The fully developed turbulent momentum and heat transfer induced by the square-ribed roughness elements on the outer wall surface in concentric annuli are studied analytically based on a modified turbulence model. The analytical results of the fluid flow are verified by experiment. The resulting momentum and heat transfer are discussed in terms of various parameters, such as the radius ratio, the relative roughness, the roughness density, Reynolds number, Nusselt number and Prandtl number. The study demonstrates that certain artificial roughness elements may be used to enhance heat transfer rates with advantages from the overall efficiency point of view.