Fast Modeling of Phase Changes in a Particle Injected Within a d.c Plasma Jet
Résumé
When spraying ceramic particles with a low thermal conductivity such as zirconia using Ar-H2 directcurrent (d.c.) plasma jets where the heat transfer is important, heat transfer phenomena take place with the propagation of melting, evaporation and even afterwards solidification fronts. Most models neglect these heat transfer phenomena assuming the particle as a lumped media. This work is aimed at developing a model coupling the effect of heat propagation within the particle along its trajectory. It uses an adaptative grid in which the coordinates of the phase change fronts are fixed. It allows minimizing the calculation costs (approximately 10 s on PC under Windows XP against 1 h with an enthalpy model). Such calculations are illustrated in an Ar-H2 (25 vol.%) for dense and porous agglomerated zirconia (low thermal conductivity) as well as iron particles with a much higher thermal conductivity and drastic evaporation.