Influence of Higher Alcohol Additives in Methanol-Gasoline Blends on the Performance and Emissions of an Unmodified Automotive SI Engine: A Review

More stringent emission norms are implemented all over the world to protect the environment from vehicular pollution. Biofuels are one of the best alternative solutions to reduce cost and environmental pollution. Among many alternate fuels, alcohol is a leading fuel used in automotive spark-ignition engines in pure or blended form. The capability of methanol to substitute gasoline has been known for a long time. This paper aims to systematically review methanol-gasoline blend with higher alcohol additives (ternary blends) as a transportation fuel in unmodified automotive spark-ignition engines. This review summarizes the previous research in methanol-gasoline blends with and without additives on spark-ignition engines' performance and emission characteristics. Many researchers found that methanol-gasoline blended fuels improve engine performance and emissions. Generally, alcohols burn very effectively and produce only fewer emissions compared to gasoline. Still, lower alcohol may cause some problems such as increased specific fuel consumption, phase separation and corrosion. These problems are further optimized using higher alcohol additives through improved energy content, kinematic viscosity, corrosion resistance, water tolerance and phase stability. Several research studies have been carried out in the past years, which focused mainly on single alcohol blended fuels for spark-ignition engines. Thus, a comprehensive survey of performance, combustion and emission characteristics of methanol-gasoline blended fuel with higher alcohol additives is necessary to show the potential of ternary blends in automotive engines.