Collision dark layer of arc jet at opposite electrodes under consideration of buoyancy

Summary form only given. Arc heating technology has been applied to volume reduction through melting of bottom and fly ash, and for producing slag. Recently, a twin torch arc, which has two torches at the cathode and anode, has been anticipated for application to disposal of medical waste because it can treat a wide area and can treat non-conductive materials. The efficiency of arc heating is changed by arc figure, current and electrodes gap. When the current and electrode gap are changed, the collision dark layer is appeared. Especially, the collision dark layer plays an important role for arc heating. For this study, a numerical simulation model of a twin torch arc at opposite electrodes was developed to elucidate the collision dark layer for high-efficiency heating using a twin torch arc. It is defined as LTE, and calculated in MHD (magneto-hydro-dynamics) equations. Ar and N₂ are used as ambient gas. The collision dark layer was investigated with thermal and transport properties of Ar and N₂. The flow velocity near cathode and anode increases with increasing the current because the flow velocity depends on current density distribution. Collision dark layer was determined by the balance of arc jet velocity and buoyancy. Thermal conductivity of N₂ is higher than that of Ar at the collision dark layer. In the case of thermal expansion coefficient 1-0.1~K^-1, arc jet velocity depends on the buoyancy, the collision dark layer depends on the thermal conductivity of Ar and N₂. In addition, the collision dark layer was measured by using the spectroscope.