膨胀石墨(EG)作为吸附材料不仅可以防止石蜡(PA)泄漏,还可以提高复合相变材料的导热系数。采用熔融混合法制备了EG含量不同的3种石蜡/膨胀石墨(PA/EG)定形复合相变材料,并对复合相变材料的潜热、热导率、热稳定性和热分解特性进行研究;搭建了可视化控温系统,在恒热流密度下采用红外热成像仪对复合相变材料传热特性进行可视化研究。研究结果表明:EG含量为30%(wt,质量分数,下同)时,复合相变材料导热系数为5.21W/(m·K),与PA相比提高约20倍;随着EG含量的增加,复合相变材料的相变焓逐渐降低,当EG含量为30%时,循环100次后复合相变材料的相变焓为183.6J/g;从熔融过程的温度可视化结果可得,复合相变材料中的EG虽然削弱了自然对流的影响,但是由于其导热系数远高于PA,所以复合相变材料温度变化较为明显。
Expanded graphite (EG) as adsorption material can not only prevent paraffin (PA) leakage,but also improve the thermal conductivity of composite phase change materials.In this paper,three kinds of paraffin/expanded graphite (PA/EG) shaped composites phase change materials with different EG mass fractions were prepared by melt mixing method.The latent heat,thermal conductivity,thermal stability and thermal decomposition of the composites were investigated.A visualized temperature control system was built to visualize the heat transfer behavior of composite phase change materials with infrared thermal imager under constant heat flux.The results showed that when 30% (wt,weight fraction) EG was added,its thermal conductivity was 5.21W/(m·K),which was about 20 times higher than that of PA.With the increase of EG amount,the phase change enthalpy of the composite phase change material gradually decreased,and when the mass fraction of EG was 30%,the phase change enthalpy of the composite PCM was 183.6J/g after 100 cycles.Through the visualized temperature control platform,it could be seen that although EG in composite PCM weakened the influence of natural convection,its thermal conductivity was much higher than that of PA,so the temperature change of composite phase change materials was more obvious.
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基金资助
国家自然科学基金(52206122);河南省中原科技创新领军人才项目(234200510011);河南省科技攻关项目(232102321089);郑州市协同创新专项(校重大重点项目培育)(2021ZDPY0107)
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