十二水磷酸氢二钠基复合相变材料的性能研究

Performance of Composite Phase Change Material Using Disodium Hydrogen Phosphate Dodecahydrate as the Supporting

摘要: 本文制备研究了2 wt%八水氢氧化钡(Ba(OH)₂•8H₂O) + 3 wt%羧甲基纤维素钠(CMC) + 十二水磷酸氢二钠(Na₂HPO₄•12H₂O)的复合相变材料，有效解决了较高冷却温度下十二水磷酸氢二钠难以完全析晶的问题。实验结果证明：十二水磷酸氢二钠的冷却温度越高，过冷度越大，完全析晶所需要的时间超过1小时。通过添加2 wt% Ba(OH)₂•8H₂O可以有效将不同冷却温度下的过冷度控制在2℃至4.5℃之间，同时可以缩短完全析晶所需的时间。XRD以及DSC测试结果表明，添加2 wt% Ba(OH)₂•8H₂O对Na₂HPO₄•12H₂O的晶体结构和热物性影响很小。添加3 wt% CMC可以明显提高循环稳定性，循环稳定的次数明显增加，同时DSC测试表明，CMC不会影响复合相变材料的热物性。复合相变材料在25℃冷却时可以在0.5 h内完全析晶，在实际生活中具有推广意义。

Abstract: A composite phase change material (PCM) consisting of 2 wt% octahydrate barium hydroxide (Ba(OH)₂•8H₂O + 3 wt% sodium carboxymethyl cellulose (CMC) + sodium phosphate dibasic dodecahydrate (Na₂HPO₄•12H₂O)) was prepared and studied in this paper. It effectively solved the problem that sodium phosphate dibasic dodecahydrate was difficult to crystal out at higher cooling temperature. The experimental results show that the higher the cooling temperature of sodium phosphate dibasic, the greater the supercooling degree, and the time needed for complete crystallization is more than 1 hour. By adding 2 wt% Ba(OH)₂•8H₂O, the supercooling degree at different cooling temperatures can be effectively controlled from 2˚C to 4.5˚C, and the time required for complete crystallization can be shortened. XRD and DSC test results show that the addition of 2 wt% Ba(OH)₂•8H₂O has little effect on the crystal structure and thermal properties of Na₂HPO₄•12H₂O. The addition of 3wt% CMC can significantly improve the cyclic stability and increase the number of cyclic stability. Meanwhile, DSC test shows that CMC does not affect the thermal properties of PCM. The crystal formation of the composite phase change material can be completed within 0.5 h when cooled at 25˚C, which is of great significance in practical life.