Effect of the pore shape on the thermal conductivity of porous media

The effect of the pore shape on the thermal conductivity of porous media is studied in this work, considering random and aligned distributions of spheroidal pores within the matrix. This is done by using the Bruggeman differential effective medium theory which is suitable for pores with different sizes, as is usually the case of practical interest. The obtained results can be applied for porous media with low as well as high porosities, and they show that: (1) the effect of the pore shape becomes stronger as the porosity increases. (2) The thermal conductivity for randomly oriented pores takes its maximum value for spherical pores and this value is the geometric average of the thermal conductivities along the three principal axes of the pores, when they are aligned. (3) In the case of aligned pores, the thermal conductivity along a principal axis increases with its length, in such a way that it is larger along the principal axis with longer dimensions. The predictions of the proposed approach are in good agreement with reported data and are expected to be useful to provide insights on the thermal behavior of porous media.