Abstract Theoretically understanding the thermal conductivity of the nanoparticle packed beds (NPBs) is critical for designing high-performance thermal insulation materials. Currently, the classical effective medium assumption (EMA) model, Nan model, just show their good prediction at a high porosity of NPBs (≥0.75). Herein, we propose a generalized model of the thermal conductivity that almost covers the whole porosity range by considering the effect of the nanoparticle deformations on the thermal contact resistance ( R ). It has been demonstrated that our model matches the experimental results great well. It is also found that at high porosity R is dominated by the phonon diffusive scatterings ( R cd ), while it is determined by the phonon ballistic scatterings ( R cb ) at a low porosity. More interestingly, R can determine the porosity at which the lowest thermal conductivity of NPBs appears. This work opens a new way to design the desired thermal insulation materials.

中文翻译：

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考虑颗粒变形的纳米颗粒填充床广义热导率模型

摘要 从理论上了解纳米颗粒填充床 (NPB) 的热导率对于设计高性能绝热材料至关重要。目前，经典的有效介质假设 (EMA) 模型 Nan 模型仅在 NPB 的高孔隙率 (≥0.75) 下显示出良好的预测。在此，我们通过考虑纳米颗粒变形对接触热阻 (R) 的影响，提出了一个几乎涵盖整个孔隙率范围的导热系数的广义模型。已经证明我们的模型与实验结果非常匹配。还发现在高孔隙率下 R 由声子漫射散射 (R cd ) 主导，而在低孔隙率下由声子弹道散射 (R cb ) 决定。更有趣的是，R 可以确定出现 NPB 最低热导率时的孔隙率。这项工作为设计所需的隔热材料开辟了一条新途径。