Forced Convection Heat Transfer In Circular Pipes


  • Ismail Tosun Middle East Technical University


One of the pitfalls of engineering education is to lose the physical insight of the problem while tackling the mathematical part. Forced convection heat transfer (the Graetz-Nusselt problem) certainly falls into this category. The equation of energy together with the equation of motion leads to a partial differential equation subject to various boundary conditions. Since heat transfer to and/or from the fluids flowing inside circular pipes has many industrial applications, such as evaporators and heat exchangers, heat transfer courses cover this topic extensively. When the heat flux at the wall is constant, the solution is rather straightforward. However, when the wall temperature is constant, the solution becomes complicated and the end result is obtained using an iterative procedure. Thus, many textbooks, as well as the instructors teaching the course, usually omit this section by simply stating that the end result yields the Nusselt number to be equal to 3.66. The purpose of this paper is to show students how to get this result without going into too much mathematical detail.

Author Biography

Ismail Tosun, Middle East Technical University

Ismail Tosun received his B.S. and M.S. degrees from the Middle East Technical University, and a Ph.D. degree from the University of Akron, all in chemical engineering. He is the author of the book Modelling in Transport Phenomena-A Conceptual Approach (Elsevier, 2002). His research is directed to the unification of solid-liquid separation processes using the multiphase equations of change.