NOx and PM are important air pollutants as vehicle management policy aspect. Medium-duty truck is the main source of the pollutants although the vehicle market share is only 3.5%. National emission portion of NOx and PM form the mobile sourece are 14% and 16% respectively. In this study it was investigated that characteristics of air pollutants emission on medium duty truck equipped with EGR and SCR system. Vehicle's test reflected driving cycle on the chassis dynamometer, and applied test cycle was WHVC(World Harmonized Vehicle Cycle) mode. The test cycle include three segments, represent urban, rural and motorway driving. Based on the test results NOx, PM, HC were less emitted form SCR vehicle than EGR vehicle. And CO was less emitted form EGR vehicle than SCR vehicle due to CO oxidation reaction on DPF surface. And most air pollutants reduced as average vehicle speed increased. Pollutants were less emitted on motorway section than urban and rural sections. But highly NOx emission on motorway section was verified according to increased EGR ratio on fast vehicle speed. HC and CO additional emission was identified as 68%, 58% respectively during SCR vehicle`s cold engine start emission test. NOx additional emission was detected by 24% on SCR vehicle`s condition of engine cold start while not detected on vehicle equipped with EGR. SCR vehicle`s additional NOx emission was derived from low reaction temperature during engine cold start condition. medium-duty truck emission characteristics were investigated in this study and expected to used to improve air pollutants management policy of medium-duty truck equipped with SCR & EGR.
In this study, we measured simultaneously particle matter (PM10 and PM2.5) mass and their heavy metal concentrations for three days at a Seoul subway station (outdoor, concourse, platform, and tunnel) to investigate airborne PM flows. The average PM10 concentration were 59 µg m-3 , 37 µg m-3 , 111 µg m-3 and 369 µg m-3 ; PM2.5 concentration were 43 µg m-3 , 28 µg m-3 , 58 µg m-3 and 132 µg m-3 in outdoor, concourse, platform and tunnel, respectively. Although PM temporal variations were highly correlated between adjacent sampling locations in subway station, PM2.5 temporal correlations were higher than PM10. The concentration of iron (Fe) was the highest among airborne trace metals in station sectors (concourse, platform, and tunnel). Using a simple mass balance model with Fe concentrations and ventilation rates, we calculated the origins of PMs in concourse and platform. 78% of PM10 and 62% of PM2.5 in platform were derived from the tunnel, whereas 84% of PM10 and 87% of PM2.5 in concourse from the filtered outdoor air. We further confirmed that the most effective way to reduce PM in platform to keep the highest peak under the national indoor air quality guideline is to reduce up to 80% PM input from tunnel source.
Particulate matter (PM) in the atmosphere has wideranging health, environmental, and climate effects, many of which are attributed to fine-mode secondary organic aerosols. PM concentrations are significantly enhanced by primary particle emissions from traffic sources. Recently, in order to reduce CO 2 and increase fuel economy, gasoline direct injected (GDI) engine technology is increasingly used in vehicle manufactures. The popularization of GDI technique has resulted in increasing of concerns on environmental protection. In order to better understand variations in chemical composition of particulate matter from emissions of GDI vehicle versus a port fuel injected (PFI) vehicle, a high time resolution chemical composition of PM emissions from GDI and PFI vehicles was measured at facility of Transport Pollution Research Center (TPRC), National Institute of Environmental Research (NIER), Korea. Continuous measurements of inorganic and organic species in PM were conducted using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The HR-ToF-AMS provides insight into nonrefractory PM composition, including concentrations of nitrate, sulfate, hydrocarbon-like and oxygenated organic aerosol, and organic mass with 20 sec time resolution. Many cases of PM emissions during the study were dominated by organic and nitrate aerosol. An overview of observed PM characteristics will be provided along with an analysis of comparison of GDI vehicle versus PFI vehicle in PM emission rates and oxidation states.
This study was designed to investigate the emission characteristics of unregulated pollutants (Aldehyde, VOCs, PAHs) as well as regulated pollutants (CO, HC, NOx and PM) from diesel medium-duty trucks. The emission characteristics of unregulated and regulated pollutants were assessed based on regulation standards (EURO 4 and EURO 5) and intake weight (2.5 ton and 5 ton). The results show that unregulated and regulated pollutants remained almost unchanged at higher speeds but decreased at below 23.5 km/h. Reduction in unregulated and regulated pollutants was noticeable in vehicles of recent regulation standards and light intake weight. The analysis of aldehyde using UPLC showed that formaldehyde and acetaldehyde of aldehyde were most dominant. The GC/MS analysis showed that benzene, toluene, ethylbenzene and xylene of VOCs was over 80% followed by toluene, xylene, ethylbenzene and benzene. In addition, the analysis of PAHs using GC/TOF-MS indicated that bi-and tricyclic aromatic ring of aromatic compounds was 73% and 53% at 2.5 ton and 5 ton vehicles, respectively. The results of this study will be contributed to establish HAPs inventory.
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