Latent heat thermal energy storage (LHTES) system offers the advantage of high energy density at the storage side and near isothermal condition at the exit of HTF (heat transfer fluid). In the present work, a 2D axisymmetric transient, fully implicit numerical model based on the finite volume method is developed to study cycle dynamics of phase change material (PCM) along with temperature distribution in HTF. Solar salt, a binary eutectic mixture, (60% NaNO3:40% KNO3) used as PCM, which behaves as a pure substance, and Therminol vp1 is the HTF. In the PCM domain, energy conservation equation discretized by the finite volume method and solved using enthalpy updating scheme with an appropriate relaxation factor. Numerical domain for the transient numerical model consists of a cross-section steel pipe of nominal size 2/8 inch of schedule 40 (inner diameter = 9.2456 mm, outer diameter = 13.716 mm), and length 1m surrounded by a concentric tube of diameter 52.5 mm and negligible thickness. The annular region between the two pipes filled with graphite incorporated PCM and HTF flows through the inner tube. PCM domain is 2D axis-symmetric where heat transfer is diffusion dominated, whereas the 1-D model considered for the flow of HTF through the pipe. Simulations are performed for charging of PCM domain considering pure PCM and PCM-Graphite composite with enhanced thermal conductivity. Apart from the above numerical model, these models were design and mesh in ANSYS Workbench, and CFD simulation was carried out in ANSYS FLUENT 18.1, and the simulation results were analyzed using post-processing. Ansys fluent simulations have been performed for 2-D planar axisymmetric and 3-D concentric tube geometries considering identical dimensions, boundary conditions, initial conditions and, PCM and HTF arrangement as in the above numerical model. For Ansys Fluent simulation, a separate user-defined scalar (UDS) code written for energy equation and enthalpy update, consequently, default energy equation and solidification and meltingmodels in the model section of Ansys Fluent is switched off.Key Words: LHTES, Enthalpy update technique, Melting, Charging, graphite incorporation compressed expanded graphite, CEG, porous graphite matrix.