CIESC Journal ›› 2021, Vol. 72 ›› Issue (6): 3074-3083.DOI: 10.11949/0438-1157.20201710

• Special column for comprehensive utilization of salt lake resouces in Qinghai • Previous Articles     Next Articles

Calculation of phase diagram and thermal stability of molten salt for ternary chloride systems containing calcium

WEI Xiaolan1(),XIE Pei1,WANG Weilong2,LU Jianfeng2(),DING Jing2   

  1. 1.School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, Guangdong, China
    2.School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou 510006, Guangdong, China
  • Received:2020-11-30 Revised:2021-01-26 Online:2021-06-05 Published:2021-06-05
  • Contact: LU Jianfeng

含钙三元氯化物体系相图计算与熔盐热稳定性

魏小兰1(),谢佩1,王维龙2,陆建峰2(),丁静2   

  1. 1.华南理工大学化学与化工学院,广东 广州 510641
    2.中山大学材料科学与工程学院,广东 广州 510006
  • 通讯作者: 陆建峰
  • 作者简介:魏小兰(1963—),女,博士,教授,xlwei@scut.edu.cn
  • 基金资助:
    NSFC-柴达木盐湖化工科学研究联合基金重点项目(U1707603);NSFC-广东省联合基金重点项目(U1601215)

Abstract:

In order to search for high temperature heat transfer and thermal storage materials for solar thermal utilization, the phase diagram calculation method with branchs/regions separation was proposed, and two ternary eutectic mixtures of NaCl-CaCl2-KCl and KCl-CaCl2-MgCl2 were designed. Based on the normal solution model, the phase diagrams of five boundary systems NaCl-CaCl2,CaCl2-MgCl2,KCl-NaCl,KCl-CaCl2, and KCl-MgCl2 of the above two ternary systems were calculated with different interaction coefficients of different branches, and the complex phase diagrams containing compounds can be calculated by using the normal solution model. The calculated complex phase diagrams of KCl-CaCl2, KCl-MgCl2 systems and the other three systems without compounds were in good agreement with the experimental phase diagrams. Then, the phase diagrams of the ternary systems were calculated by sub region method based on the different interaction coefficients from the five boundary systems, and five new eutectic points of the ternary systems were predicted to guide the preparation of molten salt materials. The lowest eutectic point was verified by differential scanning calorimetry, and the lower limit of molten salt working temperature was determined. The working temperature range was determined by mass loss method. The results show that sodium potassium calcium and potassium magnesium calcium chloride molten salts can operate stably at 550—850℃ and 480—700℃, and can be used as high-temperature heat transfer and heat storage fluids.

Key words: solar energy, chloride molten salt, phase equilibrium, interaction coefficient, phase diagram, thermal stability

摘要:

为寻求太阳能热利用高温传热储热材料,以盐湖资源为原料,提出分支/分区相图计算方法,设计NaCl-CaCl2-KCl和KCl-CaCl2-MgCl2熔盐传热储热材料。基于正规溶液模型,以不同分支不同相互作用系数,计算了5个边界体系相图,实现用正规溶液模型计算含化合物体系复杂相图。含化合物KCl-CaCl2和KCl-MgCl2体系及3个不含化合物二元体系的计算相图与实验相图十分吻合。以分区域方法计算三元体系相图,预测出5个低共熔点来指导熔盐制备。采用差示扫描量热法测试并验证熔盐最低共熔点,确定其工作温度下限;以质量损失实验,确定其工作温度上限。结果表明,钠钾钙和钾镁钙氯化物熔盐能在550~850℃和480~700℃内稳定运行,可用作高温传热储热流体。

关键词: 太阳能, 氯化物熔盐, 相平衡, 相互作用系数, 相图, 热稳定性

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