Thus the combustion process is highly worsened at lower load
in DMDF mode, and will aggravate further with the increase of
MSP. At 30% MSP, the combustion starts about 7CA earlier than
69% MSP, and there is no long tail of late combustion. First of all,
since methanol has higher heat of vaporization, which results in
cooling effect in the intake process and the compression stroke,
the temperature of intake air at 69% MSP is much lower than neat
diesel mode and 30% MSP in DMDF mode. Second, we should keep
in mind that methanol has higher octane ratings which does a negative
effect on diesel ignition [21,22]. The lean mixture of methanol
and air also prolongs the combustion duration. In addition, the
mass and duration of injected diesel is too short and the energy
given by the diesel injection is not enough to onset multiple propagation
flames. Finally, at high MSP conditions some methanol–air
Thus the combustion process is highly worsened at lower loadin DMDF mode, and will aggravate further with the increase ofMSP. At 30% MSP, the combustion starts about 7CA earlier than69% MSP, and there is no long tail of late combustion. First of all,since methanol has higher heat of vaporization, which results incooling effect in the intake process and the compression stroke,the temperature of intake air at 69% MSP is much lower than neatdiesel mode and 30% MSP in DMDF mode. Second, we should keepin mind that methanol has higher octane ratings which does a negativeeffect on diesel ignition [21,22]. The lean mixture of methanoland air also prolongs the combustion duration. In addition, themass and duration of injected diesel is too short and the energygiven by the diesel injection is not enough to onset multiple propagationflames. Finally, at high MSP conditions some methanol–air
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