Characterization of the radiative exchanges when using a cone calorimeter for the study of the plywood pyrolysis

Experimentations have been carried out on the emission of an infrared emitter on the one hand, and the absorption of a sample of wood on the other hand, in order to characterize the radiative exchanges during a study of pyrolysis using a cone calorimeter apparatus (ISO 5660 standard). The deviation from standard assumptions of black emission or black absorption has been analyzed. The emission of the cone calorimeter has been observed to be close to the ideal one of a blackbody, with some heterogeneities in the emission pattern, but obviously similar to a black emission at a temperature up to 1273 K, depending on the electric supply. On the contrary, the plywood absorption is more complex, non-grey, with important deviations from the behavior of a black absorber in some wavelengths. Average properties have been computed using Planck's means, still indicating a strong average absorptivity for the present samples of studied plywood, but ranging between 0.74 and 0.95, depending on time and irradiation source. Present observations confirm that such a non-grey absorption of the samples may result in some discrepancies when studying the pyrolysis with various emission sources like the one of Fire Propagation Apparatus or the present cone calorimeter, which could have some consequences in the interpretation of the pyrolysis process.

► Radiative exchanges during a cone calorimeter experiment are investigated.
► We measured the absorptivity of plywood samples, showing their non-grey behavior.
► Radiation emission by a cone is seen to be close to a black emission.
► Fluxes received by a given sample under the cone are computed.
► Thermal degradation is confirmed to be affected by the experimental setup.