title: Components of Particle Emissions from Light-Duty Spark-Ignition Vehicles with Varying Aromatic Content and Octane Rating in Gasoline.
abstract: Typical gasoline consists of varying concentrations of aromatic hydrocarbons and octane ratings. However, their impacts on particulate matter (PM) such as black carbon (BC) and water-soluble and insoluble particle compositions are not well-defined. This study tests seven 2012 model year vehicles, which include one port fuel injection (PFI) configured hybrid vehicle, one PFI vehicle, and six gasoline direct injection (GDI) vehicles. Each vehicle was driven on the Unified transient testing cycle (UC) using four different fuels. Three fuels had a constant octane rating of 87 with varied aromatic concentrations at 15%, 25%, and 35%. A fourth fuel with higher octane rating, 91, contained 35% aromatics. BC, PM mass, surface tension, and water-soluble organic mass (WSOM) fractions were measured. The water-insoluble mass (WIM) fraction of the vehicle emissions was estimated. Increasing fuel aromatic content increases BC emission factors (EFs) of transient cycles. BC concentrations were higher for the GDI vehicles than the PFI and hybrid vehicles, suggesting a potential climate impact for increased GDI vehicle production. Vehicle steady-state testing showed that the hygroscopicity of PM emissions at high speeds (70 mph; κ > 1) are much larger than emissions at low speeds (30 mph; κ < 0.1). Iso-paraffin content in the fuels was correlated to the decrease in WSOM emissions. Both aromatic content and vehicle speed increase the amount of hygroscopic material found in particle emissions.
authors.affiliation: Department of Chemical and Environmental Engineering, University of California- Riverside , 900 University Ave., Riverside 92507, California, United States.|College of Engineering- Center for Environmental Research and Technology, University of California- Riverside , 1084 Columbia Ave., Riverside 92521, California, United States.
authors.forename: Daniel Z
authors.initials: DZ
authors.lastname: Short
authors.affiliation: Department of Chemical and Environmental Engineering, University of California- Riverside , 900 University Ave., Riverside 92507, California, United States.|College of Engineering- Center for Environmental Research and Technology, University of California- Riverside , 1084 Columbia Ave., Riverside 92521, California, United States.
authors.forename: Diep
authors.initials: D
authors.lastname: Vu
authors.affiliation: Department of Chemical and Environmental Engineering, University of California- Riverside , 900 University Ave., Riverside 92507, California, United States.|College of Engineering- Center for Environmental Research and Technology, University of California- Riverside , 1084 Columbia Ave., Riverside 92521, California, United States.
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Durbin
authors.affiliation: Department of Chemical and Environmental Engineering, University of California- Riverside , 900 University Ave., Riverside 92507, California, United States.|College of Engineering- Center for Environmental Research and Technology, University of California- Riverside , 1084 Columbia Ave., Riverside 92521, California, United States.
authors.forename: Georgios
authors.initials: G
authors.lastname: Karavalakis
authors.affiliation: Department of Chemical and Environmental Engineering, University of California- Riverside , 900 University Ave., Riverside 92507, California, United States.|College of Engineering- Center for Environmental Research and Technology, University of California- Riverside , 1084 Columbia Ave., Riverside 92521, California, United States.
authors.forename: Akua
authors.initials: A
authors.lastname: Asa-Awuku
mesh_terms: D005742:Gasoline / Q000032:analysis*; D006841:Hydrocarbons, Aromatic / Q000032:analysis*; D018986:Motor Vehicles; D009795:Octanes / Q000737:chemistry*; D010232:Paraffin / Q000032:analysis; D052638:Particulate Matter / Q000032:analysis*; D012995:Solubility; D053260:Soot / Q000032:analysis; D001335:Vehicle Emissions / Q000032:analysis*; D014867:Water / Q000737:chemistry; D017155:Wettability
chemical_list: D005742:Gasoline; D006841:Hydrocarbons, Aromatic; D009795:Octanes; D052638:Particulate Matter; D053260:Soot; D001335:Vehicle Emissions; D014867:Water; D010232:Paraffin; C026728:octane