沈阳市国三和国四排放标准不同车型柴油车PM2.5和PM10排放因子及碳组分源谱

Emission Characteristics of Exhaust PM and Its Carbonaceous Components from China Ⅲ to China Ⅳ Diesel Vehicles in Shenyang

柴油车是机动车排放的大气颗粒物的主要来源,为研究沈阳市柴油车PM2.5和PM10的排放因子及其碳组分排放特征,采用检车线车载测试方法采集了15辆国三和国四排放标准的小型、中型、大型载客和轻型、中型、重型载货柴油车尾气样品,并对其中的碳组分进行化学分析.结果表明,国三柴油车PM2.5和PM10的排放因子分别为(0. 193±0. 092) g·km-1和(0. 338±0. 305) g·km-1,国四柴油车PM2.5和PM10的排放因子分别为(0. 085±0. 038) g·km-1和(0. 100±0. 042) g·km-1,随排放标准的提升PM2.5和PM10排放因子显著下降.同一排放标准下,排放因子随车型的增大而增大. TC为柴油车的主要组分,国四柴油车中TC的质量分数(23%~48%)明显低于国三柴油车(29%~70%).各车型柴油车元素碳(EC)的质量分数均大于有机碳(OC),OC/EC为0. 70±0. 29,且国四柴油车OC/EC值低于国三柴油车.因载客汽车总行驶里程明显高于载货汽车导致油耗较高,相同排放标准载客汽车OC和EC的质量分数高于载货汽车.国三、国四柴油车质量分数最高的碳组分均为EC2,可将EC2作为柴油车的标识组分.

Diesel vehicles were the primary source of atmospheric particulate matter(PM)emitted by motor vehicles.To study the emission factors and carbon components of PM2.5 and PM10 from diesel vehicles in Shenyang,exhaust PM samples were collected from15 diesel vehicles including small,medium,and large passenger vehicles,and light,medium,and heavy-duty trucks under ChinaⅢand ChinaⅣemission standards.This was undertaken using a dilution channel sampling system,and the carbon components were also analyzed.The results showed that the average distance-based PM2.5 and PM10 emission factors for diesel vehicles under ChinaⅢwere(0.193±0.092)g·km-1 and(0.338±0.305)g·km-1,respectively,and for ChinaⅣwere(0.085±0.038)g·km-1 and(0.100±0.042)g·km-1,respectively.This shows that the PM emission factors decreased significantly with the improvement of emission standards.Under the same emission standards,emission factors increased with the increase of vehicle passenger volume or cargo capacity.TC(total carbon)was the main component of the emissions from diesel vehicles.The mass fraction of TC under ChinaⅣ(23%-48%)was significantly lower than under ChinaⅢ(29%-70%).The mass fraction of elemental carbon(EC)for all types of diesel vehicles was greater than organic carbon(OC).The OC/EC value was 0.70±0.29,and the OC/EC value for diesel vehicles under ChinaⅣwas lower than under ChinaⅢ.The total mileage of passenger vehicles was significantly higher than that of trucks,resulting in higher fuel consumption.The mass fraction of OC and EC in passenger vehicles was higher than for trucks under the same emission standards.EC2(elemental carbon which was measured at temperatures of 700℃)was the highest carbon content of diesel vehicles under ChinaⅢand ChinaⅣemission standards,which can be used in the identification of diesel vehicles in source apportionment studies.