Response Surface Methodology Based Multi-objective Optimization of the Performance-Emission Profile of a CI Engine Running on Ethanol in Blends with Diesel

The present study is aimed at optimizing the effect of ethanol-diesel blends on the performance and emission characteristics of a single cylinder (indirect injection) four-stroke diesel engine at different loads. Hexane was used as a co-solvent for higher ethanol concentration while Diethyl ether (DEE) was added as an ignition improver. D-optimal was chosen as the Design of experiment methodology. Quadratic polynomial models were constructed for the desired emission-performance parameters based on experimental data through the Response Surface Methodology NOx, CO and HC were chosen as the emission output parameters while BSFC. Load and ethanol-hexane-DEE concentration in the diesel blend were chosen as the input parameters. Multi-objective optimization involving the objective of minimizing both the emission and BSFC simultaneously yielded an optimal input condition of 5% hexane and 15% DEE in blend with 40% ethanol and diesel at 95% full load operation with 15.3% absolute error in NOx, 17.1% in HC, 1.69% in CO and 3.4% in BSFC estimation with respect to actual experimental values at the calibrated test condition predicted through RSM model optimization.