Heat and fluid flow in porous media are frequently encountered in natural and industrial applications, such as oil recovery, water supply management in hydrogeology, ground heat storage, nuclear waste disposals, and ground water flow modeling. Fluid flow and heat transfer analyses in porous media have gained recent attention. The theoretical analysis of heat and fluid flow in porous media is troublesome. That’s why some methods were developed to overcome the difficulties. One of these methods is the macroscopic method in which the solid and fluid phases are combined and the porous media is represented as an imaginary continuum domain. For the application of the macroscopic method onto a porous medium, the macroscopic transport properties such as permeability and thermal dispersion of the corresponding medium should be known. Many parameters such as pore to throat size ratio, porosity, Reynolds number, solid-to-fluid thermal conductivity ratio influence the macroscopic transport parameters. In this study, the fluid flow and heat transfer in porous media are examined numerically to determine the effects of pore to throat size ratio on permeability, interfacial convective heat transfer and thermal dispersion coefficients. The heat and fluid flow in periodic porous media consisting of rectangular rods are investigated. A representative elementary volume is considered and the continuity, Navier-Stokes and energy equations are solved to determine the velocity, pressure and temperature fields in the voids between the rods. It is shown that the pore to throat size ratio is a significant parameter which should be taken into account to suggest a wide applicable correlation. Based on obtained computational results, correlations for determination of Kozeny constant and interfacial heat transfer coefficient in terms of pore to throat size ratio and other related parameters are proposed. An experimental study was conducted to validate the numerical results of the present study. In the experimental part, a porous channel of square rods is used and the permeability and thermal dispersion coefficient are validated with the aid of experimental measurements. A good agreement between the experimental and numerical results is observed.