Effects of driving conditions on secondary aerosol formation from a GDI vehicle using an oxidation flow reactor

Niina Kuittinen; Cavan McCaffery; Weihan Peng; Stephen Zimmerman; Patrick Roth; Pauli Simonen; Panu Karjalainen; Jorma Keskinen; David R Cocker; Thomas D Durbin; Topi Rönkkö; Roya Bahreini; Georgios Karavalakis

doi:10.1016/j.envpol.2021.117069

Effects of driving conditions on secondary aerosol formation from a GDI vehicle using an oxidation flow reactor

Environ Pollut. 2021 Aug 1:282:117069. doi: 10.1016/j.envpol.2021.117069. Epub 2021 Apr 1.

Affiliations

¹ Aerosol Physics Laboratory, Physics Unit, Faculty of Engineering and Natural Sciences, Tampere University, Tampere, FI-33720, Finland.
² University of California, Bourns College of Engineering, Center for Environmental Research and Technology (CE-CERT), 1084 Columbia Avenue, Riverside, CA, 92507, USA.
³ University of California, Department of Environmental Sciences, 900 University Avenue, Riverside, CA, 92521, USA.
⁴ University of California, Department of Environmental Sciences, 900 University Avenue, Riverside, CA, 92521, USA. Electronic address: bahreini@ucr.edu.
⁵ University of California, Bourns College of Engineering, Center for Environmental Research and Technology (CE-CERT), 1084 Columbia Avenue, Riverside, CA, 92507, USA. Electronic address: gkaraval@cert.ucr.edu.

PMID: 33831626
DOI: 10.1016/j.envpol.2021.117069

Abstract

A comprehensive study on the effects of photochemical aging on exhaust emissions from a vehicle equipped with a gasoline direct injection engine when operated over seven different driving cycles was assessed using an oxidation flow reactor. Both primary emissions and secondary aerosol production were measured over the Federal Test Procedure (FTP), LA92, New European Driving Cycle (NEDC), US06, and the Highway Fuel Economy Test (HWFET), as well as over two real-world cycles developed by the California Department of Transportation (Caltrans) mimicking typical highway driving conditions. We showed that the emissions of primary particles were largely depended on cold-start conditions and acceleration events. Secondary organic aerosol (SOA) formation also exhibited strong dependence on the cold-start cycles and correlated well with SOA precursor emissions (i.e., non-methane hydrocarbons, NMHC) during both cold-start and hot-start cycles (correlation coefficients 0.95-0.99), with overall emissions of ∼68-94 mg SOA per g NMHC. SOA formation significantly dropped during the hot-running phases of the cycles, with simultaneous increases in nitrate and ammonium formation as a result of the higher nitrogen oxide (NOx) and ammonia emissions. Our findings suggest that more SOA will be produced during congested, slow speed, and braking events in highways.

Keywords: Driving cycles; Gasoline direct injection; Oxidation flow reactor; Primary emissions; Secondary aerosol.

MeSH terms

Aerosols
Air Pollutants* / analysis
Automobile Driving*
Gasoline / analysis
Oxidation-Reduction
Vehicle Emissions / analysis

Substances

Aerosols
Air Pollutants
Gasoline
Vehicle Emissions