Particle trajectories and temperature histories of TiO2 nanoparticles synthesized in diffusion flame reactor

The computational analysis was developed to illustrate the gas temperature and velocity profiles in the oxy-methane diffusion flame reactor during the formation of TiO2 nanoparticles and the collection of the TiO2 nanoparticles by filter. The computational simulation shows that the increase in gas temperature and velocity is significantly affected by the increase in CH4 flow rate. The particle trajectory was calculated by using the model, which concerns the effects of thermophoretic force and gas velocity on the particle movement. The particles starting from different initial positions in radial direction will move in different trajectories. The particles following different trajectories have different temperature histories and also residence times in the gas phase. As the particles start at the initial position of the reactor which is further away from the central axis, they spend longer time in the gas phase and deposit on the higher position of filter. For particles starting at the initial position of the reactor which is further than 0.5 cm from the central axis, they move to deposit on the pyrex tube instead of filter. As the CH4 flow rate increases, the particles move further from the central axis, but it takes a shorter time for the particles to deposit on the filter. The particles synthesized at a higher CH4 flow rate show significantly higher temperature history than those particles synthesized at a lower CH4 flow rate. The temperature histories of particles in diffusion flame reactor can be quite important information to control the properties of TiO2 nanoparticles.