3D Unsteady State MHD Modeling of a 3-Phase AC Hot Graphite Electrodes Plasma Torch

Abstract

International audienceWe present, in this paper, the magnetohydrodynamic (MHD) modeling of a three-phase plasma torch. The MHD equations are solved using CFD software Code Saturne®, a computational fluid dynamics software which is based on colocated finite volume. The model developed is 3-D, time dependent, and assumes Local Thermodynamic Equilibrium (LTE). Regarding numerical issues, the modeling of the three-phase AC discharge is particularly tricky since the arcs ignition, by the rotating electrical potential, is relative to the electron density of the electrode gap middle. However, despite these challenging difficulties, the numerical model has been successfully implemented by a LTE assumption. After a detailed description of the model, the results are presented, analyzed, and discussed. The influence of current and nitrogen flow rate over the arc characteristics are studied in terms of temperature, arc behavior (position and motion), velocity and electrical potential. The model gave significant information on parameters that could hardly be obtained experimentally. This study has shown the strong influence of the electrode jets on the overall arc and flow behavior. This work is likely to open the way toward a better understanding of three-phase discharges, which technologies are currently encountering an important development in many application fields

Pattern formation and self-organization in plasmas interacting with surfaces

“…T = T h = T e ) are more commonly used that thermodynamic nonequilibrium (NLTE) models, particularly for the modeling of thermal plasmas (e.g. [81][82][83][84][85][86]). Nevertheless, thermodynamic nonequilibrium (two-temperature) models have been the only ones so far capable to capture the spontaneous formation of patterns in thermal plasma systems (see section 4.3 and [87,88]).…”

Electrode Phenomena in Plasma Sources

“…For different industrial uses such as nanoparticle synthesis, material treatment pyrolysis, gasification, waste treatment, plasma-assisted combustion, Rehmet et al (2013) proposed to use a plasma torch with 3-phase AC hot graphite electrodes arranged in the same plane. They showed that the mass flow emanating from the electrodes jets controls the arc motion and the shape of the postdischarge plasma flow.…”

Characteristics of DC arcs in a multi-arc generator and their application in the spheroidization of SiO2 *

“…There are several ways to enlarge an arc plasma volume to meet its applications in various fields, [15][16][17][18][19][20][21][22][23][24][25][26][27] including coal pyrolysis, [17,18] preparation of glass, [19][20][21] thermal spray [22,23] and spheroidization of alumina powder. [24,25] Unlike conventional linear plasma torches, a V-type plasma torch can pro-duce two separate arc columns, cathode arc column (CAC) and anode arc column (AAC).…”

“…[17,18] The use of multi-phase AC arc torch can also achieve the purpose of expanding the high-temperature region of arc plasma. [19][20][21]26,27] The initial multi-phase AC arc torch was powered by a 3-phase power supply. [26,27] Although the high-temperature region is expanded in this 3-phase arc torch, there are significant differences among the discharge intensities of multiple arcs due to low frequencies of arc currents causing the remarkable phase transition, which results in the intermittent discharge and arc instability.…”