2. Convective boiling for vertical tubes

In free boiling, heat transfer depends mainly on the temperature difference between the wall and the fluid, and on the properties of the fluid and the wall. For forced convection boiling, the velocities of each phase and the phase distribution also play a major role. This is why, to determine heat transfer and exchange coefficients, we need to take into account these quantities, which are characterized by flow rates and titre.

In a vertical forced-flow tube, in which the fluid enters at the base of the tube as a subcooled liquid $T_{\mathcal{l}}<T_{sat}$ , it exits as a superheated vapor if the tube is long enough. Exchange coefficients and wall and fluid...