Due to its potentials to overcome the problems of instability and intermittency of energy through using phase change material (PCM), latent heat energy storage has been used in a variety of practical applications. However, most of the phase change materials possess poor thermal conductivity resulting in a modest charging/discharging rate. To overcome this deficit, high porosity metal foam is used to improve the overall thermal conductivity of the phase change materials leading to enhancing the heat transported, and hence, promoting the PCM melting and solidification. This proposal has been utilised to improve the performance of a thermal energy storage system formed of staggered bundled tubes, which are filled with paraffin wax as a PCM compounded to open-cell copper foam. The PCM unit is charged/discharged using a relatively hot/cold water stream flowing across the tube-bundle units. The feasibility of such a configuration is examined numerically through simulating the proposed PCM-metal foam composite units and their surrounding shell computationally using the ANSYS Fluent CFD commercial code. The impact of some design and operating parameters on the charging/discharging performance has been tested including the water flow strength as well as the tube-bundle configuration. The currently proposed design of LHTES system has been found not only easy to configure, but practically efficient as well, where the overall performance achieved is remarkably outstanding, i.e. OP=(10,000~100,000). Besides, the charging/discharging rate can be remarkably boosted through a wise selection of design parameters.