AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Morphology of Particles Emitted from a GDI Engine Fuelled on Gasoline and Ethanol Blends
Brian Graves, Ramin Dastanpour, Steven Rogak, Phillip Mireault, Manuel Ramos, James S. Wallace, JASON S. OLFERT, University of Alberta
Abstract Number: 648 Working Group: Combustion
Abstract Gasoline direct injection (GDI) in combustion engines offers benefits in the realms of both power and efficiency; however, the production of nano-particulate emissions is of concern. It has been demonstrated that the introduction of ethanol into the fuel may reduce these nano-particulate emissions; however, the amount of particulate matter produced may be sensitive to fuel composition and operating conditions. Using a 2.0 litre, direct injection, inline 4 cylinder engine, the particulate emissions were characterized with regard to mass and size, and the effects of ethanol on these properties were examined.
The GDI engine was run at two set points: a simulated highway cruise, and a medium speed, low torque condition. The particle size distribution was measured using a scanning mobility particle sizer (SMPS), and the masses of various particle sizes were examined using a differential mobility analyser (DMA) and a centrifugal particle mass analyser (CPMA) in combination with a condensation particle counter (CPC). Soot samples were also taken on TEM grids using a Thermophoretic Particle Sampler (TPS) and analyzed with TEM. Results were obtained for gasoline blended with 0, 10 and 30 percent ethanol. It was found that although these relatively low concentrations of ethanol do not affect particle effective density, the medium speed condition produces lower-density particles than those resulting from the highway cruise. The mass-mobility exponents for the highway and medium speed conditions were determined to be 2.53±0.02 and 2.51±0.04 respectively. All test conditions produced count median mobility diameters between 60 and 80 nanometres, and the addition of a thermodenuder did not significantly reduce the total mass concentration of the particulate matter; however, traces of organic carbon and particle coating were observed in some samples, even when the thermodenuder was used. Samples taken at cold start and hot start conditions also changed shape under the TEM beam. This is an indication of the presence of non-EC particles.