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Supercooling Suppression and Thermal Conductivity Enhancement of Na2HPO4·12H2O/Expanded Vermiculite Form-Stable Composite Phase Change Materials with Alumina for Heat Storage
ACS Sustainable Chemistry & Engineering ( IF 7.1 ) Pub Date : 2018-03-21 00:00:00 , DOI: 10.1021/acssuschemeng.8b00631
Yong Deng 1 , Jinhong Li 1 , Yanxi Deng 1 , Hongen Nian 2, 3 , Hua Jiang 4
Affiliation  

In the heat storage applications, Na2HPO4·12H2O phase change materials (PCM) show significant defects including form instability, high supercooling degree and low thermal conductivity. Aiming at these drawbacks, the Na2HPO4·12H2O-alumina/expanded vermiculite (EVM) form-stable composite phase change materials (NEA fs-CPCMs) with supercooling suppression and heat transfer enhancement were prepared. The favorable wettability of NEA fs-CPCMs was beneficial to their form-stabilization (encapsulation mass fractions above 59.7 wt %). The supercooling degree of NE5.3 was reduced to 1.4 °C after adding 5.3 wt % alumina as the nucleating agent (decreased by 90%). The surface effects of EVM and alumina and high wettability of PCM-alumina were responsible for the supercooling suppression of PCM. Large specific surface area of EVM could provide nucleation sites for crystallization of PCM. The surface electronegativity of alumina increased the affinity ability and diffusion rate of ions, thus effectively increasing the probability of nucleation. The heat transfer of NEA fs-CPCMs was significantly enhanced by the alumina as the thermal conductivity enhancement filler. The thermal conductivity of NE5.3 reached 0.418 W/(m K). Thermal energy storage behavior analysis indicated that the NEA fs-CPCMs showed large heat storage capacity (melting process: 97–151 J/g; solidification process: 60–89 J/g). The thermal reliability of NEA fs-CPCMs was effectively improved by coated paraffin.

中文翻译:

Na 2 HPO 4 ·12H 2 O /膨胀的Ver石形稳复合氧化铝相变材料的过冷抑制和导热系数的提高

在储热应用中,Na 2 HPO 4 ·12H 2 O相变材料(PCM)表现出明显的缺陷,包括形状不稳定性,高过冷度和低热导率。针对这些缺点,Na 2 HPO 4 ·12H 2制备了具有过冷抑制和传热增强作用的O-氧化铝/膨胀ver石(EVM)形状稳定复合相变材料(NEA fs-CPCMs)。NEA fs-CPCM的良好润湿性有利于其形式稳定(封装质量分数高于59.7 wt%)。加入5.3 wt%的氧化铝作为成核剂后,NE5.3的过冷度降低至1.4°C(降低了90%)。EVM和氧化铝的表面效应以及PCM-氧化铝的高润湿性是PCM过冷却抑制的原因。EVM的大比表面积可以为PCM的结晶提供成核位点。氧化铝的表面电负性提高了离子的亲和力和扩散速率,因此有效地增加了成核的可能性。NEA fs-CPCMs的传热通过氧化铝作为导热增强填料得到了显着增强。NE5.3的热导率达到0.418W /(m·K)。热能存储行为分析表明,NEA fs-CPCMs具有很高的储热能力(熔化过程:97–151 J / g;凝固过程:60–89 J / g)。包衣石蜡可有效提高NEA fs-CPCM的热可靠性。
更新日期:2018-03-21
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