基于石墨烯气凝胶的定形相变材料储热性能研究

Investigation on thermal energy storage characteristics of form-stable phase change materials supported by graphene aerogel

使用石墨烯气凝胶(graphene aerogel,GA)为导热骨架,十六醇作为相变材料,制备出一种用以储热的定形相变材料。利用FITR、XRD、SEM、激光闪光法和DSC等手段对样品的微观形貌、化学结构以关键热物性进行了表征,同时也测试了样品实际吸/放热的速率。结果表明,GA的多孔结构可以有效防止相变材料的泄露。同时,高导热的石墨烯在相变材料中建立起额外的导热通路,使得样品的导热系数提高了20%。重复吸放热50次后发现,样品的融化/凝固焓并没有因为GA的加入明显下降,分别为229.2和229.5kJ/kg。吸/放热温度曲线表明,在以导热为主的传热过程中,拥有更高导热系数的定形相变材料比纯十六醇具有更快的融化/凝固速率。而在自然对流为主的传热过程中,由于GA较强的毛细作用,十六醇的流动性被削弱,定形相变材料的融化/凝固速率低于纯十六醇。

1-hexadecanol was infiltrated into the open-cell structure of graphene aerogel（GA）to prepare a form-stable phase change material for thermal energy storage.The morphology,chemical structure and key thermophysical properties of the as-synthesized sample were characterized by FTIR,XRD,SEM,nano flash and DSC ways.The results demonstrate that the high porosity of GA can efectively prevent the liquid PCM from leakage.In addition,the extra thermal conduction pathway provided by GA enhances the thermal conductivity of pure 1-hexadecanol by 20%.After 50 heat storage/release cycles,no obvious decrease is observed in the melting and freezing enthalpies of GA/1-hexadecanol,which are 229.2 kJ/kgand 229.5 kJ/kg,respectively. Furthermore,the improved thermal conductivity endowed GA/1-hexadecanol sample with higher cooling/freezing rates during the procedure of conduction-governed heat transfer.However,during the heat transfer process dominated by natural convection,the high porosity of GA contributed to a higher capillary force,which leads to a greater flow resistance of 1-hexadecanol,thus the cooling/freezing rates of GA/1-hexadecanol are lower than the baselines of pure 1-hexacecanol.