储能科学与技术 ›› 2022, Vol. 11 ›› Issue (3): 1044-1051.doi: 10.19799/j.cnki.2095-4239.2021.0599

• 储能新材料设计与先进表征专刊 • 上一篇    下一篇

可用于低中温热能储存的四元硝酸盐/埃洛石/石墨定型复合材料的制备与研究

李钰颖(), 魏雯珍, 李琦(), 吴玉庭   

  1. 北京工业大学环境与能源工程学院，传热强化与过程节能教育部重点实验室，传热与能源应用北京市重点实验室，北京 100124
  • 收稿日期:2021-11-12 修回日期:2021-11-18 出版日期:2022-03-05 发布日期:2022-03-11
  • 通讯作者: 李琦 E-mail:1078077214@qq.com;liqi@bjut.edu.cn
  • 作者简介:李钰颖（1996—），女，硕士研究生，研究方向为蓄热、蓄冷复合相变材料制备表征，E-mail：1078077214@qq.com；
  • 基金资助:
    北京工业大学国际科研合作种子基金项目(2021B40);内蒙古自治区科技重大专项(2019ZD014);北京工业大学高端人才计划

Preparation and investigation of quaternary nitrates/halloysites/graphite shape-stable composite phase change material with low melting temperature for thermal energy storage

Yuying LI(), Wenzhen WEI, Qi LI(), Yuting WU   

  1. MOE Key Laboratory of Enhanced Heat Transfer and Energy Conservation, Beijing Key Laboratory of Heat Transfer and Energy Conversion, Beijing University of Technology, Beijing 100124, China
  • Received:2021-11-12 Revised:2021-11-18 Online:2022-03-05 Published:2022-03-11
  • Contact: Qi LI E-mail:1078077214@qq.com;liqi@bjut.edu.cn

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摘要：

本工作报道了一种通过冷压-热烧结法制备的具备低熔点、宽温域的复合定型相变材料，其中相变基体材料为硝酸钠、亚硝酸钠、硝酸钾和硝酸钙的共晶硝酸盐，结构支撑材料为埃洛石纳米管，导热增强材料为石墨。利用差示扫描量热仪、激光导热仪、扫描电子显微镜、X射线衍射仪和傅里叶红外光谱仪等测试手段对复合相变材料的储热性能和物理化学性能进行实验研究，结果表明：复合材料的相变温度和分解温度分别为91.3 ℃和627.5 ℃，可使用温度区间为536.2 ℃，优于目前文献已有报道数据。在温度为25～625 ℃内，其储热密度达到630.15 kJ/kg；添加10%的石墨后复合材料的热导率从0.58 W/(m·K)提高到了1.18 W/(m·K)；由于埃洛石纳米管具有中空管状结构，经高温烧结后四元硝酸盐能够吸附在埃洛石纳米管中，能有效解决熔盐材料的腐蚀、泄漏以及热分解问题；埃洛石纳米管和石墨的加入没有与熔盐材料发生化学反应，证明了复合材料具备良好的化学稳定性。经100次循环后，复合相变材料的相变温度和相变潜热波动值小于3.5%，具有较好的循环稳定性。本研究丰富了熔融盐复合相变材料的配方体系和使用温度范围，为其在工业余热回收以及低中温储热领域的应用提供了基础。

关键词: 埃洛石纳米管, 四元硝酸盐, 复合相变材料, 储热

Abstract:

Herein, a shape-stable molten salt-based composite phase change material with low melting temperature and large temperature range was fabricated by cold compression-hot sintering approach and investigated. A eutectic quaternary nitrate of Ca(NO3)2-KNO3-NaNO3-NaNO2 is used as the phase change material (PCM), and halloysite and graphite are respectively employed as the structure supporting material and thermal conductivity enhancer. Several characterizations, including differential scanning calorimetry, laser thermal conductivity test, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy were conducted to investigate the microstructure, chemical compatibility, and thermal properties of the composite. The results show that a fairly low melting point about 91.3 ℃ and relatively high decomposition temperature of 627.5 ℃ were observed, giving the composite a large energy storage density exceeding 630.15 kJ/kg at a temperature range of 25—625 ℃. For the composite containing 10% graphite, the material's thermal conductivity can be increased by 44.8% from 0.58 to 1.18 W·(m·K)-1. Due to the special hollow structure of the halloysite nanotube, the molten salt can be absorbed by the halloysite, and hence the issues of salt corrosion, leakage, and decomposition can be effectively addressed. No chemical reaction occurs among the salt, halloysite, and graphite, including good chemical stability achieved in the composite. After 100 heating-cooling cycles, the fluctuation of the phase change temperature and latent heat is less than 3.5%, demonstrating the excellent cycling stability of the composites. The present results indicate that such salt-based composite with low melting temperature and high thermal performance could be an effective alternative to organic-based PCMs used in low-mid thermal energy storage systems.

Key words: halloysite nanotubes, quaternary nitrates, composite phase change materials, thermal energy storage

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