Evaluation of precursor evaporation in Si nanoparticle synthesis by inductively coupled thermal plasmas

The evaporation of a micro-sized silicon solid precursor in a laboratory scale inductively coupled thermal plasma system for nanoparticle synthesis is investigated numerically using a customized version of the commercial CFD code ANSYS FLUENT (c). Two turbulence models-the standard k-epsilon and the Reynolds stress model-and two different models for the computation of vapour production from the heated precursor-evaporation at boiling point and vaporization driven by vapour concentration gradients-are compared. The choice of the turbulence model can considerably influence the estimation of vapour production because plasma temperature reduction by plasma-particle heat exchange is increased when the flow in the torch region is predicted to be laminar, whereas the choice of the model for particle evaporation may be critical when the plasma temperature is decreased by plasma-particle heat exchange to values close to the boiling point of the material treated.