Fig 2 - uploaded by Armelle M. Vardelle
Content may be subject to copyright.
Electric arc formed by a transferred arc plasma torch and typical picture. Reproduced with permission Ó 1994 Plenum Press
Source publication
Arc plasma torches are the primary components of various industrial thermal plasma processes involving plasma spraying, metal
cutting and welding, thermal plasma CVD, metal melting and remelting, waste treatment, and gas production. They are relatively
simple devices whose operation implies intricate thermal, chemical, electrical, and fluid dynamic...
Similar publications
Weakly Interactive Massive Particles (WIMPs) are the most widely studied
candidate particles forming the cold dark matter (CDM) whose existence can be
inferred from a wealth of astrophysical and cosmological observations. In the
framework of the minimal cosmological model detailed measurements on the cosmic
microwave background by the PLANCK collab...
The combined diffusion coefficient method has been demonstrated to greatly simplify the treatment of diffusion in the modelling of thermal plasmas in gas mixtures without loss of accuracy. In this paper, an extension of this method to allow treatment of diffusion of a three-gas mixture has been achieved, provided that the gases are homonuclear and...
This paper presents results on fullerene formation during the processing of different graphite powders in an RF thermal plasma reactor. Graphite powders of different particle size and purity were fed into the reactor (Aldrich, KS4). Optical emission spectroscopy of atomic and molecular species is used as a diagnostic tool of the RF plasma flame. It...
Present paper considers processes of production and treatment of hollow particles in plasma flows. Specifics of agglomerated powders treatment and expansion of hollow droplets are analyzed theoretically. Experimental results on production of hollow micro particles of ZrO2, Ni, CoNiCrAlY alloy, SiO2 are shown here.
An aluminium vapor modifies the transport properties of argon plasma
during the thermal plasma processing of aluminium nanoparticles. In the
present paper we have studied the effect of aluminium vapors on the
transport properties of the argon plasma. Results are based on the
Murphy code which shows that transport properties are strongly affected
by...
Citations
... The measured temperature field is very useful information for validating the numerical simulation results. When performing numerical simulations of plasma arc characteristics, the Local Thermodynamic Equilibrium (LTE) approximation [30] is generally applied for simplicity, but it is known that nonequilibrium phenomena occur, for example, in low-temperature regions where the collision frequency between electrons and heavy species decreases [31]. Since the current path in the plasma arc is strongly affected by a change in electrical conductivity caused by the non-LTE phenomena, it can be an important factor for improving the calculation accuracy. ...
The Keyhole Plasma Arc Welding (KPAW) process utilizes arc plasma highly constricted by a water-cooled cupper nozzle to produce great arc pressure for opening a keyhole in the weld pool, achieving full penetration to the thick plate. However, advanced control of welding is known to still be difficult due to the complexity of the process mechanism, in which thermal and dynamic interactions among the arc, keyhole, and weld pool are critically important. In KPAW, two large eddies are generally formed in the weld pool behind the keyhole by plasma shear force as the dominant driving force. These govern the heat transport process in the weld pool and have a strong influence on the weld pool formation process. The weld pool flow velocity is much faster than those of other welding processes such as Tungsten Inert Gas (TIG) welding and Gas Metal Arc (GMA) welding, enhancing the heat transport to lower the weld pool surface temperature. Since the strength and direction of this shear force strongly depend on the keyhole shape, it is possible to control the weld pool formation process by changing the keyhole shape by adjusting the torch design and operating parameters. If the lower eddy is relatively stronger, the heat transport to the bottom side increases and the penetration increases. However, burn-through is more likely to occur, and heat transport to the top side decreases, causing undercut. In order to realize further sophistication of KPAW, a deep theoretical understanding of the process mechanism is essential. In this article, the recent progress in studies regarding the interaction mechanism of arc, keyhole, and weld pool in KPAW is reviewed.
... As a high temperature heat source as well as a chemically reactive particles source, the critical problem limiting the DC arc plasma torch applications is the electrode erosion caused by the extremely high current density and heat flux [17][18][19], which can not only reduce the service life of the device but also contaminate the plasma environment by the erosion products, further limiting the performance of arc plasma torch. Therefore, the investigations on the long life and performance of DC arc plasma torch have received extensive and sustained attention from the thermal plasma researchers [20][21][22][23][24][25]. ...
... A large number of numerical modelings [22,[26][27][28][29] and experimental studies [30][31][32][33][34] have been performed to analyze the mechanisms of anode erosion, and propose the methods to inhibit the anode erosion. The modeling found that the arc usually attached on the anode surface in the diffusive or constricted forms. ...
A novel DC arc plasma torch is designed in this paper in order to reduce the electrode erosion, and a series of experiments are carried out to investigate how to improve the lifetime and performance of the nitrogen DC arc plasma torch. The analysis of voltage characteristics of the plasma torch indicates that the interelectrode insert can increase the average arc voltage and the sudden expansion structure can reduce the voltage fluctuation, which is helpful to improve the working stability to some extent. The spectrum characteristics at the plasma torch outlet and the cold flow simulations show that the dual shielding gas mainly act near the anode and can effectively cover the entire anode wall. Combining the shielding gas distribution with anode heat transfer processes in argon and nitrogen plasma torch, it is inferred that argon shielding gas plays an important role on reducing the anode heat transfer processes in nitrogen plasma torch, which can effectively suppress the anode erosion. The life testing experimental results find that there is no significant erosion of the cathode, anode, and interelectrode insert after cumulative working time exceeding 20 hours. The maximum nitrogen plasma jet length can reach ~35 mm with the outlet jet temperature of about 20000 K at the current of 100 A and nitrogen gas flow rate of 10 slm. The maximum average specific enthalpy and thermal efficiency are respectively about 14 MJ/kg and 75% in the nitrogen plasma torch. Therefore, this newly designed DC arc plasma torch not only can suppress the electrode erosion but also has good working performance, which is expected to have excellent application prospects.
... This gun conserves powder, energy, and time. A stable energy state and efficient heat transfer to the plasma gas produce ideal circumstances for each powder particle in the plasma stream, improving deposit efficiencies and application rates [15][16][17]. The power is distributed over three separate arcs for more effective heat transmission into the plasma plume. ...
Complex concentrated alloys (CCAs) have gained a significant attention in the engineering and research community due to their unique phase structure and exceptional properties. CCAs are usually comprised of five or more principal alloying elements mixed in near-equimolar or equimolar ratio, which can derive their qualities from multiple principal elements owing to cocktail effect. In this study, atmospheric plasma spraying system equipped with a Metco Triplex Pro-210 gun was used to deposit CCAs designed coating compositions onto SS-316L steel substrate. The microstructure, mechanical and electrochemical behavior of the developed (CoCrFe-NiM nx) CCAs were analyzed and compared to commercially used WC-17Co (Diamalloy 2005NS) and NiCr-75Cr 2 C 3 (Metco 81NS) coatings deposited by APS Metco Triplex Pro-210 cascading arc plasma spray gun. The experimental results confirm that using Metco Triplex Pro-210 it is possible to manufacture a CCA coating layers with lower porosity, excellent phase stability in compare to conventional thermal spray processes. Coating characterization also reveals that the CCA coating' grains experienced a significant amount of grain refinement as compared to those in as-received CCA feedstock powder materials due to the occurrence of shot peening effect and dynamic recrystallization caused by highly deformed splat boundaries during spraying process. The elec-trochemical results indicates that the CCA coatings have a lower corrosion rate in compare to its plasma sprayed counterparts.
... For the mass sources associated with metal and plastic ablation, we use θ = f W el /∆H where f is the fraction of energy that contributes to material ablation, and ∆H is the enthalpy of vaporization [17], [18]. The heat transferred from the gas to the splitter plates is Q = αA(T − T s ) where α is the heat exchange coefficient [19], A is the splitter plates area, T is the gas temperature and T s is the average temperature of the splitter plates. Finally, the mass flow rate across the exhaust j isṁ j = β j ρ j u j S j where ρ j is the gas density, u j is the gas velocity, S j is the venting area, and β j is a fitting coefficient between 0 and 1. Fig. 6. ...
We present a system level model for estimates of the energy input and pressure build-up in low-voltage circuit breakers during short-circuit interruption. The results obtained with this model agree well with electrical and pressure measurements on the ABB Emax E4.2 air circuit breaker. The results are also consistent with computationally more expensive three-dimensional magneto-hydrodynamics multiphysics simulations. Therefore, the system level model described in this work can be used to support the design of air circuit breakers to achieve higher performance with challenging external constraints.
... In order to confirm the assumptions, described above, a laboratory experiment was carried out. Metal substrates, made of stainless steel plates of approximately equal dimensions and masses, at fixed technological parameters (as it was described in the part 1) were coated by plasma spraying (detail description of the process is available in the [12][13][14][15][16][17][18][19][20][21][22]). Then the mass gain of the plates was measured for each case, and the values of the Reynolds number, productivity, and process efficiency were calculated. ...
... By the values of the mass flow rate of the plasma forming material and formulas (16)(17)(18)(19), the values of the velocities of the corresponding flows were obtained. Table 3 The results and data of the The flow rate of the substance with a density ρ, mass flow rate G, passing through a section with an area S, is defined by 10: v n = G n S n •ρ n . ...
This paper refers to the combined study of the influence of plasma flow turbulization degree on the efficiency of the plasma spraying technological process. The basis of the study is the absence of consensus between two optimization approaches, which are used to increase the profitability of plasma systems for coating, applying by the groups of scientists, who prefer laminar or turbulent plasma flow gear. The study contains: mathematical model of the heat exchange between the metal particle and plasma flow with the variation of process parameters-flow character and the dimensions of the boarder layer, which depends from the turbulization degree, controlled by the exchange of the two perpendicularly directed parts of the flow speed; laboratory performance research experiences of the plasma spraying system with the variation of the material and flow turbulization degree, which have been controlled with the help of an innovative technique. The astounding results reduce the opinions of the mainstream scientific schools into the union point, showing that the most optimal mode for the operation of plasma devices is exploitation with the flow in condition of the laminarturbulent transition.
... The intention of scientists to develop a comprehensive mathematical model of an arc plasma torch is reflected in the papers [21][22][23][24][25][26] and represents a combination of gas dynamics, electromagnetic, and thermal energy dissipation problems, where the corresponding equations are implicitly coupled by thermodynamic and transport properties and explicitly coupled through Joule heating. ...
The paper presents an analysis of the heat transfer processes in electric arc plasma conditions between the powder material and the plasma jet in different convective states. The heat transfer processes in the plasma jet generated for coating deposition are considered based on varying the conditions for the jet–powder interaction. The formed coating deposited onto the substrate acts as an indicator of the heat transfer efficiency. The heat transfer between the plasma jet and the powder material is facilitated by the turbulent nature of the plasma jet. The presented calculation results demonstrate the influence of the plasma flow turbulence on the motion of the fine powder and heating of the generated jet at the outlet of the plasma torch. An analysis of the influence of plasma flow turbulence on the acceleration and heating of fine powder particles was carried out. The experimental results allowed for the determination of the effect of the plasma jet turbulence degree on the heat transfer processes between the plasma and fine powder: the technological efficiency of the device with varying parameters of the spraying process and the flow rates of the material supply and plasma-forming gas were presented. The values of the plasma-forming gas supply rate, the material supply rate, and the Reynolds number were obtained while the other process parameters were fixed. The research was carried out within the state assignment of the Ministry of Science and Higher Education of the Russian Federation (theme No. FSEG-2023-0012).
... The low-density plasma flow in an axial magnetic field to a disk-shaped anode in a vacuum arc were studied theoretically using a two-dimensional model by Beilis et al. 3 Engineering Research Center for Design Engineering and Digital Twin of Zhejiang Province, Zhejiang University, Hangzhou 310058, China 4 Information Science and Electronic Engineering College, Zhejiang University, Hangzhou 310027, China 5 Wenzhou Polytechnic, Wenzhou 325000, China [10]. Trelles et al. [11] presented an overview of the main aspects involved in the modeling of DC arc plasma torches: the mathematical models including thermodynamic and chemical nonequilibrium models, turbulent and radiative transport, thermodynamic and transport property calculation, boundary conditions, and arc reattachment models. ...
... The FEM simulation is likewise, conducted under the various working conditions to seek arc plasma temperature field, the electric potential field, electromagnetic field distribution. Merely the effect of temperature on dynamic viscosity of gas was studied [11] The couple algorithm is used, but there was no multiple iterations to eliminate errors [14] Physical properties of plasma medium to improve the accuracy as in Fig. 2 Algebraic multigrid iteration as in Fig. 3 Multi-physics simulation of electrical systems Using fitted function model rather than multi-physics coupling model [6] Electrode and arc plasma are separately modeled, which ignored influence of electrode on plasma directly [11] FEM simulation as in Fig. 4 Analogical semi-physical simulation in Fig. 7 where efficiency can be improved by 7.03% ...
... The FEM simulation is likewise, conducted under the various working conditions to seek arc plasma temperature field, the electric potential field, electromagnetic field distribution. Merely the effect of temperature on dynamic viscosity of gas was studied [11] The couple algorithm is used, but there was no multiple iterations to eliminate errors [14] Physical properties of plasma medium to improve the accuracy as in Fig. 2 Algebraic multigrid iteration as in Fig. 3 Multi-physics simulation of electrical systems Using fitted function model rather than multi-physics coupling model [6] Electrode and arc plasma are separately modeled, which ignored influence of electrode on plasma directly [11] FEM simulation as in Fig. 4 Analogical semi-physical simulation in Fig. 7 where efficiency can be improved by 7.03% ...
This paper presents an electrical endurance design method of multi-operation isolators using semi-physical simulation via algebraic multigrid iteration (AMG). The mathematical model of Magnetohydro dynamics (MHD) is built by simultaneous equations of mass conservation, horizontal momentum, vertical momentum, conservation equation of ion energy, as well as electromagnetic equation. In addition, the physical properties of plasma medium in non-solid state, including thermal conductivity, electrical conductivity, dielectric density over temperature are used to dynamically update the coupled multi-physics. The established model can thus be solved via AMG, which is a fast iterative method for solving large-scale sparse normal equations based on geometric multigrid method. The finite element method (FEM) is likewise conducted under the various operating conditions to seek arc plasma temperature, the electric potential, electromagnetic distribution. The electrical endurance reliability can be reckoned using the maximum likelihood estimator of the desired shape parameters and scale parameters of Weibull's distribution, by integrating analogical semi-physical simulation. The physical experiment is carried out which involves electrical safety test, the withstanding voltage test, also called Hipot test or dielectric test, arc ignition test, resistance test. It proves that the proposed method can realize the endurance design of electrical equipment with high convergence efficiency and low residual error, and is especially suitable for the analysis under multiple working conditions.
... To provide the necessary boundary conditions at the edges of the flow domain, the electrical and thermal coupling of the gas and plasma flow together with the solid electrode domains was applied. Comprehensive overviews of the modeling of DC plasma arc torches can be found in [6] and [7]. ...
Laser fusion cutting commonly applies a high-pressurized nitrogen gas jet to blow the molten material out of the cut kerf. However, theoretical considerations suggest that the use of a plasma jet may offer some advantages over this conventional approach. In this preliminary investigation, the characteristics of a non-transferred plasma jet for the application as auxiliary gas in laser beam cutting are analyzed using numerical CFD simulation. Based on this study, a first prototype of a plasma jet generator was manufactured and used in initial cutting experiments on 6 mm thick AISI 304 stainless steel. Two different cooling concepts for the plasma torch were considered and investigated in practice. Suitable values for the nozzle exit diameter, the distance between the electrodes of the plasma torch, the auxiliary gas flow rate and the electric current were identified both model-based and experimentally. The achieved cutting performance is considered a proof-of-principle of the suggested approach of a plasma-assisted laser beam cutting process.
... Obviously, a large amount of energy is required to detach a large number of electrons from a multi-electron atom. In this sense, highly ionized plasma can be called hot [1][2][3]. ...
The work is devoted to mathematical modeling of the plasma temperature field. To do this, it was represented as a conducting sphere under boundary conditions of the third kind. The simulation of the thermal process is based on the numerical integration of the heat equation. This takes into account the change in the thermal conductivity of the plasma and convective heat transfer. Also, based on the obtained result, an analysis of the behavior of the temperature field was carried out.
... where h conv represents the coefficient of convective heat transfer (h conv = 10 4 W/m 2 K), and T wall and T water represent the wall temperature and the cooling water temperature (500 K), respectively [40]. ...
Thermal plasma has emerged as a technology with tremendous promise for municipal wastes that should be disposed of sustainably. A numerical simulation of a symmetric turbulent plasma jet from a thermal air plasma torch was developed using COMSOL Multiphysics®5.4 engineering simulation software. The velocities, temperature, arc root motion, and joule heating of the plasma jet were examined under the impact of the gas mass flow rate and current. Moreover, the electrical power required for the municipal solid waste (MSW) processing was estimated. The enthalpy and the effectiveness of the plasma torch were analyzed and discussed. Subsequently an investigation was conducted into the gasification characteristics of MSW using air and steam gases. The torch’s power and efficiency could be enhanced with a higher mass flow rate and temperature. Three operating modes were identified from the current–arc flow combination. Among the plasma gas considered, the air gas plasma torch guarantees an acceptable thermal efficiency and a low anode erosion rate. Plasma gasification produces cleaner syngas with higher efficiency (84%) than the conventional process due to the elevated temperature used during the process that breaks down all the char, dioxins, and tars.
