Numerical Study of TiO2 Nanoparticle Synthesis in Methane Flame
Date Issued
2011
Date
2011
Author(s)
Pan, Tzu-Jung
Abstract
A computational model describing the particle kinetics in flame combustion synthesis process was presenting using the programming language C and computational fluid dynamics software FLUENT12.0.16. The thermal-flow field, chemical reaction, Brownian motion, sintering, Van der Waal interaction and diffusion had been considered in the model and assuming the spread of particles and aggregates are monodisperse. The particle size and the condition in the synthesis process were described by number concentration of particles (N), total particle volume per mass (V) and total particle surface area per mass (A).
As gas-phase precursors enter the flame, they will react on high temperature and the gas-phase production is produced. Because the chemical reaction rate is very fast in the flame, the oversaturated production will form nano-size production particles. Particle size will grow continuously by coagulation and sintering until particles are collected.
Using TTIP as the precursor to produce TiO2 nanoparticles in methane premixed flame to compare with the experimental result was investigated in this research and the effects of operation parameters such as oxygen/nitrogen ratio (O2/N2), total mass flow rate(Q) and TTIP concentration(XTTIP) have been discussed. Considering the collection height at 2.5cm, as O2/N2 is increased from 20/80 to 50/50, it will enhance the collision and sintering in reaction regime II and lead particle size (dp) to increase from 40.9nm to 54.2nm. As Q is increased from 1.88x10-5kg/s to 5.65x10-5kg/s, it will lengthen regimes so the collected height in three different cases are in the different regions. Therefore particle sizes are irregular as Q increases. And as XTTIP is increased from 0.2% to 0.6%, it will increase TiO2 particles produced in reaction regime I and leads to increase dp from 40.5nm to 51.0nm.
Subjects
gas-phase combustion synthesis
particle kinetics
collision efficiency
Type
thesis
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