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Emission Characteristics of Regulated and Unregulated Air Pollutants from Heavy Duty Diesel Trucks and Buses

Category: Technical Note

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DOI: 10.4209/aaqr.2018.05.0195
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Sungwoon Jung1, Sunhee Mun1, Taekho Chung1, Sunmoon Kim1, Seokjun Seo1, Ingu Kim1, Heekyoung Hong 1, Hwansoo Chong1, Kijae Sung2, Jounghwa Kim1, Youdeog Hong1

  • 1 Transportation Pollution Research Center, National Institute of Environmental Research, Incheon 22689, Korea
  • 2 HORIBA Korea Ltd., Seoul 06259, Korea

Highlights

Heavy duty diesel trucks and buses emitted regulated and unregulated pollutants.
Reduction for regulated emissions was affected by engine start conditions.
Alkanes emissions were higher than those of alkenes, cycloalkanes, and aromatics.
Formaldehyde was the major NMHC component, and PAHs were hardly detected.
Low exhaust gas temperature during urban driving cycle causes heavy air pollution.


Abstract

The low exhaust gas temperature of vehicles in the urban driving cycle is a major cause of air pollution in the Seoul Metropolitan Area, due to the common stop-and-go driving style. We herein investigated the emission characteristics of regulated (NOx, PM, CO, nonmethane hydrocarbons (NMHC)) and unregulated (volatile organic compounds (VOCs), aldehydes, polycyclic aromatic hydrocarbons (PAHs)) air pollutants for heavy duty diesel trucks and buses equipped with different after-treatment systems (diesel particulate filter (DPF)+exhaust gas recirculation (EGR) and selective catalytic reduction (SCR)) under urban driving cycle. The NOx emissions depended on the combustion and working temperatures of the SCR catalysts, and the PM emissions were found to be low. Alkane groups dominated the nonmethane volatile organic compounds (NMVOCs) emissions, with 43-59% of these emissions resulting from the low efficiency of the oxidation catalyst toward alkane emissions. The chemical components of the NMVOCs emissions were found to be influenced by the after-treatment systems and the engine start conditions due to incomplete combustion and the evaporation of liquid fuel. Formaldehyde comprised the largest portion of the aldehydes and PAHs emissions remained largely undetected. In addition, formaldehyde was the major NMHC component, ranging in adundance from 14 to 29%. These results will therefore be expected to aid in establishing a system for calculating hazardous vehicle air pollutants emissions in Korea.

Keywords

Volatile organic compounds Aldehydes Polycyclic aromatic hydrocarbons Heavy duty diesel trucks and buses After-treatment systems


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