Abstract
Hydrogen assiste d jet ignition (HAJI) is an advanced ignition process that allows ignition of ultra lean mixtures in an otherwise standard gasoline fuelled engines. The ignition system utilises a spark ignition of a rich hydrogen mixture to provide turbulent, chemically active jets for reliable ignition of mixtures as lean as l=5, three times more dilute than the lean limit with normal spark ignition. Under conditions of gasoline air-fuel ratios greater than l=1.8 NOx emissions can be maintained at almost zero (0.02 g/kW/h) and in the range l=2 to 3 thermal efficiency may be increased by 30% over stoichiometric operation. Direct cylinder injection of the gasoline is explored as a means of reducing hydrocarbon emissions close to zero. The initial results presented here indicate a 50% reduction in hydrocarbons is possible in the critical range of operation for low NOx and high efficiency.