Plasma Assisted Combustion for Environmental Applications

In the early part of the presentation, a detailed application of a plasma assisted combustor operated in a diesel exhaust line for regenerating DPF (Diesel Particulate Filter) are introduced. In this plasma assisted combustor, rotating arc is generated by a high voltage AC power and tangentially injected gas flow. The combustor generates a stable diesel flame under the harsh operating conditions, e.g. low oxygen contents (5 – 15 %) and abruptly changed mean diesel exhaust gas velocity up to 30 m/sec. In this introduction part, numerous practical data based on 80,000 km road test are provided such as DPF pressure change, emissions from the exhaust, energy cost for generating plasma. In the later part of the presentation, characteristics of a methane premixed flame generated in a rotating arc reactor are presented, which are helpful to understand the fundamental aspects of the practical combustor for regenerating DPF. In this fundamental study, phenomenological observations on flame stabilization and extension of flammability limit in the presence of plasma are conducted. One interesting finding from this observation is that the plasma generation is also clearly affected by the flame, which is resulted from interactive nature of plasma and flame. Several other tests, such as optical emission spectroscopy, analysis of the product gas (CO₂, H₂, CO, C₂ and C₃ hydrocarbons, NOx), detection of voltages, are also provided.