基于车载测试的国Ⅵ重型柴油车CO_(2)和NO_(x)排放研究

CO_(2)and NO_(x) emission characteristics from a heavy-duty China Ⅵ diesel truck based on portable emission measurement system

利用便携式尾气测量系统(PEMS)对一辆国Ⅵ重型柴油车在北京(低温)和厦门(常温)分别进行0、50%和90%负载的实际道路排放测试.结果表明,国Ⅵ重型柴油车CO_(2)基于功率平均排放为685 g·kWh^(-1),行驶阶段CO_(2)基于里程的排放因子平均为662.35 g·km^(-1).NO_(x)排放比国Ⅵ标准限值低68.3%.NO_(x)基于功率的排放因子为82.6 mg·kWh^(-1),较国V下降98.6%,行驶阶段NO_(x)基于里程的排放因子较国V下降99%,国Ⅵ重型柴油车实际道路排放控制效果良好.研究发现,较高的NO_(x)排放主要集中在急加速段,并在长下坡结束时,出现NO_(x)排放峰值.此外,6次测试冷启动NO_(x)排放占整个测试阶段总排放的23.5%~56.7%.CO_(2)和NO_(x)排放随速度增加呈下降趋势,50%负载和90%负载时NO_(x)的排放因子接近10%负载的2倍.低温时CO_(2)和NO_(x)排放因子较常温时分别升高17.7%和4.5%,低温对低速行驶时CO_(2)排放的影响更加明显.

A heavy-duty China Ⅵ diesel truck was tested in Beijing(low temperature)and Xiamen(normal temperature)at 0,50%and 90%load using portable emission measurement system(PEMS),respectively.Results showed that the average power-based emission factor of CO_(2)was 685 g·kWh^(-1).The average distance-based emission factor of CO_(2)during the driving phase was 662.35 g·km^(-1).Nitrogen oxide(NO_(x))emissions from the heavy-duty China Ⅵ diesel truck were 68.3%lower than the China Ⅵ limit.The power-based emission factor of NO_(x)was 82.6 mg·kWh^(-1),which was 98.6%lower than that of China V vehicles.Moreover,the distance-based emission factor of NO_(x)during the driving phase was 99%lower than that of China V vehicles.Which indicated the significant reduction from heavy-duty China Ⅵ diesel trucks.Higher NO_(x)emissions were mainly generated during the rapid acceleration period and at the end of the long descent.In addition,NO_(x)emissions during the cold start period from the six tests accounted for 23.5%~56.7%of the total emissions.CO_(2)and NO_(x)emission factors from the tested truck showed a downward trend with increasing speed.The NO_(x)emission factor at 50%load and 90%load was close to twice of that at 10%load.The emission factors of CO_(2)and NO_(x)at low temperature increased by 17.7%and 4.5%,respectively,compared with those at normal temperature.The effect of low temperature on CO_(2)emissions is more significant at low speed than that at medium and high speed.