Plasma process applications: Analysis of wire electrical discharge machining (EDM) process and conversion of methane to acetylene using plasma reactor

Two applications of plasma process are studied: wire electrical discharge machining (EDM) process and conversion of methane to acetylene process. On the wire EDM process, the causes of wire vibration, bowing and breakage are identified. The cross-sectional configuration of an eroded wire is determined. A computational model has been developed that can predict conditions of wire breakage by determining the stress induced by wire erosion and the stress induced by the sparks during the operation of a wire-cutting EDM machine. This model is also capable of determining the extent of wire bowing and vibrations in these machines but only in the frontal direction. The model is supported by data from experiments performed on an AGIECUT 612 wire machine cutting a 10 mm high copper bar with a 0.15 mm diameter brass wire to acquire wire breakage data. Thermal load, another major factor contributing to the wire breakage, is also discussed. Here, the temperature profile of the wire as a function of axial position is determined using quasi steady state thermal analysis. A dynamic analysis of multiple, sequential sparks in the same location on the wire was done to estimate the hot spot about 73°C after one spark, 93°C after two sparks, 110°C after three sparks, and 195°C after eight sparks.; Conversion of methane to acetylene process is also studied. A simplified calculation to determine the equilibrium number of moles and mole fractions of the final products (methane, acetylene, ethylene, and hydrogen) of the process for different process temperatures is done. Experiments to carry out the process are conducted using a plasma spray-coater reactor. Several factors affecting the final products are studied. These factors are power input, methane flowrate, amount of additives (ethane and hydrogen), and quench position. The conversion process is also carried out using an electrical-furnace reactor setup for comparison with the plasma reactor experiments.