Actually, the primary objective of

Actually, the primary objective of the current research was to
quantify the limits of methanol substitution percent over a wide
range of engine loads (loads from 6% to 100%). Consequently, for
the dual fuel experiments, the engine started with 6% of full load
with neat diesel, then an effort was made to keep the pilot amount
of diesel fuel constant. The power output of the engine was
adjusted by the amount of methanol supplied through the intake
port until the DMDF engine reached its full load or operating limits,
such as knock and misfire. Then same procedure was conducted at
different initial loads, ranging from 11% to 88% of the full load with
an 11% increment. At each test point, the period of operation was
maintained for about 4 min long, and experimental data was the
weighted average of the data stream. All experiments were
performed at a constant engine speed of 1400 r/min throughout
the test, as 1400 r/min was the speed at which the maximum
torque was achieved. Peak pressure rise rate (PPRR) of 1.5 MPa/
CA and peak cylinder pressure (PCP) of 15 MPa were set
separately as the upper limits of roar combustion and engine
knock, which are the tolerable limits for the engine designed. Limit
of PPRR is controlled due to engine noises, and limit of PCP is
controlled due to mechanical stress. Misfire bound was defined
as misfire cycles occurred on combustion analyzer. If the engine
output torque stopped increasing while fumigated methanol was
still added on, we considered that the DMDF combustion had
reached its partial burn limit because that the excess methanol
was emitted into the exhaust pipe. Based on the engine load and
the mass consumption rates of diesel and methanol, the BTE and
MSP can be calculated by using Eqs. (1) and (2) respectively [17].
Brake thermal efficiency (BTE):