Effects of nanoparticle concentration and peclet number on nanofluid droplet evaporation behavior

Effects of droplet parameters are reported using model simulations on the evaporation characteristics of droplets containing insoluble nanoparticles and related to the formation of shells of particles. The droplet parameters are initial droplet diameter (do), initial particle mass fraction (Yvo), and the Peclet number (Pe) based on the fluid evaporation rate constant (K) to particle diffusivity in the fluid (Dpl). Time-dependent phenomena of the instantaneous droplet size (d), d2 vs time (for example, following the d2-law or the deviation from it), instantaneous evaporation efficiency (i.e., effective area of evaporation due to particle inclusion on the droplet surface compared to a pure fluid droplet) are reported. Analytical expression of shell parameters at shell formation such as time to shell formation, shell size, and evaporation efficiency are derived using the initial droplet parameters and compared with the computational results. It is found that the evaporation behavior of droplets containing insoluble nanoparticles, including the deviation from d2-law, is independent of do but is strongly influenced by the product of Pe·Yvo.