Experimental investigation of spark timing on extension of hydrogen knock limit and performance of a hydrogen-gasoline dual-fuel engine

This work focused on the influence of spark timing on the hydrogen knock limit and performance of a hydrogen-gasoline dual-fuel engine. A gasoline direct injection engine with hydrogen port induction was used for this study. The engine speed was kept at 1000 rpm, with a gasoline injection quantity of 6 mg. The hydrogen flow rate was varied until engine knock was detected. The spark timing was varied from 4 to 36֯ CA BTDC with a step size of 4֯ CA. A higher hydrogen flow rate was achieved when the spark timing was retarded close to TDC. The addition of hydrogen increased the cylinder pressure, exhaust temperature, brake mean effective pressure, and brake thermal efficiency. Advancing the spark timing produced a prolonged flame development period and shorter flame propagation period. Cyclic variation increased and then decreased with spark advance. NO_X emissions increased with increase in spark advance and hydrogen flow rate, whereas spark timing had little effect on CO₂ and CO emissions.