十二水磷酸氢二钠纳米复合相变材料的过冷特性

研制了一种以十二水磷酸氢二钠（Na₂HPO₄·12H₂O）为主储能材料的中低温相变材料。通过添加成核剂纳米Al₂O₃、纳米TiO₂、纳米石墨粉、多壁碳纳米管和高分子分散剂聚丙烯酸钠（PAAS）对Na₂HPO₄·12H₂O改性。结果表明，多壁碳纳米管减少过冷度的同时会破坏Na₂HPO₄·12H₂O的相变特性，添加3%（质量分数）的纳米Al₂O₃可以减少40.7%的过冷度，添加4%的纳米TiO₂可以减少44.6%的过冷度，添加4%的纳米石墨粉可以减少62.3%的过冷度。对于添加3%纳米Al₂O₃的复合相变材料，PAAS浓度对过冷度无影响；对于4%纳米TiO₂的复合相变材料，添加4% PAAS过冷度最低为3.2℃，减少了76.1%；对于4%纳米石墨粉的复合相变材料，2% PAAS过冷度最低为1.2℃，减少了90.7%；纳米石墨粉/PAAS/Na₂HPO₄·12H₂O三元复合相变材料经过100次循环实验后，发现具有较好的热稳定性。

Supercooling characteristics of disodium hydrogen phosphate nano-composites phase change materials

A low temperature phase change material with the disodium hydrogen phosphate (Na₂HPO₄·12H₂O) as the main energy storage material was developed. The property of the Na₂HPO₄·12H₂O was modified by adding nucleators, such as nano Al₂O₃, nano TiO₂, nano-graphite powder, multi-walled carbon nanotubes (MWCNTs), and the polymer dispersant polyacrylic acid sodium(PAAS). The results showed that the adding of MWCNTs would reduce the super-cooling degree of the Na₂HPO₄·12H₂O while destroy its phase change characteristics. The super-cooling degree decreased by 40.7% after adding 3% (mass fraction) nano Al₂O₃, 44.6% by adding 4% nano TiO₂, and decreased by 62.3% after adding 4% nano-graphite powder. Compared with 3% (mass fraction) nano Al₂O₃ composite phase change material, the concentration of PAAS had no effect on the supercooling degree. Comepared with 4% nano TiO₂ composite phase change material, the minimum supercooling degree was 3.2℃, which decreased by 76.1% by adding 4% PAAS. Comepared with 4% nano-graphite powder composite phase change material, the minimum supercooling degree was 1.2℃, which decreased by 90.7% by adding 2% PAAS. It was found that the three elements composite phase change material had good thermal reliability by the cyclic experiments.