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| Effect of hybrid nanofillers on thermal conductivity of composite phase change materials |
| DING Qing1, FANG Xin1, FAN Li-wu1, CHENG Guan-hua2, YU Zi-tao1, HU Ya-cai1 |
| 1. Institute of Thermal Science and Power Systems, Zhejiang University, Hangzhou 310027, China；2. Zhejiang Energy and Radiation Institute, Hangzhou 310012, China |
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Abstract In order to study the effect of hybrid nanofillers on the thermal conductivity of composite phase change materials(PCMs), organic composite PCMs filled with carbon nanotubes and silver (or alumina) nanoparticles as binary nanofillers were prepared. The effective thermal conductivity of the samples in solid phase was measured using the transient plane source technique at room temperature. The influence of the total loading, ratio of carbon nanotubes to nanoparticles, and base PCMs on the effective thermal conductivity of the composite PCMs were investigated experimentally. It was shown that the carbon nanotubes and nanoparticles act against each other. The thermal conductivity enhancement of the composite PCMs due to the presence of hybrid nanofillers is even lower than that with pure carbon nanotubes or nanoparticles. The relatively low total loadings (up to 1.5 vol%) of the nanofillers are not sufficient to lead to formation of effective heat conduction networks. This was confirmed by the microscopic images taken on the dispersion of nanofillers. Despite the existence of fairly uniform dispersion of the hybrid nanofillers, the desired synergetic effect between the dissimilar nanofillers is absent as a result of both the difference in their heat conduction mechanisms and the relatively high thermal interface resistance. The unfavorable effect occurs instead when the heat conduction paths are blocked within each type of nanofillers.
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Published: 01 February 2015
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混合纳米填料对复合相变材料导热系数的影响
为了研究混合纳米填料对复合相变材料导热系数的影响,制备以碳纳米管和银（或氧化铝）纳米颗粒为二元混合填料的有机类复合相变材料.采用瞬态平面热源法导热仪对复合相变材料在室温下固态时的有效导热系数进行测试.研究中综合考虑填料总加载量、碳纳米管/纳米颗粒的配比以及基底相变材料对复合相变材料有效导热系数的影响.实验结果表明,碳纳米管和纳米颗粒填料之间是互相抑制的,混合纳米填料所导致的复合相变材料导热系数增长甚至低于仅添加单一碳纳米管或纳米颗粒时的效果.在本研究所关注的较低的总加载量下（最高体积分数为1.5%）,尚不足以构建出能够实现混合填料协同效果的有效导热网络.纳米填料分布的微观表征图片证实,虽然混合填料各自的分布都较为均匀,但导热机理的差异和较高的界面热阻使得不同纳米填料之间无法体现出理想的协同效应,反而导致当单一纳米填料之间的导热通路被破坏时会呈现出反效果.
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