Development and validation of skeletal/global mechanisms describing TMP-based flame inhibition

Phosphorus-based chemical compounds such as trimethylphosphate (TMP) and dimethylmethylphosphonate (DMMP) are widely used as fire suppressants. The detailed chemical kinetic mechanism by Jayaweera et al. [1] is frequently used to describe the flame inhibition process. The elementary reaction steps can be categorised into inhibitor molecule decomposition steps and radical recombination steps. The present work shows that the inhibitor decomposition process can be adequately represented by a single irreversible step for TMP. Subsequently, graph-based mechanism reduction techniques and sensitivity analysis are employed to extract the key catalytic inhibition reactions. The resultant skeletal kinetic mechanism consists of 4 species and 7 reactions. The present work also proposes a global mechanism containing 3 species and 3 reactions. In the global model, flame inhibition is described by a 2-step model. These models are validated in premixed and diffusion flame environments. Excellent agreement with the experimental measurements and detailed model predictions are obtained. Development of the skeletal/global models reduces the computational time by around 82% compared to the detailed model.