Investigation of the effects of Injection strategy on the combustion performance and emissions of Light Duty GCI engine

High-efficiency lean-burn compression ignition using high-reactivity fuels, known as Gasoline Compression Ignition (GCI), demonstrates potential in reducing particulate matter (PM) and nitrogen oxide (NOx) emissions by controlling the charge ignition through both local strength and auto-ignition chemistry. This study explores the combustion strategy for GCI fuel with a Research Octane Number (RON) of 61 under a wide range of operating conditions using a Single Cylinder Research Engine (SCRE) calibrated to Euro 5 emission standards. The SCRE, with a compression ratio (CR) of 16.50, is designed for high-reactivity fuels and features a centrally located multi-hole injector and a piston bowl shape tailored to injection and spray characteristics. At steady state and part load (IMEP = 7 bar), the study investigates the impact of fuel injection strategy and the required amount of exhaust gas recirculation (EGR). Findings indicate that a single injection strategy with a considerable amount of EGR can meet emissions targets while maintaining a reasonable pressure rise rate (PRR) and combustion noise. Under the same operating conditions, a double injection strategy shows potential in meeting emissions targets and reducing engine-out NOx and indicated specific fuel consumption (ISFC) by 40% and 15%, respectively. Experimental results at high load (IMEP = 18.50 bar) demonstrate that the double injection strategy can achieve NOx emissions below 2 g/kWh with high combustion efficiency and an advanced combustion phase. However, fuel volatility leads to bubble formation in the fuel line, affecting fuel reading and causing a slight increase in ISFC. Further investigation is recommended to optimize ISFC at high loads.