Numerical evaluation of the flame to solid heat flux during poly(methyl methacrylate) combustion

The total net heat flux of the flame from a burning solid fuel is an important issue for the formulation of comprehensive solid-phase models useful for the fire testing of materials, but measurements are often affected by significant inaccuracy. In this study, an evaluation is conducted using a state-of-the-art model, coupling the descriptions of both gas- and solid-phase processes, for a thick poly(methyl methacrylate) slab burning in a cone calorimeter. It is observed that the total net heat flux (conductive and radiant flame heat fluxes minus surface reradiation losses) remains approximately constant (about 18 kW/m2) as the intensity of the cone irradiance increases from 15 to 60 kW/m2. The influences of some model assumptions and the solid degradation kinetics on this process variable are also assessed. Acceptable agreement is obtained between the predicted and the measured mass loss rates.