Impact analysis of partially premixed combustion strategy on the emissions of a compression ignition engine fueled with higher octane number fuels: A review

Abstract

This paper reviews the effect of a partially premixed combustion strategy on the exhaust emission of a diesel engine fuelled with high research octane number fuels. For the past few years, researchers have been aiming to decrease the soot and NOx emission simultaneously and maintain high engine efficiency in diesel engines by improving the combustion which is achieved by optimizing the fuel injection tactics. Single fuel and split fuel (pilot/main) injection tactics are used in the partially premixed combustion (PPC) strategy of the diesel engine to achieve stable combustion and less soot and NOx emission. The PPC strategy in diesel engine can be easily achieved with high octane number fuel resulting in prolonged ignition delay. The air/fuel mixing would be improved by virtue of longer ignition delay (ID) and as a result, soot emission decreases in the partially premixed compression ignition (PPCI) engine. Additionally, higher octane number fuels (i.e., Ethanol, Methanol and Butanol) improve the charge cooling effect, resulting in reduced NOX emissions. Thus, the combined use of PPC mode diesel engine along with high octane number fuels in modern CI engine could be a favourable upcoming solution to meet the strict exhaust emission legislation and reduce the dependence on fossil fuels.