Chemical kinetic modeling of ammonia oxidation with improved reaction mechanism for ammonia/air and ammonia/hydrogen/air combustion

To achieve comprehensive prediction of ammonia combustion in terms of flame speed and ignition delay time, an improved mechanism of ammonia oxidation was proposed in this work. The present model (UT-LCS) was based on a previous work [Song et al., 2016] and improved by relevant elementary reactions including NH2, HNO, and N2H2. The model clearly explained reported values of laminar flame speed and ignition delay time in wide ranges of equivalence ratio and pressure. This suggests that NH2, HNO, and N2H2 reactivities play a key role to improve the reaction mechanism of ammonia oxidation in the present model. The model was also applied to demonstrate NH3/H2/air combustion. The present model also appropriately predicted the laminar flame speed of NH3/H2/air combustion as a function of equivalence ratio. Using the model, we discussed the reduction of NO concentration downstream and H2 formation via NH3 decomposition in NH3/H2 fuel-rich combustion. The results provide suggestions for effective combustion of NH3 for future applications.