COLD TEMPERATURE EFFECTS ON SPECIATED MSAT EMISSIONS FROM THREE MODERN GDI LIGHT-DUTY VEHICLES
Citation:
George, I., M. Hays, R. Snow, J. Faircloth, T. Long, AND R. Baldauf. COLD TEMPERATURE EFFECTS ON SPECIATED MSAT EMISSIONS FROM THREE MODERN GDI LIGHT-DUTY VEHICLES. CRC Mobile Source Air Toxics Workshop, Sacramento, California, February 04 - 06, 2019.
Impact/Purpose:
Vehicles are a major source of air pollution that negatively affects air quality and human health. To predict the air quality and health impacts of the transportation sector, the air pollutants in vehicle exhaust emissions need to be fully understood. In this study, vehicle emissions from three modern light-duty vehicles were characterized in detail and cold temperature effects on these emissions were studied. The results show that cold temperature and engine technologies have important effects on pollutant emissions from these vehicles. This work will help improve emissions inventories and air quality models that describe and predict the environmental impacts of mobile sources.
Description:
Speciated volatile and semi-volatile organic compound emissions (VOCs and SVOCs, resp.), including mobile source air toxics (MSATs), were characterized in vehicle exhaust from three modern gasoline direct injection (GDI) light-duty vehicles. The test vehicles were in the U.S. EPA Tier 2 Bin 5 emission standard class and represented different types of currently available GDI engine technologies. Specifically, Vehicle 1 had a 2.4 liter, naturally aspirated, wall-guided GDI engine, Vehicle 2 had a 1.8 liter, turbocharged GDI engine, and Vehicle 3 had a 1.5 liter, turbocharged, spray-guided GDI engine. Vehicle testing was conducted on a 48-inch roll chassis dynamometer housed in a climate-controlled chamber at two ambient temperatures (20 and 72 °F) to assess the impacts of cold temperature on vehicle emissions. Vehicles were operated over the three-phase EPA Federal Test Procedure (FTP) followed by a portion of the Supplemental Federal Test Procedure (or US06), the latter representing a more aggressive driving condition. The test fuel used was 10% ethanol blended with gasoline (E10) obtained from a local distributor. Vehicle exhaust emissions were diluted in a constant volume sampling dilution tunnel controlled by a critical flow venturi. Time-integrated samples of the diluted vehicle exhaust were taken for VOCs and SVOCs for each of the three FTP phases and for US06. For VOC sampling, SUMMA canister samples were collected for EPA Method TO-15 analysis and 2,4-dinitrophenylhydrazine cartridges for EPA Method TO-11A analysis of carbonyls. Sorbent tube samples were collected for SVOC sampling and analyzed by EPA Method TO-17. In this work, we present results showing the effects of cold temperature on speciated volatile and semivolatile organic MSAT emissions from GDI vehicles that are further impacted by driving phase and type of GDI technology.