WLTC与NEDC循环的排放相关性测试

Emission correlation test of WLTC and NEDC cycles

针对当前欧盟提出的轻型车测试循环工况WLTC和日益严格的法规要求,为验证WLTC与NEDC测试工况对汽车排放影响的差异性特点,分别基于上述两种循环工况采用BMD(部分流采样系统)进行排放对比试验。试验结果表明:在两种工况法中,THC排放速率相关性最好,相关系数r2达到0.95,NOx次之,r2为0.79,CO和CH_4排放速率的相关系数r2分别为0.72和0.78,CO_2最差,r2为0.67;两种不同供油模式以及两种不同排放水平对不同污染物排放速率相关性的影响不同,THC和CO_2基本不受影响,CO和NO_x影响较大;两工况冷启动阶段排放占比都较大,THC占94.7%,CH_4占75.1%,CO占63.6%,NO_x占65.1%,冷启动排放控制至关重要;高速度段WLTC工况下CO_2占35.25%,NEDC工况下CO_2占24.47%,未来CO_2排放及油耗监管将会加强;可为正在制定的国VI排放标准提供参考。

Comparative test is carried out using BMD under testing conditions WLTC and NEDC, in verification of influence disparities on vehicle emission under WLTC and NEDC, and in response to WLTC proposed by European Union and increasingly stringent laws and regulations at present. Results show that, under the two testing conditions, the emission rate of THC has the best correlation and r2 reaches 0.95, NO~ takes the second place with r2 reaching 0.79. r2 of CO and CH4 emission correlation are 0.72 and 0.78 respectively. CO2 has the worst emission rate correlation with r2 of 0.67. Two different fuel supply modes and emission levels show different influence on the correlation of emission rate of different pollutants. THC and CO2 are barely affected, while CO and NO~ are greatly affected. Emissions under both testing conditions at the cold start stage account for a considerable proportion, 94.7% for THC, 75.1% for CH4, 63.6% for CO, and 65.1% for NOx. Thus cold start emission control is crucial. At a high speed period, CO2 accounts for 35.25% under WLTC and 24.47% under NEDC. The administration of CO2 emission and fuel consumption will be strengthened in the future. The result of this research serves as a reference for the making of national VI emission standards.