Tianjin Key Laboratory of Urban Transport Emission Research, State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, PR China.
School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, PR China.
Sci Total Environ. 2022 Mar 10;811:152311. doi: 10.1016/j.scitotenv.2021.152311. Epub 2021 Dec 11.
Vehicle exhaust, an important source of air pollution, is affected by many factors, including driving conditions, combustion efficiencies, and the usage of emission control devices. In this study, the Portable Emission Measurement System (PEMS) was used to test the emissions from China V and China VI heavy-duty diesel vehicles to evaluate the integrated effects of Selective Catalytic Reduction (SCR), velocity, and air-fuel ratio on carbon dioxide (CO) and nitrogen oxide (NO) emissions. Our results reveal that the average distance-based CO and CO emission factors at high velocities (50-90 km/h) are 25% and 61% lower than those at low velocities (less than 50 km/h). The use of SCR increases CO emissions in the range of 70-90 km/h (an average increase of 10.9%). In addition, SCR leads to a 55% NO emission reduction at low velocities and 89% at high velocities, with an overall average reduction of 84%. We also find that SCR leads to a significant reduction in the correlation between NO emissions and air-fuel ratio (0.76 vs 0.47 for China V truck; 0.72 vs 0.05 for China VI truck), but it does not cause a drastic reduction in the correlation coefficients between CO emissions and air-fuel ratio, which can be used to detect whether SCR is working effectively.
车辆尾气是空气污染的一个重要来源，它受到许多因素的影响，包括驾驶条件、燃烧效率以及排放控制装置的使用等。本研究采用便携式排放测量系统（PEMS）对中国 V 号和 VI 号重型柴油车的排放进行了测试，以评估选择性催化还原（SCR）、速度和空燃比对二氧化碳（CO）和氮氧化物（NO）排放的综合影响。结果表明，高速（50-90km/h）时的平均距离基 CO 和 CO 排放因子比低速（小于 50km/h）时低 25%和 61%。SCR 的使用会导致 70-90km/h 速度范围内 CO 排放增加（平均增加 10.9%）。此外，SCR 会使低速时的 NO 排放减少 55%，高速时减少 89%，总体平均减少 84%。我们还发现，SCR 会显著降低 NO 排放与空燃比之间的相关性（中国 V 号卡车为 0.76，中国 VI 号卡车为 0.47；对于中国 V 号卡车为 0.72，对于中国 VI 号卡车为 0.05），但不会导致 CO 排放与空燃比之间的相关系数大幅降低，这可用于检测 SCR 是否有效工作。
