Flames with plasmas

Combustion, Chemistry, and Carbon Neutrality

“…Details of the coupling between the combustion process and the plasma must be understood on a fundamental basis to feasibly employ such new reaction strategies. Several recent reviews present excellent insights into plasma-assisted combustion, plasma-chemistry interaction, and plasma-supported control strategies, describing respective types of plasmas and instrumentation as well as the status of experimental analysis, reaction mechanism development, and numerical simulation. − …”

“…Thermal plasmas provide fast heating of the combustible gas mixture, and although they can be useful for ignition, they need substantial electric energy input and will produce high (thermal) NO concentrations . Nonequilibrium plasmas in comparison are characterized by high electron temperatures, and through efficient electron impact, excitation, dissociation, and ionization processes can produce chemically activated species that may not be accessible thermally. , With appropriate control over such mechanisms, e.g., by tailoring the electron energy, reaction processes can be altered or enhanced in a desired way, for example, to reduce pollutant emissions at high combustion efficiency. − , Control over the deposition of energy into the target gas, i.e., regarding vibrational or electronic excitation, dissociation, or ionization is possible over short time scales before relaxation, with very short (nanosecond) repetitively pulsed discharges. , Ignition delay times can be reduced and reactivity and burning velocities increased using appropriate plasma–combustion system designs, potentially from combining thermal and chemical effects. , As pointed out by Ju and Sun, fundamental-level experiments under well-controlled conditions are needed to improve the knowledge on the related processes and their dependence on numerous influence parameters on both, the plasma and the molecular (fuel) reaction side, and on the interdependences between such influences . In addition to the concentrations of the main and intermediate combustion species, including excited and charged particles, the electric field and electron density distribution should be determined as a function of the fuel–oxidizer–bath gas system and of the relevant discharge parameters, on the time scales of the related processes. ,, …”

“…570 Thermal plasmas provide fast heating of the combustible gas mixture, and although they can be useful for ignition, they need substantial electric energy input and will produce high (thermal) NO concentrations. 570 Nonequilibrium plasmas in comparison are characterized by high electron temperatures, and through efficient electron impact, excitation, dissociation, and ionization processes can produce chemically activated species that may not be accessible thermally. 570,573 With appropriate control over such mechanisms, e.g., by tailoring the electron energy, reaction processes can be altered or enhanced in a desired way, for example, to reduce pollutant emissions at high combustion efficiency.…”

“…570 Nonequilibrium plasmas in comparison are characterized by high electron temperatures, and through efficient electron impact, excitation, dissociation, and ionization processes can produce chemically activated species that may not be accessible thermally. 570,573 With appropriate control over such mechanisms, e.g., by tailoring the electron energy, reaction processes can be altered or enhanced in a desired way, for example, to reduce pollutant emissions at high combustion efficiency. [570][571][572]574 Control over the deposition of energy into the target gas, i.e., regarding vibrational or electronic excitation, dissociation, or ionization is possible over short time scales before relaxation, with very short (nanosecond) repetitively pulsed discharges.…”

“…[570][571][572]574 Control over the deposition of energy into the target gas, i.e., regarding vibrational or electronic excitation, dissociation, or ionization is possible over short time scales before relaxation, with very short (nanosecond) repetitively pulsed discharges. 570,573 Ignition delay times can be reduced and reactivity and burning velocities increased using appropriate plasma−combustion system designs, potentially from combining thermal and chemical effects. 570,573 As pointed out by Ju and Sun, fundamental-level experiments under well-controlled conditions are needed to improve the knowledge on the related processes and their dependence on numerous influence parameters on both, the plasma and the molecular (fuel) reaction side, and on the interdependences between such influences.…”