Multi-objective optimization of diesel engine performance and emissions fueled with diesel-biodiesel-fusel oil blends using response surface method

The interest in research on alcohol-based biofuels is on the rise. Fusel oil is a long-chain alcohol and a by-product of bioethanol synthesis. This study analyzed the effects of blended levels of fusel oil and biodiesel in diesel fuel on the performance and exhaust emissions of a single-cylinder diesel engine. The effects of input parameters (i.e., fusel oil content (%), biodiesel content (%), engine speed (rpm), and engine load (%), each at five levels) on response parameters (i.e., power, torque, fuel consumption, and emission factors, namely NOX, UHC, CO, and CO2) were investigated. Different levels were used for analyzing fusel oil (0, 5, 10, 15, and 20%), biodiesel (0, 5, 10, 15, and 20%), engine load (0, 25, 50, 75, and 100%), and engine speed (1400, 1700, 2000, 2300, and 2600 rpm). Response surface method (RSM) was employed to maximize engine performance and minimize exhaust emissions. A blend of D90F5 B-5 (5% fusel oil, 5% biodiesel, and 90% petro-diesel) and engine speed of 2026 rpm at load 46% were predicted to be an optimal value. Using a 72% desirability function, optimum results for torque (14.2 Nm), power (3.37 kW), and brake-specific fuel consumption (356.9 g/k Wh) were also obtained from RSM. Based on the optimized inputs, the optimized values of different output pollutants were 0.14 vol.% for CO, 1.62 vol.% for CO2, 23.7 ppm for UHC, and 85.17 ppm for NOX. The result illustrated that use of fusel oil decreased NOX emissions up to 20%, while UHC and CO emissions increased up to 32% and 22%, respectively. In addition, the use of fusel oil content (up to 10%) in the blended fuels improved the engine power by 5.6%.