The Fractal Model of Heat Conduction of Graphite Foam
Graphite foam is a new material for effective heat conduction, which possesses exceedingly good thermal physical properties, thus the investigation on it has absorbed wide attention of scientists and engineers. By using experimental method such a material was obtained in our lab, and the factors which influence the micro-structure of the material was preliminary discussed based on our experiments. However, the main focus of the present paper is placed on the determination of the effective thermal conductivity of the material. Firstly, in accordance with the microscopic structure of the material, a simplified geometric model was constructed. Based on it a heat conduction unit cell was proposed to calculate the effective thermal conductivity of the porous material. Then, a geometric transformation was carried out to transit the original simple model to the real fractal one. The effective thermal conductivity λ' and its averaged value λ'm for the bulk porous material were derived. Examples were provided to show the computational procedure and to confirm the availability of the method proposed. The influence factors on λm. in the fractal model were also discussed in detail.