气凝胶骨架固相热导率的分子动力学模拟

基于分子动力学理论和模拟的算法,构建了非晶态二氧化硅模型以及初级粒子模型,研究了外界环境条件和气凝胶内部结构的变化对气凝胶固相热导率的影响规律。得到了300、500、800、1200K四种环境温度下二氧化硅气凝胶材料的固相热导率,材料的固相热导率随着环境温度上升略有增加。同时探讨了初级粒子内部缺陷对骨架固相热导率的影响,一定孔隙率范围内,随着孔隙率的增加材料的固相热导率降低,当孔隙率逐渐增加至0.26后,模型能够很好地表征实际情况。所建立的非晶态气凝胶模型及算法对该类材料的微尺度传热分析及结构设计具有借鉴价值。 

Aerogel skeleton solid phase thermal conductivity by molecular dynamics simulation

A noncrystalline silica model and a primary particle model was built based on the theory of molecular dynamic and the algorithm of its simulation, and it explored how the solid phase thermal conductivity of aerogel was affected by the changes of external environmental conditions and aerogel internal structure. The results of silica aerogel solid phase thermal conductivity under four different enviromental temperatures, namely, 300,500,800K and 1200K were obtained. With the enviromental temperature rise the solid phase thermal conductivity increased slightly. The influence of the internal defect of primary particle on the solid phase thermal conductivity of skeleton was discussed. Within the range of porosity, the thermal conductivity of the solid phase decreased with the increase of the porosity. When the porosity increased gradually to 0.26, the model can well characterize the actual situation. The noncrystalline aerogel model and algorithm proposed will provide a reference for the microscale heat transfer analysis and structural design of this material.