Combustion, performance, emissions and particulate characterization of a methanol–gasoline blend (gasohol) fuelled medium duty spark ignition transportation engine

• Higher brake thermal efficiency was observed for M20 than M10.
• Gasohol produced lower mass emission of NO, CO, and smoke opacity.
• HC mass emissions from gasohol blends were higher than gasoline.
• Particulate size–number concentration was lower for gasohol blends.
• Combustion characteristics of gasohol were nearly identical to gasoline.

This paper describes the comparative performance, emissions, combustion characteristics and particulate size–number distribution of 10 and 20% methanol blends (M10 & M20) with gasoline in a medium duty spark ignition transportation engine, typically used in a mid-sized car vis-à-vis baseline gasoline. Brake thermal efficiency of methanol blends was higher than gasoline. Methanol–gasoline blends (gasohol) produced lower CO, NO and smoke emissions than gasoline. The combustion characteristics of gasohol blends were found to be almost identical to gasoline. Minor variations in cylinder pressure were observed for gasohol blends compared to gasoline. Heat release rate for gasoline begins to rise earlier than gasohol at the same engine load and also, peaks of heat release rate for gasohol were wider compared to gasoline. With increasing engine load, combustion duration decreased because at higher engine loads, combustion was relatively faster. Combustion duration of gasohol blends was higher than gasoline, suggesting slower heat release from gasohol. This study indicates that methanol and its blends can be a good replacement of gasoline for transportation engines without any hardware modification as well as any additional serious environmental impact.