Characterization of Glycerol-Diesel Emulsions Fuels

Diesel fuel emulsions have demonstrated reductions of unwanted combustion emissions.  Glycerol, a renewable and abundant resource, is an attractive fuel component since it may lower energy costs and reduce unwanted engine emissions.  In this presentation, various glycerol-diesel emulsions are prepared using an ultrasonic processing technique and resultant fuel properties are presented.  The fuels typically have higher viscosity (5-20 cps) and density (0.9-0.98 g/mL) and lower fuel energy density (36-42 MJ/kg).  The high glycerol oxygen content (52 wt.%) reduces stoichiometric A/F ratio and flame temperatures.  Surface analytical techniques and long-term stability evaluations are used to identify optimal surfactant composition for extended shelf-life.  A narrow droplet size distribution with mean of approximately 3.3 microns is achieved, which is found to be broadened with the addition of water in the glycerol up to 50/50 vol.%.  Glycerol-diesel emulsions prepared at 10 and 20 vol.% glycerol-phase resul in reduced NOx and PM emissions of 5-15% and 25-50%, respectively in a naturally-asiprated signle-cylinder diesel engine.  Thermal efficiency improvements are observed at high loads .