Atmospheric Emissions Inventory Data for Heavy-Duty Vehicles

Abstract

Heavy-duty trucks and buses are substantial contributors to the atmospheric oxides of nitrogen (NOx) inventory, but prediction of their emissions in real use remains inchoate. Continuous emissions of NOx were recorded from chassis dynamometer testing of eight vehicles using a variety of transient cycles, including the Central Business District schedule. NOx data were treated to account for sampling time lag and presented against instantaneous vehicle axle power. Data were repeatable from run to run and test schedule, but vehicle type and test cycle both influenced the instantaneous emissions rates. However, the resulting correlations may be used for mobile source NOx contribution estimation when combined with vehicle activity data. The emissions data were also presented as NOx/CO2, which are valuable for comparison with remote sensing emissions data. The overall average ratio for all of the data considered was 0.0141, which corresponds to an emissions contribution of 0.0423 g of NOx/g of diesel burned.