Measurement of Thermophysical Properties of Fire Testing Materials

An unsteady heat flux method was used to determine the thermophysical properties of Polymethyl methacrylate (PMMA) and cellulose, both of which are commonly used as standard sample materials in flame spread tests. The analysis is based on an analytical solution to a heat conduction equation with periodic heat flux. The effective thermal conductivity and diffusivity for a packed bed of each sample material were simultaneously determined from the amplitude and phase delay of the temperature response for periodic heat flux. Experiments were performed for a range of heating rates, particle sizes and apparent densities. The variation in thermophysical properties with temperature was obtained, and the effects of pyrolysis for cellulose, and phase transition for PMMA, on the thermophysical properties of these materials were investigated.