Numerical Simulation of the Impact of Spark Parameters on the Ignition of NH3/H2/Air Mixtures

This work numerically investigates the ignition characteristics of various ammonia/hydrogen/air mixtures. The Minimum Ignition Energy (MIE) (at a fixed electrode gap) is determined and compared with experimental data [1]. The simulation includes a detailed account of molecular transport (differential diffusion and thermal diffusion) and chemical kinetics (using the reaction mechanism by Shrestha et al. [2]). The MIE is calculated for a fuel-air equivalence ratio of $\phi = 0.9$ across various ignition radii, ignition durations, and geometries. The study also examines the influence of generated pressure waves on ignition.The simulation results successfully mirror the experimental trend. Ignition events where shock waves occur due to a short ignition duration require more energy for successful ignition, as a portion of the input energy is consumed in forming the shock wave. Both cylindrical and spherical geometries yield similar MIEs when the ignition volume is kept constant. Heat conduction away from the ignition volume only influences the MIE when the ignition duration exceeds $\sim 10^{-4}$ seconds for the selected conditions. Possible reasons for discrepancies between simulation and experiment are discussed.Simulations conducted without assuming constant pressure ($p \neq \text{const}$) exhibited pressure waves during ignition. ... mehrThe effect of the pressure wave is a higher MIE, because part of the energy supplied is used to form the pressure wave. Simulations using a $\sim 29\%$ smaller ignition radius ($r = 0.53\text{ mm}$) show a significantly lower ignition energy because the higher energy density results in greater temperatures within the ignition volume.

Absolutely! Here is the revised English abstract, with the specified modifications (omitting references to the figure and the figure itself) and the sources included at the end.Abstract: Numerical Study on the Ignition Characteristics of Ammonia/Hydrogen/Air MixturesThis work numerically investigates the ignition characteristics of various ammonia/hydrogen/air mixtures. The Minimum Ignition Energy (MIE) (at a fixed electrode gap) is determined and compared with experimental data [1]. The simulation includes a detailed account of molecular transport (differential diffusion and thermal diffusion) and chemical kinetics (using the reaction mechanism by Shrestha et al. [2]). The MIE is calculated for a fuel-air equivalence ratio of $\phi = 0.9$ across various ignition radii, ignition durations, and geometries. The study also examines the influence of generated pressure waves on ignition.The simulation results successfully mirror the experimental trend. Ignition events where shock waves occur due to a short ignition duration require more energy for successful ignition, as a portion of the input energy is consumed in forming the shock wave. Both cylindrical and spherical geometries yield similar MIEs when the ignition volume is kept constant. Heat conduction away from the ignition volume only influences the MIE when the ignition duration exceeds $\sim 10^{-4}$ seconds for the selected conditions. Possible reasons for discrepancies between simulation and experiment are discussed.Simulations conducted without assuming constant pressure ($p \neq \text{const}$) exhibited pressure waves during ignition. The effect of the pressure wave is a higher MIE, because part of the energy supplied is used to form the pressure wave. Simulations using a $\sim 29\%$ smaller ignition radius ($r = 0.53\text{ mm}$) show a significantly lower ignition energy because the higher energy density results in greater temperatures within the ignition volume.References[1] Essmann S., Dymke J., Höltkemeier-Horstmann J., Möckel D., Schierding C., Hilbert M. et al. Ignition characteristics of hydrogen-enreiched ammonia/air mixtures, Applications in Energy and Combustion Science, 17, 2024.[2] Shrestha, K.P., Seidel, L., Zeuch, T., Mauss, F. Detailed Kinetic Mechanism for the Oxidation of Ammonia Including the Formation and Reduction of Nitrogen Oxides, Energy & Fuels 32(10) 2018.