This study investigates the impact of wavy tubes and CaCl6H2O + Al2O3 nanoPCM on the thermal performance of a shell-and-tube heat exchanger during the charging process through numerical simulations. To validate the accuracy of the findings, the findings are compared with data from a previously published experimental study. The experimental setup involved circulating hot water at 65 °C through U-tube heat exchanger tubes, with a phase change material positioned between the tubes and the outer shell. Al2O3 was incorporated into the phase change material at concentrations of 1%, and 2%. Wavy tubes were employed exclusively for the nanoPCM with no additives. The results demonstrate that the utilization of wavy tubes, as opposed to straight tubes, resulted in a significant decrease in the time required for melting —specifically by 64%, 76%, and 80% for CaCl6H2O nanoPCM with 1% Al2O3 and 2% Al2O3, respectively. These findings underscore the potential of combining nanoPCM with wavy tubes to enhance thermal performance in comparison to conventional straight-tube heat exchangers, with the added benefit of potentially reducing pump-related costs.