Methanol/Ethanol/Butanol-Gasoline Blends Use in Transportation Engine—Part 1: Combustion, Emissions, and Performance Study

Primary alcohols such as methanol, ethanol, and butanol have exhibited excellent potential as possible alternative fuels for spark ignition (SI) engines because they are renewable, cleaner, and safer to store and transport. However, it is important to investigate the technical feasibility of adapting these primary alcohols in existing SI engines. In this research, a multi-point port fuel injection (MPFI) system equipped SI engine was used for assessing and comparing the combustion, performance, and emission characteristics of various alcohol-gasoline blends (gasohols) vis-à-vis baseline gasoline. The experiments were performed at different engine loads at rated engine speed. Experimental results exhibited relatively superior combustion characteristics of the engine fueled with gasohol than the baseline gasoline, especially at medium engine loads. Among different test fuels, the methanol-gasoline blend (GM10) exhibited relatively more stable combustion characteristics than the ethanol-gasoline blend (GE10) and butanol-gasoline blend (GB10). In this study, relatively superior engine performance of the gasohol-fueled engine was observed at all engine loads and speeds. GB10 exhibited the highest brake thermal efficiency (BTE), followed by GM10 amongst all test fuels. The effect of improved combustion was also reflected in the emission characteristics, which exhibited that GB10 emitted relatively lower carbon monoxide (CO) and hydrocarbons (HCs) than other test fuels. GB10 emitted relatively higher nitrogen oxides (NO_x) than GM10 and GE10. Unregulated emission results exhibited that the engine fueled with gasohols emitted relatively lower sulfur dioxide (SO₂), ammonia (NH₃), and various other saturated and unsaturated HCs than the baseline gasoline. The GM10-fueled engine was relatively more effective in reducing unregulated emissions among all test fuels. This study concluded that methanol and butanol blending with gasoline resulted in superior engine performance and reduced harmful emissions in MPFI transport engines. This offered an excellent option to displace fossil fuels partially and reduce emissions simultaneously.