Numerical simulation of using nanoparticles to enhance solar thermal energy storage system of shell and different shape finned tubes

Developing a latent heat storage system is crucial for enhancing the efficiency of heat that is absorbed from the sun to storing in the solar thermal energy storage system. In present study, numerical analysis using CFD with experimental validation is used to simulate the effect of geometrical shape (tube, nozzle, and reducer) rounded by fins with circular shape to enhance the latent heat storage of phase change material (PCM). In addition to analysis the effect of 2% and 5% of aluminum oxide nanoparticles to the PCM. The predicted results showed that the nozzle shape give the fastest melting time compared between the other shapes where the melting time decreased by 9.1% and 10.36% at a 5% and 2% concentration of aluminum oxide respectively, compared to the tube. In contrast, the results of using the tube compared to the reducer showed that the melting time decreased by 26.66% and 23.1% at a 5% and 2% concentration of aluminum oxide, respectively. Overall, the melting performance follows the order: nozzle, tube, and reducer, for both nanoparticle concentrations. Increasing the Al₂O₃ concentration enhances thermal responsiveness and shortens charging time, but the effectiveness of this enhancement depends strongly on the geometric configuration. Therefore, combining improved geometry with nano-optimization is a key design factor for enhancing the efficiency of latent thermal energy storage systems.