三元硝酸盐@二氧化硅微胶囊相变材料的制备及其性能研究

Preparation and properties of ternary nitrate-@silica microencapsulated phase change materials

针对当前无机熔盐相变材料在中低温储热领域研究的不足,本工作开发制备出一种相变温度为150~220℃的多元熔盐相变微胶囊复合材料,并对其微结构和热物性进行观察表征。本工作首先进行三元混合硝酸盐的制备,STA测试结果表明纯三元盐的熔融点为156.04℃,相变潜热为95.5 kJ/kg,分解温度达到626.3℃;之后在其基础上利用凝胶-溶胶法进行熔盐胶囊化封装,采用SEM-EDS、FT-IR、XRD和DSC等手段对微胶囊复合材料的微观结构、化学成分、晶体结构、物理化学兼容性和相变特性进行测试分析。结果显示三元硝酸盐可被有效地包覆在二氧化硅壳体中,所形成的微胶囊材料粒径范围为10~40μm,最高包覆率可达90.9%,微胶囊化后的熔融焓为86.81 kJ/kg,储热利用效率达78.36%,研究结果证明三元硝酸盐@二氧化硅微胶囊在中低温热能储存方面具有较高的应用潜力。

This study focuses on the development of a ternary salt-based microencapsulation phase change composite by the sol-gel approach.This composite exhibited a melting temperature range of 150-220 ℃ and could be effectively used for thermal energy storage.The thermophysical properties of the pure ternary nitrate salt were first evaluated.The salt exhibited a melting point of 156.04 ℃,latent heat of 95.5 k J/kg,and decomposition temperature of 626.3 ℃.Then,the microencapsulated composite was fabricated and investigated based on the results of the pure ternary salt.Various characteristic methods,including scanning electron microscopy with energy-dispersive X-ray spectroscopy,Fouriertransform infrared spectroscopy,X-ray diffraction,and differential scanning calorimetry,were employed to evaluate the thermal energy storage performance of the microencapsulated composite.The results indicated that the nitrate salt could be efficiently encapsulated by SiO2.This resulted in a diameter of 10-40 μm of the composite,endowing it with a great ability to overcome liquid leakage.Meanwhile,the composite exhibited an encapsulation ratio of 90.9%,a latent heat of 86.81 kJ/kg,and a thermal energy utilization efficiency of 78.36%.The results presented in this study demonstrate that the microencapsulated composite achieves excellent thermal energy storage performance and can be an feasible candidate for low and medium thermal energy storage.