Compacted exfoliated natural graphite as heat conduction medium

Graphite has been used in mixtures with adsorptive or reactive material in order to manufacture compressed blocks with heat conductive properties [Oli ves, These de doctorat, Universite de Perpignan, 1999]. In the present work , the intrinsic transfer properties of recompressed exfoliated graphite hav e been studied. Porous graphite matrices with a bulk density of 50 to 1800 kg m(-3) were fabricated by one-directional pressing of exfoliated graphite powders, in order to use them as heat conductive media. They were characte rized using optical microscopy and helium pycnometry. Gas permeabilities an d thermal diffusivities were measured for graphite matrices with different bulk densities. The gas permeability was in the range of 10(-11) to 10(-16) m(2). Thermal conductivity values in the axial and the radial directions w ere in the range 3 to 9 and 3 to 350 W m(-1) K-1, respectively. A semi-empi rical model was developed to Correlate the heat and mass transfer propertie s of the material with the solid conductivities, bulk density and porosity. (C) 2001 Elsevier Science Ltd. All rights reserved.