在用国Ⅲ/国Ⅳ/国Ⅴ柴油公交车的颗粒物质量及固态PM2.5数量排放特性

利用法规认证全流稀释定容采样系统以及满足精度要求的颗粒物排放分析系统,运行GB/T 19754—2005《重型混合动力电动汽车能量消耗量试验方法》推荐的中国典型城市公交循环(CCBC),分析了在用国Ⅲ/国Ⅳ/国Ⅴ柴油公交车以及在用国Ⅲ柴油公交车进行DOC(氧化催化转化器)+CDPF(催化型颗粒捕集器)改造后的颗粒物质量、固态PM_2.5数量排放特性.结果表明:国Ⅲ、国Ⅳ、国Ⅴ柴油公交车的颗粒物质量排放因子分别为63.77、63.20和14.42 mg/km,固态PM_2.5数量排放因子分别为3.87×1013、3.10×1013和2.77×1013 km-1.与国Ⅲ柴油公交车相比,国Ⅳ柴油公交车的颗粒物质量、固态PM_2.5数量排放因子分别降低了1%和20%；国Ⅴ柴油公交车分别降低了77%和28%；进行DOC+CDPF改造的国Ⅲ公交车颗粒物质量、固态PM_2.5颗粒数量排放因子分别为1.78 mg/km和3.19×1011 km-1,比未改造前分别降低了97%和99%.中国典型城市公交循环的低速(0～21.8 km/h)、中低速(0～37.5 km/h)、中高速(0～51.7 km/h)和高速(0～60.0 km/h)4类行驶工况中,低速行驶工况的固态PM_2.5数量排放因子最高,约是整个循环的2倍；在加速、匀速、减速、怠速4种行驶模式中,加速行驶模式产生的固态PM_2.5单位时间排放量最高,其分别为减速和怠速行驶模式下的10和6倍.研究显示,提高柴油公交车的平均车速,降低加速行驶比例有利于降低其颗粒物排放；DOC+CDPF可显著降低国Ⅲ柴油公交车的颗粒物排放. 

Emission Characteristics of Particulate Matter Mass and Quantity of Solid PM2.5 Number from In-Use China Ⅲ/Ⅳ/Ⅴ Diesel Buses

Several tests were conducted to study the characteristics of particle matter(PM), including the number characteristics of solid PM_2.5(diameter≤2.5 μm), emissions from in-use China Ⅲ, Ⅳ, and Ⅴ diesel buses, as well as a China Ⅲ bus retrofitted with DOC+CDPF after-treatment. The tests were conducted by running the China typical cites bus driving cycle(CCBC) recommended by the Test Methods for Energy Consumption of Heavy-duty Hybrid Electric Vehicles(GB/T 19754-2005) with a constant volume dilution sampling system(CVS) and a particulate matter emission analysis system satisfying the accuracy grade requirement of emission regulation. The results demonstrated that the PM mass emissions of in-use China Ⅲ, Ⅳ, and Ⅴ buses were 63.77, 63.20 and 14.42 mg/km respectively, and the numbers of solid PM_2.5 emissions from China Ⅲ, Ⅳ, and Ⅴ buses were 3.87×1013, 3.10×1013, and 2.77×1013 km-1 respectively. The PM mass emissions and the number of solid PM_2.5 emissions from China Ⅳ diesel bus respectively decreased by 1% and 20% compared to those of China Ⅲ diesel bus, and they decreased 77% and 28% respectively from China Ⅴ diesel bus compared with those of China Ⅲ diesel bus. Furthermore, the PM mass emission and the number of solid PM_2.5 emissions were reduced to 1.78 mg/km and 3.19×1011 km-1, decreases of 97% and 99% respectively, when the in-use China Ⅲ bus was retrofitted with DOC+CDPF after-treatment. Among the four driving conditions(i.e.low speed(0-21.8 km/h), medium low speed(0-37.5 km/h), medium high speed(0-51.7 km/h) and high speed(0-60.0 km/h)) during CCBC, the emission factor per driving distance of the solid mass PM_2.5 from low speed driving condition was the highest, about two times higher than that of the entire CCBC. Meanwhile, among the acceleration, deceleration, uniform speed and idling driving mode, the emission rate per driving time of the number of solid PM_2.5 from acceleration driving mode was the highest, about 10 times than that of deceleration and 6 times that of idling. In conclusion, increasing average speed and decreasing the proportion of acceleration working condition of the buses would be beneficial to reduce of the quantity of solid PM_2.5 emission, and DOC+CDPF after-treatment can significantly decrease the quantity of solid PM_2.5 emission from China Ⅲ diesel bus.