Study of the real-world operation and nitrogen oxide emission characteristics of China Ⅵ non-urban in-use diesel vehicles
Non-urban diesel vehicles occupy a large market share among heavy-duty diesel vehicles,and it is of great significance to characterize the operating conditions and emissions characteristics of China Ⅵ non-urban in-use diesel vehicles for the improvement of on-road emission test methods and the reduction of nitrogen oxide(NOx)emissions in the next stage.The operating conditions and NOx emissions characteristics of China Ⅵ N2 and N3 non-urban diesel vehicles were systematically investigated by using the portable emission measurement system(PEMS)and remote monitoring data of in-use diesel vehicles,and the differences were analyzed with the results of the PEMS tests.The results showed that the percentage of time and NO,emission contribution of China Ⅵ non-urban diesel vehicles operating under urban and suburban operating conditions was lower than that of the PEMS test,while the percentage of time and NOx emission contribution of China Ⅵ non-urban diesel vehicles operating under high-speed operating conditions was significantly higher than that of the PEMS test.It was recommended that the proportion of non-urban vehicle operating conditions in the PEMS test should be further optimized in the next revision of the standard to more realistically reflect their actual NOx emission levels.In addition,the NOx specific emissions of ChinaⅥ non-urban diesel vehicles showed a decreasing trend with increasing vehicle speed and engine load,and the NO,specific emissions of N2 and N3 category vehicles were reduced by 72.1％and 64.7％,respectively,under high-speed operating conditions compared to urban operating conditions.Almost 13％of the N2 category diesel vehicles in service had low exhaust temperatures under urban operating conditions,resulting in a low conversion efficiency of the selective catalytic reduction(SCR)aftertreatment system.Therefore,the low-temperature conversion efficiency of SCR aftertreatment system should be improved in order to reduce the actual NOx emissions under urban operating conditions.
non-urban diesel vehiclereal world roadPEMS testremote monitoringNOx emissions
NETL
NSTL
万方数据
