Multi-Objective Optimization of Diesel Engine Operating Parameters Under Highway Drive Conditions

Experimental and optimization work is carried out to study the effects of fuel injection pressure, boost pressure, pilot injection timing, pilot injection quantity, and main injection timing as input parameters. A four-cylinder, automotive model direct injection diesel engine, incorporated with a variable geometry turbocharger, was chosen for the experiment. Engine test runs are conducted at a driving condition of 80.3 N m torque and an engine speed of 1750 rpm, respectively, corresponding to highway driving conditions, using 10% of exhaust gases recirculated. The response surface methodology is employed to design experiments and analyze the experimental data to optimize engine parameters, considering the mentioned parameters as input parameters. A multi-objective response approach is adopted to optimize engine-operating parameters to obtain desired performance and engine-out emissions. Confirmatory tests are conducted at design conditions to validate the results predicted by the model. It is observed that for the chosen engine configuration, the optimum performance and emission characteristics could be obtained with 120 kPa boost pressure, 61.1 MPa fuel injection pressure, and 11.5% of total fuel amount as pilot injection and remaining as main injection quantity at 332 deg and 359 deg crank angle, respectively. Overall, fairly better engine performance was observed with the use of selected ranges. It is noted that with the procedures adopted, improved engine performance and a significant reduction in harmful emissions are obtained without using major add-ons. The investigation revealed excellent potential for a diesel engine to be an effective prime mover.