Model integration for metal nanoparticle synthesis by an rf thermal plasma flow with counterflow cooling

Comprehensive modeling is attempted to simulate metal nanoparticle synthesis by an RF thermal plasma flow. On the basis of electromagnetic hydrodynamics, plasma heat transfer, and aerosol dynamics, the significant processes are modeled and integrated. The numerical results show good agreements with the experimental ones, which supports the validity of the present model. The model is applied to the efficient nanoparticle production system with counterflow cooling. The result shows that the RF thermal plasma flow has a high temperature zone over 9 000 K and a recirculating zone due to the Lorentz force. Nanoparticles are first formed at the interface between the plasma flow and the counterflow. Subsequently, the nanoparticles increase their sizes by coagulation among them with the decrease of their number and by heterogeneous condensation with vapor consumption. Because of the saturation pressure difference, a larger number of the platinum nanoparticles are produced and they provide a smaller volume mean diameter than the titanium nanoparticles.