A nanocomposite phase change thermal energy storage material was prepared by intercalating stearic acid into the nano-layers of modified bentonite in liquid media. XRD patterns showed that the intergallery distance of...A nanocomposite phase change thermal energy storage material was prepared by intercalating stearic acid into the nano-layers of modified bentonite in liquid media. XRD patterns showed that the intergallery distance of the nanocomposite material was larger than that of modified bentonite owing to intercalating of stearic acid. The phase change temperature of the nanocomposite phase change material was different from that of stearic acid,and its phase change latent heat was equivalent to the calculated value based on the mass ratio of stearic acid in the composite. The experimental results of thermal energy storage and release indicated that the heat transfer rate of the nanocomposite material was obviously higher than that of stearic acid. After the nanocomposite experienced 1500 times cooling-heating cyclic test,its phase change temperature and latent heat showed little change,which suggested that the stearic acid/bentonite nanocomposite phase change material exhibited good stability of structure and properties. This method of intercalating organic phase change material into the nano-layers of bentonite provides a new route to prepare phase change materials with high performances.展开更多
水合盐相变储热材料普遍存在的过冷和相分离现象是影响其热稳定性和热性能的关键问题。以中低温水合盐相变储热材料三水醋酸钠(SAT)为研究对象,采用熔融共混法将羧甲基纤维素(CMC)和十二水磷酸氢二钠(DHPD)作为添加剂对三水醋酸钠进行...水合盐相变储热材料普遍存在的过冷和相分离现象是影响其热稳定性和热性能的关键问题。以中低温水合盐相变储热材料三水醋酸钠(SAT)为研究对象,采用熔融共混法将羧甲基纤维素(CMC)和十二水磷酸氢二钠(DHPD)作为添加剂对三水醋酸钠进行了改性研究,通过各成分的配比优化制备了高性能相变储热复合材料,利用DSC及熔融-凝固装置对改性材料进行了热物性和稳定性的测试,分析了不同质量分数的添加剂对相变储热复合材料的相变焓、相变温度、过冷度及相分离现象的影响;在此基础上采用改性的SAT相变储热复合材料构建了高密度储热器并搭建了相变储能热水实验系统,研究了不同运行工况下相变储热器的储/放热性能。结果表明:添加0.5%CMC和2%DHPD的相变储热复合材料有效改善了纯SAT的相分离严重和过冷度大的问题,具有良好的热稳定性,多次循环后复合样品的相变焓为258 k J?kg^(-1),相变温度为57℃,过冷度在2℃以内;相变储能热水系统在不同放热工况下出口水温度均超过50℃,放热过程中相变材料温度变化平稳,储热器的储放热效率高于90%,放热功率大于10 k W,且随着入口水温下降,放热功率、放热量及储放热效率都提高,相变储热器的储能密度是传统水箱的2.6倍。展开更多
文摘A nanocomposite phase change thermal energy storage material was prepared by intercalating stearic acid into the nano-layers of modified bentonite in liquid media. XRD patterns showed that the intergallery distance of the nanocomposite material was larger than that of modified bentonite owing to intercalating of stearic acid. The phase change temperature of the nanocomposite phase change material was different from that of stearic acid,and its phase change latent heat was equivalent to the calculated value based on the mass ratio of stearic acid in the composite. The experimental results of thermal energy storage and release indicated that the heat transfer rate of the nanocomposite material was obviously higher than that of stearic acid. After the nanocomposite experienced 1500 times cooling-heating cyclic test,its phase change temperature and latent heat showed little change,which suggested that the stearic acid/bentonite nanocomposite phase change material exhibited good stability of structure and properties. This method of intercalating organic phase change material into the nano-layers of bentonite provides a new route to prepare phase change materials with high performances.
文摘水合盐相变储热材料普遍存在的过冷和相分离现象是影响其热稳定性和热性能的关键问题。以中低温水合盐相变储热材料三水醋酸钠(SAT)为研究对象,采用熔融共混法将羧甲基纤维素(CMC)和十二水磷酸氢二钠(DHPD)作为添加剂对三水醋酸钠进行了改性研究,通过各成分的配比优化制备了高性能相变储热复合材料,利用DSC及熔融-凝固装置对改性材料进行了热物性和稳定性的测试,分析了不同质量分数的添加剂对相变储热复合材料的相变焓、相变温度、过冷度及相分离现象的影响;在此基础上采用改性的SAT相变储热复合材料构建了高密度储热器并搭建了相变储能热水实验系统,研究了不同运行工况下相变储热器的储/放热性能。结果表明:添加0.5%CMC和2%DHPD的相变储热复合材料有效改善了纯SAT的相分离严重和过冷度大的问题,具有良好的热稳定性,多次循环后复合样品的相变焓为258 k J?kg^(-1),相变温度为57℃,过冷度在2℃以内;相变储能热水系统在不同放热工况下出口水温度均超过50℃,放热过程中相变材料温度变化平稳,储热器的储放热效率高于90%,放热功率大于10 k W,且随着入口水温下降,放热功率、放热量及储放热效率都提高,相变储热器的储能密度是传统水箱的2.6倍。
