Enhancing composite phase change material thermal performance by tuning phase change materials properties with nanoparticles

Thermal Energy Storage (TES), particularly latent heat TES, is a promising solution for waste heat recovery. However, phase change materials (PCMs), the main TES media in LHTES systems, face challenges such as limited thermal conductivity and large volume changes during phase transitions. Encapsulating PCMs within porous matrices to fabricate Composite Phase Change Materials (CPCMs) can address these issues, though CPCMs are attained through expensive and/or complex processes and/or have relatively low PCM content. This study introduces the use of SiO₂ nanoparticles to enhance CPCMs, enabling the fabrication of CPCMs with high PCM content over 72 % through a simple mix sintering approach. The incorporation of nanoparticles enhances structural integrity and thermal performance. A CPCM, with 72 % NaNO₃ content, achieves structural integrity, surpassing the 60 % PCM limit typically achieved without nanoparticles. The sample showcases only a 14 % decrease in energy storage density compared to pure NaNO₃ with a 28 % increase in thermal conductivity and a much lower coefficient of thermal expansion compared to the PCM. Further research in this area can potentially resolve the current material level issues of latent heat TES.