Thermal effusivity of two-phase wood cement-based composites

This study presents a method for estimating the thermal effusivity of wood cement-based composites used in the dry state. Two models, based on an Ohm's law approach, will be displayed herein: the unit cell of the parallel model and the model of Jackson and Black have both been used to predict the effective thermal effusivity of wood composites. Various topological parameters, such as the tortuosity factor and the stereological concept of contiguity, have been introduced in order to take into account the effect of the pore structure on the thermal effusivity. Furthermore, the porosity correction term and the correction term which accounts both for the effect of the randomization of particle distribution and for the effect of the ratio of thermal effusivities (beta(s)/beta(f)) have been determined empirically. Measurements of the thermal effusivity have been performed inside a closely controlled climatic cell at ambient temperature (20 +/- 0.5 degrees C) using a heat plane source technique. Calculated values of the thermal effusivity of these materials have been compared with experimental results. The values predicted by the two models are all in very close agreement with experimental values.