Optimization of Performance and Emission Parameters of a CI Engine Fueled with Waste Cooking Oil Biodiesel Using Response Surface Methodology (RSM)

Interest in biofuels and other alternative fuels has grown due to environmental concerns and the rising demands and costs of traditional liquid fuels. This study evaluated the biodiesel's engine emissions and performance indicators prepared from waste cooking oil. A regression model, Box Behnken Design (BBD), was used for the multi-response optimization of various input parameters, i.e., load, blend, and preheating temperature, to enhance engine performance and the optimization of emissions. The performance metrics examined included brake specific fuel consumption (BSFC), brake thermal efficiency (BTE), while emissions included carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NOₓ), and unburned hydrocarbons (UBHC). The highest desirability score of 0.724 was achieved with the combination of B23, a load of 57%, and a preheating temperature of 62°C, which was also validated with an error margin of less than 5%. Optimized results showed a 5.88% decrease in BSFC and a 0.84% increase in BTHE. Furthermore, CO2 and NOx emissions were increased by 9.73% and 2.88% respectively; however, emissions of CO and UBHC were reduced by 25% and 54% respectively.