Solidification behavior and thermal conductivity of bulk sodium acetate trihydrate composites with thickening agents and graphite
Solidification behavior and thermal conductivity of bulk sodium acetate trihydrate composites with thickening agents and graphite
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DOI：
10.1016/j.solmat.2015.10.038
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发表时间：
2016-02-01
影响因子：
6.9
通讯作者：
Furbo, Simon
中科院分区：
文献类型：
--
作者：
Dannemand, Mark;Johansen, Jakob Berg;Furbo, Simon
如果积极利用过冷，三水醋酸钠是一种有前途的相变材料，可用于长期储存太阳热能。性能良好的热能存储需要能够以高速率充电和放电。相变材料的相对较低的热导率限制了与储存器之间的热交换容量速率。限制传热的另一个因素是盐水合物在相变过程中的收缩和膨胀。这种密度变化导致固体存储材料内部形成空腔。本文研究了基于三水合乙酸钠结晶的复合材料的凝固行为、空腔形成和导热性，无论是否过冷。使用 ISOMET 热盘表面测量探头测量热导率。未经过冷而结晶的样品倾向于在传热表面附近形成固体晶体，并在远离传热表面的地方形成空腔。固体三水合乙酸钠中测得的热导率高达 0.7 W/m K。从过冷状态结晶的样品形成较少的大空腔，但具有较低的导热率。由三水乙酸钠、增稠剂和 5% 石墨片组成的复合材料的导热系数高达 1.1 W/m K。 (C) 2015 Elsevier B.V. 保留所有权利。
Sodium acetate trihydrate is a promising phase change material for long term storage of solar thermal energy if supercooling is actively utilized. Well performing thermal energy storages need to be able to charge and discharge energy at a high rate. The relatively low thermal conductivity of the phase change material limits the heat exchange capacity rate to and from the storage. Another factor that limits the heat transfer is the contraction and expansion of the salt hydrate during the phase change. This density change causes formation of cavities inside the solid storage material. Investigations of the solidification behavior, the formation of cavities and thermal conductivity of composites based on sodium acetate trihydrate crystalizing with or without supercooling are presented in this paper. The thermal conductivity was measured with an ISOMET hot disc surface measurement probe. Samples that crystalized without supercooling tended to form solid crystals near the heat transfer surface and cavities away from the heat transfer surface. The measured thermal conductivity was up to 0.7 W/m K in solid sodium acetate trihydrate. Samples that crystalized from supercooled state formed fewer large cavities but had a lower thermal conductivity. A composite with sodium acetate trihydrate, thickening agent and 5% graphite flakes had a thermal conductivity of up to 1.1 W/m K. (C) 2015 Elsevier B.V. All rights reserved.