Evaluation of effective thermal conductivity of porous foams in presence of arbitrary working fluid

The Effective Thermal Conductivity (ETC) of open-cell porous foams can be either measured using experimental techniques or predicted from the detailed numerical simulation, considering the complex foam structure obtained from three-dimensional (3D) Computed Tomography (CT)-scan images. An alternative approach could be to consider simplified models for a quick and accurate estimation of the ETC. A model for ETC of open-cell porous foams, using an extremely simplified approach, has been proposed recently by Mendes et al. [1] and it provides an expression for the ETC with one adjustable parameter. It relies upon a single numerical prediction of the dimensionless ETC under vacuum condition, based on the detailed foam structure, obtained from 3D CT-scan information. Using experimental techniques, however, the vacuum condition is difficult to achieve. Therefore, it would be more suitable to conduct the measurement of ETC in presence of a commonly available fluid, like air or water, in order to determine the model parameter. From present result it can be concluded that lower thermal conductivity working fluid, like air, is the most suitable for evaluating the model parameter. Nevertheless, higher thermal conductivity working fluid, like water, also yields an accurate estimation of the model parameter if the thermal conductivity of the solid matrix is also sufficiently high.