Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.
Steady laminar forced convection heat transfer in the
thermal entrance region of a circular pipe including viscous
dissipation has been studied assuming the flow to be
hydrodynamically fully developed and thermally developing.
The circular pipe is subjected to constant wall temperature.
Two entry temperatures have been considered. 1) A
temperature that varies with the radial coordinate obtained in an
adiabatic pipe due to viscous dissipation while the flow is
hydrodynamically developing. This temperature is termed as
the dissipative entry temperature. 2) A uniform temperature
equal to the bulk mean value of the dissipative entry
temperature. It has been shown that the difference in the
Nusselt numbers and heat transfer obtained with these two
entry temperatures is insignificant. Thus, the simplicity of
classical assumption of uniform entry temperature can be
retained when the entry temperature has been chosen as the
bulk mean of the dissipative entry temperature.
