Numerical simulation and parameterization of the heating and evaporation of a titanium (IV) isopropoxide/p-xylene precursor/solvent droplet in hot convective air

Abstract

Flame spray pyrolysis (FSP) is an excellent method to produce metal-oxide powders in the nano-size range. In this framework, the heating and evaporation of precursor solutions in hot oxidizing environments is investigated. A single spherically symmetric precursor/solvent droplets of titanium (IV) isopropoxide (TTIP) – Ti[OCH(CH3)2]4 in p-xylene – C6H4(CH3)2 at room temperature in convective hot air at atmospheric pressure is considered. Both variable liquid and gas thermophysical properties are incorporated and the non-random two-liquid (NRTL) model is used to describe the real behavior of the mixture. The bi-component droplet interior is not physically resolved and time-dependence is considered through the distillation-limit model for droplet heating and the rapid-mixing model accounts for droplet vaporization. A parameter study of the heating and evaporation characteristics of the single precursor/solvent droplet on the initial droplet size, the initial TTIP mass fraction in the droplet, the ambient air temperature, and the relative gas and droplet velocity is performed and discussed. The results are parameterized and tabulated in terms of polynomial fits of the individual mass evaporation rates of the components, the droplet surface temperature, and the normalized droplet surface area. A computer code in the programming language C is provided that can be incorporated into more complex simulations of FSP.