to fall down to about 10% at full load. And an interesting phenomenon
occurs, as shown in Fig. 6, that the premixed methanol with
low reactivity auto-ignites before the diesel injects. This phenomenon
differs from most of the current literatures stating that
methanol fumigation increases ignition delay. The high load condition
together with high intake temperature provides more heat for
methanol to undergo pre-combustion heat addition. And the
advanced methanol injection through the intake port gives the
methanol in the charge air more time to carry on pre-combustion
chemical reaction [24]. Even though the methanol in the charge air
has already commenced combustion when diesel fuel is introduced,
the effect on diesel combustion process is not very significant.
From Fig. 6 we can see that methanol and diesel fuel
almost combust separately, and there is only little change on the
combustion process of diesel fuel compared to neat diesel condition.
But the auto-ignition of methanol results in greatly increased
inter-cycle variability in in-cylinder pressure parameters such as
peak pressure and maximum rate of pressure rise with relatively
minimal effects on the engine work output. At knock conditions,
peak cylinder pressure reaches 17 MPa at 7CA ATDC, limiting
the further increase of MSP.
to fall down to about 10% at full load. And an interesting phenomenon
occurs, as shown in Fig. 6, that the premixed methanol with
low reactivity auto-ignites before the diesel injects. This phenomenon
differs from most of the current literatures stating that
methanol fumigation increases ignition delay. The high load condition
together with high intake temperature provides more heat for
methanol to undergo pre-combustion heat addition. And the
advanced methanol injection through the intake port gives the
methanol in the charge air more time to carry on pre-combustion
chemical reaction [24]. Even though the methanol in the charge air
has already commenced combustion when diesel fuel is introduced,
the effect on diesel combustion process is not very significant.
From Fig. 6 we can see that methanol and diesel fuel
almost combust separately, and there is only little change on the
combustion process of diesel fuel compared to neat diesel condition.
But the auto-ignition of methanol results in greatly increased
inter-cycle variability in in-cylinder pressure parameters such as
peak pressure and maximum rate of pressure rise with relatively
minimal effects on the engine work output. At knock conditions,
peak cylinder pressure reaches 17 MPa at 7CA ATDC, limiting
the further increase of MSP.
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