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Progress in Plasma Processing of Materials, 1999

ISBN:
1-56700-126-2 (Print)

NUMERICAL ANALYSIS OF MOMENTUM, HEAT AND MASS TRANSFER BETWEEN A NITROGEN PLASMA JET AND B203 PARTICLES INJECTED IN AN AXISYMMETRIC REACTOR

Predrag Lj. Stefanovic
Institute of Nuclear Sciences "Vinca", Laboratory for Thermal Engineering and Energy, Mike Petrovica-Alasa 12-14, PO Box 522,11001 Belgrade, Yugoslavia

Dejan B. Cvetinovic
Institute of Nuclear Sciences "Vinca", Laboratory for Thermal Engineering and Energy, Mike Petrovica-Alasa 12-14, PO Box 522,11001 Belgrade, Yugoslavia

Pavle B. Pavlovic
The VINCA Institute of Nuclear Sciences, Laboratory for Thermal Engineering and Energy, P. O. Box 52211001 Belgrade, Yugoslavia

Zivota G. Kostic
Institute of Nuclear Sciences "Vinca", Department for Thermal Engineering and Energy Research -11001 Belgrade, PO Box 522, Yugoslavia

Abstract

For thermal plasma processing of solid particles (including processes like plasma spraying, spheroidizing, decomposition, melting or fuming of fine particles, synthesis of ultrafine particles, etc.) injection and mixing, i.e. momentum, heat and mass transfer between solid particles and plasma flow is of great importance for the quality of the product. There are numerous effects involved in plasma-particle interactions. Effects have different ranges of influence in particular plasma process or reactor. This paper present the results of a numerical analysis of the evaporation and decomposition of B203 powder (with particle diameter less than 100 μm) injected in a nitrogen plasma axisymmetric, shielded reactor. This analysis serves as a basis for the optimization of the plasma reactor parameters, used for the plasma synthesis of BN ultrafine powder or boron powder production when B203 powder is used as a precursor.
The computed fields of stream function and plasma temperature, particle trajectories and some parameters (plasma and particle temperature, particle Re, Nu and Kn* numbers, influence of evaporation and noncontinuum effects on momentum heat and mass transfer and instantaneous particle diameter) along particle trajectories are presented and discussed.