Combustion characteristics and emissions of 2-methylfuran compared to 2,5-dimethylfuran, gasoline and ethanol in a DISI engine

Although 2,5-dimethylfuran (DMF) has been considered as a new bio-fuel candidate for spark ignition (SI) engines, since the discovery of improved methods of its production, 2-Methylfuran (MF) which is another main product of the process of dehydration and hydrogenolysis of fructose, has also been brought into the sight of fuel researchers. The energy density of MF is comparable to DMF and gasoline however very little is known about its combustion behaviors especially in automotive applications. This paper examines the results of a single cylinder spray guided direct-injection spark-ignition (DISI) engine fuelled with MF, compared to gasoline, ethanol and DMF. The regulated emissions (CO, NOx and HC) and particulate matter (PM) as well as the unregulated emissions (formaldehyde and acetaldehyde) were measured and studied. The experiments were conducted at stoichiometric air–fuel ratio with the engine speed of 1500 rpm and loads between 3.5 and 8.5 bar IMEP using the fuel-specific optimum spark timings (MBT). The test results show that the knock suppression ability of MF is similar to DMF and superior to gasoline. Although MF has a similar chemical structure to DMF, its combustion characteristics are significantly different. Within the tested load range, MF consistently produces higher indicated thermal efficiency by some 3% compared to gasoline and DMF. This increase is attributed to the fast burning rate and notable better knock suppression ability. MF has resulted in approximately 30% lower volumetric indicated specific fuel consumption compared with ethanol. The overall regulated emissions from MF are comparable to the other tested fuels, whereas the aldehyde emission is much lower than gasoline and bio-ethanol.