SINOPSIS

A theoretical treatment is presented of preheating effects due to wall and fluid heat conduction in forced convection heating of hydrodynamically developed laminar flows. The geometry of interest consists of a long circular tube heated for a finite, or semi-infinite length. The occurrence of full thermal development in the preheating region is demonstrated. An exact functional dependence between the asymptotic Nusselt number and two parameters, the Conduction Influence Parameter and the Péclet number, is finally derived and discussed.