Influence of ethanol–gasoline–hydrogen and methanol–gasoline–hydrogen blends on the performance and hydrogen knock limit of a lean-burn spark ignition engine

This study investigates the effects of ethanol–gasoline and methanol–gasoline blends on the performance of a lean-burn spark ignition engine and the hydrogen knock limit of the engine with hydrogen-enriched fuel. The experimental setup includes liquid in-cylinder fuel injection and hydrogen port induction. Ethanol and methanol are blended with pure gasoline up to 50% by volume (20%, 35% and 50%) and all fuels are drip-fed with hydrogen until combustion knock is detected in step size of 2LPM. The hydrogen knock limit extension is achieved with ethanol–gasoline and methanol–gasoline blends and is further extended by spark-timing retardation. Retarded spark timing and ethanol–methanol blended fuels reduce the brake thermal efficiency, brake mean effective pressure, and peak in-cylinder pressure. The cyclic variation increases with ethanol and methanol addition and decreases with spark-timing retardation and hydrogen enrichment. Unlike hydrogen enrichment, ethanol and methanol addition reduce the CO₂ and NO_x emissions but increase the CO emission.