Studies of eutectic hydrated salt/polymer hydrogel composite as form-stable phase change material for building thermal energy storage

The inorganic phase change material (PCM) is a promising energy storage material in the construction field because of their characteristics, such as high latent heat, low price and nonflammability. However, from the perspective of construction engineering applications, conventional inorganic phase change materials have some inherent performance defects, such as high phase change temperature , phase separation and leakage. To overcome these performance deficiencies, a novel eutectic hydrated salt/polymer hydrogel composite form-stable phase change material (HP-FSPCM) suitable for building thermal storage was developed, which used Na 2 SO 4 ·10H 2 O–Na 2 CO 3 ·10H 2 O eutectic salt (SCES) as PCM, sodium polyacrylate (PAAS) as thickener and packaging material, borax as nucleating agent and flake graphite as thermal conductivity enhancer. The phase change temperature and crystal structure characteristics of SCES were analyzed by means of step cooling curve method and X-ray diffraction technique (XRD). The microstructure and thermal properties of HP-FSPCM were tested and analyzed by scanning electron microscopy (SEM), differential scanning calorimeter (DSC) and transient planar thermal conductivity instrument. The test results showed that the cross-linked network formed by PAAS can eliminate the phase separation and leakage of SCES, and the latent heat value, melting temperature and crystallization temperature of HP-FSPCM were 165.5 J/g, 22.4 °C and 13.8 °C, respectively. The thermal cycle reliability of HP-FSPCM was tested, the latent heat loss of HP-FSPCM was only 2.2% after 300 thermal cycles. • A novel HP-FSPCM suitable for building thermal storage was developed. • PAAS can effectively restrict phase separation and encapsulate SCES. • The HP-FSPCM maintains good thermal reliability after 300 thermal cycles.