CHF mechanism for pool boiling of R-113 on a horizontal heater

In the present study, new experimental attempts are made to directly observe the physical boiling phenomena of bubbles and dry areas simultaneously from the bottom of the heater surface. In addition, we took the side views of bubbles to obtain the two-dimensional bubble behavior. From the visualization results, the formation of bubbles and dry spots occurs simultaneously. At CHF, the surface rewetting is repeated by the local nucleate boiling around the large vapor film. At just after CHF, nucleate boiling at the wetted region is extinguished, resulting in the dryout of the whole heater surface. Therefore, we conclude that CHF is initiated from the nucleate boiling limitation at the wetted region rather than any hydrodynamic instability