One of the major issues facing by humans during the last years has been the topic of energy. Among the different types of energy used nowadays, more than 70 percent is exchanged in the form of heat. On the other hand, increase in thermal performance and heat transfer enhancement in heat exchange equipment is one of the areas of interest to researchers. There are many ways to enhance heat transfer in heat exchangers. One of these methods is the use of porous media. Porous media used in heat exchangers is made of metal foam with high thermal conductivity and has a large contact area with the passing fluid. Hence by putting "suitable amount" of porous materials with "favorable configuration" at "optimal position" in the presence of reasonable pressure drop, can force the fluid to pass near the adjacent wall and thereby the boundary layer thickness decreases and increases heat transfer. In the present study, using constructal theory, a fixed volume of porous material in the tube was placed in such a way that the heat transfer was improved in the presence of the reasonable pressure drop. Laminar forced convection flow through a tube partially filled with a porous material was considered. The tube wall was subjected to constant heat flux. The results were reported for different parameters include porous layers number, ratio of effective thermal conductivity of porous region to clear fluid, position of layers, layers volume ratio and permeability. The Darcy–Brinkman–Forcheimer model was used for the ?ow traort in the porous medium. One-equation model was employed for energy traort, which assumed a local thermal equilibrium between the fluid and the solid phases. The analysis was done for the Darcy number from Da=10 -6 to Da=10 -1 and ratio of effective thermal conductivity of porous region to clear fluid, tkr=k e /k f =1, 10. Also, the fixed porosity, ratio between tube length to tube radial (L/r 0 ), Reynolds number and Prandtl number equal to 0.95, 20, 100 and 0.74 were considered, respectively. The results showed that for cases one-layer and two-layer with tkr=1 and Da=10 -1 and 10 -2 , the amount of Performance Evaluation Criteria (PEC) was observed less or about 1. Therefore, the use of porous media with this situation does not justify. For Da=10 -3 and tkr=1, the highest PEC was observed in reference case (Porous material at the core of the tube), However, the highest heat transfer enhancement was observed for case two-layer, and the heat transfer is increased by 10% in comparison with reference case. For Da=10 -4 -10 -6 and tkr=1, the highest PEC was observed in case two-layer with PEC value about 1.22. Also the highest heat transfer enhancement was obtained for case two-layer, and the heat transfer was increased by 29%, 34% and 35% in comparison with reference case, respectively. In the all cases, volume ratio of porous layer fixed at the core tube was high and second porous layer close to the fixed layer. for Da=10 -1 and tkr=10, the highest PEC was observed in case one-layer when porous layer attached to the wall, However, the highest heat transfer enhancement was obtained for case two-layer, and the heat transfer was increased by 20% in comparison with reference case. For Da=10 -2 and 10 -3 with tkr=10, the highest PEC was observed in case two-layer when second porous layer attached to the wall, and the highest heat transfer enhancement was obtained for case two-layer, and the heat transfer was increased by 14% and 12% in comparison with reference case, respectively. For Da=10 -4 -10 -6 and tkr=10, the highest PEC and heat transfer enhancement were obtained similar to the tkr=1. This is due to the fact that heat conduction in the porous matrix plays a more signi?cant role with increasing permeability and decreasing the gap between porous medium and wall. Keywords: Heat transfer enhancement, Numerical simulation, Porous media, Flow inside tube, Performance evaluation criteria