Ammonium dinitramide (ADN)-based energetic ionic liquid propellants (ADN-EILPs) are promising monopropellants with high energy density, high thermal/chemical stability, and low toxicity. To predict the ignition and combustion characteristics of ADN-EILPs, this study aimed to construct a detailed reaction model of ADN-EILPs in the gas phase by combining conventional thermal decomposition models of the components in ADN-EILPs, the NO2 chain-growth reaction cycle, and additional reactions based on hydrogen abstraction between component species of ADN-EILPs and two radicals, NO2 and OH. The additional reactions were computed using quantum chemistry calculations. The structures of the reactants, products, and transition states were optimized at the ωB97XD/6-311G++(d,p) level of theory, and the total electron energies of these optimized structures were determined at the CBS-QB3 level. The simulated results with the constructed detailed chemical reaction model (EILPs-G-01 model) agreed with the experimental results at approximately 1.2 MPa. The EILPs-G-01 model revealed that the gas-phase combustion of ADN-EILPs has three reaction cycles depending on the radical-related reactions. Moreover, the EILPs-G-01 model clarifies the relationships between the pressure deflagration limit of ADN-EILPs and the weight ratio of methylamine nitrate in the ADN-EILPs.
green monopropellant, ammonium dinitramide, combustion modeling, radical reaction, energetic ionic liquid propellants