储能科学与技术 ›› 2023, Vol. 12 ›› Issue (9): 2778-2788.doi: 10.19799/j.cnki.2095-4239.2023.0346

• 储能材料与器件 • 上一篇    下一篇

MgSO4-LiCl@MEG复合储热材料的制备与吸附储热性能

张雪龄(), 叶强, 谷军恒, 荀浩云, 张琦(), 程传晓, 金听祥, 张业强   

  1. 郑州轻工业大学能源与动力工程学院,河南 郑州 450002
  • 收稿日期:2023-05-22 修回日期:2023-07-12 出版日期:2023-09-05 发布日期:2023-09-16
  • 通讯作者: 张琦 E-mail:zhangxueling268@163.com;1990922zhangqi@zzuli.edu.cn
  • 作者简介:张雪龄(1986—),女,博士,副教授,硕士生导师,研究方向为热化学吸附储热、多孔介质及微纳尺度的流动与换热,E-mail:zhangxueling268@163.com
  • 基金资助:
    河南省重点研发科技攻关项目(232102320201)

Preparation and adsorption heat storageperformance study of MgSO4-LiCl@MEG composite heat storage materials

Xueling ZHANG(), Qiang YE, Junheng GU, Haoyun XUN, Qi ZHANG(), Chuanxiao CHENG, Tingxiang JIN, Yeqiang ZHANG   

  1. School of Energy and Power Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002, Henan, China
  • Received:2023-05-22 Revised:2023-07-12 Online:2023-09-05 Published:2023-09-16
  • Contact: Qi ZHANG E-mail:zhangxueling268@163.com;1990922zhangqi@zzuli.edu.cn

摘要:

水合盐热化学吸附储热技术因其低储热温度、高储能密度、长期无损储存和清洁无污染的特性而受到广泛关注。本工作首先对膨胀石墨改性,获得亲水改性的膨胀石墨(MEG)。通过调配MgSO4与LiCl的不同质量比,采用混合球磨法制备MgSO4-LiCl@MEG复合储热材料。通过吸附实验,优选出混合盐的最佳比例为9∶1。对优选的混合盐添加4种不同比例的MEG,发现复合材料的吸水率高于该含盐量下的理论值,说明添加MEG有效改善了MgSO4的结块和LiCl的液解问题。脱附过程均可在120 min内完成。采用线性驱动力学模型(LDF)拟合得到四种样品的吸附动力学常数,约为0.005 s-1。复合储热材料的平衡吸水率随着湿度的增加而增加,随温度的增加而减小。SEM和XRD测试结果表明混合盐通过物理结合并均匀分散在MEG的片状孔隙中。MEG10展现出最好的储热性能,其储热密度为957 kJ/kg,储热峰值温度为115.2 ℃,吸水率为0.925 g/g,导热系数为2.07 W/(m·K),是MgSO4的16.97倍。经过40次循环测试,MEG10的储热密度仅降低了29.4%,吸脱附性能分别降低15.1%和19.6%,表现出良好的热稳定性和吸脱附性能。该混合球磨法大大提高了复合储热材料的含盐量,为长周期和高密度蓄热技术提供了较好的参考。

关键词: 水合盐, 热化学吸附储热, 储热密度, 导热系数, 混合球磨法

Abstract:

Hydrated salt thermo-chemisorption heat storage has attracted immense attention due to its low heat storage temperature, high energy storage density, long-term nondestructive storage, and clean and pollution-free characteristics. This study obtained hydrophilic modified expanded graphite (MEG) by modifying expanded graphite. And a composite heat storage material MgSO4-LiCl@MEG was prepared by mixing MgSO4 with LiCl using a mixed ball milling method. The optimal ratio of mixed salt was 9∶1, and four different ratios of MEG were used to prepare the composite heat storage materials. The water absorption rate of the composite was found to be higher than the theoretical value under the same salt content, indicating that MEG was added to effectively alleviate the caking of MgSO4 and the solution of LiCl while improving the adsorption capacity. The desorption process could be completed within 120 min.The linear driven force (LDF) model was used to fit the adsorption kinetic constants of the composite, which were about 0.005 s-1. The equilibrium water absorption of the composite increased with the increase inhumidity and decreased with the increase intemperature. The composite was characterized using scanning electron microscopy(SEM) and X-ray diffraction(XRD), showing that the mixed salt was physically bonded and dispersed uniformly in the flake pores of MEG. MEG10 showed the best performance of heat storage, where the heat storage density was 957 kJ/kg, the peak heat storage temperature was 115.2 ℃, the water absorption rate was 0.925 g/g, and the thermal conductivity was 2.07 W/(m·K), which was 16.97 times that of MgSO4. After 40 cycles of testing, the heat storage density of MEG10 was only reduced by 31.2%, and the adsorption and desorption rates were reduced by 15.1% and 19.6%, respectively, indicating excellent thermal stability and adsorption and desorption performance. The mixed ball milling method significantly increased the salt content of the composite and served as a good reference for a long period and high-density heat storage technology.

Key words: hydrated salt, thermochemical adsorption heat storage, heat storage density, thermal conductivity, mixed ball milling method

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