Effect of Ethanol Emulsion on Diesel Engine

Abstract

Alcohol (Methyl and Ethyl) represents a renewable energy source that can be locally produced and used to extend petroleum fuel sources. However, its non miscibility with diesel especially at high alcohol ratios, low cetane number and poor lubricating characteristics limited the utilization of alcohols in diesel engines. Past research has focused on four primary methods of introducing alcohol into a compression ignition engine: fumigation, unstable emulsions, neat ethanol fuels, and stabilized ethanol-diesel blends. The major advantage of blending is the absence of modifications in intake and injection systems, and the ease of implementation. Usually, when ethanol contents in the blends reach 20–40%, high concentrations of additives are needed to ensure the mixture homogeneity in the presence of high water contents, and to attain the required cetane number for suitable ignition. Therefore, selection of suitable additives plays vital role to increase the solubility of ethanol in larger amount. Similarly selection of surfactant is very important to obtain long lasting emulsions. Tetra Methyl Ammonium Bromide by virtue of its favorable properties is focused in this study to stabilize the ethanol diesel and water emulsions and as an alternate fuel. A single-cylinder, air-cooled, direct injection diesel engine developing a power output of 5.2 kW at 1500 rev/min is used. Base data is generated with standard diesel fuel Subsequently, four fuel emulsions namely 90D:10E:5W, 80D:20E:5W, 75D:25E:5W and 70D:30E:5W percentages by volume of diesel, ethanol and water along with 2% Tetra Methyl Ammonium Bromide were prepared and tested in the diesel engine. Engine performance and emission data were used to optimize the blends for reducing emission and improving performance. Results show improved performance with D: E: W emulsions compared to neat fuel for all conditions of the engine. However, 90D: 10E:5W emulsion recorded a brake thermal efficiency of 32.8%. Other blends recorded marginal decrease in brake thermal efficiency. Minor increase in smoke density is found with the emulsions as compared to neat diesel with reduction in HC emissions. However, NOx emissions were found to be increased for emulsions than neat diesel. Thus the result shows 2% Tetra Methyl Ammonium Bromide by virtue of its properties is capable to stabilize 30% ethanol addition with 70% diesel and 5% water by volume as emulsions, and thereby can be used as a fuel with diesel to replace 30% of diesel in a compression ignition engine with significant reduction in exhaust emissions as compared to neat diesel.