Heating of ceramic and silicate material surfaces by an arc plasma filament

The heating of ceramic and silicate material surfaces by a heavy current arc plasma filament is investigated in an air atmosphere. The possibility of using optical pyrometry methods for highly heated surfaces is studied for T > 2000°K.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 42, No. 4, pp. 604–608, April, 1982.     

Thermal turbulence in an electric arc

By analyzing the correlations of current-voltage characteristics we show the predominance of turbulent heat exchange by convection and conduction in a longitudinally blown helium arc. The presence of thermal turbulence in the near-axial zone of this arc has been verified experimentally by investigating the radiation intensity.Academic Scientific Complex. A. V. Lykov Institute of Heat and Mass Transfer, Belarus Academy of Sciences, Minsk. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 62, No. 5, pp. 691–700, May, 1992.     

Anisotropic model of an emitting electric arc

An analytical procedure is proposed for obtaining exponential dimensionless equations to calculate the characteristics of an electric arc in a plasmatron channel that is based on using an exponential approximation of the temperature dependence of electric conductivity with different exponents for longitudinal and transverse coordinates.Notation density - C _p specific heat at constant pressure - electrical conductivity - thermal conductivity - V velocity - T temperature - E electric-field strength - r, z radial and longitudinal coordinates - thermal conductivity function - G gas flow rate - Q bulk radiation density - R, D radius and diameter of channel - I strength of current - r/R - z/R - m R/r _*=1/r _* - S S–S _* - b _Q Q ₀/S ₀ - a, k,k ,n ,C ₀₀, constants - J ₀,J ₁,Y ₀ Bessel functions - ₁, _n roots of characteristic equations - j current density - q heat flux density - Po, Pe Pomerantsev and Pecklet numbers, respectively - Nu Nusselt number - _K , _U , _q ,K _Q ,K _S similarity numbers - U voltage - heat-transfer coefficient Indexes z longitudinal component - * boundary of conducting band - 0 base value - 1 value on the wall - 00 axial value - I, II conducting and nonconducting bands, respectively Academic Scientific Complex A. L. Luikov Institute of Heat and Mass Transfer of the Academy of Sciences of Belarus, Minsk. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 68, No. 5, pp. 820–826, September–October, 1995.     

Dynamic characteristics of an electric dc arc

An equivalent electric circuit diagram is proposed for a dc plasmatron excited with alternating current. On the basis of this circuit diagram and with the aid of the dynamic characteristic, the phase angle of the excitation current is then calculated.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 22, No. 3, pp. 514–519, March, 1972.     

Optimization of the heating of a metal by an electric arc

We investigate and generalize the results of experimental measurements of heat fluxes in a metal anode from a plasma jet of a plasmatron with an external arc (PEA) whose operating conditions vary over a wide range.Notation efficiency of heating of the metal - Q_el heat flux into the calorimeter - I current of the electric arc - U voltage drop across the electric arc - V linear velocity of rotation of the sensor - r_o thermal radius of arc spot - _o time until surface of calorimeter begins to melt - t_p melting point of copper - t_o initial temperature of calorimeter surface - q specific heat flux in the heating spot - a thermal diffusivity - D diameter of rotating calorimeter - t₁ temperature of surrounding medium - t₂ temperature of the surface of the rotating calorimeter - G argon flow rate - h_s specific enthalpy of argon in the region near the anode - h_a specific enthalpy of argon at the surface of the calorimeter - k Boltzmann constant - T_e electron temperature in the anode region - e charge of the electron - U_a potential drop at the anode - _a work function of electrons leaving copper - L length of open part of the arc—distance from the cut in the nozzle of the PEA to the sensor - h depth of cathode insertion into the nozzle—distance from the cut in the PEA nozzle to the cathode - d diameter of the PEA nozzle - U _a ^* effective voltage equivalent Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 39, No. 4, pp. 687–691, October, 1980.     

Velocity of an electric arc in an annular gap

We investigate the influence of the current, magnetic-field induction, air flow, and interelectrode gap on the arc velocity in an annular gap between concentric electrodes. Generalized equations in critical (dimensionless) form are presented for the experimental data.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 19, No. 6, pp. 1046–1051, December, 1970.     

Electron emission from solid surfaces stimulated by electric field and heterogeneous chemical reaction

A method for monitoring the process of electron accommodation during chemical reactions at the gas-solid (metal, semiconductor) interface is proposed. It is established that the tunneling electron current from a solid surface (Ni, Cu, Si steel) increases by a factor of 10³–10⁵ when a heterogeneous chemical reaction (H+H→H₂) proceeds on the surface. Autooscillations of the reaction-stimulated tunneling current have been observed. A method of investigation of the structure of surface catalytic centers on a nanometer resolution level is proposed.     

Utilization of electric arc furnace dust as a solid catalyst in biodiesel production

Clean Technologies and Environmental Policy - World’s energy sources like petrochemical oils, natural gas and coal cause global warming and environmental pollution. Therefore, the traditional...     

Minimizing the three-phase unbalance in an electric arc furnace

A method is proposed to reduce impedance imbalance in the electrode arms of an arc furnace. Conducting plates or tubes are used to shield the magnetic fields around busbars in order to minimize the mutual inductance. The volume integral equation method is used to calculate bus impedances, current distribution, and eddy current losses. The numerical results indicate a significant improvement in system balance even during bus movement. Two types of shields are investigated. Shielding the center phase by using a large tube reduces the unbalance at the coplanar bus positions, but it has little effect when one bus is offset. Shielding by two conducting plates standing between buses yields good balance and constant reactance for all bus positions. The power loss in the shields is only a small percentage of the bus loss, the shields can be replaced by parallel conducting bars bounded at ends. By combining the new method with a smaller center bus diameter, better results have been achieved     

Anodic current density of an electric arc with carbon electrodes

We present the results obtained in measuring the current density of anode spots in a carbon arc in air and we show its relationship to the magnitude of the arc current, analogous to the cathode spot.     

Flow turbulence in a cylindrical channel encompassing an electric arc

The effect of an electric arc on the gas flow in a cylindrical channel is investigated. It is shown that the striking of an arc in a laminar flow leads to its turbulence at the boundary of the arc column. Within the arc column, the flow is rendered laminar by the high viscosity of the arc plasma. However, thermal turbulence may develop in the central part of the arc.Academic Scientific Combine A. V. Lykov institute of Heat and Mass Exchange, Academy of Sciences of Belarus', Minsk. Translated from Inzhenerno-Fizicheski Zhurnal, Vol. 62, No. 4, pp. 601–607, April, 1992.     

Experimental study of an electric arc moving in an annular ventilating gap by the action of electromagnetic forces

Formulas are derived for calculating the velocity of an electric arc in an annular ventilating gap under atmospheric pressure when an external magnetic field is applied, also for calculating the air density in front of the moving arc.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 20, No. 2, pp. 306–313, February, 1971.     

Interaction of the electric arc in a two-jet plasmatron with the surface of a solid body

The electrical and thermal characteristics of a magnetically controlled arc in a two-jet plasmatron interacting with a flat surface are presented.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 50, No. 4, pp. 635–640, April, 1986.     

Heat exchange in the cathode spot of an electric arc in an argon medium

The dependence of heat removal through a cathode spot on the current, magnetic induction in the circular gap, and the argon flow rate is studied.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 21, No. 3, pp. 505–509, September, 1971.     

Determining the current density of the electrode spots of an electric arc

The energy balance and the Lambert-Bouguer law are used to obtain a mathematical relationship between the current density for the electrode spots of a carbon arc and the current. Theoretical calculations are confirmed by experiment.     

Heating of three-layer solid aerosol particles by laser radiation

The heating of lidar-irradiated multilayer particles is analyzed theoretically and numerically by solution of the heat conduction equation. The internal intensity and temperature distributions are presented for particles composed of air, quartz, and carbon. It is shown that the heating times of such particles substantially depend on particle radii, layer position, and shell thickness. In particular, the decrease in thickness of the surface carbon layer can result in a reduction of the heating time of multilayer particles.     

Production and properties of ultrafine inorganic powders in an electric arc plasma

The article generalizes the results of investigations carried out by the present author in the field of plasmochemical production of ultrafine inorganic powders under conditions of electric arc low-temperature plasma. The results of a comprehensive study of specific chemical and physicochemical properties of synthesized ultrafine powders are considered.     

A theoretical and experimental investigation of the parameters for an electric arc

A new method is presented for the determination of the temperature distribution over the cross section of a cylindrical arc, as well as of the volt-ampere characteristics, and these are compared with experimental data.     

Thermal action of an electric arc on the wall of a planar gap

The distribution of thermal flux from a. dc arc with i=200–400 A located in a moving planar gap is studied experimentally. A model is proposed for the interaction of the moving heated gas flow, the dielectric wall, and the calorimeter.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 52, No. 4, pp. 605–611, April, 1987.