A forced convection air-cooling of two identical heat sources mounted in a horizontal channel is numerically studied. Four effects of Reynolds number, separation distance, height and width of the components on the flow structure and heat transfer inside the channel have been examined. The entropy generation minimization method (EGM) is employed to optimize the heat transfer and fluid flow in the channel. The flow field is governed by the Navier– Stokes equation and the thermal field by the energy equation. The finite volume method and the SIMPLER algorithm are used to solve the continuity, momentum, energy and entropy generation equations. Results show that the mean Nusselt number increases with increase of the following parameters: Reynolds number, separation distance, height and width of the components. However, these parameters increase the total entropy generation, and thus provokes the degradation of the fan energy. The optimal values of separation distance, height and width heat source are: [(Sopt= 1 with W=0. 25, C=0. 25, Re=50, η =1. 134), (Copt=0. 3 with W=0. 25, S=0. 25, Re=100, η =0. 895) and (Wopt= 0. 1 S=0. 25, C=0. 25, Re=200, η =1. 004)], respectively, where η is the optimization factor (=Num/ST ∗ ) and is defined as the ratio of Nusselt number to the total entropy generation. Finally, the optimal and the best configuration for maximum heat transfer and minimum entropy generation is observed at Re=50, S=1, C=0. 25 and W=0. 25.