Microexplosion mechanisms of aluminum/carbon slurry droplets

• Published in: Combustion and flame 1992-04, Vol.89 (1), p.64-76
• Main Authors: Wong, Shwin-Chung, Lin, Ar-Cheng
• Format: Article
• Language: English
• Subjects: 400800 - Combustion, Pyrolysis, & High-Temperature Chemistry; ALUMINIUM; Applied sciences; CARBON; CHEMICAL REACTIONS; Combustion. Flame; CONVECTION; DECOMPOSITION; DISPERSIONS; DROPLETS; ELEMENTS; Energy; ENERGY TRANSFER; Energy. Thermal use of fuels; Exact sciences and technology; EXPLOSIONS; FLUIDS; GASES; HEAT TRANSFER; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; MASS TRANSFER; MATHEMATICAL MODELS; METALS; Miscellaneous; MIXTURES; NONMETALS; PARTICLES; PYROLYSIS; SIMULATION; SLURRIES; SUSPENSIONS; TEMPERATURE DISTRIBUTION; Theoretical studies. Data and constants. Metering; THERMOCHEMICAL PROCESSES
• ISSN: 0010-2180; 1556-2921
• DOI: 10.1016/0010-2180(92)90078-4

The microexplosion mechanisms of Al/C/JP-10 slurry droplets have been studied experimentally and theoretically. Experimental work includes measurements of transient internal temperature distributions in convective hot gas flows for slurry droplets with and without surfactant. While surfactant-free slurry droplets are heated to the wet-bulb temperature of JP-10, the internal temperatures of the droplets with surfactant rise continuously, and microexplosion occurs as the outer part of the droplet becomes superheated. The presence of surfactant and fine carbon particles (< 0.1 μm) is found to suppress the evaporation of JP-10, promote the superheating and heterogeneous nucleation, and, with shell formation aided by surfactant pyrolysis, lead to microexplosion. With an appropriate amount of carbon (4 wt.% in the solid phase), no significant shrinking appears before microexplosion even for slurries of relatively low solids loadings (e.g., 30 wt.%). However, with carbon decreased (< 2 wt.%), the droplets shrink substantially before microexplosion. The microexplosion process is thus significantly delayed and resemble that observed for boron slurries by Takahashi et al. A semiempirical model is proposed to yield satisfactory simulation of the heating processes of Al/C/JP-10 slurry droplets. For various initial droplet diameters and ambient temperatures, the model is found satisfactory in predicting disruption times for both high-loading (66 wt.%) and low-loading (30 wt.%) slurries.