Effect of EG particle size on the thermal properties of NaNO3–NaCl/EG shaped composite phase change materials

Abstract

The adsorption capacity of expanded graphite (EG) with three different particle sizes of 32 mesh, 50 mesh, and 80 mesh was studied by the water-soluble adsorption method. The self-made NaNO3–NaCl (95–5 wt%) was selected as the phase change heat storage material, and the three kinds of EG were used as additives. The 80 wt% NaNO3–NaCl/20 wt% EG shaped composite phase change materials (CPCM) were prepared and their properties were tested and analyzed. The research results showed that the smaller the particle size, the stronger the adsorption capacity of EG. However, the choice of EG should consider the particle size of the phase change material (PCM). The 50 mesh EG was more suitable as the adsorption carrier of NaNO3–NaCl. Compared with pure NaNO3–NaCl, NaNO3–NaCl/EG had a lower degree of supercooling, which improved the heat storage capacity of the material. As the particle size of EG decreased, the thermal conductivity increased slightly. The study analyzed the relationship between the EG adsorption capacity and its particle size, and prepared NaNO3–NaCl/EG heat storage material with high heat storage density and high thermal conductivity. It was helpful to promote the application of EG based composite heat storage materials and the development of heat storage technology.