AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
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Measurement of the Volatility Distribution of Emission Factor of Diesel Automobile by Isothermal Dilution
YUJI FUJITANI, Kei Sato, Kiyoshi Tanabe, Katsuyuki Takahashi, Jyunya Hoshi, National Institute for Environmental Studies
Abstract Number: 52 Working Group: Combustion
Abstract The volatility distribution of emission factor (volatility basis set) at combustion sources is improving inventory of PM2.5 and it enable to predict properly atmospheric organic aerosol concentrations by air quality model. Emission from diesel automobile is one of the major emissions of PM2.5 and SVOC in urban area and we conducted isothermal dilution studies using light duty diesel truck equipped with oxidative catalyst. Tail pipe exhaust was diluted with HEPA and charcoal filtered air and dilution ratios were controlled at ranging from 10 to 13000 times (corresponding organic aerosol concentrations were 2251 to 0.5 μg/m3). Temperature in diluted exhaust was kept at 25℃ for any dilution ratio and online measurements and sampling were conducted.
Aerosols were measured by SP-AMS, DustTrak, Aethalometer, and SMPS. SVOC and VOC were measured by PTR-MS. Also, aerosol was collected with filters, and SVOC and VOC were sampled with adsorbents and canister, respectively. Offline analysis for OC, EC, ions, metals, and up to 300 organic species were conducted. From these data, we obtained volatility distributions by different methods and the results were compared. SP-AMS data show that emission factor of particle phase of organics decrease as increase dilution ratio, and this relationship was used to determine volatility distribution of emission factor for log C* =-2 to 3. The PTR-MS data were used to derive for log C* = 4-6 using relationship between molar mass and C* of organic species contained in diesel exhaust. Bimodal distribution of emission factor was obtained with maximum at log C* = 5 to 6 and minor peak was at log C* = 0 in log C*= -2 to 6. We are going to compare the volatility distribution derived from offline data of organic species.