Methanol as a fuel additive: effect on the performance and emissions of a gasoline engine

Abstract

The use of alternative fuels, such as alcohol-based fuels, has received a significant attention as a substitute for gasoline in spark-ignition engine. This study examines the influence of methanol-gasoline blends on both performance and emissions of a single-cylinder, spark-ignition engine. The engine is tested under full load conditions and at speeds range varying from 1000 to 3000 rpm. Four fuel blends labeled M0, M10, M20, and M40, were used, where the numbers represent the percentage by volume of methanol in the blend. It has been shown that the addition of methanol improves the power output and the torque of the engine. The highest improvement observed in engine power is 37% for M20 blend. Specific fuel consumption and thermal efficiency have also been improved with increasing methanol blending ratio. M40 showed a decrease in fuel consumption by 38% and an enhancement in thermal efficiency by 95%, at medium speed, compared to pure gasoline. Additionally, the results have shown significant reduction in CO and CO2 emissions, more particularly at low engine speeds (below 2000 rpm), where the addition of methanol (up to M40) has led to reducing CO emission with up to 70% compared to that of M0. However, NOx emissions increased with increasing methanol blending ratio. The highest increase in NOx levels was given by M40 by about 60% at low engine speed.