The Computational Fluid Dynamic (CFD) Analysis of Heat Pipe Heat Exchanger (HPHE) is done to predict the temperature distribution using ANSYS-ICEM modular/meshing and FLUENT solver. In this study, HPHE is modeled in four different cases with and without fillet near the inlet and outlet sections including (standard HPHE, with enlarge inlet and outlet sections, with horizontal plate near the entrance zone, using three different cone of angles (36.03 degree, 30 degree and 45 degree)). The mass flow rate 3.75kg/sec of hot air or gas as given at the inlet section. The Standard k- -Realizable turbulence model was used for fluid flow in simulations. The magnitude and location of the temperature distribution, velocity, and turbulence kinetic energy are influenced by prescribed conditions. However, pressure drop is reduced up-to certain extent (due to change in turbulence kinetic energy) for all the cases in which round corner/fillet at the inlet and outlet section was made in the model. At the same time jet type flow is also reduced because of reduction in axial velocity and increment of Y & Z directional velocity which tends to expansion of flow toward the y and z direction.