天然气制油公交车实际道路的瞬态颗粒排放特性

On-road Transient Particle Emission from a Diesel Bus with GTL Fuel

为了给城市机动车颗粒污染治理提供参考依据,采用EEPS瞬态排气颗粒数量及粒径测试仪研究了柴油公交车实际道路的瞬态颗粒数量与粒径分布特性、颗粒质量排放特性。选用1辆满足国Ⅳ排放标准的柴油公交车进行实际道路测试,采用车载导航系统连续记录车辆位置,并获得实时车速。所用燃料分别为纯柴油、纯天然气制油(GTL柴油)、50%掺混配比的GTL柴油混合燃料,试验路线有市区主干道、市区次干道和市区快速路3种道路类型。结果表明:公交车实际道路的排气流量、排气颗粒数量、排气颗粒质量与车速变化有很好的跟随性;急加速时,公交车排气颗粒数量、排气颗粒质量出现急剧增加;该车在各道路类型下排气颗粒数量的粒径分布均呈现双峰对数分布,在快速路上的各粒径排气颗粒数量均较低,在次干道上的各粒径排气颗粒数量均较高;与纯柴油相比,GTL柴油同时降低了公交车核态和聚集态颗粒的数量排放;随着车速增加,公交车单位里程的排气颗粒总数量和质量开始略有增加,随后呈现缓慢下降;GTL柴油降低了公交车在主干道、次干道和快速路的颗粒排放,也降低了各车速区间的排气颗粒数量和排气颗粒质量。

In order to provide reference for particle pollution control over particle mass automotive vehicles in cities, on-road transient particle number and size distribution, and emission of diesel buses were studied by using EEPS transient particle measurement system. A diesel bus, which meets China national iV emission standard, was used for real road test, and the bus location was recorded in real time using global position system, the bus speed was also obtained. Test fuels included pure diesel, pure gas-to-liquids （GTL） and GTL-diesel fuel with 50% blend ratio, and test roads included city arterial road, secondary road and express road. The results show that exhaust flow, the particle number and mass have a good following performance with transient change of vehicle speed. The particle number and mass of the bus increase sharply at rapid acceleration. Sizes distributions of particles of the bus on three different roads are bimodal, and the particle numbers of all sizes on the express road are low, and those on the secondary road are high. Compared with pure diesel fuel, the GTL fuel simultaneously reduces nucleation and accumulation mode particle number. With vehicle speed increasing, the particle number and mass in unit distance increase firstly, and then decrease slowly. The GTL fuel reduces real road particle emissions at the arterial road, secondary road and express road, as well as particle number and mass at the different vehicle speed intervals.