Fluid Dynamics and Particle Trajectories in a Diffusion Flame Reactor to Synthesize TiO₂ Nanoparticles

Temperature and velocity profiles were simulated by a computational fluid dynamics method for the synthesis of TiO₂ nanoparticles by a diffusion flame reactor and also for the collection of the TiO₂nanoparticles by a filter. Computational grids were created by GAMBIT and all governing equations for momentum, energy and mass balances were solved by FLUENT code. The effects of O₂ flow rate on the fluid dynamics and particle trajectories are illustrated. An increase in O₂ flow rate reduces the flame temperature but significantly enhances the gas velocity. The particle trajectory differs according to the starting position. The effect of O₂ flow rate on the particle trajectory can be seen clearly at the starting position r ₀ = 0.2 cm from the central axis. The particles at higher O₂ flow rate move closer to the central axis and deposit earlier on the filter than the particles at lower O₂ flow rate. The particles starting at r ₀ = 0.4 cm at higher O₂ flow rate move further away from the central axis and deposit at a higher position on the filter. Information on gas temperature, velocity profiles and particle trajectories can be quite useful in designing a diffusion flame reactor to synthesize high-performance TiO₂ nanoparticles.