Thermal energy storage is a practical and important way inconserving available energy and improving its utilization.Unlike the sensible heat storage method, the latent heat storagemethod provides much higher storage density, with a smallertemperature difference between charging and discharging heatphase. This work presents a numerical study of a latent heatstorage exchanger filled with phase change material (PCM).Water flows by forced convection through the inner tube andtransfers the heat to PCMs. A mathematical model based on theconservation energy equations was numerically resolved by acommercial FLUENT 6.3.2 code. Several numericalinvestigations were conducted in order to examine the impact ofthe key parameters: mass quantity of PCM used, number of passand the mass flow rate of the water. This parametric studyprovides guidelines for system thermal performance and designoptimization.