体系Mg(NO_3)_2-MgCl_2-H_2O作为相变储能材料的相图预测

Phase Diagram Prediction of the System Mg(NO_3)_2-MgCl_2-H_2O as Phase Change Materials

应用修正的BET热力学模型对Mg(NO3)2-MgCl2-H2O体系在273～373 K的相图进行预测,发现两个共晶点,并通过实验对共晶点组成材料的吸热和放热行为进行测定,发现三元共晶点Mg(NO3)2·6H2O(45.6%)-Mg(NO3)2·2H2O(29.6%)-MgCl2·6H2O(24.8%)储能效果较差,而二元共晶点Mg(NO3)2·6H2O(61.6%)-MgCl2·6H2O(38.4%)在熔点附近具有很好的储放热能力,其相变热焓经差热分析为136.8 J·g-1,说明该材料可用作潜在的相变储能材料.

The modified BET thermodynamic model was applied to predict phase diagram of the system Mg（NO3）2-MgCl2-H2O from 273 to 373 K,in which two eutectic points were found.The exothermal and endothermal behavior of the predicted eutectic points were measured and the results showed that the ternary eutectic point Mg（NO3）2·6H2O（45.6%）-Mg（NO3）2·2H2O（29.6%）-MgCl2·6H2O（24.8%） has poor en-ergy-storage ability,while another binary eutectic point Mg（NO3）2·6H2O（61.6%）-MgCl2·6H2O（38.4%） has good exothermal and endothermal ability near the melting temperature with melting heat 136.8 J·g-1 deter-mined by differential thermal analysis（DTA）,and is expected to be used for the potential phase change material.