Properties, performance, and emissions of methanol-gasoline blends in a spark ignition engine

One of the major problems for the successful application of a methanol-gasoline blend as a motor fuel was the realization of a stable homogeneous liquid phase. This paper studied the effect of ethanol as the co-solvent in the methanol-gasoline blend in order to overcome this problem. In this way, not only was the phase separation problem solved but the methanol ratio in the blend was also increased. The critical phase separation temperature (CPST) of the methanol-gasoline blend increased with increasing water content in the blend, and the addition of ethanol caused the CPST to decrease. M10 (gasoline containing 8.5 vol % methanol and 1.5 vol % ethanol) and M25 (gasoline containing 19 vol % methanol and 6 vol % ethanol) were exploited to test the performance, the fuel consumption, and the exhaust emissions. The results show that the specific fuel consumption of M10 was almost the same as that of gasoline, but that of M25 was higher for all engine speeds at full load. The specific energy consumption of gasoline was higher than that of blends for all engine speeds at full load and that of M25 was lower under low load at a fixed engine speed. The engine torque and power output were observed to be lower than those of gasoline, and it was found that the higher the volume fraction of methanol in blend, the larger the reduction. The hydrocarbon emission concentration of M25 was higher and the nitrogen oxides emission concentration was lower than those of gasoline and M10 for all engine loads. Under low and moderate loads, the carbon monoxide concentration of gasoline was higher than that of methanol-gasoline blends, but under high loads that of M25 was higher.