AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Comparison of Real-World Tailpipe Emissions to MOVES 2010 Model Predictions as a Function of Road Grade
BRITT HOLMÉN, Karen Sentoff, Wenchao Zhang, University of Vermont
Abstract Number: 452 Working Group: Combustion
Abstract MOVES2010 is the new regulatory model required by EPA for project-level mobile source emissions estimation. This study is the first to compare MOVES2010a emissions output to real-world tailpipe emissions data. The University of Vermont Total On-board Tailpipe Emissions Measurement System (TOTEMS) collected second-by-second real-world exhaust emissions and vehicle operating parameters from two light-duty vehicles – one conventional and one hybrid-electric Toyota Camry – while driving the Chittenden County Vermont road network. Three 400-meter road sections with different road grade (-5.7 to +6.0%) were selected from the downtown Burlington portion of the route to examine road grade effects on tailpipe gas and particle emissions and the ability of MOVES2010a to reproduce the measured real-world emission rates. A methodology was developed to generate second-by-second MOVES2010a emissions based on TOTEMS vehicle activity data (speed and grade) at the project-level for each road segment. Project-level MOVES could effectively model instantaneous emissions of the conventional vehicle for the downhill link, but flat and uphill link 1Hz emissions were overestimated by up to a factor of 35 (uphill link). Aggregating MOVES emissions for the flat and uphill links resulted in MOVES emissions that were 3 to 4 times higher than TOTEMS data. Omitting MOVES emissions for two specific operating modes (OpModes 28 and 29: VSP 18 – 30 kW/t at 25-50 mph) improved agreement between measured and modeled emissions somewhat. The hybrid vehicle results for flat and uphill were surprisingly similar to those for the conventional vehicle, but MOVES could not model the downhill link emissions of the hybrid vehicle that operated in “electric-only” mode. New modeling strategies are needed for hybrid-electric vehicle tailpipe emissions as they become a larger fraction of the on-road fleet.