According to Increasing human needs for energy and to avoid energy waste researchers are struggling to increase the efficiency of energy production or energy conversion. One of these methods, is increasing heat transfer and reducing heat dissipation in heat exchangers. Using porous materials in the fluid path is one of the passive methods for increasing heat transfer in heat exchangers. The presence of porous media in the flow path, improve the matrix of thermal conductivity and effective flow thermal capacity and also matrix of porous-solid increase radiation heat transfer, especially in two phase flow (gas-water) systems. In this study using porous media inside a tube and effects of porosity percentage, material and different geometric structure on heat transfer changes has been investigated. Fluid used in the test was water, flow was turbulence and Reynolds number )Re) was varied from 3800 to 5073. The test is performed on a part of a tube in a boiler with constant temperature boundary condition. Before testing on porous media, performance of devices has been verified by comparing of simulation and experimental data for an empty tube. The maximum uncertainties associated with 480 L/hr, where the difference in the heat transfer coefficient obtained from the experimental data with the simulation values is 16.22% and average error in total flow rate is 8.65%. After testing on porous media, the results showed that in two samples with the same material and porosity, the geometric structure can increase the heat transfer coefficient by 1.7 times, Also due to the effect of hydraulic diameter on the calculation of Nusselt number in the porous medium, the Nusset number is not a accurate criterion for comparing the increase in heat transfer. Comparison of samples with a approximately the same porosity percentage and a different geometric structure was concluded that the geometric structure has a very significant effect on the performance of the porous medium, in some cases the geometric structure reduces heat transfer and undesirable effects on the system, Depending on the geometric structure, the increase of heat transfer may also occur in a certain range of Reynolds numbers. Finally, the highest heat transfer coefficient enhancement in this study was 5.7 times the heat transfer coefficient in an empty tube. Also in some cases, the presence of porous medium reduced the heat transfer coefficient to 89.45% of the heat transfer coefficient in an empty tube. Keywords: Porous media, Heat transfer enhancement, Heat exchanger, Constant temperature, Experimental investigatio