An Investigation of the Collapse and Surface Rewet in Film Boiling in Forced Vertical Flow

A transient boiling experiment has been run in such a way that one can acquire data in forced convection film, transition, and nucleate boiling regions for a specified pressure, quality, and mass flux. Transient boiling experiments were conducted at the Nuclear Energy Division of the General Electric Company for water in a 0.492 in. ID inconel X-750 tube at mass fluxes of 50,000, 100,000, and 250,000 lbm/hr-ft², quality range of 30–100 percent and a pressure of 1000 psia. The reduced boiling curves for these data indicated temperature differences at burnout on the order of 100–200° F and temperature differences at the minimum ranging from 700 to 1100° F. These results (higher than in other experiments) are felt to be caused by scale deposit, axial conduction, and roughnesses on the test surface. Physical evidence indicates that the test surface became coated with an appreciable scale deposit when subjected to the initial temperatures in excess of 1500 °F in a steam atmosphere. It has been found (reference [1]) that BWR fuel will normally have scale deposit on the heat transfer surface and thus the qualitative effects of scale deposits in this report are expected to apply in BWR Loss-of-Coolant accident evaluation. An empirical correlation was developed for the data for minimum film boiling temperature differences. The correlation was based on Berenson’s minimum pool film boiling temperature difference correlation in order to provide a technique for extrapolating to different pressures.