AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Assessing the Impact of Driving Pattern on Emission Factor Variability Using a Gasoline Direct Injection Light-duty Passenger Vehicle
NAOMI ZIMMERMAN, Jon M Wang, Cheol-Heon Jeong, Nathan Hilker, Kelly Sabaliauskas, Robert Healy, Greg J. Evans, SOCAAR, University of Toronto
Abstract Number: 191 Working Group: Urban Aerosols
Abstract Real-world vehicle emission factors (EFs) provide valuable insight into the impact of environmental factors, such as meteorology, driving patterns, and traffic conditions, on actual vehicle emissions; measurement of these environmental factors is not possible in laboratory studies. The variability of real-world EFs is an open question, particularly for near-road EF measurements where the environmental factors vary to a larger extent. Near-road EF measurements are distinct in that they can capture large numbers of vehicles and measure their emissions on a vehicle-by-vehicle basis, thus despite their variability they remain important contributors to the development of EFs for emission models and inventories.
To assess the impact of environmental factors on near-road EF variability, a light-duty 2013 Ford Focus SE sedan, equipped with a gasoline direct injection (GDI) engine, was driven past a near-road field sampling site located in downtown Toronto, Canada under a series of driving conditions, in early to mid-2014. Similar to diesel engines, GDI engines produce a strong particle signal, making them high emitting vehicles. Three driving conditions were assessed: 1) engine idle, 2) cruising at 40 km/h, and 3) hard acceleration to 50 km/h. The vehicle was equipped with a GPS logger to record precise vehicle location and speed. The high meteorological variation characteristic of seasonal changes in Toronto enabled measurements across a broad temperature spectrum.
As the vehicle drove past the field site, measurements of CO2, CO, NOx, black carbon, VOCs, and particle number concentration and size distribution were recorded and fuel-based emission factors were calculated. For each emission factor detected, wind speed, wind direction, and temperature were also recorded. Preliminary study findings indicate that near-road EF variability is minimized for engine idle or cruising conditions as compared to driving conditions involving acceleration or braking. The methodology and implications of this study will be discussed in this presentation.