The microexplosion of a slurry droplet is investigated theoretically for a fixed concentration of surfactant of 0.03 at an ambient temperature of 500K~900K and atmospheric pressure of 1 atm in the quiescent environment. The microexplosion of the slurry droplet is considered to be promoted by heterogeneous nucleation of liquid carrier, which is due to the suppression of evaporation by surfactant of low volatility and subsequent superheating of liquid carrier.
A semiempirical model is formulated to simulate the temperature history at the evaporation front and predict the microexplosion time by postulating the limit of superheat for heterogeneous nucleation. The simulation results yield reasonable agreements compared with experimental results for Al/n-heptane slurry droplets with various solid loadings.($Y_s=0.1~0.4$) The microexplosion time increases with increasing initial slurry droplet diameter or decreasing ambient temperature, or decreasing initial solid loading. For details, the process before microexplosion is composed of three regimes according to their physical features, i.e., a heating stage, a shell formation stage, and a pressure build up stage. This is for estimating the contribution of each stage to the microexplosion time. As for the numerical calculation, fully implicit method is adopted for both the droplet interior and the gas field. Also evaluated is the pressure build up in the porous region of the droplet in order to explain swelling or disruption phenomena qualitatively.
