Abstract
In terms of energy savings and protection of global environment against air pollution is a very important problem. Vegetables oil is an interesting alternative to fossil diesel fuel, as they are renewable source of energy, have a low sulfur content, and are safe to store. However, using vegetable oils in order to fuel direct injection diesel engines creates problems due to their low heat energy, low volatility and high viscosity and surface tension.
These problems are reduced to minimum by subjecting the vegetable oils to the process of tranesterification. Same problems remain, like as spray parameters - injection velocity, injection cone angle, spray penetration, droplets size - modified by different fuel properties.
The viscosities of methyl ester biodiesel fuels may vary as much as 80% and may be a contributing factor to the difference in performance among some biodiesel fuels. The variation of surface tension for methyl ester biodiesel fuels is 22% on average, and thus has medium influence on the atomization characteristics. The difference in the Sauter Mean Diameter between some biodiesel fuels is as high as 6%. The SMDs of methyl ester biodiesel fuels vary from 8 to 14% higher than diesel fuel.
Keywords: biodiesel, atomization, injection velocity, jet penetration, droplet size