Evaporation and micro-explosion performances of nano-fuel droplets

To investigate the effect of nanoparticles on the evaporation evolution of nano-fuels and reveal the mechanism of heterogeneous heat and mass transfer induced by the dispersion of nanoparticles, carbon nanotubes and CeO2 nano-fuels with different mass concentrations and particle sizes were prepared based on the two-step method and inspected using a laser particle size analyzer. An evaporation visualization apparatus for a single suspended droplet and an image processing technology were utilized to study the evaporation of diesel and nano-fuels at 400 and 700 degrees C. At 400 degrees C, the evaporation of diesel and nano-fuel droplets accorded with the D2-law and can be categorized as constant-volume and quasi-steady evaporation stages. The addition of nanoparticles suppressed the evaporation of fuel droplet and increasing the mass concentration or particle size can intensify the extent of suppression. At 700 degrees C, however, the micro-explosion of droplets occurred, and the variation in the droplet diameter did not conform with the D2-law. Evaporation can be categorized into the constant-volume and fluc-tuating evaporation stages. Nanoparticles, as heterogeneous nucleation sites, enhanced the expansion and micro -explosion intensities, thereby promoting the fuel droplet evaporation. An increase in the mass concentration or a decrease in the particle size can promote evaporation significantly.