Experimental investigation on heat transfer behaviour of nanoparticle-enhanced phase change material for energy storage systems

The intermittent nature of renewable and sustainable energy sources necessitates the integration of efficient energy storage systems. Phase change materials (PCMs) have emerged as a promising solution due to their high energy density and ability to store thermal energy through latent heat. However, many PCMs, especially organic, suffer from low thermal conductivity, leading to inefficient heat transfer during melting and solidification. To address this issue, researchers have explored the use of nanoparticle-enhanced PCMs (NePCMs), where high-conductivity nanoparticles are added to improve thermal performance without altering system geometry, unlike traditional methods such as fins or metal foams. In this study, the thermal performance of NePCMs is experimentally evaluated using an organic PCM with a melting point of 37 °C. Three types of nanoparticles—Al₂O₃, CuO, and Cu—are tested at a concentration of 1 wt%. Samples are prepared using a two-step method involving stirring and ultrasonication to ensure stable dispersion. A labscale experimental test cavity with a constant temperature boundary condition is used to study melting and solidification behaviors. Cu-based NePCM exhibits the highest thermal conductivity enhancement (125%) but also the greatest viscosity increase (up to 600%). Despite better conductivity, the Cu-based NePCM displays the slowest phase change rate (melting and solidification).