本文首先使用Callaway热导率模型对SiO_2纳米颗粒的热导率进行了近似计算,然后耦合堆积纳米孔隙内的导热和辐射、颗粒接触热阻,基于颗粒堆积单元结构模型的一维传热分析,最终推导得到了颗粒堆积有效热导率关于颗粒直径和温度、堆积孔隙率、颗粒热导率、气相热导率、辐射传热和接触热阻的关系式,并用该式进行了相关讨论。研究结果表明,对于纳米颗粒堆积,界面接触热阻不容忽略;在低孔隙率和颗粒不参与辐射的条件下,由于受到接触热阻的影响,存在最佳孔隙率（或密度）使得堆积热导率存在最大值。
The theoretical investigation on thermal conductivity of silica nanoparticles was carried out using the relaxation-time method based on Callaway model.Then a model was established to obtain the effective thermal conductivity of the silica-nanoparticle-packed powder by coupling the conduction,radiation in nanopores and contact thermal resistance.A formula was derived to predict the effective thermal conductivity depending on particle size,packing porosity,gas thermal conductivity, nanoparticles thermal conductivity,radiation heat transfer and contact resistance etc..Finally, the effect of contact resistance on the effective thermal conductivity was analyzed.It turns out that the contact resistance could not be ignored in nanoscale.If silica nanoparticles are nonparticipating in radiation and packed with low porosity,there has a maximum value for the effective thermal conductivity of the powder with an optimum packing porosity when the contact resistance taken into account.
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