Effective and coupled thermal conductivities of isotropic open-cellular foams

The effective and the coupled thermal conductivity of the solid microstructure of open-cellular foams and an accompanying saturation fluid are defined in a conceptual representation of conductive heat transfer in a two-phase system of which the phases are in a thermal nonequilibrium state. The effective and coupled thermal conductivities were determined from a close observation of the relationship between microscopic and macroscopic temperature distributions. Temperature distributions were obtained from the numerical solution of the three-dimensional (3-D) conduction equation in a representative geometrical model of the foam solid microstructure and the fluid pores. Empirical correlations are provided for the effective and coupled thermal conductivities in terms Of the solid and the fluid thermal conductivity and foam porosity. Thermal radiation was not considered in the energy transfer process. (C) 2004 American Institute of Chemical Engineers.