六水硝酸镁-硝酸锂共晶盐/膨胀石墨复合相变材料的制备及性能强化  

Preparation and property enhancement of magnesium nitrate hexahydrate-lithium nitrate eutectic/expanded graphite composite phase change materials

作　　者：次恩达 王会 李晓卿 张英 张振迎 李建强[2,3] CI Enda;WANG Hui;LI Xiaoqing;ZHANG Ying;ZHANG Zhenying;LI Jianqiang(College of Civil and Architectural Engineering,North China University of Science and Technology,Tangshan 063210,Hebei,China;CAS Key Laboratory of Green Process and Engineering,National Engineering Research Center of green recycling for strategic metal resources,Institute of Process Engineering,Chinese Academy of Sciences,Beijing 100190,China;School of Materials Science and Engineering,University of Science and Technology Beijing;Institute for Advanced Materials Technology,University of Science and Technology Beijing,Beijing 100083,China)

机构地区：[1]华北理工大学建筑工程学院,河北唐山063210 [2]中国科学院过程工程研究所战略金属资源绿色循环利用国家工程研究中心,中国科学院绿色过程与工程重点实验室,北京100190 [3]北京科技大学材料科学与工程学院 [4]北京科技大学新材料技术研究院,北京100083

出　　处：《储能科学与技术》2022年第1期30-37,共8页Energy Storage Science and Technology

基　　金：赤峰市“科技兴蒙”行动重点专项“大型高效节能环保型储热系统研发与示范”,中国科学院洁净能源先导科技专项(XDA21070302)。

摘　　要：采用熔融共混法在六水硝酸镁中掺入不同质量分数的硝酸锂成功制备了六水硝酸镁-硝酸锂共晶相变材料。六水硝酸镁-硝酸锂共晶盐的共晶点在质量比85∶15附近。利用差示扫描量热仪得到了共晶相变材料的相变温度为72.46℃,相变潜热为193.7 kJ/kg,通过步冷曲线测得共晶盐的放热平台明显且过冷度小于1.5℃,X射线衍射测试表明共晶盐中六水硝酸镁和硝酸锂并未发生化学反应。经过数次冷热循环,共晶盐的相变温度变化小且未出现相分离现象,稳定性较好。由于共晶相变材料的吸光能力弱,采用添加膨胀石墨来提高共晶相变材料的光热性能。本工作获得的相变材料具有合适的相变温度以及较高的潜热值,解决了六水硝酸镁的相变温度与供热末端温区不匹配的问题,并且具有较好的光吸收能力,可作为建筑采暖末端为散热器的太阳能清洁供暖系统等领域的候选材料。Magnesium nitrate hexahydrate-lithium nitrate eutectic phase change materials were successfully prepared by melting blending method with different mass percentage of lithium nitrate.The eutectic point of magnesium nitrate hexahydrate-lithium nitrate eutectic salt is around 85∶15 mass ratio.The phase transition temperature and latent heat of eutectic phase change materials were 72.46℃and 193.7 kJ/kg by differential scanning calorimeter.The exothermic platform of eutectic salt was obvious and the supercooling degree was less than 1.5℃by step cooling curve.X-ray diffraction test showed that there was no chemical reaction between magnesium nitrate hexahydrate and lithium nitrate in eutectic salt.After several cold and hot cycles,the eutectic salt has good stability with little change of phase transition temperature and no phase separation phenomenon.In order to improve the photothermal properties of eutectic phase change materials,expanded graphite was added to improve the photothermal properties of the materials due to their weak light absorption.The phase change materials obtained in this work have suitable phase change temperature,high latent heat value,it solves the problem that the phase change temperature of magnesium nitrate hexahydrate mismatches the heating end temperature area and has good light absorption capacity,which can be used as candidate materials in the field of solar clean heating system with the radiator at the end of building heating.

关 键 词：相变材料 六水硝酸镁 硝酸锂 膨胀石墨 

分 类 号：TK124[动力工程及工程热物理—工程热物理]