Plasma Assisted Ammonia Combustion: Experimental And Modeling Study Of Chemical Kinetics In A Well-Stirred Plasma Reactor

Abstract: Adaptation of existing infrastructure is key for meeting the green-house gas emission targets of the Paris Climate Accords. Ammonia has broad potential to serve as a carbon-free means of renewable energy storage for mobile applications and power generation, with energy density and storage costs superior to hydrogen and existing battery technologies. Its widescale adoption, however, has been limited by its tendency to emit high levels of NOx and its poor combustion characteristics. Using plasma-assisted reforming, ammonia can be modified to be compatible with current engine technology with only minor alterations. Plasma chemical processes initiated by high-frequency nanosecond-duration pulsed energy deposition can dissociate ammonia efficiently and selectively produce hydrogen and amino radicals, and when used in conjunction with oxidizer, can also produce nitrous oxide, among other combustion enhancing species. The presented research will introduce a novel, well-stirred plasma reactor for studying the chemistry of ammonia and ammonia-air mixtures in a plasma. Gas chromatograph and optical measurements are taken using this reactor, measuring hydrogen yields, oxygen consumption and uniformity of discharge. A chemical kinetic model for ammonia and air in a plasma discharge is constructed and compared to the measurements using a zero-dimensional plasma chemistry solver. Along with ignition simulations, the measurements and developed kinetic mechanism demonstrate how plasma discharges can enhance ammonia combustion and reduce emissions.