Analysis of Chemical Reactions in Gliding-Arc Reactors With Water Spray Into Flowing Oxygen

In this paper, a mathematical model describing the chemical-reaction kinetics for gliding-arc discharge reactors with water-spray injection in a carrier gas of oxygen is developed based upon assumed temperature profiles and high-temperature reactions for nine chemical species. The plug-flow reactor model shows that rapid quenching of OH by steep temperature drops strongly favors the production of stable molecular species such as H₂ and H₂O₂. Increasing the water flow rate leads to higher H₂ and H₂O₂ production at fixed inlet oxygen carrier flow rates; however, the H₂O₂ production rate levels off at higher water feed. The mathematical model can describe within a factor of two, the experimentally reported production rates of H₂ and H₂O₂ if account is made for some water and gas bypassing of the electrode/plasma region. The model is used to assess the two applications of such a discharge including the following applications: (1) destruction of chemical species by high-temperature OH radical reactions and (2) efficient formation of H₂O₂ by lower energy pulsed discharge. In the first case, the large amounts of OH radical formed in the high-temperature region of the discharge can lead to rapid and effective degradation of compounds that even have low reactivity with OH. In the second case, lower power, hence lower temperature, can lead to optimal production of H₂O₂ for postplasma applications.