Simulation Of Growth Process Of Titania Nanoparticles Synthesized By Flame CVD Process

Flame CVD process to materials synthesis is well established for manufacture of several commodities, and may have been greater potential for the future development of new materials with unique properties. The growth or coagulation of particles in aerosol processes influences strongly the particle size, size distribution and morphology, and therefore is of fundamental interest in the synthesis.In this dessertation, size characteristics of TiO₂ nanoparticles synthezed by the oxidation of titanium tetrachloride (TiCl₄) in propane/air flame have been investigated. From counting for particle from TEM pictures, frequency and cumulative size distributions of 16 samples of TiO₂ nanoparticles at different operational conditions have been obtained. Median size and relative spread of size distribution have been obtained from cumulative size distribution.Using commercial CFD-code Fluent, the simulation of gas velocity and temperature profile in propane/air turbulent diffusion flame for TiO₂ nanoparticle production have been .detailed performed in this paper. The results of three types k-eturbulent models have been discussed at different Near-Wall Treatments. The simulation shows that the results from Non-Equilibrum Wall Functions agree nicely with the flame shape observed in experiments. Using Standard k-sturbulent model, sixteen runs of gas concentration and temperature profiles in propane/air turbulent diffusion flame for TiO₂ nanoparticle production have been simulated in details. The simulation shows flame length agrees nicely with those visually observed, and flame temperature agrees nicely when the mole ratio of O₂/C₃H₈ is high than stoichiometrical ratio.Using commercial CFD-code Fluent, the growth of titania nanoparticles synthesized in propane/air flame has been simulated by particle dynamics of the Kruis model and the model based on integral collision kernel. Comparisons on cumulative and number frequency size distributions between measured and predicted have been made and the results showed that the Kruis model generally under-predicted the particle size and gave very narrow size distributions, the model based on integral collision kernel gave reasonable predictions.