Thermodynamic Analysis of Evaporation Characteristics of Moving Two-Component Liquid Fuel Droplets in Pre-Vaporizer Systems

In the current study, a thermodynamic model is presented for predicting the vaporization characteristics of moving two-component fuel droplets, at an ambient temperature of 350 K, atmospheric pressure and with an initial droplet diameter of 100 microns, as typically observed in a gas turbine pre-vaporizing system. Liquid fuels considered are iso-octane (surrogate of gasoline) and decane (surrogate of diesel), blended with ethanol and methyl-butyrate (surrogate of biodiesel), respectively. The model evaluates the vapor-liquid equilibrium based on activity coefficients calculated using UNIFAC group contribution method. The gas-phase properties are calculated as functions of temperature and mixture molecular weight. The temporally varying parameters such as equilibrium surface temperature, concentration of the higher volatile fuel component, evaporation constant and droplet Reynolds and Nusselt numbers have been studied. Variation of integrated parameters such as time-average evaporation constant, droplet lifetime, average velocity and the final droplet penetration distance are also discussed.