Numerical investigation of particle size distribution, particle transport and deposition in a modified chemical vapor deposition process

Abstract

Modified chemical vapor deposition (MCVD) process in a rotating tube reactor is an important technology for manufacturing fiber optic preforms, whose performance strongly depends on the uniformity of the deposited particles on the tube wall. In this study, the Eulerian–Eulerian model with Population Balance Model (PBM) is applied to predict particle size distribution (PSD) of SiO2 particles in the reaction zone, and subsequently Discrete Particle Model (DPM) is used to represent typical particles and investigate trajectories and deposition locations of the SiO2 particles. The temperature, reaction components, and particle size distribution along the axial and radial directions within the tube are predicted reasonably. The deposition distances of the particles with size of 10 nm, 200 nm and 10 μm are mostly smaller than 120 mm for the condition with the peak wall temperature of 2000 K. The deposition distance and flight time of the particles increase with the increase of particle size. With increase of the wall temperature, the reaction zone and particle formation zone become larger, which promotes the growth of the SiO2 particles. The competing effects between the thermophoretic force and inertial force caused by the increase of the wall temperature lead to firstly an increase and then a decrease in the deposition distance and flight time of the particles.