The focus has recently been directed towards the engine out soot from Diesel engines. Running an engine in PPC (Partially Premixed Combustion) mode has a proven tendency of reducing these emissions significantly. In addition to combustion strategy, several studies have suggested that using alcohol fuels aid in reducing soot emissions to ultra-low levels. This study analyzes and compares the characteristics of PM emissions from naphtha gasoline PPC, ethanol PPC, methanol PPC and methanol diffusion combustion in terms of soot mass concentration, number concentration and particle size distribution in a single cylinder Scania D13 engine, while varying the intake O2. Intake temperature and injection pressure sweeps were also conducted. The fuels emitting the highest mass concentration of particles (Micro Soot Sensor) were gasoline and methanol followed by ethanol. The two alcohols tested emitted nucleation mode particles only, whereas gasoline emitted accumulation mode particles as well. Regarding soot mass concentration measurements; methanol never exceeded 1.6 mg/m3 while when operating on gasoline this value never descended below 1.6 mg/m3. From this result it can be concluded that the main contributor to PM mass emissions is mainly increasing CMD (Count Mean Diameter) in the accumulation mode size range, but can in diffusion combustion also be caused by a high amount of nucleation mode particles. A probable cause of higher particle number emissions, when running the engine on methanol compared to ethanol, is the corrosiveness of the fuel itself. Except for the ultra-low PM mass emitted from alcohol combustion, it is also possible to alter the EGR concentration with a higher level of freedom without having to consider the NOX - soot tradeoff.
|Original language||English (US)|
|Number of pages||11|
|Journal||SAE International Journal of Engines|
|State||Published - Oct 17 2016|
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: The author would like to acknowledge the Swedish Energy Agency, Scania CV AB, Wärtsilä Sweden AB, Stena Rederi AB, Volvo Lastvagnar AB, Volvo Personvagnar AV for their funding and support. This study is included in the “Highly Efficient Methanol Engine Systems for Fossil Free Transportation 2030” with the project number 38272-1.