Impacts on real-world extra cold start emissions: Fuel injection, powertrain, aftertreatment and ambient temperature. (1st May 2023)

• Record Type: Journal Article
• Authors: Wu, Xian; Zhao, Haiguang; He, Liqiang; Yang, Xinping; Jiang, Han; Fu, Mingliang; Yin, Hang; Ding, Yan
• Is Part Of: Environmental pollution. Volume 324(2023)
• Publication Date: 2023-05-01
• Subjects: Extra cold start emissions -- RDE test -- Ambient temperature -- GDI -- HEV -- GPF; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2023.121339
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: 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 CO2 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 CO2 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. Graphical abstract: Image 1 Highlights: Real-world extra cold start emissions (ECSEs) of eleven China 6 vehicles were measured. GDI vehicles emitted 318% more ECSEs of PN than PFI vehicles did. The GPF filtration efficiency for ECSEs was higher in GDI vehicles than PFI vehicles. The ESE of PN from the GDI-engine HEV accounted for 23% of the total emission. ECSEs of PN from PFI vehicles was 2.1 times those from GDI vehicles at 32 °C.