基于LBM的多孔陶瓷有效热导率和相变传热分析

Effective Thermal Conductivity and Phase Change Heat Transfer Analysis of Porous Ceramic Based on LBM

多孔氮化铝陶瓷具有高导热、耐熔盐腐蚀等优点在相变材料封装方面具有较大应用前景。本文采用微米计算机断层扫描(CT)得多孔氮化铝的灰度图像,并精准重构三维孔隙结构。并采用四参数随机生长、堆积颗粒、维诺结构等数值方法建立结构模型。基于介观尺度的格子玻尔兹曼方法(LBM),计算了多孔陶瓷的有效热导率,结果表明维诺结构与CT真实重构的热导率接近。采用三维焓法LBM模拟了多孔骨架内的相变传热过程,获得了孔隙尺度对流相变的传热机理,并分析了不同孔隙率时的储热密度和复合材料的有效热导率。基于CT扫描和LBM的相变传热模拟有助于快速分析骨架的热特性,为多孔骨架的设计提供理论基础。

Porous aluminum nitride ceramics have the advantages of high thermal conductivity and rcsistancc to molten salt corrosion,which have application potential on the phase change materials.In this work,the gray images of porous ceramics are obtained by micro-Computed Tomography(CT),so as to accurately reconstruct the three-dimensional pore networks.The pore networks are compared with the structure generated by numerical method including quartet structure generation set,particle packing,and Voronoi structure.Based on the mesoscopic lattice Boltzmann method(LBM),the effective thermal conductivity of porous ceramic was calculated.The three-dimensional enthalpy-based LBM was used to simulate the heat transfer process of the phase change inside the pore.The heat transfer mechanism of the pore-scale convective phase change was obtained.The heat storage density of porous ceramics with different porosity were analyzed.The simulation based on CT scanning and LBM is helpful to analyze the thermal properties of porous structure and provide theoretical basis for the design of porous skeleton.