AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Exploring the Secondary Organic Aerosol Formation Potential and Subsequent Secondary Trends from Gasoline Direct Injection Vehicles with Varying Experimental Conditions
PATRICK ROTH, David R. Cocker III, Georgios Karavalakis, Akua Asa-Awuku, TSI Incorporated
Abstract Number: 662 Working Group: Combustion
Abstract The goal of this work was to aggregate the data collected from all vehicle exhaust irradiation experiments utilizing UCR’s Mobile Atmospheric Chamber (MACh), and attempt to explain trends in the secondary aerosol formation. This aggregation contains data from four independent studies measuring the secondary organic aerosol (SOA) formation from new technology, low mileage, gasoline direct injection (GDI) vehicles. The data set includes nine vehicles, in 36 testing configurations, and 88 individual tests. These studies explored the emissions from stock vehicle configurations, additional after-treatment configurations, and vehicles operating on varying fuel compositions.
No trends with the formation of inorganic salt were found with either NOx or NH3 indicating both reactants can act as the limiting reagent in the salt formation. The SOA formation potential measured in this work were right in line with previous experiments with chambers exploring the secondary potential of vehicle exhaust. We observed a decrease in the SOA potential of the vehicle exhaust as the certification standard increased. Similarly as the ethanol content of the fuel increased, so did the secondary organic aerosol potential.
In regards to observed trends in the exhaust, as NMHC emission factors increased, so did the SOA formation potential. The trend was very strong in emissions over 20 mg/mi however there was much more variability in the lower emission levels.
The yield of the vehicle exhaust was also explored, and the trend was quite broad when looking at all tests as a whole. However, when exploring the similar reaction conditions, it was found that when tests were split by VOC:NOx emission ratios, the corresponding yield changed based on the ratio. More relationships with the yield and various concentrations were also explored.