Stearic–capric acid eutectic/activated-attapulgiate composite as form-stable phase change material for thermal energy storage

•S–C/a-ATP form-stable PCM was prepared by vacuum fusion method.•Maximum mass fraction of S–C in composite without leakage is as high as 50 wt%.•The phase change temperature and latent heat is measured to be 21.8 °C and 72.6 J/g.•Thermal and chemical reliable with respect to a large number of thermal cycling.•The S–C/a-ATP has great potential in building energy conservation.

The aim of this research was to prepare a novel form-stable PCMs (FSPCM) for latent heat thermal energy storage (LHTES) in low temperature, by incorporating eutectic mixture of stearic-capric acid (S–C) into activated-attapulgite (a-ATP) which acted as supporting material in the composite. The a-ATP is open-ended tubular capillary with large specific surface area, which is beneficial for the adsorption of PCMs. The maximum mass fraction of stearic-capric binary fatty acid loaded in a-ATP is determined as high as 50 wt% without melted S–C seepage from the composite. The phase change temperatures and latent heats of FSPCM are measured to be 21.8 °C and 72.6 J/g for melting process, and 20.3 °C and 71.9 J/g for freezing process, respectively, indicating it has suitable phase change temperature and high latent heat storage capacity. Moreover, the S–C/a-ATP FSPCM shows good thermal and chemical reliability after 1000 times thermal cycling test, which is identified by differential scanning calorimetry (DSC) and Fourier transformation infrared (FTIR). Therefore, the S–C/a-ATP FSPCM is an effective LHTES building material to reduce energy consumption.