三元硝酸盐/陶瓷基相变材料的制备及热物性研究

Study of Preparation and Thermal Properties of Ternary Nitrate/Ceramic-based Phase Change Materials

为提高硝酸盐相变材料导热性能和研究三元硝酸盐的共晶特性,采用饱和溶液法配制了不同质量配比的KNO_(3)、LiNO_(3)和Ca(NO_(3))_(2)·4H_(2)O样品,测试了其熔点和相变潜热,并采用直接浸泡法制备了KNO_(3)-LiNO_(3)-Ca(NO_(3))_(2)/陶瓷基相变材料,测试其相变温度、相变潜热及导热系数等热物性参数。实验筛选出相变温度较高,潜热较大的三元硝酸盐KNO_(3)-LiNO_(3)-Ca(NO_(3))_(2)·4H_(2)O为60∶30∶10配比,其相变温度为116.8℃,相变潜热为46.7 J/g。实验结果表明:所测三元硝酸盐/陶瓷基相变材料和三元硝酸盐的相变温度基本一致,单位相变潜热是三元硝酸盐试样的35.43%;三元硝酸盐/陶瓷基相变材料的导热系数在常温下相较三元硝酸盐提高了9.27倍,且随温度的升高呈下降趋势;三元硝酸盐/陶瓷基相变材料的分解温度为620℃,较纯三元硝酸盐提高了20℃,增强了其高温稳定性。

To improve the thermal conductivity of nitrate materials and study the eutectic properties of ternary nitrate, KNO_(3),LiNO_(3) and Ca(NO_(3))·4 H_(2)O with different mass ratios were prepared by the saturated solution method.The melting point and latent heat of phase change were tested.The KNO_(3)-LiNO_(3)-Ca(NO_(3))_(2)/ceramic-based phase change material was prepared by direct immersion method, and its thermophysical parameters such as phase change temperature, phase change latent heat and thermal conductivity were tested.For higher phase change temperature and larger latent heat, the ternary nitrate ratio KNO_(3)-LiNO_(3)-Ca(NO_(3))_(2)=60∶30∶10 was selected, whose phase change temperature is 116.8 ℃ and latent heat is 46.7 J/g.The experiment found that the phase change temperature of the ternary nitrate/ceramic-based phase change material is basically the same as that of the ternary nitrate, while the latent heat per unit phase change was 35.43% of the ternary nitrate.At room temperature, the thermal conductivity of the ternary nitrate/ceramic-based phase change material is 9.27 times higher than that of the ternary nitrate.As the temperature increases, the thermal conductivity of the ternary nitrate/ceramic-based phase change material will tend to decrease.The decomposition temperature of the ternary nitrate/ceramic-based phase change material is 620 ℃,which is increased by 20 ℃ compared with pure ternary nitrate, further improving high temperature stability.