Latent heat thermal energy storage system (LHTESS) is one of the most effective ways to correct the disparity between energy consumption and availability. However, the efficiency of the LHTESS decreases due to the lower
thermal conductivity of the phase change materials (PCMs). Therefore, this study numerically analyzes a wavy
thermal energy storage (TES) unit embedded in a porous medium, enhanced with a middle plate for improved
heat transfer and energy storage. The enthalpy-porosity methodology is employed to simulate the PCM phase
change mechanism numerically, while the porosity of the porous medium is supposed to be equal to the liquid
fraction value in each cell. Integrating upper, lower, and middle plates within the PCM container, coupled with
wavy walls, significantly improved heat conduction, resulting in faster and more uniform phase transitions. The
unit with a middle plate exhibited the highest thermal efficiency, achieving the quickest charging and discharging times. RT-35 was identified as the most impressive PCM due to its rapid thermal response and high heat storage rate. Key outcomes include a 59.79 % reduction in melting time and a 147.4 % increase in heat storage rate
in Case 3 (case with bottom, top, and middle plates), and a 75.77 % decrease in discharging time with a
303.49 % increase in rate of heat release. Optimal porous medium at 95 % porosity balanced rapid melting and
effective heat storage, while adjusting the inlet water temperature to 328.2 K reduced melting time by 19.86 %
and increased the rate of heat storage by 26.78 %. Higher Reynolds numbers significantly improved melting efficiency. This study offers insights into optimizing the LHTESS through design modifications, material selection,
and operational control, with future studies potentially refining these approaches for building heating applications.