Split injection strategy control map development through prediction-based calibration approach to improve the biodiesel-fuelled diesel engine characteristics.

Karanja oil blended with diesel acts as a good alternative for a CI engine due to its low emission and high oxygen content as compared to pure diesel which leads to the non-toxic and biodegradable nature of the fuel. The objective of this project is to enhance the performance and emission characteristics of a diesel engine that runs on biofuel by accurately calibrating its fuel injector control parameters. To achieve this goal, the project focuses on creating optimal split injector control maps using a novel global model-based calibration approach that considers the entire range of engine speed-load conditions. To develop the model, the experimentation was conducted using the I-optimal design of the experiment technique. To establish a relationship between the calibration parameters and engine performance parameters based on experimental data, the study employed response surface methodology (RSM). With the support of a developed model and multi-objective optimization approach under equivalent importance to performance and emissions, the optimum injector control points are derived. For the developed engine map for 20% KBD (Karanja bio-diesel)-blended fuel, the BTE (brake thermal efficiency) reaches up to 30% and lower BSFC (brake specific fuel consumption) of 0.37 kg/kW-hr. After optimization, the split injector control map showed significant improvements over the un-optimized map. At 19 Nm and 3000 rpm, the optimized map resulted in a 31.36% increase in BTE and a 29.31% decrease in BSFC. Moreover, the optimization successfully balanced the trade-off between reducing nitrogen oxide (NO) emissions and smoke emissions. However, the optimized fuel map for 20% KBD-blended fuel shows slightly lower performance compared to diesel fuel. While the optimization process led to a decrease in smoke emissions about 22.3%, it also resulted in elevated NO emissions about 9.83% when compared to diesel fuel. Furthermore, emissions of CO and HC are reduced by 12.8% and 19.2%, respectively, in an optimized control map of 20% KBD-blended fuel compared to un-optimized map.