis; D010083:Oxidants, Photochemical / Q000032:analysis; D010316:Particle Size; D052638:Particulate Matter; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis; D014481:United States; D014484:United States Environmental Protection Agency; D001335:Vehicle Emissions / Q000032:analysis / Q000331:legislation & jurisprudence*
chemical_list: D005742:Gasoline; D010083:Oxidants, Photochemical; D052638:Particulate Matter; D011084:Polycyclic Aromatic Hydrocarbons; D001335:Vehicle Emissions; D002248:Carbon Monoxide; D009585:Nitrogen Dioxide