Numerical simulations of polymer pyrolysis rate: Effect of property variations

摘要

The mass loss rate (MLR) of poly(methyl methacrylate) (PMMA) exposed to known radiant fluxes is simulated with two recently developed numerical codes, the National Institute of Standards and Technology (NIST) Fire Dynamics Simulator (FDS) and the Federal Aviation Administration (FAA) ThermaKin. The influence of various material properties (thickness, thermal conductivity, specific heat, absorption of infrared radiation, heat of reaction) on mass loss history is assessed, via their effect on the ignition time, average MLR, peak MLR, and time to peak. The two codes predict the influence of material parameters on the MLR in the order of decreasing importance: heat of reaction, thickness, specific heat, absorption coefficient, thermal conductivity, and activation energy of the polymer decomposition. Changes in the material properties also influence the MLR curves by switching the sample from thermally thick to thermally thin. The two numerical codes are generally in very good agreement for their predictions of the MLR vs time curves, except when in-depth absorption of radiation was important.