This paper proposes the method of finned pipe heat exchanger modelling using porous medium approach. In this approach fins are changed to the porous medium by means of a formal algorithm using ANSYS CFX. The last one permits to develop heat exchanger design take into account the temperature and pressure fields. Then the modelling results can be used for the stress analysis and in the construction optimization process. The paper scope is to introduce a simple, cost-efficient method, which is capable to simulate a gas flow of a heat exchanger and can be integrated into more complex simulations.