Effect of exhaust gas recirculation on fuel consumption and nitrogen oxides emissions

This final report focuses on the study of the effect of exhaust gas recirculation on engine-out emissions of a spark ignition engine. The experiments concentrated primarily on the reduction of nitrogen oxides emissions. The effect of exhaust gas recirculation on fuel efficiency was also considered as it is also desirable to reduce fuel consumption.; The experiments were carried out in a lab facility with an engine dynamometer. The dynamometer was utilised to simulate urban and highway speed/load conditions. The engine used was a General Motors 3.1 L, 6-cylinder engine with a computerised fuel and ignition timing management system.; The experimental trials showed encouraging benefits to using exhaust gas recirculation up to certain levels. For urban simulated conditions, below 10% exhaust gas recirculation, there is a significant reduction in nitrogen oxides emissions and a modest improvement in fuel consumption. Above 10% exhaust gas recirculation, the study shows that there is a reduction in combustion efficiency, which has a negative impact on hydrocarbon emissions and a lowered improvement of the nitrogen oxides emissions. Similarly, the fuel consumption increases past 10% exhaust gas recirculation.