Abstract The bimodal-pore distributed features of mesoporous silica particles have great effects on their thermal conductivity variations. In this paper, a simplified bimodal-pore distribution model is proposed to depict the variation in thermal conductivity of mesoporous silica particles (such as MCM-41 and SBA-15) at nitrogen pressure. The model is analytically described by a parallel connection of the gas heat conduction in pores and the two different apertures, and the scaling factor F is added to consider the gas-solid coupling effect. To verify the correctness of the proposed model, the microstructure parameters of mesoporous silica particle samples are measured by the Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and the nitrogen adsorption method, and the thermal conductivity is further measured via the transient hot-strip method in a nitrogen atmosphere of 0–15 MPa. The results show that the theoretical model yields a good agreement with the experimental data, and hence can be used to study the effect of bimodal-pore distributed features on the thermal conductivity of mesoporous materials.

中文翻译：

---

基于双峰孔分布模型的介孔二氧化硅颗粒的气体热导率研究

摘要 介孔二氧化硅颗粒的双峰孔分布特征对其热导率变化有很大影响。在本文中，提出了一种简化的双峰孔分布模型来描述介孔二氧化硅颗粒（如 MCM-41 和 SBA-15）在氮气压力下的热导率变化。该模型通过孔隙内气体热传导与两个不同孔径的并联进行解析描述，并加入比例因子F以考虑气固耦合效应。为了验证模型的正确性，通过扫描电子显微镜（SEM）、透射电子显微镜（TEM）和氮吸附法测量了介孔二氧化硅颗粒样品的微观结构参数，在 0-15 MPa 的氮气氛中通过瞬态热剥离法进一步测量热导率。结果表明，该理论模型与实验数据吻合较好，可用于研究双峰孔分布特征对介孔材料热导率的影响。