A FRACTAL MODEL OF EFFECTIVE THERMAL CONDUCTIVITY IN POROUS MEDIA EMBEDDED WITH ROUGH DISSYMMETRIC TREE-LIKE NETWORKS

Heat convection is a complex and important heat transfer mode in dissymmetric tree-like networks. However, most research on heat transfer properties of networks tend to overlook the heat convection induced by fluid flow in pipelines. Based on fractal characteristics of the networks and fundamental laws of thermodynamics, this research considers heat conduction and convection and establishes a fractal model of effective thermal conductivity (ETC) of porous media embedded with randomly distributed dissymmetric tree-like networks with rough surfaces. The generalized optimal structure of the dissymmetric tree-like network is derived based on minimum thermal resistance. To validate the model's effectiveness, the predicted results are compared with available experimental data, showing good agreement. The results indicate that heat convection plays a dominant role in heat transfer. The ETC of the porous media is positively correlated with the thermal conductivity of the solid matrix, length ratio, branching level, and porosity, while it is negatively correlated with the diameter ratio and branching angle. Therefore, this analysis can enrich the theory of heat transfer in porous media and provide theoretical support for the design or optimization of relevant energy materials.