碳纳米管/石蜡复合相变储能材料的导热性能研究

Thermal conductivity of CNTs/paraffin phase change composites

以多壁碳纳米管为填料，采用两步法制备了不同质量分数（0．1％～1．O％）的CNTs／石蜡复合相变材料。采用Hot—Disk热分析仪测试了CNTs／石蜡复合相变材料在不同纳米颗粒质量分数、温度和粒径下的导热系数。研究表明，CNTs／石蜡复合相变材料的固、液态导热系数随CNTs颗粒质量分数的增加而大幅度提高，在25℃时，质量分数为0．5％的复合相变材料的导热系数提高了13．2％，体现了良好的强化导热效果。复合相变材料的导热系数对温度的依赖性不强，但在55℃时，复合相变材料的导热系数在固一液相变过程时出现了较大程度的增长。此外，复合相变材料的导热系数随CNTs颗粒粒径的增加而降低，25℃时，质量分数为0．1％的复合相变材料中，添加10nm的碳纳米管后其导热系数提高了7．8％，添加100nm的碳纳米管后其导热系数提高了2．2％。

Using multi-walled carbon nanotubes （MWCNTs） as the enhanced thermal conductivity fillers, CNTs/ paraffin composite phase change materials （PCMs） with various mass fractions （0. 1% -1.0% ） of CNTs are prepared by a two-step method. The effects of mass fractions of CNTs particle, temperature and particle size on the thermal conductivity of the composite PCMs are experimentally investigated by a HotDisk thermal constants analyzer. The thermal conductivity of liquid and solid composite PCMs is shown to increase significantly with the increase in mass fraction of CNTs. For composite PCMs with 0. 5 wt% of CNTs at 25℃, the relative thermal conductivity enhancement is nearly 13.2% ,which shows a favorably enhanced thermal conductivity. The effect of temperature on the thermal conductivity is not obvious, except for 55 ℃ at which a sudden increase is seen due to the solid-liquid phase change. In addition, thermal conductivity is found to decrease with increase in particle size of CNTs. For composite PCMs with 0. 1 wt% of CNTs and 10 n of particle size at 25℃, the relative thermal conductivity is improved by nearly 7. 8% , while for composite PCMs with 0. 1 wt% of CNTs and 100 nm of particle size at 25℃, the relative thermal conductivity is improved by nearly 2. 2%.