芒硝/蛭石复合材料蓄冷-释冷性能研究

Investigation on the cold storage-release performance of mirabilite/vermiculite composite material

膨胀蛭石(expanded vermiculite,EV)通过真空浸渍芒硝制备复合相变蓄冷材料(composite phase change material,CPCM),其添加剂包括9%的氯化铵为相变温度调节剂,3%的硼砂(Borax)为成核剂;经筛选得到,EV对芒硝的最大负载质量比是1∶6,此时CPCM的相变特征温度为16.20℃,潜冷蓄冷量为105.98 kJ/kg。因载体膨胀蛭石(expanded vermiculite,EV)提高了复合材料的比热容,提供了14.70 kJ/kg的显冷蓄冷量,使得总蓄冷量达到120.68 kJ/kg;同时EV微孔充满芒硝后导热系数明显提升,利于复合材料封装后的热利用。搭建了蓄冷-释冷循环测试装置,对CPCM进行100次融化-凝固循环,对循环后CPCM片层进行了SEM表征,结合DSC热分析可知,CPCM热性能稳定,片层结构无损,无相分离发生。复合相变蓄冷材料在循环水24.00℃进口温度时释冷速率最高。所制备的复合蓄冷材料CPCM适用于空调技术中的储冷,提高释冷供冷经济性。

Mirabilite/expanded vermiculite(EV)composite phase change material(CPCM)was prepared by vacuum impregnation method,among which,9 wt%ammonium chloride is the phase change temperature regulator and 3 wt%sodium borate(Borax)is the nucleating agent.And the maximum load mass ratio of EV to phase change materials mirabilite is 1:6.The characterized phase change temperature of CPCM is 16.20℃,and the latent cold storage capacity is 105.98 kJ/kg.Because the carrier of EV improves the specific heat capacity of the composite,which provides 14.70 kJ/kg of apparent cooling storage,and makes the total cooling capacity achieving to 120.68 kJ/kg.At the same time,the thermal conductivity of CPCM is obviously improved for the EV micropores filled and packaged with mirabilite.The test device for cold storage and cold release cycle is built,and the CPCM is characterized by SEM after 100 melting and solidification cycles.The DSC thermal analysis shows that the CPCM thermal properties are very stable,the lamellar structure is nondestructive,and no phase separation occurs.When using circulating water of inlet temperature of 24.00℃,the cooling releasing rate of CPCM is highest.The CPCM is suitable for cooling storage and cooling release in air conditioning technology to improve its cooling economy.