To achieve green and clean energy heating and improve the performance of phase-change material energy-storage heating systems, a novel magnesium chloride hexahydrate (MgCl₂·6H₂O)/expanded graphite (EG)/calcium hydroxide (Ca(OH)₂) composite phase-change material (CPCM) was developed. The thermal properties and phase-separation characteristics of the CPCM were experimentally investigated. The results show that the magnesium chloride hexahydrate/EG CPCM containing 7.5% EG has good thermal storage performance without its phase-change performance being affected. On this basis, the nucleating agent calcium hydroxide was added to eliminate further the supercooling of the material. The thermophysical properties of the ternary CPCM were tested, and the samples were characterized and analyzed in terms of microstructure. The thermal conductivity of the ternary CPCM is 2.825 W/(m K), about 4.66 times that of pure magnesium chloride hexahydrate (0.606 W/(m K)), and its supercooling degree is 0°C. These thermal characteristics show that the magnesium chloride hexahydrate/EG/calcium hydroxide CPCM has great application potential in clean and green energy heating systems.

中文翻译：

---

新型复合相变清洁供热材料性能实验研究

为实现绿色清洁能源供热，提高相变材料储能供热系统性能，一种新型六水氯化镁(MgCl ₂ ·6H ₂ O)/膨胀石墨(EG)/氢氧化钙(Ca(OH) ₂）开发出复合相变材料（CPCM）。对CPCM的热性能和相分离特性进行了实验研究。结果表明，含有7.5%EG的六水氯化镁/EG CPCM具有良好的蓄热性能，且其相变性能不受影响。在此基础上添加成核剂氢氧化钙，进一步消除材料的过冷现象。测试了三元CPCM的热物理性能，并对样品进行了微观结构表征和分析。三元CPCM的导热系数为2.825 W/(m·K)，约为纯六水氯化镁(0.606 W/(m·K))的4.66倍，过冷度为0℃。这些热特性表明六水氯化镁/EG/氢氧化钙CPCM在清洁绿色能源供热系统中具有巨大的应用潜力。