基于空心球聚合体的多孔介质有效导热系数的两种模型

根据硬硅钙石型微孔硅酸钙的结构特点,将其简化成空心球聚合成的多孔介质,建立了点接触空心球壳与面接触空心立方体两种单元体模型.采用一维热传导分析,推导出有效导热系数的理论计算公式.计算结果表明,模型计算值与硅酸钙实验值有较好的一致性.理论模型可应用于与微孔硅酸钙具有类似结构的多孔介质导热系数的估算.

Two Effective Thermal Conductivity Models of Porous Media with Hollow Spherical Agglomerates

Based on the structure feature of xonotlite-type micro-pore calcium silicate, micro-pore calcium silicate is simplified as porous media with hollow spherical agglomerates, and two element models, point-contact empty spherical shell model and area-contact empty cubic model, are developed. Through applied one-dimensional heat conduction in the cell, the models for calculation of the effective thermal conductivity of micro-pore calcium silicate are derived. As compared with the experimental data of calcium silicate, the results show that the calculating results by the models have better agreement with those by experiment, and the models can be used to approximately calculate the effective thermal conductivity of porous media which have similar structure feature with micro-pore calcium silicate. In addition, the effect of temperature and contact parameter on the effective conductivity is analyzed, and it implies that the extent of contact between the hollow spherical agglomerates in xonotlite-type calcium silicate is not very high.