Study the heat and mass transfer in packed bed heat exchangers particularly in nuclear application is subject of many new researches. In this paper numerical analysis of forced convection heat transfer from two tandem circular cylinders embedded in a packed bed, which is made of spherical aluminum particles, is investigated in laminar flow. The porous medium increases the overall heat absorbed from two cylinders and cooling effect but increases the pressure drop, significantly. Also, the effect of increase the horizontal distance between two tandem circular cylinders on flow pattern and heat transfer is investigated. For the empty channel, the total wall heat flux in very small distances have a minimum due to generation of closed vortex region and for longer distances, by increases the... distance between two tandem cylinder, the total wall heat flux increases. It is shown that for two circular cylinders embedded in the packed bed, the total wall heat fluxes from two cylinders and the fluid outlet temperature increase to a maximum quantity and then decrease with negative gradient. Also, the quantities of the empty channel are too smaller than the amounts of porous medium.