Wu Xian, Zhao Haiguang, He Liqiang, Yang Xinping, Jiang Han, Fu Mingliang, Yin Hang, Ding Yan
State Environmental Protection Key Laboratory of Vehicle Emission Control and Simulation, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China; Vehicle Emission Control Center of Ministry of Ecology and Environment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.
State Environmental Protection Key Laboratory of Vehicle Emission Control and Simulation, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China; Vehicle Emission Control Center of Ministry of Ecology and Environment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.
Environ Pollut. 2023 May 1;324:121339. doi: 10.1016/j.envpol.2023.121339. Epub 2023 Feb 28.
Vehicles emit substantial amounts of pollutants during start periods. Engine starts mainly occur in urban areas, causing serious harm to humans. To investigate the impacts on extra cold start emissions (ECSEs), eleven China 6 vehicles with various control technologies (fuel injection, powertrain, and aftertreatment) were monitored with a portable emission measurement system (PEMS) at different temperatures. For conventional internal combustion engine vehicles (ICEVs), the average ECSEs of CO increased by 24%, while the average ECSEs of NOx and particle number (PN) decreased by 38% and 39%, respectively, with air conditioning (AC) on. Gasoline direct injection (GDI) vehicles had 5% lower CO ECSEs, but 261% higher NOx ECSEs and 318% higher PN ECSEs than port fuel injection (PFI) vehicles at 23 °C. The average PN ECSEs were significantly reduced by gasoline particle filters (GPFs). The GPF filtration efficiency was higher in GDI than PFI vehicles due to particle size distribution. Hybrid electric vehicles (HEVs) generated excessive PN extra start emissions (ESEs), resulting in a 518% increase compared to ICEVs. The start times of the GDI-engine HEV accounted for 11% of the whole test time, but the proportion of PN ESEs relative to total emissions were 23%. Linear simulation based on the decrease in ECSEs with increasing temperature underestimated the PN ECSEs from PFI and GDI vehicles by 39% and 21%, respectively. For ICEVs, CO ECSEs varied with temperature in a U shape with a minimum at 27 °C; NOx ECSEs decreased as ambient temperature increased; PFI vehicles generated more PN ECSEs at 32 °C than GDI vehicles, stressing the significance of ECSEs at high temperature. These results are useful for improving emission models and assessing air pollution exposure in urban aeras.
车辆在启动阶段会排放大量污染物。发动机启动主要发生在城市地区，对人类造成严重危害。为了研究对超低温启动排放（ECSEs）的影响，使用便携式排放测量系统（PEMS）在不同温度下对11辆采用各种控制技术（燃油喷射、动力总成和后处理）的国六车辆进行了监测。对于传统内燃机车辆（ICEVs），开启空调（AC）时，CO的平均ECSEs增加了24%，而NOx和颗粒数（PN）的平均ECSEs分别下降了38%和39%。在23°C时，汽油直喷（GDI）车辆的CO ECSEs比端口燃油喷射（PFI）车辆低5%，但NOx ECSEs高261%，PN ECSEs高318%。汽油颗粒过滤器（GPFs）显著降低了平均PN ECSEs。由于颗粒尺寸分布，GDI车辆的GPF过滤效率高于PFI车辆。混合动力电动汽车（HEVs）产生了过多的PN额外启动排放（ESEs），与ICEVs相比增加了518%。GDI发动机HEV的启动时间占整个测试时间的11%，但PN ESEs相对于总排放量的比例为23%。基于ECSEs随温度升高而降低的线性模拟分别低估了PFI和GDI车辆的PN ECSEs 39%和21%。对于ICEVs，CO ECSEs随温度呈U形变化，在27°C时最低；NOx ECSEs随着环境温度升高而降低；PFI车辆在32°C时产生的PN ECSEs比GDI车辆更多，突出了高温下ECSEs的重要性。这些结果有助于改进排放模型和评估城市地区的空气污染暴露情况。
