Numerical study on evaporation process of feedstock powder under transient states in pulse-modulated induction thermal plasmas for nanoparticle synthesis

A numerical model was developed on the evaporation process of intermittently fed feedstock into pulse-modulated induction thermal plasma (PMITP). This experimental method combining the PMITP with intermittent feedstock feeding has been developed for synthesis of large amounts of nanoparticles. To treat this method, a full transient numerical model for the PMITP was combined with transient equations of particle behaviour with different time steps. Transient two-way interactions from particle evaporation to the PMITP was also taken into account at each time step as source terms in mass, momentum and energy conservations. The temperature, gas flow field and mass fraction of feedstock vapor were obtained in transient state in the PMITP with motion of feedstock particles. The calculation results were compared with the experimental results for Ar I line and feedstock atomic line. They were found to be in fair agreement even in transient state.