Key Laboratory of Enhanced Heat Transfer and Energy Conservation, The Ministry of Education, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China.
Guangdong Engineering Technology Research Center of Efficient Heat Storage and Application, South China University of Technology, Guangzhou 510640, China.
Molecules. 2019 Jan 21;24(2):363. doi: 10.3390/molecules24020363.
Developing phase change materials (PCMs) with suitable phase change temperatures and high latent heat is of great significance for accelerating the development of latent heat storage technology to be applied in solar water heating (SWH) systems. The phase change performances of two mixtures, NH₄Al(SO₄)₂·12H₂O-MgCl₂·6H₂O (mixture-A) and KAl(SO₄)₂·12H₂O-MgCl₂·6H₂O (mixture-B), were investigated in this paper. Based on the DSC results, the optimum contents of MgCl₂·6H₂O in mixture-A and mixture-B were determined to be 30 wt%. It is found that the melting points of mixture-A (30 wt% MgCl₂·6H₂O) and mixture-B (30 wt% MgCl₂·6H₂O) are 64.15 °C and 60.15 °C, respectively, which are suitable for SWH systems. Moreover, two mixtures have high latent heat of up to 192.1 kJ/kg and 198.1 kJ/kg as well as exhibit little supercooling. After 200 cycles heating-cooling experiments, the deviations in melting point and melting enthalpy of mixture-A are only 1.51% and 1.20%, respectively. Furthermore, the XRD patterns before and after the cycling experiments show that mixture-A possesses good structure stability. These excellent thermal characteristics make mixture-A show great potential for SWH systems.
开发具有合适相变温度和高潜热的相变材料（PCM）对于加速潜热储能技术在太阳能水加热（SWH）系统中的应用具有重要意义。本文研究了两种混合物 NH₄Al(SO₄)₂·12H₂O-MgCl₂·6H₂O（混合物-A）和 KAl(SO₄)₂·12H₂O-MgCl₂·6H₂O（混合物-B）的相变性能。基于 DSC 结果，确定了混合物-A 和混合物-B 中 MgCl₂·6H₂O 的最佳含量为 30wt%。结果表明，混合物-A（30wt%MgCl₂·6H₂O）和混合物-B（30wt%MgCl₂·6H₂O）的熔点分别为 64.15°C 和 60.15°C，适合 SWH 系统。此外，两种混合物的潜热高达 192.1kJ/kg 和 198.1kJ/kg，且过冷度较小。经过 200 次加热-冷却循环实验后，混合物-A 的熔点和熔融焓的偏差仅分别为 1.51%和 1.20%。此外，循环实验前后的 XRD 图谱表明混合物-A 具有良好的结构稳定性。这些优异的热特性使混合物-A 在 SWH 系统中具有巨大的应用潜力。
