Abstract:

This study was conducted to better understand the real-world emissions of current truck engines and emission control technologies in China. The study analyzes on-road and laboratory tests conducted on two N3 trucks certified to the China VI-b emission standard. The tests were performed by the Xiamen Vehicle Emission Testing Center and, based on the results, the authors make policy recommendations for the next generation of heavy-duty vehicle (HDV) standards, China VII. Although both vehicles complied with the China VI emission standard for emissions of regulated pollutants, the tractor-trailer (Vehicle 2) tended to have higher air pollutant and greenhouse gas (GHG) emissions than the straight truck (Vehicle 1) in all the parallel portable emissions measurement system test cycles and on the same chassis dynamometer test cycle. Additionally, both are far from meeting the limits that have been proposed for the upcoming Euro VII standard. In particular, tests showed that control of emissions of nitrogen oxides (NO_x) did not perform well in certain circumstances, including cold-start, long-idling, and low-load conditions. Given this, China’s next regulations should include clear regulatory provisions that target these. Many technologies exist that can simultaneously reduce NO_x and CO₂ emissions, and many more can reduce NO_x without increasing CO₂.