四元体系LiNO_3-Mg(NO_3)_2-NH_4NO_3-H_2O相图预测及相关相变储能材料的研究

Phase Diagram Prediction of the Quaternary System LiNO_3-Mg(NO_3)_2-NH_4NO_3-H_2O

应用修正的BET热力学模型对Mg(NO3)2-NH4NO3-H2O三元体系和LiNO3-Mg(NO3)2-NH4NO3-H2O四元体系在273～320 K的相图进行预测,并找到一个相变温度较低的四元共晶点Mg(NO3)2.6H2O-LiNO3.3H2O-NH4NO3,其质量百分数组成为:25.5%的硝酸铵,28.4%的硝酸锂,13.8%的硝酸镁和32.3%的水,通过实验对共晶点组成材料的吸放热行为进行测定,发现其熔化温度为286.3 K,且DSC测试其相变热焓为192.7 J.g-1,表明该材料可用作潜在的低温相变储能材料。

The modified BET thermodynamic model was applied to predict phase diagram of the systems Mg（NO3）2-NH4NO3-H2O and LiNO3-Mg（NO3）2-NH4NO3-H2O from 273 K to 320 K,in which one quaternary eutectic point（its composition：25.5% NH4NO3,28.4% LiNO3,13.8% Mg（NO3）2 and 32.3% H2O.） with low melting temperature was found.The exothermal and endothermal behavior and DSC measurement of the predicted eutectic point were measured and the results showed that the melting temperature is 286.3 K and melting heat is 192.7 J.g-1,and the predicted material is expected to be used for the potential low temperature phase change material.