Parametric optimization of a direct injection ‐ compression ignition engine fuelled with butanol/diesel blend using response surface methodology

This paper presents results of a simulation study on the performance and emission characteristics of a direct injection compression ignition engine, fuelled with butanol/diesel blend (20% of butanol‐by volume, called as Bu20). The aim of this study is identify optimum values of the engine operating parameters for this Bu20 fuel, which give the best performance with minimum emissions. CONVERGE CFD software was used to carry‐out the simulation studies. Simulation studies were carried out by varying four operating parameters of the engine, viz., compression ratio (CR) (16.5, 17.5, and 18.5), fuel injection pressure (FIP) (200, 220, and 240 bar), start of injection (SOI) (21, 23, and 25° CA bTDC) and exhaust gas recirculation (EGR) (0, 10, and 20%). The engine performance was evaluated in terms of indicated specific fuel consumption (ISFC), soot and oxides of nitrogen (NOx). Response surface methodology was employed for developing response models for the three output parameters considered, that is, ISFC, NOx, and soot. From the analysis of variance, it was observed that all the developed response models were statistically significant. Desirability approach was used to find the optimum combination of the input parameters with an objective of minimizing the three output responses that is, ISFC, NOx, and soot. The analysis showed that engine operation with optimum values of the operating parameters, that is, CR of 17.5, FIP of 240 bar, SOI of 25° CA bTDC and EGR rate of 10% would give better performance with minimum emissions for Bu20 fuel, compared to the engine performance with baseline configuration.