Numerical study on the effective thermal conductivity and thermal tortuosity of porous media with different morphologies  

作　　者：DU Shen LI Dong LI Meng-Jie HE Ya-Ling 

机构地区：[1]Key Laboratory of Thermo-Fluid Science and Engineering of Ministry of Education,School of Energy and Power Engineering,Xi’an Jiaotong University,Xi’an,710049,China

出　　处：《Science China(Technological Sciences)》2024年第6期1685-1694,共10页中国科学（技术科学英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.52306272 and 52341601)。

摘　　要：Effective thermal conductivity and thermal tortuosity are crucial parameters for evaluating the effectiveness of heat conduction within porous media.The direct pore-scale numerical simulation method is applied to investigate the heat conduction processes inside porous structures with different morphologies.The thermal conduction performances of idealized porous structures are directly compared with real foams across a wide range of porosity.Real foam structures are reconstructed using X-ray computed tomography and image processing techniques,while Kelvin and Weaire-Phelan structures are generated through periodic unit cell reconstruction.The detailed temperature fields inside the porous structures are determined by solving the heat conduction equation at the pore scale.The results present that the equivalent thermal conductivity of Kelvin and Weaire-Phelan structures is similar to and greater than that of the real foam structure with the same strut porosity.The thermal tortuosity of real foam structure is relatively larger and the heat conduction path becomes straighter by adopting the anisotropic design.The thermal tortuosity of the fluid channels for Kelvin,Weaire-Phelan,and real foam structures is close to one.The thermal conductivity of porous structures with heat transfer fluid increases as the thermal conductivity ratio of fluid to solid becomes larger.A small porosity of porous media leads to a larger equivalent thermal conductivity due to the dominant contribution of porous skeleton in the heat conduction process.Correlations derived from parallel and series models,as well as the Maxwell-Eucken models,provide decent predictions of effective thermal conductivity,with an average error of less than 8%in the entire range of thermal conductivity ratio.

关 键 词：volumetric solar receiver porous morphology direct pore-scale simulation equivalent thermal conductivity thermal tortuosity empirical correlation 

分 类 号：TK124[动力工程及工程热物理—工程热物理]