AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Particle Size Distributions from a Light-Duty Conventional Vehicle and Comparable Hybrid-Electric Vehicle During Real-World Driving
KAREN SENTOFF, Britt Holmén, University of Vermont
Abstract Number: 450 Working Group: Combustion
Abstract Exposure to ultrafine particles characteristic of motor vehicle tailpipe emissions has been linked to various adverse health implications in humans. Although hybrid-electric vehicles have an increasing portion of the light-duty vehicle market share, little research to date has quantified the particle number emissions from this new vehicle technology. The Total Onboard Tailpipe Emissions Measurement System (TOTEMS) was employed in a conventional model year 2010 Toyota Camry vehicle and its hybrid counterpart. Each test vehicle was operated by a single driver over a real-world, 32-mile route during an 18-month data collection campaign. An Engine Exhaust Particle Sizer (TSI EEPS) and an Ultrafine Condensation Particle Counter (TSI UCPC) measured the size distributions and total particle number from the tailpipe of each vehicle simultaneous to collection of vehicle operation parameters (i.e. speed, acceleration, engine load) and environmental factors (i.e. road grade, ambient temperature, relative humidity). The vehicle specific power (VSP) and speed were used to define the various modes of operation across the real-world route according to the framework for EPA’s regulatory model – the Motor Vehicle Emission Simulator (MOVES). Particle number emission rates across the size distributions from each vehicle type were compared at differing modes of operation encountered along the real-world route. Although a bimodal particle distribution was characteristic of both vehicles, the hybrid demonstrated inconsistent modal diameters as compared to the conventional across vehicle operating modes. Additionally, mean emission rates were greater for the hybrid across nearly all operating modes, with the exception of operation at high speed (50 mph and above) and high vehicle specific power (30 kW/ton and above). The differences between vehicle types were most pronounced for low speed operation with VSP of 6 kW/ton and above, as well as for speeds greater than 25 mph and VSP of 12 kW/ton and above.