基于CO2窗口法的在用柴油公交车NOx排放评估方法研究

Study on NOx Emissions Assessment of in⁃use Urban Buses Based on CO2 Window Method

在用车辆的排放情况备受关注。公交车辆由于具有近人群的特点,其排气污染物更具危害性。在对在用柴油公交车采用便捷式排放测试系统(portable emission measurement system,PEMS)进行整车测试时,发现普遍存在难以从OBD (on-board diagnostic system)获取发动机运行参数的问题,导致采用功基窗口法难以评估车辆排放状况。为此,依据整车PEMS测试规程,对3辆柴油公交车进行污染物排放测试,引入CO2窗口法评估整车NOx排放状况,通过与功基窗口法评估结果对比,确定CO2窗口法符合性因子。结果表明,CO2窗口法能够有效测量和评估在用车辆的排放,不再受制于OBD信息读取,更便于开展车辆在用符合性监管。

The emissions from vehicles in use have attracted much attention.Being close to the crowd,the exhaust pollutants of public transport vehicles are more harmful.In the testing of in⁃use diesel urban buses with the portable emission measurement system(PEMS),it is usually difficult to obtain the engine operating parameters through the on⁃board diagnostic system(OBD),which makes it difficult to assess the emissions from a vehicle using the work⁃based window method.To address this issue,emis⁃sions tests were conducted on three diesel buses according to the test procedures of PEMS,and the CO2 window method was introduced to evaluate the NOx emissions.The assessment results were compared with those of the work⁃based window method to determine the emissions compliant factors of the CO2 window method.The results showed that the CO2 window method could effectively measure and evaluate the emis⁃sions of vehicles in use,no longer limited by the OBD information reading,which is more convenient for the supervision of the emissions compliance of vehicles in use.