Simulation Of The Growth Process Of Titania Nanoparticle Synthesized By Flame CVD

Considerable interest lies in the synthesis and the use of nanosized particles for a variety of applications. Commodities such as carbon blacks, pigmentary titania or optical fibers for telecommunications are typical products of industrial aerosol reactors. Particle characteristics like size and size distribution or the morphology mainly influence the final product quality. This emphasizes the need for a tool for optimization of the reactor geometry and the operating parameters.Using the commercial CFD-code FLUENT, the simulation of the growth process of Titania nanoparticle synthesized in a flame CVD process for nanoparticles is performed. With the suppose that the combustion reaction occurs in a single step, the calculated results show that the RNG k-ε turbulent model produces reasonable predictions for the temperature profile and the shape of the flame with the Non-Equilibrium wall function in comparison with other method. On the base of that, the oxidation of TiCl₄ was also included in this turbulent model with the pseudo-component titania and the effects of particles to the fluid are ignored. By using the additional fluid-particle dynamics (Schild et al. 1999)and Kn modified fuction by HongyongXie, growth processes of Titania nanoparticle in the turbulent diffusion flame was simulated, where the process of all precursor molecules converting to free TiO2 "monomer" molecules firstly when the reactions occurred; after that these monomers turned into large particles or aggregates by coagulation caused by Brown collisions between particles in the high temperature flame. Based on those assumptions, the size of particles is simulated, and the effects of flame temperature and the flow rates of oxygen on the sizes of particles and aggregates have been calculated. The results indicate a flame of higher temperature more easily leads to big particles; the size of particles or aggregates become bigger with the longer residence time.