Thermal transport in graphitic carbon foams

A number of carbon foam products are being developed for use as insulator, heat spreaders, and compact heat exchanger cores. Such foams have voids that are typically of the order of 100 mum, and the pore walls are about 10 mum. The carbon in the foam may be graphitized by heat treatment during processing. The arrangement of graphene planes in graphitic foams is a function of position within the structure of the foam. Therefore, the thermal transport process is highly dependent on the microstructure. This results in bulk conductivities that range from 1 to 200 W/m K. The bulk properties of such a porous medium are difficult to determine analytically, particularly in the case of high concentration of nonspherical pores, or when the porous material is anisotropic or nonhomogeneous. A finite element analysis has been developed to calculate the bulk thermal conductivity of carbon foams with anisotropic microstructure. The effective thermal conductivity is then evaluated by comparing the results of the analytical and numerical models.