Improvement of performance and emission in a lean-burn gas fueled spark ignition engine by using a new pre-chamber

Lean burn combustion of natural gas in spark-ignited engines is a promising approach to improving engine performance and efficiency by reducing pollutant emissions and better fuel consumption. However, inducing excessive lean mixture to the engine makes the combustion unstable, and misfire happens in a significant number of cycles. The pre-chamber ignition technology is a useful solution that can make spark-ignition engines more efficient. In this study, the lean mixture's combustion was empirically investigated with a new pre-chamber spark plug in a one-cylinder engine fueled with natural gas. Tests were performed at 11.5, 13.5, and 16 compression ratios and a wide range of air-fuel ratios. With the pre-chamber spark plug usage, the lean operating limit is enlarged by 10%-45% and gives 4% and 3% the average lower in-cylinder pressure and exhaust gas temperature than the conventional spark ignition system. The brake-specific fuel consumption was improved by 4%-11% using the pre-chamber spark ignition. The HC, CO, and NOx formation is about 11%, 16.3%, and 10% lower than the conventional spark ignition usage. Outcomes confirmed that the new design pre-chamber plug gives 1% improved COVIMEP than the standard spark plug. The use of pre-chamber due to the lean-burn combustion causes larger ignition delay and increases brake thermal efficiency by up to 9%. It can be concluded that the pre-chamber increases the ignition ability, and the lean mixture limit is extended.