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Environ Sci Technol

Title:		"Comparison of Gasoline Direct-Injection (GDI) and Port Fuel Injection (PFI) Vehicle Emissions: Emission Certification Standards, Cold-Start, Secondary Organic Aerosol Formation Potential, and Potential Climate Impacts"
Author(s):		Saliba G; Saleh R; Zhao Y; Presto AA; Lambe AT; Frodin B; Sardar S; Maldonado H; Maddox C; May AA; Drozd GT; Goldstein AH; Russell LM; Hagen F; Robinson AL;
Address:		"Department of Mechanical Engineering, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States. College of Engineering, University of Georgia , Athens, Georgia 30602, United States. Aerodyne Research Inc. , Billerica, Massachusetts 01821, United States. California Air Resource Board , Sacramento, California 95814, United States. The Ohio State University , Columbus, Ohio 43210, United States. University of California, Berkeley , Berkeley, California 94720, United States. University of California , La Jolla, California 92093, United States. Scripps Institution of Oceanography , La Jolla, California 92037, United States"
Journal Title:		Environ Sci Technol
Year:		2017
Volume:		20170509
Issue:		11
Page Number:		6542 - 6552
DOI:		10.1021/acs.est.6b06509
ISSN/ISBN:		1520-5851 (Electronic) 0013-936X (Linking)
Abstract:		"Recent increases in the Corporate Average Fuel Economy standards have led to widespread adoption of vehicles equipped with gasoline direct-injection (GDI) engines. Changes in engine technologies can alter emissions. To quantify these effects, we measured gas- and particle-phase emissions from 82 light-duty gasoline vehicles recruited from the California in-use fleet tested on a chassis dynamometer using the cold-start unified cycle. The fleet included 15 GDI vehicles, including 8 GDIs certified to the most-stringent emissions standard, superultra-low-emission vehicles (SULEV). We quantified the effects of engine technology, emission certification standards, and cold-start on emissions. For vehicles certified to the same emissions standard, there is no statistical difference of regulated gas-phase pollutant emissions between PFIs and GDIs. However, GDIs had, on average, a factor of 2 higher particulate matter (PM) mass emissions than PFIs due to higher elemental carbon (EC) emissions. SULEV certified GDIs have a factor of 2 lower PM mass emissions than GDIs certified as ultralow-emission vehicles (3.0 +/- 1.1 versus 6.3 +/- 1.1 mg/mi), suggesting improvements in engine design and calibration. Comprehensive organic speciation revealed no statistically significant differences in the composition of the volatile organic compounds emissions between PFI and GDIs, including benzene, toluene, ethylbenzene, and xylenes (BTEX). Therefore, the secondary organic aerosol and ozone formation potential of the exhaust does not depend on engine technology. Cold-start contributes a larger fraction of the total unified cycle emissions for vehicles meeting more-stringent emission standards. Organic gas emissions were the most sensitive to cold-start compared to the other pollutants tested here. There were no statistically significant differences in the effects of cold-start on GDIs and PFIs. For our test fleet, the measured 14.5% decrease in CO(2) emissions from GDIs was much greater than the potential climate forcing associated with higher black carbon emissions. Thus, switching from PFI to GDI vehicles will likely lead to a reduction in net global warming"
Keywords:		*Aerosols Air Pollutants California Certification Climate *Gasoline Motor Vehicles *Vehicle Emissions;
Notes:		"MedlineSaliba, Georges Saleh, Rawad Zhao, Yunliang Presto, Albert A Lambe, Andrew T Frodin, Bruce Sardar, Satya Maldonado, Hector Maddox, Christine May, Andrew A Drozd, Greg T Goldstein, Allen H Russell, Lynn M Hagen, Fabian Robinson, Allen L eng 2017/04/26 Environ Sci Technol. 2017 Jun 6; 51(11):6542-6552. doi: 10.1021/acs.est.6b06509. Epub 2017 May 9"