A comparative analysis of the performances of a syngas port injection plus gasoline direct injection combined-injection spark-ignition engine under lean-homogeneous charge and Lean-Stratified Charge modes

Abstract

This study conducts a comparative analysis of the performances of a syngas port injection plus gasoline direct injection combined-injection spark-ignition engine operating in Lean-Homogeneous Charge (LHC) and Lean-Stratified Charge (LSC) modes. Results demonstrate that adjusting direct injection timing achieves LHC with early intake stroke injection and LSC with late compression stroke injection. Regarding mixture charge, increasing excess air ratio (λ) or syngas injection proportion (SIP) in LHC mode improves mixture homogeneity, while a higher SIP in LSC mode enhances mixture distribution for ignition. Concerning combustion characteristics, both modes benefit from lower λ and higher SIP with increased peak cylinder pressure, heat release rate, flame speed, and in-cylinder temperature. A higher λ extends CA0-10 and CA10-90, while a higher SIP shortens these durations. Regarding emissions, a higher λ positively affect HC, CO, and NOx emissions, whereas a higher SIP reduces HC, CO and soot but increases NOx emissions. The comparison between LHC and LSC highlights the superior combustion efficiency of LSC, whereas LHC excels in emission control.