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 TiO2 nanoparticles 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.