上海交通大学 制冷与低温工程研究所， 上海 200240
收稿日期:2019-04-16出版日期:2020-10-28发布日期:2020-11-09通讯作者:李廷贤，男，副教授，博士生导师，电话(Tel.)：021-34206335；E-mail：Litx@sjtu.edu.cn.作者简介:李文琛（1997-），男，山东省济宁市人，硕士生，主要从事相变储能研究.基金资助:国家自然科学基金（51876117），国家重点研发计划（2018YFE0100300）资助项目Preparation and Thermal Storage Properties of Sodium Acetate Trihydrate-Expanded Graphite as Phase Change Composite
LI Wenchen,CAI Yifan,YAN Taisen,LI Tingxian,WANG RuzhuInstitute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai 200240, China
Received:2019-04-16Online:2020-10-28Published:2020-11-09摘要/Abstract
摘要： 水合盐储能材料普遍存在热导率低、过冷度大及相分离问题.本文通过熔融共混制备了以三水合醋酸钠(SAT)为主体的复合相变材料(CPCM).采用膨胀石墨(EG)作为高导热添加物强化导热系数，同时作为成核剂改善其过冷度问题.采用黄原胶(XG)为增稠剂改善复合相变材料的相分离问题.研究了复合相变材料的导热性能、相变性能及热稳定性，并基于该复合相变材料(SAT/EG/XG)搭建了高储热密度的相变储热器，研究了该装置在85℃热源、20℃冷源下的储放热性能.结果表明：膨胀石墨的加入可明显增强热导率及消除过冷度.添加2%～4%(质量分数)膨胀石墨，复合相变材料热导率可达1.12～1.81W/(m·K)，为纯SAT热导率的2～3倍，且添加0.5%～1.2%(质量分数)黄原胶可明显抑制相分离.复合相变材料具有很好的热稳定性，50次循环后其熔化温度保持在58.0℃左右，凝固温度稳定在57.6℃左右，无明显过冷度，相变焓为250～255kJ/kg.基于该复合相变材料的储热器的储热密度可达442.7kJ/L，是传统水箱的1.7倍，储放热效率达96.4%，具有明显的储热优势.
关键词: 三水合醋酸钠, 膨胀石墨, 相变储能, 导热系数, 热性能
Abstract: Salt hydrate as an energy storage material has the problems of low thermal conductivity, phase separation, and large supercooling. In this paper, a composite phase change material (CPCM) with sodium acetate trihydrate (SAT) as the main body is fabricated by melting blending. Expanded graphite (EG) is used as a high heat conduction additive to enhance the thermal conductivity, and as a nucleating agent to decrease supercooling degree simultaneously. Xanthan gum (XG) is used as a thickening agent to suppress the phase separation of the composite phase change material. The phase change properties, thermal stability and, thermal conductivity of the composite phase change materials are studied. A high energy-density heat storage device is built by using the composite phase change material (SAT/EG/XG) and its thermal property is analyzed by heating at 85℃ and cooling at 20℃. The results show that the addition of EG can obviously enhance the heat conductivity and eliminate the supercooling. With the addition of 2%—4% (mass fraction)expanded graphite, the thermal conductivity of CPCM reaches to 1.12—1.81W/(m·K), which is 2—3 times of the pure SAT. Besides, the addition of 0.5%—1.2% (mass fraction)XG can significantly inhibit phase separation. The composite phase change material has a good thermal stability. After 50 cycles, the melting temperature is kept at about 58.0℃, the solidification temperature is stable at about 57.6℃, there is no obvious supercooling, and the phase change enthalpy is 250—255kJ/kg. Moreover, the thermal storage device filled with composite phase change material has a heat storage density of 442.70kJ/L, which is 1.7 times that of the traditional water tank, and its heat storage and release efficiency reaches to 96.4%, which shows obvious advantages.
Key words: sodium acetate trihydrate, expanded graphite, latent energy storage, thermal conductivity, thermal performance
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