Evaluating the Effects of Aromatics Content in Gasoline on Gaseous and Particulate Matter Emissions from SI-PFI and SIDI Vehicles

Abstract

We assessed the emissions response of a fleet of seven light-duty gasoline vehicles for gasoline fuel aromatic content while operating over the LA92 driving cycle. The test fleet consisted of model year 2012 vehicles equipped with spark-ignition (SI) and either port fuel injection (PFI) or direct injection (DI) technology. Three gasoline fuels were blended to meet a range of total aromatics targets (15%, 25%, and 35% by volume) while holding other fuel properties relatively constant within specified ranges, and a fourth fuel was formulated to meet a 35% by volume total aromatics target but with a higher octane number. Our results showed statistically significant increases in carbon monoxide, nonmethane hydrocarbon, particulate matter (PM) mass, particle number, and black carbon emissions with increasing aromatics content for all seven vehicles tested. Only one vehicle showed a statistically significant increase in total hydrocarbon emissions. The monoaromatic hydrocarbon species that were evaluated showed increases with increasing aromatic content in the fuel. Changes in fuel composition had no statistically significant effect on the emissions of nitrogen oxides (NOx), formaldehyde, or acetaldehyde. A good correlation was also found between the PM index and PM mass and number emissions for all vehicle/fuel combinations with the total aromatics group being a significant contributor to the total PM index followed by naphthalenes and indenes.

Gasoline aromatics: a critical determinant of urban secondary organic aerosol formation

“…Significant differences in the EFs among different gas-and particle-phase species were observed. For example, the EFs of primary PM in both number and mass concentration using F3 fuel were only 20 % larger than those using F2 fuel, consistent with previous studies (EPA, 2013;Karavalakis et al, 2015). Similar results were also obtained for most of the alkane VOCs as well as NO.…”

“…Therefore, the higher emission of aromatic VOCs will likely result in more SOA formation potential. Existing fuel-effect experimental and model studies have shown that high-aromatic fuel in gasoline fuel will lead to more emissions of primary PM as well as some aromatic VOCs (Zervas et al, 1999;EPA, 2013;Karavalakis et al, 2015;Wang et al, 2016), indicating the considerable potential impact of gasoline aromatic content on SOA production. Furthermore, though aromatic content in diesel fuel may have an insignificant impact on SOA formation (Gordon et al, 2014b), SOA production from gasoline vehicle is considered more sensitive to aromatic content than that from diesel vehicle (Jathar et al, 2013).…”

On-road gaseous and particulate emissions from GDI vehicles with and without gasoline particulate filters (GPFs) using portable emissions measurement systems (PEMS)

“…GDI technology enables both an increase in specific power and a better fuel economy (with simultaneous reduction in CO 2 emissions), compared to traditional port fuel injection (PFI) engines (Alkidas, 2007). However, GDI engines are known to produce higher PM mass, black carbon, and particle number emissions than PFI engines and modern technology diesel engines equipped with diesel particulate filters (DPFs) (Karavalakis et al, 2015;Saliba et al, 2017;Zinola et al, 2016). PM formation in GDI engines is due to partially evaporated liquid fuel leading to fuel rich regions in the combustion chamber that promote the generation of PM (Karlsson and Heywood, 2001;Piock et al, 2011).…”

Components of Particle Emissions from Light-Duty Spark-Ignition Vehicles with Varying Aromatic Content and Octane Rating in Gasoline

“…A companion paper to this study presents the criteria pollutant and air toxic emissions associated with this study. 24 …”