NaNO_3/SiO_2复合定形相变材料的溶胶-凝胶法制备与表征

Preparation of Sodium Nitrate/Silica Composite as Shape-stabilized Phase Change Material via Sol-Gel Method and Its Characterization

以硅酸钠和硝酸为原料,采用溶胶-凝胶法制备了硝酸钠/氧化硅(NaNO3/SiO2)复合定形相变材料,分析了材料的组成、物相、热稳定性和相变性能.结果表明,原位生成的NaNO3作为相变物质分散在载体SiO2的多孔网络结构中形成定形相变材料,仅是NaNO3与SiO2的物理复合,制备和焙烧过程中都没有产生新物质.材料在低于600℃时具有良好的热稳定性,融熔热和结晶热分别为144.1和142.6 k J/kg,融熔和结晶温度分别为302.3和301.2℃.经100次热循环后,材料的相变热和相变温度基本保持不变.

NaNO3）/SiO2 composite was prepared as a shape-stabilized solid-liquid phase change material （PCM） by sol-gel method with Na2SiO3 as silica source. In this composite, the in-situ generated NaNO3 acted as the latent heat storage material, and SiO2 as the supporting material. Its chemical composition, morphology, structure and thermal properties were characterized. The results showed that the prepared composite PCM was a physical hybrid of NaNO3 and SiO2 only, NaNO3 was well dispersed in the porous network of SiO2. The composite had good thermal stability in the temperature range of less than 600 ℃, its phase change latent heats of melting and freezing were 144.1 and 142.6 kJ/kg, and the temperatures of melting and freezing 302.3 and 301.2 ℃, respectively. Furthermore, the NaNO3/SiO2 composite maintained good thermal energy storage and release ability even after 100 cycles of melting and freezing.