Abstract

In order to develop a carbon-free engine using ammonia as fuel, it is necessary to investigate the ignition characteristics of ammonia. In the present study, ignition delay times were measured for ammonia-air mixtures in a high-pressure shock tube. Computer simulations were also performed based on the UT-LCS model. The calculated ignition delay times overestimated the experimental data, so the reaction model was modified. The rate coefficients for some elementary reactions such as competitive reactions for NH2 consumption, NH2+NO=N2+H2O and NH2+NO=NNH+OH, and reactions of NH2 and NH with oxygen molecules were corrected within the limits of uncertainty. Conclusively, the modified reaction model was successful in reproducing the measured ignition delay times even in a relatively low temperature range.