This paper presents a numerical and experimental investigation of the effects of stagnant and dispersion conductivities on non-Darcian forced convection in square packed-sphere channels. The theoretical prediction of Nusselt number are found to be in good agreement with the experimental data. A larger near-wall damping of stagnant conductivity is found for the present water-steel medium than for that described by the mixing rule based on the volume fraction. A nonlinear Peclet number dependence. Pe(lambda) and lambda = 0.88, for dispersion conductivity is found to induce better agreement between the theoretical and experimental results especially for the cases of high Peclet number and high D(e)/d.