Effects of injection conditions on temperature and component distributions in a CVD furnace for large-size silica glass

Silica glass is a superior functional material due to its excellent thermophysical properties. With the increasing demand for large-size and high-purity silica glass, a novel chemical vapor deposition (CVD) furnace characterized by a crucible has been proposed, which requires a deep understanding of heat and mass transport characteristics inside for better control. Aimed at this, a comprehensive simulation model is developed in the paper. The model is well verified with the experimentally measured temperature and is then used to examine distributions of temperature and critical components in the furnace. Effects of the injection conditions are further investigated, among which the H-2-O-2 equivalence ratio and flow rate have a great influence on the temperature and components distributions, whereas the SiCl4 flow rate mainly affects the SiO2 distribution. An improved injection condition is put forward finally, which is much better than the reference case; the average for the temperature and SiO2 concentration on the deposition surface is increased, respectively, by 23 K and 0.018 mol/m(3), and sufficient homogeneity is maintained.