Vaporization characteristics of suspended droplets of biodiesel fuels of Indian origin and their diesel blends - An experimental study

For a liquid fuel, its vaporization characteristics are important. The determination of vaporization rates for alternative fuels such as biodiesel and its diesel blends is reported in this work. For this purpose, suspended droplet technique in conjunction with optical measurement of the droplet diameter is used. The physical processes occurring during the vaporization are studied at temperatures lower than the boiling point of the respective fuels to ascertain all the regimes of vaporization. Further, the vaporization characteristics are related to the composition of the fuel, which governs its thermal and physical properties. This study becomes important due to absence of such a comprehensive data in literature, and attempts to create a useful data-base for vaporization rates and related features of biodiesel fuels produced from sources such as jatropha, karanja, palm and coconut, and their diesel blends. The overall evaporation rates of neat and fuel blends are reported systematically. For neat fuels, the vaporization rates are seen to correlate directly with two parameters namely, heat transport and mass transport parameters, constituted using the gas-phase thermal and physical properties, as well as the liquid-phase density. Also, the vaporization rate is seen to inversely vary with a parameter called long chain saturation factor. All these parameters depend on the composition of the fuel.