摘要
采用两步法制备了八水合氢氧化钡/碳酸钡/纳米铁复合相变蓄热体系。八水合氢氧化钡是一种质量储热密度较大的低温相变材料,其熔点温度为78℃,相变潜热为264kJ/kg,但其在相变过程中存在过冷且导热性能差的问题。通过在八水合氢氧化钡中添加碳酸钡为成核剂,纳米铁粉作为添加剂改善其热力学性能。实验结果表明,复合蓄热体系添加质量分数为1.0%的碳酸钡和0.2%的纳米铁时效果最优。通过DSC测试以及导热系数测量,其相变潜热为276.4J/g,导热系数为1.368 W/(m·K),比八水合氢氧化钡溶液上升11.7%。添加BaCO3后,过冷问题得到有效解决,也没有出现化学降解问题。
Barium hydroxide octahydrate/barium carbonate/nano iron composite phase change heat storage sys- tem was prepared by a two-step method. Barium hydroxide octahydrate possesses a larger mass heat storage capacity among low temperature phase change materials. Its latent heat is 264 KJ/kg, and its melting temperature is 78 ℃ It had a serious super-cooling degree and poor thermal conductivity during its phase change period. Barium hydroxide octahydrate was used as a phase change material, barium carbonate was used as a nucleatirlg agent, and nano-iron was added to improve the thermal conductivity in the composite heat storage system. Results showed that optimal performance was obtained when the mass ratio of Barium carbonate and nano-iron was 1.0% and 0. 2%. Thermal perfor- mance of the composites was investigated by a differential scanning calorimetry and a thermal constant analyzer. The results showed that the latent heat of the composites was 276.4 J/g. The thermal conductivity of the composites was 1. 368 W/（m · K）, increased by 11.7 % compared with pure barium hydroxide octahydrate. The results also showed that the problem of super-cooling was effectively improved by adding barium carbonate and chemical degradation of composites didn＇t occur.
基金
"十二五"农村领域国家科技支撑计划课题(2013BAD19B01)
关键词
蓄热相变材料
八水合氢氧化钡
纳米铁
过冷度
热力学性能
heat storage phase change materials
barium hydroxide octahydrate
nano iron
super-cooling
thermal performance
