储能科学与技术 ›› 2024, Vol. 13 ›› Issue (5): 1451-1459.doi: 10.19799/j.cnki.2095-4239.2023.0840

• 储能材料与器件 • 上一篇    下一篇

低熔点四元硝酸盐基定型复合相变材料的制备与研究

许荣玉(), 陆海涛, 郭荷渡, 汤占赟, 李琦(), 吴玉庭   

  1. 北京工业大学机械与能源工程学院,传热强化与过程节能教育部重点实验室,传热与能源利用北京市重点实验室,北京 100124
  • 收稿日期:2023-11-21 修回日期:2023-12-12 出版日期:2024-05-28 发布日期:2024-05-28
  • 通讯作者: 李琦 E-mail:2899355899@qq.com;liqi@bjut.edu.cn
  • 作者简介:许荣玉(2000—),女,硕士研究生,研究方向为蓄热复合相变材料制备表征,E-mail:2899355899@qq.com
  • 基金资助:
    国家重点研发计划(2023YFB2406500);北京市自然科学基金(3222026)

Form-stable quaternary nitrate salt-based composite phase change material with low melting temperature for low-medium-temperature thermal energy storage

Rongyu XU(), Haitao LU, Hedu GUO, Zhanyun TANG, 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:2023-11-21 Revised:2023-12-12 Online:2024-05-28 Published:2024-05-28
  • Contact: Qi LI E-mail:2899355899@qq.com;liqi@bjut.edu.cn

摘要:

采用冷压-热烧结方法制备研究了一种形态稳定的硝酸盐基复合相变材料,该材料具有较低的熔点和较宽的温度使用范围,适用于中低温领域的热能储存。研究选取NaNO3-NaNO2-KNO2-LiNO3共晶四元硝酸盐为相变基体材料,氧化镁为结构支撑材料,石墨为导热增强剂,并对其微观结构、化学相容性、热物理性能和循环稳定性进行了一系列表征,结果表明:在烧结前后四元硝酸盐、氧化镁以及石墨之间不发生化学反应,具有良好的化学相容性及化学稳定性。在不同质量比的样品中,四元硝酸盐与氧化镁质量比为6∶4时,为复合材料的最佳配比,且其负载质量分数8%的石墨后,仍表现出优异的结构稳定性;该复合材料的熔点较低,约为70 ℃,分解温度达到610 ℃;在50~580 ℃的温度范围内,具有超过749 kJ/kg的储能密度;添加8%的石墨后复合材料的热导率从0.41 W/(m·K)提高到了0.77 W/(m·K);经150次循环后,复合材料表现出良好的热循环稳定性。这种具有低熔点、宽温域的盐基复合材料是中低温热能存储的有力候选者,本研究为其在中低温领域的应用提供了实践依据。

关键词: 四元硝酸盐, 复合相变材料, 低熔点, 宽温域, 热能储存

Abstract:

A form-stable molten salt-based composite phase change material (PCM) with a low melting point suitable for low-medium-temperature thermal energy storage was prepared and investigated. A so-called cold compressing and hot sintering approach was used for the material preparation, in which a eutectic quaternary nitrate of NaNO3-NaNO2-KNO2-LiNO3 is utilized as the PCM, MgO as structure supporting material and graphite as thermal conductivity enhancer. A series of characterizations were performed to evaluate the composite microstructure, chemical compatibility, thermal properties, and cycling stability. The results showed that there was no chemical reaction among the quaternary nitrate, MgO, and graphite before and after sintering, indicating excellent chemical compatibility and stability in the composite. Among the different composite mass ratios, the 6∶4 quaternary nitrate-to-MgO mass ratio was optimal. In addition, the composite exhibited an excellent appearance when containing 8% graphite. A fairly low melting point of approximately 70 ℃ and a relatively high decomposition temperature of 610 ℃ were observed, offering the composite a large energy storage density exceeding 749 kJ/kg in the temperature range of 50—580 ℃. The thermal conductivity of the composite containing 8% graphite can be increased from 0.41 W/(m·K) to 0.77 W/(m·K). The composite exhibited excellent cycling stability after 150 heating-cooling cycles. This salt-based composite with a low melting point and a large temperature range is an excellent candidate for thermal energy storage, and this study offers a basis for its practical application in low-medium-temperature thermal energy storage fields.

Key words: quaternary nitrate, composite PCM, low melting point, large temperature range, thermal energy storage

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