The use of renewable energy has a characteristic that requires energy storage. One form of energy storage is thermal energy storage (TES). Research on TES by using paraffin wax as latent heat storage media that has been done a lot. The difficulty in experimental research is the timing of the melting process of paraffin wax is unpredictable. Related to these difficulties, can be overcome by applying numerical simulations using ANSYS Fluent computational fluid dynamics (CFD) software. This study aims to obtain the result of an investigation of the melting process paraffin wax RT52 in a TES tube in axial direction and radial direction with variations temperature inlet of incoming water in the direction of the tube axis using ANSYS Fluent computational fluid dynamics (CFD) software. The geometry configuration consists of two tubes. The inner tube contains full paraffin wax, while the outer tube as aplace of hot water flows. Hot water as heat transfer fluid (HTF) in the heat-exchanger is flowed through an inlet-outlet chanel that is in the direction of the tube axis. The inlet-outlet diameter of 3,8 cm with a length of 6 cm each from the outer end of the tube. Dimension of tube in diameter 10 cm and length 40 cm. The outer tube is 12,65 cm in diameter and 50 cm in length. This study was conducted by numerical simulation using CFD ANSYS Fluent 18.0 with variation of inlet temperature (55 ℃, 60 ℃, and 65 ℃). The method used is using boussinesq assumption on PCM density. The numerical simulation using the enthalpy porosity of 106 with the optimum value of 430.718 elements mesh obtained orthogonal quality of 0,48 with good qualification. The results showed that heat transfer in the paraffin wax melting process in TES occurred by conduction and convection, where the influence of temperature difference is very large. The greater the temperature difference then the absorption of heat by paraffin wax also the greater, this resulted in the time the formation of the process of melting of paraffin wax faster. The contour of melting paraffin wax that formed is not symmetrical, this is due to the influence of natural convection. Impact caused by natural convection is the emergence of a driving force that forces the fluid to circulate due to differences in mass type. The lightest type of mass will occupy the room on the top layer.