Research on Real-World NOx Emission Analysis Methods for Heavy-Duty Diesel Vehicles

PEMS is used to conduct the real-world emission tests on six typical China-VI diesel vehicles. Based on the work-based MAW（China and the EU），NTE method（U. S. EPA）and 3B-MAW method（U. S. CARB），the real-world NOx emission characteristics of heavy diesel vehicles are studied，and the characteristics and applicability of different analysis methods are discussed. The results show that the NOx emission results based on the work-based MAW method can meet the regulatory requirements of China and the EU，but the NOx emission compliance based on the NTE method and 3B-MAW method is uncertain. The low utilization of NOx emission data leads to the inability of NTE method to effectively analyze the real-world NOx emission characteristics. And the 3B-MAW method is worthy of reference for NOx emission classification management. Cold-start NOx emission accounts for 47.3%-80.7% of the PEMS test，and the cold-start NOx emission of heavy-duty diesel vehicles should be paid at⁃ tention to. However，the current real-world NOx emission analysis methods for heavy-duty vehicles in China，the EU and U. S. are unable to effectively evaluate cold-start NOx emission. Therefore，the supervision of cold-start NOx emission in the next stage of emission regulations should put forward the specific test cycle，analysis methods and emission limit，to effectively reduce the actual NOx emission of heavy diesel vehicles. © 2024 SAE-China. All rights reserved.