Characterization of particulate matter from diesel passenger cars tested on chassis dynamometers

Emission characterization of particle number as well as particle mass from three diesel passenger cars equipped with diesel particulate filter（DPF）, diesel oxidation catalyst（DOC）and exhaust gas recirculation（EGR） under the vehicle driving cycles and regulatory cycle.Total particle number emissions（PNEs） decreased gradually during speed-up of vehicle from 17.3 to 97.3 km/hr. As the average vehicle speed increases, the size-segregated peak of particle number concentration shifts to smaller size ranges of particles. The correlation analysis with various particulate components such as particle number concentration（PNC）,ultrafine particle number concentration（UFPNC） and particulate matter（PM） mass was conducted to compare gaseous compounds（CO, CO2, HC and NOx）. The UFPNC and PM were not only emitted highly in Seoul during severe traffic jam conditions, but also have good correlation with hydrocarbons and NOxinfluencing high potential on secondary aerosol generation. The effect of the dilution temperature on total PNC under the New European Driving Cycle（NEDC）, was slightly higher than the dilution ratio. In addition, the nuclei mode（DP： ≤ 13 nm） was confirmed to be more sensitive to the dilution temperature rather than other particle size ranges. Comparison with particle composition between vehicle speed cycles and regulatory cycle showed that sulfate was slightly increased at regulatory cycle, while other components were relatively similar. During cold start test, semivolatile nucleation particles were increased due to effect of cold environment. Research on particle formation dependent on dilution conditions of diesel passenger cars under the NEDC is important to verify impact on vehicular traffic and secondary aerosol formation in Seoul.

Characterizations of organic compounds in diesel exhaust particulates

To characterize how the speed and load of a medium-duty diesel engine affected the organic compounds in diesel particle matter（PM） below 1 μm, four driving conditions were examined. At all four driving conditions, concentration of identifiable organic compounds in PM ultrafine（34–94 nm） and accumulation（94–1000 nm） modes ranged from 2.9 to 5.7 μg/m3 and 9.5 to 16.4 μg/m3, respectively. As a function of driving conditions, the non-oxygencontaining organics exhibited a reversed concentration trend to the oxygen-containing organics. The identified organic compounds were classified into eleven classes： alkanes,alkenes, alkynes, aromatic hydrocarbons, carboxylic acids, esters, ketones, alcohols, ethers,nitrogen-containing compounds, and sulfur-containing compounds. At all driving conditions,alkane class consistently showed the highest concentration（8.3 to 18.0 μg/m3） followed by carboxylic acid, esters, ketones and alcohols. Twelve polycyclic aromatic hydrocarbons（PAHs）were identified with a total concentration ranging from 37.9 to 174.8 ng/m3. In addition, nine nitrogen-containing polycyclic aromatic compounds（NPACs） were identified with a total concentration ranging from 7.0 to 10.3 ng/m3. The most abundant PAH（phenanthrene）and NPACs（7,8-benzoquinoline and 3-nitrophenanthrene） comprise a similar molecular（3 aromatic-ring） structure under the highest engine speed and engine load.