硬脂醇@Co3O4/膨胀石墨复合相变材料的制备及性能

Preparation and thermal properties of stearyl alcohol @ Co3O4/Expanded Graphite composite phase change material for heat storage

摘要:

以硬脂醇 (Stearyl alcohol，SAL) 作为相变材料，Co3O4/膨胀石墨(Expanded graphite，EG) 作为支撑材料，通过熔融共混-压制成型制备了一种新型的SAL@Co3O4/EG复合相变材料(PCM)。EG的添加用于改善PCM的导热性能，同时采用ZIF-67煅烧后的Co3O4对其进行了化学改性。由ZIF-67衍生而来的Co3O4具有丰富的微孔结构和大的比表面积。采用扫描电子显微镜(SEM)对Co3O4/EG的结构进行了表征，表明Co3O4/EG具有三维耦合网络和分级多孔结构。同时，EG可以有效防止金属有机骨架(MOF)衍生材料结构的坍塌和团聚。采用SEM，DSC和红外成像仪器对复合相变材料的形貌和热性能进行了表征与分析。结果表明：复合相变材料SAL@ Co3O4/EG-8%的熔化温度为51.25℃，其潜热为191.63 kJ/kg。随着Co3O4和EG比例从1:1一直增加到1:8，复合相变材料SAL@ Co3O4/EG 的导热系数呈现上升趋势。当Co3O4 ：EG为1:8时的复合相变材料的热导率大约是纯SAL（0.248 W/(m?K)）的47倍。而红外成像结果则验证了复合相变材料样品的瞬态温度变化与其热导率密切相关。所有测试结果表明，新型复合材料是一种极具前景的相变材料，由于其优异的热性能，因而在储热领域具有较大的潜在应用价值。

Abstract:

A novel stearyl alcohol @ Co3O4/Expanded graphite composite phase change material (PCM) was prepared. Stearyl alcohol (SAL) and Co3O4/Expanded Graphite were selected as phase change material and supporting material, respectively. Expanded Graphite (EG), which was used to improve the thermal conductivity of PCM, was chemically modified using Co3O4. Co3O4 derived from ZIF-67 has abundant pore structure and large specific surface area. The structure of Co3O4/EG additive was characterized by SEM analyzing method. The prepared Co3O4/EG has the three-dimensional coupled network and hierarchical porous structure. Meanwhile, EG can effectively prevent the structural collapse and aggregation of Metal-Organic Framework (MOF) derivatives. The morphology and thermal properties of composite PCMs were analyzed with SEM, DSC and infrared imager. These results showed that the melting temperature of SAL@ Co3O4 /EG-8% composite phase change material was 51.25℃, and its latent heat was 191.63 kJ/kg. As the ratio of Co3O4 to EG increased from 1:1 to 1:8, the thermal conductivity of the composite phase change material SAL@Co3O4 /EG showed an increasing trend. When Co3O4: EG was 1:8, the thermal conductivity of PCM was about 47 times that of pure SAL(0.248 W/(m?K)).The infrared imaging results confirmed that the transient temperature variation of the composite phase change material sample was closely related to its thermal conductivity. All the test results showed that the new composite was a promising phase change material， because of its excellent thermal properties, it had a great potential application value in the field of heat storage.