不同行驶工况下轻型柴油车瞬时排放的CMEM模拟研究

Instantaneous Emission Simulation for Light-Duty Diesel Vehicle with Different Driving Cycles by CMEM Model

以轻型柴油车为研究对象,给出了轻型柴油车瞬时排放计算模型的结构和主要输入参数,并将车辆在实际道路上的瞬时排放计算结果与实测数据作了对比验证.结果表明,THC、CO以及NOx排放的相对误差分别为14.2%、3.7%和32.7%,相关系数分别达到0.73、0.72和0.87,表明CMEM模型能够较好地反映车辆在实际道路上排放的瞬时变化.对车辆在日本10-15工况、欧洲ECE工况、美国FTP城区工况及上海城市主干道路况上的排放和燃油经济性进行了模拟计算.CMEM模拟结果发现,污染物排放水平随着车速的提高而下降;特别是超低速段0-10 km·h^-1向10-20 km·h^-1过渡时,污染物排放水平变化显著.车辆的加速过程在污染物排放过程中起主导作用,其对污染物排放的贡献在30%以上,个别甚至超过70%.上海城市主干道工况的怠速过程对THC和CO的贡献率分别接近40%和30%,CO、THC、NOx排放因子分别是欧美日的1.3、1.5、1.4倍,1.5、2.1、1.9倍以及1.2、1.3、1.3倍.模拟车辆在上海城市主干道上的燃油经济性最差,仅9.56 km·L^-1.国外行驶工况不能真实地反映我国机动车在实际道路上的行驶状况.

CMEM model for calculating time based instantaneous emission from light duty diesel vehicle and its input parameters were introduced. On-board test data were used to validate the simulation results. The relative error of THC, CO, and NOx are 14.2% , 3.7 % and 32.7 % , respectively, while the correlation coefficients reach 0.73, 0.72 and 0.87. The instantaneous emissions of the light duty diesel vehicle simulated by CMEM model are strongly coherent with the transient driving cycle in Shanghai. The simulation of instantaneous emissions and fuel economy under the ECE-15 cycle, FrP cycle, Japan 10-15 cycle and the cycle of shanghai arterial road show that the instantaneous emissions decline with the increase of the vehicle speed, especially from 0-10 km·h^-1 to 10-20 km·h^-1 . The acceleration process dominated the whole emissions, which contributes over 30 % of the total emission, and sometimes it even reaches over 70 %. The contributions of shanghai arterial road for idle condition are 40% and 30% ,emission factors of CO are 1.3, 1.5 and 1.4 times of ECE-15 cyele,FTP cycle,Japan 10-15 cycle respectively; THC are respectively 1.5, 2.1 and 1.9 times of above cycles; and emission factors of NO, are respectively 1.2, 1.3 and 1.3 times of ECE-15 cycle, FTP cycle and Japan 10-15 cycle. The fuel economy of the light-duty diesel car on shanghai arterial road is the worst, which is 9.56 km· L^-1 . The driving cycles used on abroad can not reflect the actual driving conditions in China.