A numerical analysis on a heat exchanger in aluminum foam with flat tubes is accomplished. The flow equations in two-dimensional steady state regime are written considering the local volume averaging process. The foam considered as an open porous medium is modelled in local thermal non-equilibrium (LTNE) under the Darcy-Brinkman-Forchheimer hypothesis. The metal foam behaviors such as porosity and pore density (pore per inch, PPI) are assigned equal to 0.9353 and 20. Several configurations of the flat tube with different dimensions are considered. A fixed surface temperature on the flat tube is selected and several mass flow rates are examined. The numerical solutions are carried out by means of the Ansys-FLUENT code Pressure drop in the system and average heat transfer coefficient on the flat tube external surfaces are presented. Moreover, pressure and temperature fields are reported for the different configurations. At the end, a comparison with the same scheme characterized by a circular tube is accomplished.