Pyrolysis model parameterization and fire growth prediction: The state of the art

A failure to accurately predict fire growth on a solid object can be frequently traced to our inability to fully resolve coupling between the gas-phase processes of flaming combustion and condensed-phase processes of pyrolysis, responsible for generation of gaseous fuels. Two key quantities that define this coupling are the rate of heat flow (or heat flux) into the condensed phase and the rate of mass flow (or mass flux) of decomposition products into the gas phase. Recognizing that an improvement in our ability to compute the latter quantity may hold the key to accurate fire growth predictions, a systematic effort has been made by the fire science community to develop progressively more sophisticated models of pyrolysis. State-of-the-art pyrolysis solvers can simulate complex, multi-reaction thermal decomposition mechanisms coupled with physically diverse heat and mass transfer processes taking place in the condensed phase. However, parameterization of these models remains a non-trivial effort requiring a large number of careful measurements and inverse modeling, which is necessary because some of the processes cannot be fully decoupled through experimental design. Here we review formulation and parameterization of the state-of-the-art pyrolysis models, discuss their limitations and the impact of these limitations on fire growth predictions.