Fire Safety Science Digital Archive

This study presents the experimental measurements of temperature profiles and temperature histories within specimens of surrogate refuse derived fuels (RDFs) exposed to irradiance in a cone calorimeter. The surrogate RDFs, representing typical municipal solid waste collected in the city of Newcastle, Australia, were developed to improve the reproducibility of experimental measurements. These materials consist of loose polydispersed particles of grass, wood, paper, plastic, bread and sugar. A specialised sample holder was constructed to accommodate four fine thermocouples (76 ?m in diameter), which facilitated measurement of the temperature profiles within RDF samples undergoing oxidation and pyrolysis. An additional thermocouple was positioned at the base of the sample to verify the assumption of heat transfer in a semi-infinite slab, prior to ignition. This assumption was applied previously within the context of integral analysis to obtain a value of the effective thermal conductivity. The temperature profiles prior to ignition were combined with measurements of the surface temperature collected by the pyrometer. Mass-loss measurements were performed, but only after the onset of the flaming combustion, as a consequence of flow-field induced fluctuations. A separate data-acquisition system was used to allow a faster sampling rate than 1 Hz permitted by the default setting of the cone calorimeter. The experiments determined the critical mass flux at extinction and identified three combustion regimes occurring in fires of RDF-type materials: i) flaming combustion, ii) a transitional regime involving simultaneous flaming combustion and char pyrolysis, and iii) char pyrolysis. The measurements were consistent with results of the earlier fire experiments performed in the cone calorimeter.