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 [Olives, These de doctorat, Universite de Perpignan, 1999]. In the present work, the intrinsic transfer properties of recompressed exfoliated graphite have 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 characterized using optical microscopy and helium pycnometry. Gas permeabilities and 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 were in the range 3 to 9 and 3 to 350 W m(-1) K-1, respectively. A semi-empirical model was developed to Correlate the heat and mass transfer properties of the material with the solid conductivities, bulk density and porosity. (C) 2001 Elsevier Science Ltd. All rights reserved.