AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Detailed Characterization of Particulate Matter (PM) Emitted by Pre-commercial High-Efficiency Spark Ignition Direct Injection Gasoline Engine
ALLA ZELENYUK, Paul Reitz, Mark Stewart, Dan Imre, David Rothamer, David Foster, Mitchell Hageman, Axel Maier, Stephen Sakai, Michael Andrie, Roger Krieger, Kushal Narayanaswamy, Paul Najt, Arun Solomon, Pacific Northwest National Laboratory
Abstract Number: 395 Working Group: Aerosol Sources from Emerging Energy Technologies and Production
Abstract Current engine development aims to reduce consumption of limited fuel resources and reduce carbon dioxide emissions by increasing fuel efficiency. While diesel engines achieve the highest fuel efficiency, they also generate the highest particulates mass, shown to be harmful to human health and the environment. Spark Ignition Direct Injection (SIDI) is a gasoline engine technology with potential to achieve very high fuel efficiency by operating more like diesel engines, blurring the lines that have traditionally existed between gasoline and diesel engines. At present, the studies providing detailed characterizations of particulate emission from these new engines are very sparse.
We present the results of a study, in which we characterized in detail the number concentration, size, composition, morphology, effective density, and mass of individual exhaust particles emitted by a single-cylinder SIDI test engine. These measurements were used to calculate particles’ fractal dimension, average diameter of primary spherules, and number of spherules, void fraction, and dynamic shape factors as function of particle size.
We find that SIDI PM varies dramatically depending on engine operating condition and fuel, which is a marked contrast with diesel. Under some operating conditions, two distinct particle modes were observed: regions of rich air/fuel mixture in the combustion region lead to fractal agglomerates with smaller diameter of primary spherules, while the larger primary spherules may be linked to wall/piston impingement. In addition, we find the SIDI PM to contain 40-60% organics that are tightly bound within the elemental carbon, making it impossible to remove them by thermo-denuder or in an evaporative chamber.
These results point to significant differences between the properties of PM produced by diesel engines and that generated by SIDI engine, requiring adaptation of existing after-treatment technologies used to reduce particulate emissions and their environmental impact.