AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Morphology of Particles Emitted during Cold Start and Hot Start Operating Conditions of a GDI Engine Fuelled on Gasoline and Ethanol Blends
RAMIN DASTANPOUR, Steven Rogak, Phillip Mireault, Manuel Ramos, James S. Wallace, University of British Columbia
Abstract Number: 223 Working Group: Combustion
Abstract Although gasoline direct injection engines offer benefits such as high power and low fuel consumption, their emissions are a concern. It has been shown that a large portion of the emissions from an engine over an operating cycle, are produced during the start period (cold start and hot start). There is limited data on particle number and size distribution, and no data available on the morphology of the particles formed during these transient conditions.
Concentration and size distribution of particulate matters produced during cold start (CS) and hot start (HS) were measured with an Engine Exhaust Particle Sizer (EEPS). Using a thermophoretic particle sampler (TPS), soot samples were collected for Transmission Electron Microscope (TEM) analysis from CS and HS operating conditions of a 2.0 litre, direct injection, inline 4 cylinder engine. Variations in the morphology of soot and particulate matter produced during CS and HS periods, and the effects of ethanol on these emissions were investigated using E0 (gasoline) and E30 fuels (gasoline blended with 30% ethanol).
For both fuels, it was found that the concentration and size of the soot aggregates decrease with time over the period of CS and HS. TEM and EEPS results show the presence of two distinct types of particulate matter emissions in CS. At the beginning of CS (~17 s), all emitted particles were fractal-like aggregates. After this period a mixture of small spherical particles (d<4 nm) and reduced concentration of soot was observed. The size of the spherical particles increased over the CS period. In spite of the utilization of hot dilution and a themodenuder, samples taken after the first 17 seconds of HS show the presence of a mixture of soot, volatile cubes, and small spherical particles for E30, while only soot was observed in the E0 samples.