CH3COONa·3H2O/flaky modified vermiculite composite phase change materials enhanced phase change behavior and thermal storage through curing lotus root starch modification

Abstract

With the establishment of the basic policy of environmentally-friendly and resource-saving society, the energy storage technology using phase change materials (PCMs) as the medium has developed unprecedentedly. Hydrated salt PCMs plays a vital role due to its large latent heat density, wide range of phase transition temperature, and high thermal conductivity. However, the problems of low enthalpy, poor thermal stability and phase separation are critical drawbacks of composite phase change materials (CPCMs), which limited the extensive use in fields of energy storage. In this work, the flaky vermiculite (MEVM) was fabricated by the acid treatment and alkali leaching, and the cured lotus root starch (CLRS) was embedded and used to enhance the water holding capability of hydrated salts. A series of sodium acetate trihydrate (SAT)-CLRS/MEVM was prepared, and the form-stable composite phase change materials (SAT fs-CPCMs) were obtained. Results showed that the encapsulation capacity of SAT fs-CPCM with 2 wt% CLRS was 71.3 %, and the thermal enthalpy reached 180.1 J/g, which was 43.7 % higher than that of SAT/MEVM. The contact angle of the sample with H2O was 22.24°, which represented hydrophilicity. SAT fs-CPCM also had good thermal stability and thermal reliability. After 200 thermal cycles, the enthalpy loss of the SAT fs-CPCM was only 5.2 %, and the 200th enthalpy value was 173.72 J/g. In addition, Calculations indicated that there were hydrogen bonds and van der Waals weak interaction between SAT and CLRS. This work provides a new perspective for the improvement of the thermal properties of hydrated salt and offers a promising approach for the applications of PCMs in cost-effective energy storage.