Electrostatic Atomization of Vegetable Oil
figureposted on 01.09.2010, 00:00 by Ghazi Al-Ahmed
Raw (or used) vegetable oils can be used as liquid fuels; however, due to their high viscosity (more than 20 times higher than the viscosity of diesel fuel), atomization of these oils presents a major challenge of using them for internal combustion engines thus preventing from obtaining a clean combustion for such oils. In our research, we introduce the use of electrostatic atomization technique for biomass fuels such as soybean oil by introducing electro-magnetic forces to breakup the liquid and enhance its atomization by coulomb forces obtaining smaller and dispersed spray droplets for cleaner combustion. Electrostatic atomization is the addition of electric charge to the liquid jet introducing disruptive electrical forces breaking the jet into fine droplets and improving the spray characteristics. This image shows the jet breakup for soybean oil compared with diesel fuel, using the electrostatic atomization method. Spray photography was taken by focusing shadow back lighting with illumination by a 1 μs light duration light strobe on the opposite side of the camera. Photographs were taken using Cannon S3 camera system. Electric charges injected to liquid using a needle electrode connected to a high voltage power supply. Needle electrode tip was positioned at 0.250 mm from the atomizer orifice entrance. The images were taken at average jet velocity of 10 m/s, atomizer orifice diameter of 0.250mm and applied voltage to needle electrode of -8 kV and -11 kV for diesel fuel and soybean oil, respectively. The jet breakup and spray atomization mechanisms show differences for soybean oil and diesel fuel. For soybean oil, a bending/spinning instability phenomenon was seen due the high viscosity effect similar to the phenomenon found in liquid jets for high viscosity polymer solutions.