A model simulating combustion of solids and its use in fire analysis with the code ECART

A model capable to simulate the combustion of solid materials was developed and implemented into a fluid-dynamic code. The combustion model, called PM, calculates the release of volatile burnable compounds from a slab of solid material undergoing combustion. The temperature profile and the advancement of the reaction within the material, as a function of time, are accounted for. The production of volatile substances is assumed to be a one-step reaction, of which kinetic behavior is modeled through an Arrhenius-type law. The PM model could account for vaporization of water from the material whereas at the moment vaporization is not implemented. The kinetic equation is coupled with the mass and the energy balance. The computer code ECART simulates the overall thermodynamic behavior of the system, the chemistry of the gaseous phase and the transport of toxic gases and aerosols. This complex tool, provides the model PM with the required boundary conditions, as the temperatures of the environments and the heat fluxes. An ad-hoc Montecarlo method has been adopted to calculate the view factors among the flame and the surfaces, in order to have a realistic simulation of the combustion itself and evaluate the possible propagation of the fire to other walls and environments. The release rates of volatile compounds predicted by PM are used by ECART to calculate chemical equilibrium, energy and mass transfers in the fire zone and in the whole system. The results obtained by PM and its coupling with ECART are compared with literature experimental data.