三水合乙酸钠/蛭石复合相变蓄热材料性能优化研究

Study on performance optimization of sodium acetate/vermiculite composite phase change thermal storage material

中文关键词: 真空吸附  复合相变材料  过冷度  相分离  热循环性能

英文关键词: vacuum adsorption  composite phase change material  supercooling  phase separation  thermal cycling performance

中文摘要:

      采用真空浸渍法将三水合乙酸钠（sodium acetate trihydrate,SAT）吸附在膨胀蛭石（expanded vermiculite,EV）微孔内，选择EV吸附SAT能力最佳的质量比为1:6。通过扫描电子显微镜（scanning electron microscopy,SEM）观察复合相变材料（composite phase change material,CPCM）的微观结构，显示EV微孔几乎完全被SAT填充。X射线衍射（X-ray diffraction,XRD）表明SAT与EV化学相容性较好，二者仅发生物理相互作用。通过差式扫描量热法（differential scanning calorimetry,DSC）测试EV在最大吸附能力下，复合材料的相变温度为57.6℃，接近SAT理论相变温度58.1℃；相变潜热为238.8kJ/kg。热重分析（thermogravimetric analysis,TG）结果显示复合材料热稳定性良好。因为EV负载体将SAT间隔为无数微单元，有效改善SAT相变过程中过冷和相分离现象，起到成核剂和悬浮剂的作用。实验研究结果表明，制备的CPCM具有较好的热物性以及稳定的热循环性能，有望成为相变蓄热材料应用于冬季供暖。

英文摘要:

      Sodium acetate trihydrate (SAT) was adsorbed and loaded into the micropores of expanded vermiculite (EV) by vacuum impregnation and the composite phase change material (CPCM)was prepared . The optimal mass ratio of EV adsorbing SAT was 1:6. The microstructure of the CPCM was investigated by Scanning Electron Microscopy (SEM), showing that the micropores of EV were nearly completely filled with SAT. Chemical compatibility of SAT and EV was showed by X-ray Diffraction (XRD), only physical adsorption occurring. Under the maximum adsorption capacity of EV, the phase transition temperature of the CPCM was 57.6°C measured by Differential Scanning Calorimetry (DSC), which was close to the theoretical temperature of 58.1°C of SAT, and the latent heat of CPCM was 238.84 kJ/kg. The CPCM showed a good thermal stability from Thermogravimetric Analysis (TG) tests, and the crystal water lost little during the phase transition. The SAT was divided into innumerable cells in the EV interspace, locking water in the salt liquid phase, effectively improving the phase separation phenomenon, and depressing supercooling. The prepared CPCM is expected to guide the phase change material development for winter heating for the excellent thermal properties and cycle stability.