Diesel engine evaluation of a nonionic sunflower oil-aqueous ethanol microemulsion

A nonionic sunflower oil-aqueous ethanol microemulsion was formulated, characterized and evaluated as a fuel in a direct injection, turbocharged, intercooled, 4-cylinder Allis-Chalmers diesel engine during a 200 hr EMA cycle laboratory screening endurance test. Differences in engine operation between a baseline Phillips 2D reference fuel and the experimental fuel were observed. The major problem experienced while operating with the microemulsion was an incomplete combustion process at low-load engine operation. Significant lubricating oil dilution was observed initially, followed by an abnormal increase in the viscosity of the lubricative oil. Heavier carbon residue on the piston lands, in the piston ring grooves and in the intake ports was noted. In addition, premature injection-nozzle deterioration (sticking of the needle) was experienced. At present, the sunflower oil-aqueous ethanol microemulsion studied cannot be recommended for long-term use in a direct-injection diesel engine, but further modifications in formulation may produce acceptable sunflower oil microemulsions as alternative diesel fuels.