7. Tube Surface Conditions

Tube surface condition: either uniform wall temperature condition (UWT) condition, or a uniform wall heat flux condition (UWH).

For \(T_w=\text{ constant}\), i.e., \((dT_w/dx)=0\): If a phase change were occurring at outer surface.

For \(q_w=h(T_w-T_m)=\text{ constant}\): If the tube wall were heated electrically or, if the outer surface were uniformly irradiated.