Experimental study on the evaporation performance of suspended CeO2 nano-fuel droplets

Abstract

In order to study the influence of nanoparticles on the evaporation of nano-fuel and reveal the mechanism of heterogeneous heat and mass transfer induced by the dispersion of nanoparticles, CeO2 nano-fuels with different mass concentration and particle size were prepared based on the two-step method. The visualized evaporation apparatus for single suspended droplets was utilized to investigate the evaporation performance of diesel and nano-fuels at 673K and 973K using image processing technology. The results show that at 673K, evaporation of diesel and nano-fuel droplets accorded with classical D 2 -law and can be divided into a constant-volume evaporation stage and a quasi-steady evaporation stage. The addition of nanoparticles suppressed the evaporation of diesel droplets while increasing concentration or particle size can intensify the extent of suppression. At 973K, however, microexplosions of droplets occurred, and the variation of droplet diameter did not conform with classical D 2 -law. Evaporation was divided into a constant-volume evaporation stage and a fluctuating evaporation stage. Nanoparticles as heterogeneous nucleation sites enhanced the expansion intensity and micro-explosion intensity of droplets, in turn promoting the evaporation of fuel. With the increase of mass concentration or decrease of nanoparticle size, the promotion effect of nanoparticles on evaporation was more significant.