Experimental study on performance of new composite phase-change material for clean heating

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.