高忠明 许丹丹 徐军辉 李博

摘  要：本文基于一辆国六排放水平的N2重型柴油车，分析探讨了载荷及工况对车辆NOx和颗粒物数量（PN）排放的影响。结果表明：相比于空载，半载NOx比排放降低了2.22%，PN比排放升高了1.73%;满载NOx比排放降低了12.36%，PN比排放升高了12.97%。相比于城市工况，市郊工况NOx比排放降低了72.1%-79.8%，PN比排放增加了35.2-142.5倍;高速工况NOx比排放降低了95.9%-97.6%，PN比排放增加了36.1-154.5倍。基于发动机后处理的工作原理，对上述结果进行了简单分析并提出了解决方法，以减小载荷及工况对国六重型柴油车排放的影响。

关键词：柴油车;载荷;工况;NOx;PN

中圖分类号：U461           文献标识码：A     文章编号：1005-2550（2021）02-0016-06

Abstract： Based on an N2 CHINA Six-stage heavy-duty diesel vehicle，this paper analyzes and explores the effect of load and operating conditions on NOx and particle number（PN） emission. The result shows that compared to no-load， half-load NOx specific emission is reduced by 2.22%， and PN specific emission is increased by 1.73%; Full-load NOx specific emission is reduced by 12.36%， and PN specific emission is increased by 12.97%. Compared with urban conditions， NOx specific emission in suburban conditions is reduced by 72.1% -79.8%， PN specific emission is increased by 35.2-142.5 times; NOx emission in high-speed conditions is reduced by 95.9% -97.6%， and PN specific emission is increased by 36.1-154.5 times. Based on the working principle of engine post-processing， the above results are briefly analyzed and solutions are proposed to reduce the effect of load and working conditions on the emission of CHINA Six-stage Heavy-duty diesel vehicle.

Key Words： Diesel Vehicle; Load; Operating Condition; NOx; PN

柴油机以热效率高、燃油经济性好、可靠性高和动力性强的优点受到人们青睐[1]。但柴油机排出的大量有害物质也给环境带来严重污染，危害人类的健康[2]。氮氧化物进入人体会导致肺部和支气管疾病[3]。柴油机排出的颗粒中核模态粒子占有较大数量百分比[4]，这种细小的颗粒对人体的危害更加严重[5]。随着排放法规的日益加严，各种污染物限值进一步降低，相对于国五标准[6-7]，国六重型车排放标准[8]加严了NOx排放限值，并针对柴油车增加了PN的检测。

车辆在实际使用过程中会出现空载、满载极端的运行工况，部分车辆因用途单一存在实际运行速度偏低的情况，这些情况均会影响车辆的正常排放。比如郭佳栋等[9]研究表明，某些装有选择性催化还原（SCR）系统的国Ⅳ公交车因运行速度偏低导致实际NOx排放比国Ⅲ公交车高，Velders等[10]研究表明，欧Ⅴ的卡车在实际使用中排放并没有达到法规加严所达到的预期，并且这种情况在城市工况更为明显。……