Effect of Direct Injection Timing and Premixing Ratio on the Deterministic Characteristics of Combustion Dynamics Diesel-Butanol RCCI Engine

The population growth has led to a significant rise in car demand, raising pollution levels. It compelled governments to enact more stringent pollution standards. Researchers are exploring alternative fuels and advanced low-temperature combustion modes to meet the emission standards. The reactivity-controlled compression ignition strategy is one of the potential combustion strategies to reduce the particulate matter and NOx simultaneously while maintaining higher fuel conversion efficiency. This study investigated the influence of Diesel injection timing and premixing ratio on the cyclic variation of RCCI engines fueled with gasoline and butanol as low reactivity fuel. The experiments were carried out on the single-cylinder diesel engine modified to operate in RCCI mode. All the experiments were carried out at constant load and engine speed. A developmental ECU was used to regulate fuel mass and injection time. The recurrence plot and recurrence quantitative analysis were used to investigate the deterministic features of combustion. Results showed that the COVIMEP and COVTHR decrease with advanced diesel injection timing and lower premixing ratio. Also, the butanol-diesel RCCI and gasoline diesel RCCI both have similar trends for COVIMEP. It was also observed that the combustion phasing advances with a higher premixing ratio and higher injection timing. The recurrence plot shows the combustion at a higher premixing ratio is more deterministic in nature. The relationship between the various combustion parameters has also been examined to manage and optimize the RCCI combustion.