Optimization of flex fuel parameters to improve the characteristics of methanol powered direct injection spark ignition engine

A novel approach has been explored to examine the most appropriate conditions for methanol flex-fuel operation in direct injection spark ignition (DISI) engine. The research findings indicate a significant amelioration in brake thermal efficiency (BTE) from 18.27% to 27.73%. Although, brake-specific fuel consumption (BSFC) shows an increasing trend and M40 exhibits the highest value of 506 g/kWhr. Moreover, carbon monoxide (CO) and hydrocarbon (HC) emissions decreased to 1.22 %vol and 119 ppm, respectively. Contrarily, the emissions of carbon dioxide (CO2) and nitrogen oxides (NOx) increased for blended fuel by about 14.21 %vol and 521 ppm. The effects of operating parameters on output characteristics are investigated using analysis of variance (ANOVA), and the results demonstrate the statistical significance of all parameters. Using a multi-criteria decision-making model, these outcomes are then utilized to identify optimal operating conditions with different weighting criteria. A hybrid approach of stepwise weight assessment ratio analysis (SWARA) and additive ratio assessment (ARAS) is adopted for this. Based on the optimization findings, the top ten optimal engine operating conditions are ranked and summarized in this work. Among the top ten rankings, the blended fuel of methanolgasoline gives an optimal engine response in most operating conditions under flex-fuel mode.