The exhaust emission characteristics of a water-emulsified diesel/sunflower oil blend fuel by ionic liquid surfactants

Abstract

A fuel microemulsion based on blend of diesel fuel:sunflower oil (4:1), water, 1-butanol (co-surfactant), and a blend of Tween 80, Span 80 and 1-buthyl-3-methylimidazolium nitrate ionic liquid as surfactant is formulated and optimized regarding the amounts of co-surfactant, water and oily phase. The fuel microemulsions were for upto one year stable on the bench and their density and viscosity were comparable to neat diesel fuel. The size of water droplets in fuel microemulsions are measured by dynamic light scattering (about 10 nm) with a very narrow size distribution. The optimum results are obtained by using a blend of Span 80:Tween 80:1-buthyl-3-methylimidazolium nitrate, 70:26.25:3.75, respectively, as surfactant. The engine combustion tests at various engine speeds and full load indicated that the brake-specific fuel consumption, torque, brake power and exhaust gas temperature are decreased in fuel microemulsion compared to neat diesel fuel. Carbon dioxide and nitrogen oxide emissions were reduced by 4–5%, and unburned hydrocarbons and carbon monoxide emissions were increased by 18.4% and 1.18%, respectively, for optimum fuel microemulsion compared to neat diesel fuel. The results are promising to introduce a way to improve the diesel fuel performance in terms of its environmental impacts.