Effect of the Electrode Material on Ignition of Ethylene-Air Mixtures

This article presents an experimental quantification of the ignition risk of flammable mixtures in conditions relevant to industry and aviation environment. More specifically, the effect of resistive material on ignition of flammable mixtures was investigated by applying a 500-ns duration high-voltage pulse between pin-to-pin electrodes located across a jet flow of ethylene and air, at atmospheric pressure. Fuel-rich, stoichiometric, and fuel-lean equivalence ratios were considered. A parametric study of the effect of the applied voltage and electrode material was performed. The electrical energy deposited in the discharges was determined from current and voltage measurements. Direct visualization of the sparks and the ignition kernel was performed in order to better understand the early stages of the ignition process. The results showed that the use of highly resistive electrodes compared to metallic electrodes: 1) could significantly reduce the energy deposition in the interelectrode area; and 2) could increase the minimum ignition energy. Therefore, the use of highly resistive material wires instead of metallic wires could offer safer conditions with respect to the ignition hazard in flammable environments.