Many previous investigations were p

Many previous investigations were performed with a DMCC
system. Recently, using a 4-cylinder direct-injection diesel engine
with fumigation methanol, Cheng et al. [17] showed that the
concentration of nitrogen oxides is significantly reduced except
under full load conditions. There is also a reduction in the smoke
opacity and the particulate matter mass concentration. With the
same engine setup and operating conditions, Zhang et al. [18]
found that under low engine loads, the brake thermal efficiency
(BTE) decreases with the increase of fumigation methanol; but
under high loads, it is slightly boosted with the increase of fumigation
methanol. Using the same engine with the present study, Geng
et al. [19] observed that the mass and number concentrations of
particulate matter significantly decrease at low and medium loads,
while they increase when the tested engine operated at high loads.
Li et al. [20] developed a multi-dimensional model to investigate
the combustion and emission characteristics of a fumigated
methanol and diesel reactivity controlled compression ignition
engine. They found that methanol addition is an effective way to
achieve the efficient and clean combustion and all the emissions
are reduced with moderate methanol addition.
The above brief survey of the relevant literatures shows that,
though many studies have examined DMDF combustion on single-
cylinder naturally aspirated light-duty engines, few researchers
have reported DMDF combustion results from multi-cylinder
turbocharged heavy duty engines. Furthermore, hardly any
researchers have focused on the operating range and combustion
characteristics of DMDF combustion. Based on the authors’ previous
studies on DMDF engines, methanol substitution percent
(MSP) and brake thermal efficiency (BTE) of DMDF combustion
depended greatly on engine load. In order to further understand
the effect of MSP on a DMDF engine, this work concentrated on
establishing the operating range with regard to MSP and engine
load on a methanol fumigated six-cylinder turbocharged heavy
duty diesel engine and investigated the combustion characteristics
of conditions at each range bound.