重型机动车实际排放特性与影响因素的实测研究

Testing research on real world emission characteristics of heavy duty vehicles and influencing factors

利用美国Sensors公司生产的SEMTECHD车载排放测试仪在上海随机选择了7辆重型柴油车开展实际道路的排放测试,该实验累积测试道路长度为186km,共取得29090个逐秒的有效工况点数据,其中城市主干道12979个,次干道12368个,快速干道3743个.给出了车辆在不同道路上的工况点分布,分析了速度、加速度对燃油消耗、尾气排放的影响.测试结果表明,在选定的城市道路上,车流的平均怠速工况比为17%,加速工况比23.6%,等速工况比为31.0%,减速工况比为28.5%.被测车辆的CO、THC、NOx平均排放因子分别为(4.41±2.46)g·km-1、(1.77±1.17)g·km-1和(6.96±1.93)g·km-1,车辆排放状况因车速、加速度等因素而不同.测试结果基本反映了目前上海道路的交通状况和柴油卡车的排放现状,同时也说明过低的车速和频繁加减速是加重机动车污染的重要原因.

Real world vehicle emission tests of seven heavy-duty diesel trucks were conducted using SEMTECH-D, an instrument provided by the US Sensors Company. The road distance of testing was 186 km. Data were obtained for 29,090 seconds effective driving cycles, including 12,979 on main roads, 12,368 on second-class roads, and 3,743 on throughways. The profile of fleet speed and acceleration-deceleration on different types of road was explored, and the influence of vehicle speed and acceleration on emissions was analyzed. Results showed that the average idling operating ratio on the selected roads was 17% of the total time, the acceleration operating ratio occupied 23.6%, regular speed operating ratio was 31.0%, and deceleration operating ratio was 28.5%. The averaged emission factors of CO, THC, and NO_x for the selected vehicles are 4.41 g·km^(-1), 1.77 g·km^(-1) and 6.96 g·km^(-1), respectively, and their corresponding standard deviations are 2.46 g·km^(-1), 1.17 g·km^(-1) and 1.93 g·km^(-1), respectively. The vehicle emission levels varied greatly with factors like speed and acceleration. The testing results were believed to basically reflect the traffic situation and the current emission status of diesel trucks in Shanghai. Low speed conditions and frequent acceleration were regard as the main factors that aggravate vehicle emissions. Because of the limited testing equipment and methods available, PM_(10) did not measured in this research, and future study will include the measurement of fine particles.