Abstract

ABSTRACT Due to the common stop-and-go driving style, the low temperature of vehicular exhaust gas in the urban driving cycle is a major cause of air pollution in the Seoul Metropolitan Area. We herein investigate the characteristics of regulated (NOx, PM, CO, and non-methane hydrocarbons (NMHC)) and unregulated (volatile organic compounds (VOCs), aldehydes, and polycyclic aromatic hydrocarbons (PAHs)) air pollutants emitted from 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) in urban conditions. NOx emissions depended on the combustion and working temperature of the SCR catalysts, and PM emissions were low. Alkanes dominated the non-methane volatile organic compound (NMVOC) emissions, 43–59% of which resulted from the low efficiency of the oxidation catalyst for alkane. The after-treatment system and the engine start conditions influenced the chemical components of the NMVOC emissions due to incomplete combustion and the evaporation of liquid fuel. Formaldehyde comprised the largest portion of the aldehydes, whereas PAH emissions remained largely undetected. Furthermore, formaldehyde was the largest contributor to the NMHCs, forming 14–29%. The results of this study will aid in establishing a system for calculating hazardous air pollutants emitted by vehicles in Korea.

Highlights

  • Since 1990, the major pollutants (carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and particulate matter (PM)) emitted from vehicles in Korea have been systematically regulated with stringent emission standards and inventories

  • We investigate the characteristics of regulated (NOx, PM, CO, and non-methane hydrocarbons (NMHC)) and unregulated (volatile organic compounds (VOCs), aldehydes, and polycyclic aromatic hydrocarbons (PAHs)) air pollutants emitted from 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) in urban conditions

  • Emission Characteristics of Regulated Air Pollutants Emission characterization was initially performed to measure the quantities of regulated air pollutants emitted from the heavy duty diesel trucks and buses equipped with different after-treatment systems

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Summary

Introduction

Since 1990, the major pollutants (carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and particulate matter (PM)) emitted from vehicles in Korea have been systematically regulated with stringent emission standards and inventories. No emission standards currently exist for the control of such emissions from automobile sources. The Seoul Metropolitan Area, which includes Seoul, Incheon, and other regions of the Gyeonggi Province, has low air quality as a result of pollution emitted from road vehicles. In 2016, the total number of road vehicles was Automobile-related NOx, unburned HC, CO and PM emissions are major pollutants significantly impacting the urban environment (Keogh et al, 2009), and vehicle emissions are main sources of gaseous and particulate matter pollution in urban atmosphere (Jung et al, 2017). It has been reported that the primary precursors of photochemical smog are formed by gaseous emissions

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