中文摘要：

本文首先对纳米尺度受限空间中分子自由程进行了修正，进而提出了受限空间中气体的“净热导率”模型，并使用DSMC结果验证了该模型。采用扩散集团凝聚（DLCA）方法构造了气凝胶三维物理模型。结合提出的气相“净热导率”模型，采用LBM方法对气凝胶中气相贡献热导率进行了数值求解。结果表明：数值预测结果与实验值吻合较好。

英文摘要：

In this paper, the mean free path of gas confined in nanospace was modified. Based on the modified gas mean free path, a model for predicting the thermal conductivity of gas in nanospace was proposed and validated by DSMC results. With the proposed gaseous thermal conductivity model, the gas-contributed thermal conductivity of aerogel was studied with the method of LBM, in which the 3-D aerogel structure was reconstructed by the three-dimensional diffusion-limited cluster-cluster aggregation （DLCA） method. The results show that the numerical results are in good agreement with the available experimental data.