The onset of piloted ignition (flash point) of combustible polymers is predicted by a gas phase combustion energy density of 1.9 MJ/m~3 that describes the lower flammability limit of fuel vapor-air mixtures. The mass flux (1 g/m~2 s) and (virtual) heat release rate (24 kW/m~2 ) of the solid at incipient ignition derived from this observation are in general agreement with experimental data for piloted ignition of plastics. Sustained ignition marks the transition from lower-limit to stoichiometric burning and the critical heat release rate increases proportionally to 66 kW/m . A critical heat release rate, unique among ignition criteria, is independent of material composition because of the implicit coupling between the gas and condensed phase processes. Published by Elsevier Inc. on behalf of The Combustion Institute.
展开▼
