Subsurface Chemical Kinetics and Phase Transition

The global decomposition model of RDX proposed by Brill et al. [12], derived from a well-calibrated temperature-jump/Fourier transform infrared (T- 

Reaction (Rl) is an exothermic, low-temperature pathway, whereas reaction (R2) is an endothermic, high-temperature pathway. The reaction rates are obtained from a model of the T-jump/FTIR experiment [15], which takes into account the heat transfer of the filament and sample. 

The two global decomposition reactions are nearly thermally neutral at temperatures around 600 K. Subsequent reactions among the products of (Rl) and (R2) may occur and provide the energy to sustain pyrolysis. Brill [12] examined several plausible secondary reactions, such as CH2O + NO2, CH2O + N2O, and HCN + NO2, and their corresponding reaction rates. Results indicated that the following reaction 

In addition to the thermal decomposition and its subsequent reactions (Rl-R3), thermodynamic phase transition from liquid to vapor RDX is considered to provide a complete description of the mass conversion process. 

Based on gas-kinetic theory, the net evaporation rate is taken to be the difference between the evaporation and condensation rates [33] and is expressed 

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