Energy storage and melting heat transfer of coconut oil-CuO aluminum open cell composite embedded in a double wavy wall cavity

The melting heat transfer and thermal energy storage were addressed in a latent heat thermal energy storage (LHTES) unit. The LHTES unit is made of wavy channels filled with Coconut oil-CuO nano-enhanced phase change material (NePCM). The aim is to address the impact of nanoparticles and enclosure wall corrugation of energy storage. The phase change from solid to liquid was based on the enthalpy-porosity method. A mesh adaptation technique was employed to refine the mesh at the melting interface and increase the accuracy and stability of the simulations. The wavy surface design allows more heat transfer surface between the NePCM inside the enclosure and the working fluid. The Taguchi optimization method maximized the melting (thermal charging). The impact of porosity, volume fraction of nanoparticles, and wave number on the melting rate and stored energy were investigated. The results showed that increasing the porosity reduces the melting rate, particularly in the lower regions of the enclosure. Varying the wave number could change the flow and heat transfer patterns, but it showed a minimal impact on the melting rate. The melting rate was maximum for the maximum volume fraction of nanoparticles (nanoparticles volume fraction = 0.05), minimum porosity (0.05), and two undulations (wave number = 2).