| Vehicle exhaust emissions were measured with a portable measurement system. This system was designed to operate on any automobile to provide real-time/on-road instantaneous emission rates and monitor vehicle operating parameters. The instantaneous emissions (HC, CO and NOx) rates of the vehicle were then used to determine the emission factors represented in grams per kilometer. In this study, a single test vehicle/driver combination was examined and emission testing occurred during commuting driving sequences throughout one full year of operation. The analysis has shown the presence of two emission factors describing the pre and post-catalyst light-off operating regions. The variables of ambient temperature and non-zero average vehicle speed were used to develop a model allowing the emission factors for this test vehicle to be predicted. This work provides the foundation, including the measurement system and analysis algorithms, to extend this research to any on-road vehicle and testing scenario. |
