Nano enhanced phase change materials for thermal energy storage system applications: A comprehensive review of recent advancements and future challenges

Phase change materials (PCMs) are gaining significant attention for their efficiency in thermal energy storage. Recent research shows that PCMs can enhance heat storage systems' effectiveness when used in photovoltaic (PV) panels. By adding nanoparticles, thermal conductivity and heat transmission are improved. This study aimed to review the recent advancements and future challenges of PCMs based on metallic, carbonic, ceramic, and hybrid nanomaterials. The up-to-date references were taken from the Google search engine. Results indicated that metallic nanoparticles like copper (20 nm) can increase thermal conductivity by up to 46.3 % and diffusivity by 44.9 % with minor changes in phase transition temperatures. While carbonic materials like expanded graphite (EG) show latent heat retention trade-offs, they are 40 times more conductive than pure paraffin. Ceramic nanoparticles, such as Al₂O₃ and Fe₃O₄, enhance structural stability and reduce super-cooling, with Fe₃O₄ composites showing a 60 % conductivity increase. Hybrid systems validated by predictive machine learning techniques integrate conductivity, nucleation, and thermal stability, using materials like graphene-WO₃ nano-fluids and SiO₂-CeO₂-paraffin. These developments highlight nanomaterials' potential to improve paraffin's low conductivity while balancing nanoparticle integration to maintain energy density. Challenges remain in addressing trade-offs like restricted natural convection and decreased latent heat (up to 35 % at high filler loadings). Structural modifications, such as radial fins combined with Al₂O₃ nanoparticles, result in a 28.3 % faster melting rate, compensating for convection losses. Real-world applications demonstrate scalability, with Cu-paraffin composites achieving a 1.7 % efficiency gain and Gr-Ag hybrids extending operation by three hours. Environmentally friendly methods, such as plant-derived iron oxide nanoparticles, prioritize sustainability without compromising functionality. Future research should focus on scalable synthesis, optimal filler interactions, and durability testing to meet global demands for effective, sustainable thermal energy storage solutions.