Simulation Of Process Of Titania Nanoparticles Synthesized By Flame CVD Process With Detailed Chemical Reaction Mechanism

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. In the method, nano-particles generate in the combustion process, the particle size and morphology is determined by the flame, and structure, electricity, light, mobile, sintering and other properties of Nanoparticles also are determined by the particle size and morphology; Therefore, accurate description of combustion processes, can provide the right preconditions for studying the formation of particles.Based on the previous experimental work of TiO₂ nanoparticles synthezed by the oxidation of titanium tetrachloride (TiCl₄) in propane/air flame, size characteristics of TiO₂ nanoparticles have been investigated. Using commercial CFD-code Fluent, the detailed chemical reaction simulation of progress in propane/air turbulent diffusion flame for TiO₂ nanoparticle production have been performed in this paper, and the results produced were compared with the experimental results in the process of particles, particle cumulative size distributions, the average particle size, the relative size distribution width.Taking into account the volume of particles as small dispersed phase, which simulated the process of convection ignore its impact on the market, in this assumption, the simulation work includes two parts:First, the flame simulation. multi-step reaction numerical simulation is performed with EDC turbulent combustion model and Casimir's propane combustion detailed mechanism for the four conditions; the results were compared with the experimental results from the speed distribution, flame temperature, composition distribution and flame length respectively; Simulation Results are basically consistent with the experimental results; In velocity vector map, there is a partial backflow, and it can be to eliminate by adjusting the structure. Compared with one step reaction simulation results, It show that multi-step reaction simulation results are better. While we can also analyze some combustion intermediate product, and get more information of flame field which can not be getted by one-step reaction simulation. As the same time, these product formation and development process are analyzed; simulation results are consistent with the actual results. In short, multi-step reaction simulation can reflect combustion process better, it can provide a correct premise for particles growth process simulation. Second, the particles growth process simulation, and creating a model of fluid dynamics and particle dynamics model, this paper simulate the model based on integral collision kernel by particle dynamics. The results show that the particle formation process reflected by the model is in line with the actual situation; It can also show detailed particle growth process which can't be observed in experiment, and distribution law of particle diameter at exit. In the model based on integral collision kernel, the simulation results of conservation of particle volume size (nv=c) is consistent with the experimental results, the simulation results of conservation of particle surface area (na=c) and conservation of (nd^2.5=c) are larger than experimental results. So nv=c model is a correct model, and can be used to study particles growth process.