Abstract
ABSTRACT The emission characteristics of mobile air pollution sources belonging to the non-road sector have yet to be thoroughly investigated, especially when compared to those of on-road vehicles. Hence, the present study employed an engine dynamometer to evaluate the emissions of a diesel engine complying with Tier 3 standards during various driving modes (KC1-8, NRSC, and NRTC) and a portable emissions measurement system (PEMS) to assess those of two excavators, one complying with Tier 3 and the other with Tier 4 standards, during real-world working and driving conditions. The characteristics and chemical composition of the emitted regulated pollutants (carbon monoxide (CO), non-methane hydrocarbon (NMHC), nitrogen oxide (NOx), and particulate matter (PM)) and hazardous air pollutants (HAPs), e.g., volatile organic compounds (VOCs), aldehydes, and polycyclic aromatic hydrocarbons (PAHs), were then determined. For the regulated pollutants, NRTC mode generated the highest emissions owing to the rapid changes in engine load and speed during transitions. As a result of the after-treatment systems, which utilized a diesel oxidation catalyst (DOC) and selective catalytic reduction (SCR), CO, NMHC, and NOx emissions from the Tier 4-compliant excavator were lower than those from the Tier 3-compliant diesel engine and excavator. The operating conditions of the diesel engine and construction equipment as well as the after-treatment systems significantly affected the composition of the non-methane volatile organic compound (NMVOC) emissions, which were dominated by alkanes that comprised 23 detected species. Sampling the particle-phase PAHs, we found phenanthrene, fluoranthene, and naphthalene; furthermore, we estimated the concentrations of the gas-phase PAHs with models to obtain the total PAH concentrations. Formaldehyde, which contributed the largest fraction of the aldehydes, was more abundant than the other species. Thus, emissions from non-road sources, including construction equipment, must be controlled because of the considerable health risks from pollutants such as formaldehyde and benzene. Our results will aid in the establishment of a national emission inventory for HAPs.
Highlights
Mobile sources of air pollution can be categorized into on-road transport vehicles, such as cars, vans, buses, and trucks, and non-road non-transport vehicles, such as construction equipment, agricultural machines, vessels, and aircrafts
Engines complying with Tier 3 emission standards do not have a reduction device, but engines and excavators complying with Tier 4 emission standards have exhaust gas recirculation (EGR), diesel oxidation catalyst (DOC), and selective catalytic reduction (SCR) systems installed
Emission Characteristics of Regulated Pollutants We provided measurements in various test modes using the engine dynamometer and portable emissions measurement system (PEMS) of the construction equipment
Summary
Mobile sources of air pollution can be categorized into on-road transport vehicles, such as cars, vans, buses, and trucks, and non-road non-transport vehicles, such as construction equipment, agricultural machines, vessels, and aircrafts. According to the national air pollutant emissions data of 2016, non-road construction equipment is a major emission source among mobile sources, In Korea, pollutants such as carbon monoxide (CO), nitrogen oxides (NOx), hydrocarbons (HCs), and particulate matter (PM), from mobile sources, such as construction equipment, are regulated and managed based on the existing emission standards and inventory setup. Aerosol and Air Quality Research, 20: 2012–2024, 2020 increasing the importance of managing hazardous air pollutants (HAPs), such as VOCs, aldehydes, and PAHs. In particular, among the pollutants emitted from diesel engines used in construction equipment, very small amounts of HAPs are detected; their prolonged exposure is extremely hazardous to human health as these entities are toxic, carcinogenic, and bioaccumulative (NIER, 2018a). HAP emissions from the exhausts of mobile sources, such as construction equipment, are difficult to manage owing to the lack of control standards
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