A numerical investigation on using hydrogen as a fuel additive to a spark-ignition engine fueled by a gasoline-methanol blend

• Using methanol in gasoline engines increased fuel consumption significantly • Adding hydrogen to gasoline-methanol blends greatly reduced fuel consumption • Using methanol and hydrogen caused a slight change in engine power and efficiency • Hydrogen is recommended as a fuel additive for gasoline-alcohol blends Using alcohols and hydrogen as renewable alternative fuels for gasoline engines can reduce dependence on fossil fuels and decrease emissions. The objective of this study was to numerically evaluate the performance and combustion characteristics of a spark-ignition engine fuelled by gasoline, a gasoline-methanol blend with a methanol proportion of 20% (M20), and different M20-hydrogen mixtures with hydrogen proportions ranging from 5% to 15%. The engine spark timing, speed, and excess air factor (λ) were optimized during the engine full-load operational condition. It was demonstrated that adding methanol to gasoline significantly increased the engine brake specific fuel consumption (BSFC). However, fuel consumption was greatly reduced when hydrogen was utilized as a fuel additive in the gasoline-methanol blend. In addition, the engine brake power increases when methanol and hydrogen are used as fuel additives to gasoline, causing a small change in the engine brake thermal efficiency (BTE). The maximum heat release rate and in-cylinder pressure increased when the hydrogen proportion in the M20-hydrogen blend increased from 5% to 15%. However, the variation in the combustion period was not significant. The optimum engine performance was achieved when the engine operated with a spark timing of 10° before top head center, a stoichiometric air-fuel mixture, and a speed of 2,000 rpm. The blend of M20 with 15% hydrogen was the optimum investigated fuel because its use generated the lowest engine BSFC associated with high engine brake power and BTE.