Despite improvements in internal combustion engine efficiency, fossil fuel reliance remains a challenge for sustainable energy. Syngas, a hydrogen-carbon monoxide mixture produced from gasification, typically of carbon-based feedstocks, offers a viable transitional fuel due to its compatibility with existing combustion technologies and reduced emissions. However, its low ignition propensity elevated intake temperatures or pressures, a limitation that can be overcome through diesel pilot injection in dual-fuel engine configurations.
This study extends prior single-cylinder research to a 1.6 L four-cylinder HCCI engine operating in dual-fuel mode, resembling a Reactivity Controlled Compression Ignition (RCCI) engine. The analysis focuses on cylinder-to-cylinder combustion variation, thermal efficiency, and pollutant emissions, with particular emphasis on the influence of diesel pilot injection timing. Experimental evaluations are conducted across a range of injection timing and Syngas flow rates (100 to 160 L/min). Key metrics include ignition delay, heat release rate, maximum pressure rise rate, coefficient of variation of indicated mean effective pressure, and pollutant emissions.
Results indicate that diesel pilot injection timing significantly affects combustion phasing, heat release dynamics, and overall engine efficiency. Advancing or retarding the injection timing alters ignition delay and heat release characteristics, with optimal settings improving Syngas utilization and reducing particulate emissions. These findings highlight the importance of injection strategy optimization for realizing the full potential of Syngas in multi-cylinder engines, supporting their integration into cleaner and more efficient propulsion systems.