Computational fluid dynamics modelling of nanopowder production by chemical vapour synthesis process

The chemical vapour synthesis (CVS) process has been applied to the production of nanosized metallic, intermetallic and ceramic particles of 5-200 nm sizes. A multiphase computational fluid dynamics model, which incorporates the gas phase governing equations of overall continuity, momentum, energy and species mass transport in two- and three-dimensional frameworks, has been used as an integral part of the CVS research. The population balance model is coupled with the gas phase equations to describe the formation and growth of nanoparticles. The quadrature method of moments, which allows direct tracking of local particle size distribution, is used to solve the particle population balance. The model has been applied to the CVS of tungsten carbide, aluminiumand silica nanopowders from the vapour-phase reactions of precursors. Comparisons of the model predictions with experimental results in terms of average particle size and other process parameters have shown reasonable agreements. The effects of operating conditions, such as reaction temperature and carrier gas feedrate, on the particle size distribution have been evaluated. The model has shown a considerable potential as a tool for designing and scaling up these particle synthesis processes.