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.
Original language | English |
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Article number | 117069 |
Journal | Environmental Pollution |
Volume | 282 |
DOIs | |
Publication status | Published - 1 Aug 2021 |
MoE publication type | A1 Journal article-refereed |
Funding
We acknowledge funding from CARTEEH (Center for Advancing Research in Transportation Emissions, Energy, and Health), a US Department of Transportation's University Transportation Center and USDA-NIFA Hatch (Project No. CA-R-ENS-5072-H, Accession No. 1015963). Niina Kuittinen acknowledges funding from Tampere University Graduate School and the American-Scandinavian Foundation. Niina Kuittinen and Topi Rönkkö acknowledges funding for the Black Carbon Footprint project, granted by Business Finland, Finnish authorities and companies. The authors thank the late Mr. Kurt Bumiller for helping setting up the experiment and dedicate this publication to his memory. We thank Mr. Mark Villela and Mr. Daniel Gomez of the University of California, Riverside for their contribution in conducting testing for this research program.
Keywords
- Driving cycles
- Gasoline direct injection
- Oxidation flow reactor
- Primary emissions
- Secondary aerosol
- Vehicle Emissions/analysis
- Oxidation-Reduction
- Air Pollutants/analysis
- Aerosols
- Automobile Driving
- Gasoline/analysis