title: In-use NOx emissions from model year 2010 and 2011 heavy-duty diesel engines equipped with aftertreatment devices.
abstract: The California Air Resources Board (ARB) undertook this study to characterize the in-use emissions of model year (MY) 2010 or newer diesel engines. Emissions from four trucks: one equipped with an exhaust gas recirculation (EGR) and three equipped with EGR and a selective catalytic reduction (SCR) device were measured on two different routes with three different payloads using a portable emissions measurement system (PEMS) in the Sacramento area. Results indicated that brake-specific NOx emissions for the truck equipped only with an EGR were independent of the driving conditions. Results also showed that for typical highway driving conditions, the SCR technology is proving to be effective in controlling NOx emissions. However, under operations where the SCR's do not reach minimum operating temperature, like cold starts and some low load/slow speed driving conditions, NOx emissions are still elevated. The study indicated that strategies used to maintain exhaust temperature above a certain threshold, which are used in some of the newer SCRs, have the potential to control NOx emissions during certain low-load/slow speed driving conditions.
authors.affiliation: California Air Resources Board, 1001 I St Sacramento, California 95814, USA. cmisra@arb.ca.gov
authors.forename: Chandan
authors.initials: C
authors.lastname: Misra
authors.forename: John F
authors.initials: JF
authors.lastname: Collins
authors.forename: Jorn D
authors.initials: JD
authors.lastname: Herner
authors.forename: Todd
authors.initials: T
authors.lastname: Sax
authors.forename: Mohan
authors.initials: M
authors.lastname: Krishnamurthy
authors.forename: Wayne
authors.initials: W
authors.lastname: Sobieralski
authors.forename: Mark
authors.initials: M
authors.lastname: Burntizki
authors.forename: Don
authors.initials: D
authors.lastname: Chernich
mesh_terms: D002384:Catalysis; D009569:Nitric Oxide / Q000032:analysis*; D001335:Vehicle Emissions
chemical_list: D001335:Vehicle Emissions; D009569:Nitric Oxide