采用车载排放测试系统对满足国Ⅳ排放标准的天然气公交车进行了实际道路排放测试，研究其微粒排放特征及粒径分布随道路类型和车流量的变化规律。结果表明：天然气公交车在主干道和次干道上的微粒数量、质量排放因子均相差不大，但显著高于快速路；在主干道、次干道和快速路上，公交车排气微粒数量浓度均呈较为明显的多峰对数分布，总微粒、核态微粒和聚集态微粒数量浓度均依次递增，且核态微粒占大部分比例。相同道路类型下，高峰时微粒数量和质量排放因子均明显高于平峰；就天然气公交车全程微粒排放水平来看，平峰时段微粒数量和质量排放率分别比高峰时段高26．3％和62．8％，排放因子分别比高峰时段低32．2％和12．6％。%An on-road emission testing was conducted on a China Stage Ⅳ compressed natural gas (CNG) bus by the portable emission measurement system (PEMS) and the particle emission characteristics and size distribution under different road types and different traffic conditions were investigated .The results show that the particle number and mass emission factors of CNG bus on arterial roads and secondary roads are almost the same and are significantly higher than those of expressway .On those three types of roads ,the particle number concentration shows the multimodal logarithmic distribution .The total particle num-ber ,nucleation mode particle number and accumulation mode particle number increase successively and the nucleation mode par-ticle number accounts for the highest proportion .On the same type of road ,the particle number and mass emission factors in the rush hours are significantly higher than those in other traffic time .As for the particle emission of CNG bus in the whole process ,the particle number and mass concentration in other traffic time are 26 .3% and 62 .8% respectively higher than those in rush hours and their emission factors are lower by 32 .2% and 12 .6% respectively .
展开▼
