Particle number emissions from fully warmed gasoline vehicles at various ambient temperatures

• Published in: Chemosphere (Oxford) 2022-11, Vol.306, p.135522-135522, Article 135522
• Main Authors: Wang, Yachao, Zhao, Haiguang, Hou, Pan, Lyu, Tao, Lai, Yitu, Xu, Chunlin, Zhang, Wulong, Yin, Hang, Yang, Zhengjun, Su, Sheng, Ge, Yunshan
• Format: Article
• Language: English
• Subjects: Cold ambient temperatures; Fully-warmed vehicles; PN emission; Vehicle resistances
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2022.135522

Road vehicles have become the primary source of fine particles in many large cities. Vehicle hot-start PN emissions at various ambient temperatures were studied previously. Still, these studies used the same rolling resistance setting at different ambient temperatures and the tests at various ambient temperatures have similar PN emissions. Vehicles get larger resistance at cold ambient temperatures, so this experimental setting (same resistance at various ambient temperatures) is beyond the natural conditions. To evaluate how ambient temperatures affect the PN emissions from fully warmed vehicles, two vehicles were tested at four ambient temperatures: −10 °C, 0 °C, 23 °C, and 40 °C. Vehicle resistance variations under different ambient temperatures were taken into consideration. The observed results proved that PN emission would significantly deteriorate under cold conditions even when the vehicles are thoroughly warmed. The PN emission factor at −10 °C could be six times higher than at 23 °C. The deteriorated PN emission is caused by enhanced fuel enrichment and GPF regeneration, and larger vehicle resistance under cold ambient temperatures is the underlying reason for the increased PN emission. For the first time, this study proved that PN emission from fully warmed vehicles would significantly deteriorate when the ambient temperature decreases. The results could be used for emission models, inventory, and regulations. [Display omitted] •Particle Number (PN) emission is assessed at various ambient temperatures.•Vehicle resistance variation under different ambient temperatures is considered.•PN emission from fully-warmed vehicle at −10 °C could be 6 times higher than 23 °C.•Increased PN is caused by fuel enrichment and gasoline particle filter regeneration.•Increased vehicle resistance is the underlying reason for PN deterioration.