Droplet evaporation characteristics of aviation kerosene surrogate fuel and butanol blends under forced convection

Abstract

A droplet evaporation model for blends of aviation kerosene surrogate fuel (n-decane and toluene) and butanol (a promising bio-jet fuel) was presented and validated by conducting droplet suspension experiments. The model incorporates the non-ideal effects of blended fuels using the component activity coefficient, which turns out to greatly deviate from unity for test fuels and thus significantly influence their evaporation rate. The effects of recirculation inside the suspended droplet on the heat and mass diffusion were also considered. The experimental data were largely consistent with simulated results under different ambient temperatures and different convention velocities. With increasing butanol content, the droplet evaporation rate increased and the micro-bubble phenomenon was more likely to occur. The convection velocity exhibited a significant influence on the evaporation process as Reynolds number and Sherwood number rose under forced convection conditions. The discrepancy between experimental data and simulated results at the convection velocity of 0.05 m/s was small and comparable with that at the convection velocity of 0.1 m/s and 0.5 m/s, which implies the model could reflect the convection effect reasonably. Temporal evolutions of component concentrations at the liquid surface demonstrated that butanol and toluene were likely to evaporate at a faster rate than n-decane.