7. Post-CHF Heat Transfer in Flow Boiling

The various regimes in pool boiling were discussed in Section 3.1 and shown in Figure 3.1.1. The regimes in flow boiling are basically the same. In a surface temperature-controlled system, critical heat flux (CHF) is followed by transition boiling in which heat flux decreases with increasing wall temperature. This continues until the minimum film boiling temperature (MFBT) is reached. With further increase in wall temperature, film boiling starts during which heat flux increases with increasing wall temperature. In a heat flux-controlled system, film boiling starts immediately after CHF, and thus there is no transition boiling.