Comprehensive Investigations on Split Injection System Using Diesel/Biodiesel Blends Powered Common Rail Direct Injection Engine: Multi-Objective Optimization

A combined effect of injection pressure (IP) and split injection mechanism (SIM) on performance, combustion, and emission characteristics of a CRDI engine operated with diesel-lemongrass biodiesel (LGB20) blend was analyzed and optimized the IP from the experimental results using RSM and ANOVA. The CRDI engine was tested under SIM conditions at various injection pressures (IPs) of 200, 300, 400, 500, and 600 bar, with limitations observed concerning specific engine characteristics. The SIM is accomplished by splitting the injection into two phases during the compression stroke. It was noted that the engine characteristics were improved concerning IPs in SIM by minimizing the intensity of heterogeneity of the mixture. The CRDI engine with 600 bar pressure registered higher in-cylinder pressure, heat release rate, and brake thermal efficiency (BTE) with lower specific fuel consumption (SFC) when compared to the engine operated with other IPs. It also registered lower exhaust pollutants except oxides of nitrogen (NOx) and carbon dioxides (CO₂) due to better combustion at 600 bar pressure. The CRDI engine was operated efficiently at 64.61% load with 600 bar IP and recorded engine parameters as 29.94% of BTE, 0.373 kg/kWh of SFC, 0.64% of CO, 4.55% of CO₂, 244 ppm of NOx, 37.2 ppm of HC, and 64.58 HSU of smoke emissions. This study concluded that 600 bar IP is the optimum for better engine characteristics of CRDI engines operated with LGB20 fuel.