2013 Volume 56 Issue 1 Pages 52-57
Ultrasonic preparation of two-phase water-in-oil (W/O) emulsion fuel was carried out using an ultrasonic apparatus with a rod horn. The effect of the position of the horn tip emitting ultrasound into the sample mixture on emulsion stability was investigated for water (10 vol%)/diesel fuel/surfactant (2 vol%) mixtures. In addition, the effects of ultrasonication time and vegetable oil addition on viscosity, water droplet size and combustion characteristics of the emulsion fuels prepared by ultrasonic treatment were studied for water (5 vol%)/diesel fuel/surfactant (2 vol%) and water (5 vol%)/diesel fuel/vegetable oil (5 vol%)/surfactant (2 vol%) mixtures. The stability of the emulsion fuel significantly depended on the tip position of the ultrasonic horn immersed in the mixture. Both the stability and viscosity of the emulsion increased with sonication time for the first 10 min and then remained constant. The water droplets in the emulsions of water/diesel fuel/surfactant and water/diesel fuel/vegetable oil/surfactant were extremely fine and median diameter of the droplets was about 0.3 μm. The water content in the W/O emulsion fuels was significant in the reduction in soot, NO and NOx during combustion.