A Study of Fuel Auto-ignitability on Premixed Compression Ignition Characteristics

It has been clarified that diesel fuel properties have a great effect on the exhaust emissions and fuel consumption of a conventional diesel combustion regime. And as other diesel combustion regimes are applied in order to improve exhaust emissions and fuel consumption, it can be supposed that the fuel properties also have significant effects. The purpose of this study is to propose the optimum diesel fuel properties for a premixed compression ignition (PCI) combustion regime.

In this paper, the effect of the auto-ignitability of diesel fuels on exhaust emissions and fuel consumption was evaluated using a heavy-duty single-cylinder test engine. In all experiments, fuels were injected using an electronically controlled, common-rail diesel fuel injector, and most experiments were conducted under high EGR conditions in order to reduce NOx emissions. From the engine experiments, it is clarified that a decrease in the auto-ignitability of a fuel can delay the timing of an auto-ignition near a top dead center so that the mixing periods of fuel/in-cylinder gas can be extended. Consequently, a decrease in the auto-ignitability of a fuel can result in a great reduction in soot emissions. This can contribute in turn to an enhancement in the low-emission operation range of both conventional and PCI combustion.