Preparation and characterization of an aluminum ammonium sulfate dodecahydrate-based composite phase change material with low supercooling and high thermal conductivity

Aluminum ammonium sulfate dodecahydrate (AASD) is a promising hydrated salt-type phase change material. However, its application is severely hindered by its large undercooling and low thermal conductivity. Herein, Al2O3 nanoparticles and xanthan gum are utilized as additives to prepare the modified AASD and improve its supercooling. The modified AASD is adsorbed into the porous modified expanded graphite to prepare a shape-stable composite phase change material (CPCM). Differential scanning calorimeter, thermal constant analyzer, X-ray diffractometer, and scanning electron microscopy are used to characterize the CPCM. Results show that the supercooling of CPCM decreases from 48 to 10 °C, and the latent heat and thermal conductivity of CPCM are 235.40 kJ/kg and 4.086 W/(m·K), respectively. Compared with pure AASD, the CPCM loses around 10.7 % latent heat, while the thermal conductivity is boosted for more than eight times. After 300 melting-solidification cycles, the latent heat of CPCM only decreases by 5.9 %. Besides, the 600-h corrosion test demonstrates that the 316 L stainless steel is suitable for manufacturing containers for the CPCM. In sum, the developed CPCM owns low supercooling, high thermal conductivity, high cycle stability, and good material compatibility, and hence has a great potential in the field of building and domestic heating.