Preparation and thermal properties of stearic acid-palmitic acid/boron nitride/nanoparticle composite phase change materials

Abstract

With the booming development of thermal storage technology, phase change materials are being used more often in solar thermal systems. The SA-PA binary mixture is used as the phase change material, and hexagonal boron nitride with a high specific surface area is added as the support structure to investigate the ability of boron nitride particles at different ratios to mitigate the leakage problem of the phase change material. Two thermal conductivity enhancers, TiO₂ and CuO, were selected to study the effect of nanoparticles on enhancing the thermal conductivity of the materials. A composite phase change material with high latent heat, high thermal conductivity, and good thermal stability was prepared using the melt blending method. The microstructure and thermochemical properties of the material were characterized. Results showed that the melting temperature of both phase change materials (SA-PA-BN-TiO₂) CPCM7 and (SA-PA-BN-CuO) CPCM11 was 58.8 °C, and the latent heat of fusion was 162.9 J/g and 161.2 J/g, respectively. The solidification temperatures of CPCM7 and CPCM11 were 46.8 °C and 48.4 °C, respectively, while the latent heat of solidification was 162.2 J/g and 160.6 J/g. These results indicate suitable phase transition temperatures and high latent heat. The thermal conductivity of CPCM7 and CPCM11 is 0.469 and 0.331 W/(m·K), respectively, which are 1.769 and 1.249 times higher than that of SA-PA-BN. CPCM7 also exhibited better temperature response and temperature uniformity in heat release experiments. In addition, CPCM7 and CPCM11 exhibited good thermal stability below 100 °C. Furthermore, the basic thermal properties of the materials showed no significant changes before and after 100 cycles, demonstrating excellent cycling stability for practical applications. Therefore, the composite phase change material has enormous potential for application in solar thermal systems.