Particle number emission factors from diesel trucks at a traffic intersection: Long-term trend and relation to particle mass-based emission regulation
Particle number emission factors from diesel trucks at a traffic intersection: Long-term trend and relation to particle mass-based emission regulation
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DOI：
10.1016/j.aeaoa.2019.100055
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发表时间：
2020-01-01
影响因子：
4.6
通讯作者：
Kobayashi, Shinji
中科院分区：
文献类型：
--
作者：
Fujitani, Yuji;Takahashi, Katsuyuki;Kobayashi, Shinji
在包括日本在内的世界大部分地区，汽车尾气中的颗粒物（PM）是通过PM质量而不是颗粒数（PN）来控制的，因此从是否应该引入PNC法规来降低PNC的角度来看，PM质量法规对大气PN浓度（PNC）的影响是一个值得关注的问题。本研究考察了日本交通路口和其他地点的PNC和其他污染物的长期（2004 - 2017）监测。在交通路口的元素碳浓度的衰减率很好地匹配的柴油卡车尾气排放中的PM质量的减少，表明大气浓度的减少直接反映了更清洁的汽车尾气。减少交通量和以符合更严格规定的新车型取代旧车型都被认为可以减少排放。然而，对于颗粒直径D-p <100 nm的排气相关PNC（排除光化学形成的气溶胶后），发现减少趋势较慢。基于PN的混合车队排放系数（EFPN）2005 - 2016年期间，中型和重型柴油卡车（D-p = 10 - 100 nm）的冬季和夏季估计分别为1.1 - 4.9 x 10（14）km（-1）veh（-1）和0.5 - 7.4 x 10（14）km（-1）veh（-1），在城市驾驶条件下（0 - 50 km h（-1））。对于按法规年份划分的柴油卡车EFPN，使用交通数据和应用于环境数据的正矩阵因子分解模型进行估计，符合1988 - 1990法规的柴油卡车EFPN在10（16）km（-1）车辆（-1）时最高，而符合最新排放法规的柴油卡车EFPN最高（2009 - 2010），需要柴油氧化催化剂，柴油颗粒过滤器（DPF）和NOx催化剂，最低为1.4 x 10（13）km（-1）veh（-1）。最新法规柴油卡车的EFPN比2016年柴油卡车混合车队的EFPN低一个数量级。因此，当所有柴油卡车都被符合最新排放法规的柴油卡车取代时，预计大气PNC将降低一个数量级。然而，在相同的颗粒物质量排放水平下，从环境数据中获得的最新受规管柴油货车的EFPN比颗粒物测量计划规例中的非挥发性颗粒物限值高出两个数量级。此外，由于所有符合最新排放法规的柴油卡车都配备了DPF，因此大部分非挥发性颗粒应该通过DPF从排气中去除。因此，可冷凝颗粒物及其前体物（如半挥发性化合物）预计是造成这一差距的原因;因此，需要采取这些控制政策，以进一步减少环境中车辆尾气来源的PN。
Particulate matter (PM) in automobile tailpipe exhaust is regulated by PM mass but not particle number (PN) in most parts of the world, including Japan, so the effect of PM mass regulations on the atmospheric PN concentration (PNC) is of interest from the point of view of whether a PNC regulation should be introduced to reduce PNCs. This study examined long-term (2004-2017) monitoring of PNCs and other pollutants at a traffic intersection and other sites in Japan. The decay rate of elemental carbon concentrations at the traffic intersection excellently matched the reductions of PM mass in tailpipe emissions from diesel trucks, indicating that the reduction in atmospheric concentrations directly reflected cleaner vehicle exhausts. Both the reduction of traffic volume and the replacement of older vehicles with newer models that comply with tighter regulations were found to reduce emissions. However, a slower reduction trend was found for exhaust-related PNCs (after excluding photochemically formed aerosols) with particle diameter D-p < 100 nm. The mixed fleet emission factor (EF) on a PN basis (EFPN) (D-p = 10-100 nm) of medium- and heavy-duty diesel trucks during 2005-2016 was estimated to range over 1.1-4.9 x 10(14) km(-1) veh(-1) and 0.5-7.4 x 10(14) km(-1) veh(-1) in winter and summer, respectively, under urban driving conditions (0-50 km h(-1)). For the EFPN of diesel trucks by regulation year, which was estimated using a combination of traffic data and the positive matrix factorization model applied to environmental data, the EFPN of diesel trucks that meet the 1988-1990 regulation was the highest at 10(16) km(-1) veh(-1) and that of those that meet the latest emission regulation (2009-2010), which requires a diesel oxidation catalyst, a diesel particulate filter (DPF), and a NOx catalyst, was the lowest at 1.4 x 10(13) km(-1) veh(-1). The EFPN of the latest regulation diesel trucks was one order of magnitude lower than that of the mixed fleet EFPN of diesel trucks in 2016. Therefore, when all diesel trucks have been replaced by diesel trucks that meet the latest emission regulation, it is expected that the atmospheric PNC will be reduced by one order of magnitude. However, the EFPN of the latest regulation diesel trucks obtained from environmental data was two orders of magnitude higher than the limit value of the Particulate Measurement Programme regulation for non-volatile particles when comparing at the same emission level of PM mass. Further, since all diesel trucks that meet the latest emission regulation are equipped with a DPF, most of the non-volatile particles should be removed from the exhaust by the DPF. Therefore, the condensable particles and their precursors such as semi-volatile compounds are expected to be the cause of this gap; thus, these control policies are needed to further reduce the vehicle-exhaust-derived PN in the environment.