The influence of gaseous heat conduction to the effective thermal conductivity of nano-porous materials
The influence of gaseous heat conduction to the effective thermal conductivity of nano-porous materials
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DOI：
10.1016/j.icheatmasstransfer.2015.08.027
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发表时间：
2015-11
影响因子：
7
通讯作者：
Hu Zhang;Wen-Zhen Fang;Zengyao Li;W. Tao
中科院分区：
文献类型：
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作者：
Hu Zhang;Wen-Zhen Fang;Zengyao Li;W. Tao
建立并研制了基于瞬变平面源法的开孔材料有效导热系数测试装置，用于测量不同气压下开孔材料的有效导热系数。在0.001~1 Mpa的气压范围内，测量了孔隙率为88.5%的开放纳米多孔二氧化硅材料的有效导热系数。用不同气压下的有效导热系数减去极限真空下的有效导热系数，分解出气体导热系数对材料有效导热系数的贡献。研究发现，气体导热系数的贡献与纳米多孔材料中的气体导热系数和自由空间中的气体导热系数有很大差异。理论分析和数值模拟结果也证明了这一点。
A thermal conductivity test apparatus based on transient plane source method is built and developed to measure effective thermal conductivity of open porous materials at different gas pressures. The effective thermal conductivity of open nano-porous silica materials with porosity of 88.5% is measured under gas pressures ranging from 0.001 Pa to 1 MPa. The contribution of gaseous heat conduction to the effective thermal conductivity of materials is decomposed by subtracting the effective thermal conductivity at ultimate vacuum from that at different gas pressure. It is found that the contribution of gaseous heat conduction is much different with the gas thermal conductivity in nano-porous materials and that in free space. The result is also demonstrated by theoretical analysis and numerical simulation.