相变材料复合八水氢氧化钡的制备及热性能

纯八水氢氧化钡相变蓄热材料在使用过程中存在凝固过冷、相分离及体积变化等问题，因此需要对其进行相应的改性研究。本文根据相变蓄热材料成核机理，以八水氢氧化钡为相变蓄热材料基材，一水氢氧化钡及去离子水作为复合添加剂，制备了混合比例为95.1% Ba（OH）₂·8H₂O+2% Ba（OH）2·H₂O+2.9% H₂O的复合相变蓄热材料。对该复合相变蓄热材料进行了热性能测试，结果表明：复合相变蓄热材料的平均热导率为1.2W/（m·K）、相变潜热值为263.7kJ/kg；在复合相变蓄热材料融化过程中进行升温-压力实验，测试数据显示容器内部的相对压力不超过0.09MPa；利用恒温金属浴仪器对该复合相变蓄热材料进行300次融化/凝固循环实验，测试数据显示复合相变蓄热材料过冷度增加量0.7℃、相变潜热值降低0.796%。改性后的复合相变蓄热材料相变温度适宜、热性能稳定，可推广应用于中低温相变储热系统。

Preparation and thermal properties of composite barium hydroxide octahydrate for energy storage

Pure barium hydroxide octahydrate has some problems such as super-cooling, phase separation and volume change, so it needs to be further improved. According to the nucleation mechanism of the phase change material, the composite phase change materials, with 95.1% Ba(OH)₂·8H₂O+2%Ba(OH)₂·H₂O+2.9%H₂O, were prepared by using the barium hydroxide octahydrate as the base material,the barium hydroxide monohydrate and deionized water as compound additives. The thermal performance test of the composite phase change material showed that the thermal conductivity coefficient was 1.2W/(m·K),and the latent heat was 263.7kJ/kg. During the melting process of composite phase change material,temperature-pressure test was carried out. The relative pressure inside the container was less than 0.09MPa. The melting/solidification cycle experiment of the composite phase change material was conducted 300 times in the thermostatic bath. The test data showed that the super-cooling degree of the composite phase change material increased to 0.7℃,and the phase change latent heat decreased by 0.796%. The composite phase change material has suitable melting temperature and stable thermal performance, so it can be widely applied to the phase change thermal energy storage system.