CIESC Journal ›› 2017, Vol. 68 ›› Issue (11): 4016-4024.DOI: 10.11949/j.issn.0438-1157.20170490

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Supercooling characteristics of inorganic phase change material CaCl2·6H2O

HE Meizhi1,2, YANG Luwei1,3, ZHANG Zhentao1,3   

  1. 1 Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China;
    2 University of Chinese Academy of Sciences, Beijing 100049, China;
    3 Beijing Key Laboratory of Thermal Science and Technology, Beijing 100190, China
  • Received:2017-04-27 Revised:2017-07-31 Online:2017-11-05 Published:2017-11-05
  • Supported by:

    supported by the National Natural Science Foundation of China(21606244).

无机相变材料CaCl2·6H2O的过冷特性

何媚质1,2, 杨鲁伟1,3, 张振涛1,3   

  1. 1 中国科学院理化技术研究所, 北京 100190;
    2 中国科学院大学, 北京 100049;
    3 热力过程节能技术北京市重点实验室, 北京 100190
  • 通讯作者: 杨鲁伟
  • 基金资助:

    国家自然科学基金项目(21606244)。

Abstract:

As a common room temperature inorganic hydrated salt phase change material(PCM), calcium chloride hexahydrate(CaCl2·6H2O) is being widely focused due to its low cost, easy availability and high thermal energy storage. CaCl2·6H2O was prepared in terms of mass ratio of anhydrous CaCl2 and H2O as 1.027:1, whose crystal structure was characterized by X-ray diffraction(XRD). CaCl2·6H2O was modified by adding nucleating agents SrCl2·6H2O and Ba(OH)2. The results showed that the combination of SrCl2·6H2O and Ba(OH)2 could suppress supercooling phenomenon. The average supercooling degree was 1.07℃ in the process of melting-cooling for 10 cycles. The phase change latent heat of CaCl2·6H2O before and after adding nucleating agents, characterized by differential scanning calorimetry(DSC), decreased from 223.54 J·g-1 to 160.41 J·g-1. In order to enlarge the scope of phase change temperature of CaCl2·6H2O, 5%, 10%, 15%, 20% and 25%(mass) magnesium chloride hexahydrate(MgCl2·6H2O) was added into CaCl2·6H2O respectively, which indicated the phase change temperature of CaCl2·6H2O decreased linearly with the increase of MgCl2·6H2O content, however, not exceeding 20%(mass). The modification of CaCl2·6H2O-20% MgCl2·6H2O binary eutectic salt phase change thermal energy storage material was designed by adding 1% SrCl2·6H2O and 0.5% CMC, and the results suggested that the degree of supercooling was reduced to 0.57℃. The phase change latent heat of this material was 141.09 J·g-1, which was lower than that of CaCl2·6H2O(223.54 J·g-1) and MgCl2·6H2O(163.35 J·g-1). The above study showed that inorganic hydrated salt CaCl2·6H2O had significant application value as an inorganic PCM.

Key words: CaCl2·, 6H2O, phase change, preparation, supercooling, nucleation, latent heat, MgCl2·, 6H2O, binary eutectic salt

摘要:

CaCl2·6H2O作为一种常见的常温无机水合盐相变材料,由于成本低、易获取、蓄热强而受到广泛的关注。按无水CaCl2与H2O的质量比为1.027:1制备了CaCl2·6H2O,经X射线衍射(XRD)表征其晶体结构;通过添加成核剂SrCl2·6H2O和Ba(OH)2对CaCl2·6H2O改性,发现两者的联合作用可抑制过冷,10次熔化-冷却循环平均过冷度1.07℃。采用差示扫描量热仪(DSC)测定CaCl2·6H2O添加成核剂前后相变潜热,发现潜热由223.54 J·g-1降至160.41 J·g-1;为了扩大CaCl2·6H2O相变温度的范围,通过添加质量分数分别为5%、10%、15%、20%和25%的MgCl2·6H2O,发现相变温度随MgCl2·6H2O质量分数的升高呈线性降低,但不宜超过20%;选取CaCl2·6H2O-20% MgCl2·6H2O二元共晶盐相变储热体系为改性目标,通过添加1% SrCl2·6H2O和0.5% CMC,过冷度降至0.57℃,相变潜热为141.09 J·g-1,低于单独组成盐CaCl2·6H2O的潜热223.54 J·g-1和MgCl2·6H2O的潜热163.35 J·g-1。研究表明,CaCl2·6H2O作为无机相变材料具有显著的应用价值。

关键词: CaCl2·, 6H2O, 相变, 制备, 过冷, 成核, 潜热, MgCl2·, 6H2O, 二元共晶盐

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