Applications in Energy and Combustion Science (Jun 2023)
Testing of NH3/H2 and NH3/syngas combustion mechanisms using a large amount of experimental data
Abstract
A possible solution to improve the combustion properties of ammonia is to blend it with other fuels. Two of the most usually used co-fuels are hydrogen and syngas (H2/CO). To investigate the chemistry of the co-combustion with these fuels, a large amount of indirect experimental data for the combustion of neat NH3, and NH3/H2 and NH3/syngas fuel mixtures were collected from the literature including ignition delay times measured in shock tubes, concentration measurements in jet stirred and flow reactors, and laminar burning velocity measurements. Altogether, 4898 data points (in 472 data series) were recorded which cover wide ranges of equivalence ratio, temperature, and pressure. These experimental data are available in data files in the ReSpecTh site (http://respecth.hu). The performances of 18 recently published detailed reaction mechanisms were quantitatively assessed using the collected experiments. There are significant differences between the performances of the models, and the performance of a mechanism may also vary significantly with the different types of experiments. The best-performing mechanisms are POLIMI-2020, Han-2020, and KAUST-2021 for NH3/H2 fuel mixtures, and Shrestha-2021, Mei-2021, and Mei-2020 for NH3/syngas systems. The results indicate that further mechanism development is needed to reproduce the measurements more accurately. Local sensitivity analysis was carried out on the kinetic and thermodynamic parameters of the best-performing mechanisms. Even though the investigated models have different parameter sets, the most important reactions and thermodynamic properties are similar. The most important reactions are not the same for the different types of experiments but most of them include the NH3, NH2, and/or NNH species. Among the thermodynamic parameters, model outputs are most sensitive to the data of NH3 and NH2.
