[en] An analysis for hydrodynamically and thermally fully developed heat transfer in a circular tube coupled with heat conduction in the tube wall is presented. The energy equations for the fluid and solid body are solved simultaneously under the conditions of continuity in the heat flux and temperature at the interface. Circumferential as well as radial temperature gradients are permitted in both energy equations along with internal heat generation in the tube wall. Solution of the equations are found by the method of separation-of-variables along with superposition of particular solutions. As an application, cooling of the first wall in a fusion reactor is considered. Comparisons of temperature profiles in the tube wall are made for high (aluminum) and low (stainless steel) thermal conductivity materials. Comparisons are also made under the assumption that radial temperature gradients are negligible