国Ⅳ公交车实际道路排放特征  

Real-World Emission Characteristics of China Ⅳ Buses

作　　者：郭佳栋[1] 葛蕴珊[1] 谭建伟[1] 韩秀坤[1] 郝利君[1] 余林啸[1] 

机构地区：[1]北京理工大学,汽车动力性与排放测试国家专业实验室,北京100081

出　　处：《环境科学研究》2014年第5期477-483,共7页Research of Environmental Sciences

基　　金：国家自然科学基金项目(51276021)

摘　　要：满足国Ⅳ标准的公交车已被广泛用于北京等大城市,为了评价其相对于国Ⅲ公交车的实际减排效果,使用PEMS(车载排放测试系统)测试了4辆装有SCR(选择性催化还原)系统的国Ⅳ公交车和1辆国Ⅲ公交车在实际运行条件下的污染物排放并进行对比.结果表明:相对于国Ⅲ公交车,装有SCR系统的国Ⅳ公交车在实际运行工况下有效降低了污染物排放,CO、THC和PM分别比国Ⅲ限值降低了60.8%、94.2%和86.2%;但由于实际运行工况中排气温度较低,致使SCR系统效率偏低,只有一辆国Ⅳ公交车NOx排放低于国Ⅲ限值,其他3辆车的NOx排放分别比国Ⅲ限值高187.3%、228.7%和157.3%.国Ⅳ混合动力车的CO2、CO和PM排放比常规动力车分别降低了42.9%、48.8%和89.5%,但NOx排放反而增加了112.1%.实际运行工况下,测试车辆只有12.7%的工况点分布在A转速(1 478 rmin)以上;而ETC工况中在A转速以上的工况点占整个循环的80.5%,造成了满足ETC等型式认证的车辆在实际工况下NOx排放偏高.因此,需要对公交车的实际排放进行有效监督.To reduce urban air pollution, more and more low-emission transit buses have been deployed in cities in China. To assess the effectiveness of the adoption of China IV buses on emissions reductions, real-world pollutant emissions of four China IV buses with SCR （selective catalytic reduction） technology, together with one China Ⅲ bus, were measured and analyzed in this study. PEMS （portable emission measurement system） was used for the measurement. The results demonstrate that China Ⅳ buses with SCR had 60.8% lower CO emissions, 94.2% lower THC emissions, and 86.2% lower PM emissions compared with the China Ill bus. However, because of the lower conversion efficiency of the SCR systems as a result of a low exhaust temperatures in real-world operating conditions, three of the China IV buses emitted higher NO, than the China Ⅲ bus; their NOxemissions were 187.3% , 229.7% and 157.3% greater than the limit value of the current China IV standard. Among the China IV buses, the hybrid bus emitted 42.9% less CO2 , 48.8% less CO, and 89.5% less PM. The hybrid bus encountered higher NO, issues as well. Monitoring of the real-world operating conditions showed that the buses were operating at an engine speed higher than A-speed （1478 r/min） only 12.7% of the time. However, the percentage is as high as 80.5% in the ETC testing procedure. The discrepancy between certification cycles like the ETC and real-world operation leads to high NOx emissions under real-world operating conditions. It was concluded that more effective supervision of heavy-duty vehicle emissions should take more real-world operating conditions into consideration.

关 键 词：公交车 实际排放特征 选择性催化还原 NO X 

分 类 号：X705[环境科学与工程—环境工程]