测试循环对国五轻型汽油车低温排放的影响研究

A Study on the Influence of Test Cycles on the Low-temperature Emissions of China-Ⅴ Light-duty Gasoline Vehicles

本文中使用国V汽油在底盘测功机上对4辆不同技术路线的直喷、非直喷轻型汽油车进行了测试循环对低温尾气排放影响的试验研究,测试循环包括欧洲的ECE、美国的FTP75和最新的世界统一循环WLTC。重点研究了循环对汽油车在低温环境下CO,THC/NMHC和NOx排放及油耗的影响,并对车辆冷起动瞬态排放进行了分析。结果表明,循环对汽油车低温CO,THC/NMHC和NOx排放影响明显,针对不同技术路线车辆总体上这几种污染物排放从高到低依次为ECE>WLTC3>FTP75,说明相同限值下,欧V和国V循环低温排放控制较严,美标循环较为宽松。研究还发现,70%以上低温排放主要产生在车辆冷起动后的100s内,且第一个怠速时间和第一个加速度是影响整个循环排放量的主要因素。

In this paper,an experimental study is conducted on chassis dynamometer on the effects of different test cycles on the low-temperature exhaust emissions of four gasoline vehicles with different technical schemes( direct injection and non-direct injection) fueled with China-V gasoline. Test cycles cover European ECE,the US's FTP75 and new world-harmonized light-duty vehicle test cycle( WLTC). The study focuses on the effects of cycles on CO,THC/NMHC and NOxemissions and fuel consumption of gasoline vehicles in low temperature environment,with the transient emissions of vehicle in cold starting analyzed. The results show that test cycles have significant effects on the low-temperature emission of CO,THC/NMHC and NOxof vehicles,and the order of overall pollutant emission levels the vehicles with different technical schemes with different test cycles from high to low are ECE > WLTC3( the first three segments of WLTC) > FTP75,indicating that under the same limit,the controls of Euro-V and China-V cycles on low-temperature emission are more stringent,while that of the US cycles are looser.The study also reveals that more than 70% of low-temperature emissions are generated mainly in the first 100 seconds of cold starting phase,and the first idle time and the first acceleration are the main factors affecting the total emissions of whole cycle.