Developing a versatile detail mechanism for NH₃ combustion

Ammonia (NH₃) is a carbon-free fuel. Therefore, many researchers have proposed detailed mechanisms for NH₃, yet the existing mechanisms have widely varied combinations of reactions and were validated using different experimental datasets. Thus, this study suggests developing a NH₃ mechanism by exploring the vast reaction pool of the five existing mechanisms. Several reaction combinations from the reaction pool were tested to validate the experimental datasets. The developed mechanism showed the lowest mean squared error (MSE) among the referenced mechanisms for predicting the ignition delay times (IDT). Furthermore, the MSE of the laminar burning velocity (LBV) prediction was less than those of the three referenced mechanisms. Although the mechanism was developed by employing only NH₃ fuel mixtures, the estimated IDT and LBV of NH₃/H₂ fuel mixtures showed low MSE. Analyses of many tested sample mechanisms revealed that the rate coefficients of NH₃ combustion reactions should be further elucidated for enhanced prediction.