Mathematical Modeling of High Intensity Electric Arcs Burning in Different Atmospheres

Abstract

Previous works attempting to simulate DC arcs have assumed the plasma gas to be composed by 100% air, consequently, the arc region has been represented by solving the equations that govern the process, i.e. heat and mass conservation equations coupled to the turbulent Navier–Stokes equations. A real plasma gas is composed by a complex mixture of several gases, such as air (from environment), CO and CO₂ (coming from decarburization and post combustion), H₂O and H₂ (from humidity) as well as metallic and non-metallic vapors coming from scrap melting. The real plasma composition is unknown, however, if air does not represent the atmosphere in which a DC arc burns, the following question arises: How is the arc being affected by burning in different atmospheres? To answer this question, in this work a mathematical model was developed to represent a DC arc burning in different gases such as nitrogen, argon, hydrogen, oxygen, CO₂ and CO. The model was used to study the effect of the gas composition on the electrical characteristics of the arc. It was found that air followed by CO and CO₂ are the most efficient gases to melt and heat up the bath. Argon is a special case since has the highest conductivity and lowest heat capacity that would be very useful for long arc length applications.