CHARACTERIZATION OF DC PLASMA SPRAY TORCH USING ENERGY BALANCE DYNAMICAL CONSIDERATION TECHNIQUE AND THERMO-FLUID

A non-transferred plasma torch is characterized. Electrothermal efficiency of the plasma torch and the stagnation enthalpy of the plasma jet were calculated using the energy balance technique. Argon and argon + 10% nitrogen mixture were the plasma forming gases. Average electrical conductivity of the plasma jet at the nozzle was calculated from the arc characteristics. The temperature, velocity, thrust, density and the degree of ionization of the plasma jet were also calculated from the thermofluid dynamical method. In addition the heat transfer from plasma jet to the solid wall was also considered. In all the calculations the experimental values of the parameters were used. The calculated efficiency ranged from 59-65%. Efficiency was found to increase with addition of nitrogen. The temperature and the degree of ionization were found to be in the range 1400-7500°K and 0.4-5 x respectively. The results are explained and discussed qualitatively.