The predicted dimensionless excess temperature distributions
for solids and fluids, defined in Eqs. (12) and (13), compared with
those predicted by the conventional uniform heat flux model, are
shown in Fig. 5. The near-wall fluid and foam ligament temperature
gradient predicted in the present model is much higher than
that in the uniform heat flux model both in the annular and inner
spaces. However, local temperature differences between the fluid
and solid matrices in the case of conjugated conditions are lower
than the values for a given constant heat flux in the inner tube.
In the interface wall, the two predicted temperatures are almost
the same due to the high heat conductivity of solid wall.