Development of a novel shape-stabilized phase change material stearic acid-octadecanol-lauric acid/coal gangue/expanded graphite with high thermal conductivity

Phase change energy storage technology can balance the temporal mismatch between energy supply and demand, thereby effectively reducing global building energy consumption. To expand the temperature application range of organic phase change materials (PCMs), a ternary fatty acid/alcohol eutectic material SA/OD/LA (SOL) was innovatively prepared using stearic acid (SA), octadecanol (OD), and lauric acid (LA) as raw materials. Meanwhile, porous solid waste coal gangue (CG) and expanded graphite (EG) were employed for the synergistic adsorption of SOL to mitigate its leakage tendency and low thermal conductivity. The phase change characteristics, heat transfer performance, and thermal stability of the prepared specimens were tested. And the microstructure and material composition of the specimens were also characterized. The melting and freezing temperatures of the composite PCMs can be reduced to 29.1°C and 25.5°C, respectively, while the latent heat values for melting and solidification can reach as high as 118.9 J/g and 111.1 J/g, respectively. SOL is homogeneously distributed within CG/EG, with good chemical compatibility among SOL, CG and EG. Furthermore, the thermal conductivity of the optimal composite PCM reaches as high as 3.6274 W/(m·K), and it possesses remarkable heat storage and release performance as well as good thermal stability. Based on quantitative analysis, the composite PCM prepared in this study exhibits favorable economic efficiency and environmental benignity. In summary, based on eutectic theory and by adopting the vacuum adsorption method, a solid waste-based composite PCM with remarkable thermal energy storage performance and shape stability is innovatively developed in this study.