膨胀石墨/石蜡复合相变材料的碳纳米管掺杂改性研究

Study on the preparation and characterization of CNTs modified expanded graphite/paraffin composite PCM

为了制备兼具高相变潜热和高导热系数的膨胀石墨/石蜡(EG/PA)复合相变材料,使用真空浸渍法并通过碳纳米管(CNTs)掺杂对复合相变材料进行了改性。导热性能测试分析发现,当复合相变材料中石蜡质量分数较高时,CNTs掺杂可以有效地增强复合相变材料的导热系数,并且随着CNTs掺杂含量的提高复合相变材料的导热系数也逐渐增大,但是当CNTs掺杂量高于0.8%(质量分数)时导热系数增大速度变慢,因此优化的CNTs掺杂含量为0.8%(质量分数)。在此优化参数下,复合相变材料的熔化潜热从145.27J/g变到144.39J/g几乎没有变化,而导热系数从2.141W/(m·K)提升至4.106W/(m·K),提升了约1倍,并且在100次热循环之后仍然保持很好的储热能力,具有较好的热循环稳定性。

In order to fabricate expanded graphite/paraffin (EG/PA) composite PCM with high latent heat and high thermal conductivity,the CNTs modified EG/PA composite PCM was prepared by vacuum impregnation method.The thermal conductivity analysis showed that the doping of CNTs in the composite PCM could significantly increase the thermal conductivity of the composite PCM when the paraffin mass fraction was high.Also,the thermal conductivity of the CNTs modified composite PCM increased with the CNTs doping amount.However,the growth trend of the thermal conductivity could be slow when the doping amount of CNTs exceed 0.8wt%.The optimized CNTs doping amount was found to be 0.8wt%.Under the optimized parameter,the latent heat of the composite PCM varied from 145.27 to 144.39 J/g,while the thermal conductivity of which increased from 2.141 to 4.106 W/(m·K).Moreover,the CNTs modified EG/paraffin composite PCM could maintain good thermal storage capability after 100 times heating and cooling cycles,which indicated that the CNTs modified composite PCM had good thermal cycle stability.