基于石墨烯气凝胶的定形相变材料储热性能研究

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

中文关键词: 石墨烯  气凝胶  定形  相变材料  导热系数

英文关键词: paraffin  aerogel  form-stable, PCMs, thermal conductivity

中文摘要:

      使用石墨烯气凝胶(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 kJ/kg和229.5 kJ/kg。吸/放热温度曲线表明,在以导热为主的换热过程中,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换热过程中,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。

英文摘要:

      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 the key thermophyscial proppteries of the as-synthesized sample were characterized by FTIR, XRD, SEM, nano flash and DSC ways. The results demonstrated that the high porosity of GA could effectively prevent the liquid-state PCM from leakage. In addition, the extra thermal conduction pathway provided by GA enhanced the thermal conductivity of pure 1-hexadecanol by 20%. After 50 heat storage/release cycles, no obvious decrease was observed in the melting and freezing enthalpies of GA/1-hexadecanol, which were 229.2 kJ/kg and 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 led to a greater flow resistance of 1-hexadecanol, thus the cooling/freezing rates of GA/1-hexadecanol were lower than the baselines of pure 1-hexacecanol.