Abstract: The authors studied the vehicle particle number emission and its characterization in the real world driving conditions. Emission factors were estimated based on the long-term field measurement data from both background and kerbsides stations near highway and urban street in Copenhagen, Danmark. The results show that the particle number emission factors of average fleet for highway and urban street are (215.4±5.3) ×10¹² km^-1 and (187.1±3.1) ×10¹² km^-1, respectively. Emission factors of heavy-duty and light-duty vehicle are also estimated. The ratio of heavy-duty vehicle particle number emission factors to that of light-duty vehicle are around 20, both higher at urban site than them at highway site. Particle size distribution varies with measurement locations. There are dominating Bi-modes of particle number concentration appeared at both sites, a 10 nm mode at highway site, a 20?30 nm mode at urban site and a common 50?80 nm mode at both sites. There is uncertainty of estimating the emission factor in real environment caused by measurement locations, environment etc. and vehicle count of different types, which affects the emission factors for heavy-duty and light-duty vehicles.

Key words: particle number emission factor, particle size distribution, pollution of vehicle emission

摘要： 为了对现实环境中机动车颗粒物数排放因子及其排放特征进行研究, 在丹麦哥本哈根市高速公路和城区分别设立了交通站点和背景站点, 经过长期观测计算得到交通源排放的贡献, 并结合机动车数据估算了颗粒物数浓度排放因子。结果表明, 在高速公路和城区平均车流的颗粒物数排放因子分别是(215.4±5.3)×10¹² km^-1和(187.1±3.1)×10¹² km^-1。重型车和轻型车颗粒物数的排放因子都是在城区较高, 重型车颗粒物数的排放因子大约是轻型车颗粒物数排放因子的20倍左右。 机动车排放颗粒物数谱具有双峰特征, 峰值因观测地点的不同而变化, 高速公路边的峰值在10 nm左右, 城区的峰值在20~30 nm之间, 高速公路和城区都出现50~80 nm的第二峰值。颗粒物数排放因子主要由粒径小于100 nm的颗粒物数决定。轻型车和重型车的颗粒物数排放因子对机动车数量和类型有一定的依赖性, 观测地点和环境等因素也会造成现实环境中机动车颗粒物数排放因子研究结果的不确定性。

关键词: 颗粒物数排放因子, 颗粒物数谱分布, 机动车污染