EXPERIMENTAL AND NUMERICAL STUDY OF EFFECTIVE THERMAL CONDUCTIVITY MODELS LIMITATIONS AND SELECTION OF POROUS MEDIA: REVIEW

Abstract

Efficient thermal conductivity (ETC) within porous material is an important aspect of numerous engineering endeavors such as geothermal energy systems, thermal insulation and material science. The correct modeling of ETC is critical to the heat transfer awareness mechanism of porous structures, which may possess complicated pore stratagems. This literature review examines the drawbacks and the criteria used to select different thermal conductivity models to use on porous materials. It looks at the classical models, including Zehner-Schlunder and Maxwell and more sophisticated models, including fractal models, percolation theory and Lattice Boltzmann simulations. The performance of every model is compared with other physical conditions; however, the attention is paid to the issues of pore size distribution, fluid saturation, or geometry. The review points to the necessity of choosing the models depending on the properties of the porous medium, i.e., metal foams, granular substances, or sintered structures. The major findings indicate that at the small-scale level, traditional models can be useful in simple structures but cannot be relevant in more complicated geometries including the ones that are found in fractured rocks or nanoporous materials. Besides, the review reiterates the significance of the fact that temperature and fluid saturation effects should be considered as in many models they tend to be disregarded. The experiments are also essential in order to fine-tune the predictions of these models. Finally, it is possible to infer that the current research proposes that additional research is needed to make ETC models more accurate through the inclusion of more realistic geometries of pores, temperature dependencies and fluid interactions. It additionally requires the creation of hybrid models that integrate theory with numerical models to deal with the details of the porous materials in the world.