摘要
本文研究并建立了气凝胶复合隔热材料传热计算模型.针对气凝胶纳米多孔材料的分形结构特征,结合规则交叉球杆结构,提出了气凝胶纳米多孔材料的分形交叉球杆结构模型,并以此结构模型为基础,建立了气凝胶纳米多孔材料热导率分形计算模型,模型中同时考虑了尺寸效应对气相、固相传热方式的影响.对气凝胶中添加的遮光剂、增强纤维等微米典型结构,以Mie辐射散射理论为基础,结合Rossland扩散近似模型,考虑了辐射传热对热量传递的增强作用;同时结合经典的两相系统等效热导率计算公式,获得复合材料的辐射导热耦合热导率计算模型.本文从纳米尺度的气凝胶多孔材料传热模型到微米尺度的气凝胶复合隔热材料传热模型,建立了完整的气凝胶纳米多孔复合隔热材料等效热导率计算模型.模型与多个文献中气凝胶材料热导率实验数值进行比较,获得了满意的结果,验证了模型应用于气凝胶复合隔热材料等效热导率预测计算方面的有效性.
In this paper, the effective thermal conductivity model of silica aerogel composite insulating materials was established. A fractal-intersecting sphere model was proposed for the nano-porous silica aerogel in which the scale effect on gas conduction and solid-matrix conduction were both considered. While for composite insulating materials, Rossland approximation were used to account for the radiative thermal conductivity. The radiative properties of additives （opacifier particles and fibers）, which are needed for calculating the radiative conductivity in Rossland equation, were determined by Mie theory. The established theoretical model was compared with several experimental results of thermal conductivities of insulating materials, including nano-porous silica aerogel as well as kinds of aerogel composite materials. The comparisons show the effectiveness of the theoretical model in predicting effective thermal conductivity of aerogel composite insulating materials.
出处
《工程热物理学报》
EI
CAS
CSCD
北大核心
2014年第2期299-304,共6页
Journal of Engineering Thermophysics
基金
国家重点基础研究发展计划(973计划)资助项目(No.2013CB228303,No.2013CB228304)
教育部高等学校博士学科点专项科研基金优化发展领域项目(No.20120201130006)
关键词
传热
分形结构
辐射
等效热导率
heat transfer
fractal model
radiation
effective thermal conductivity
作者简介
谢涛（1987-），男，博士研究生，主要从事多孔介质传热研究。
通信作者：何雅玲，教授，主要从事能源的高效利用与节能理论和新方法，新能源利用，流动与传热过程的数值预测原理及其应用，以及航天航空中的热科学问题等方面的研究，yalinghe@mail．xjtu．edu．cn
