Bubble Lift-Off Diameter in Forced Convective Boiling Flow

A series of experiments were carried out to investigate the bubble nucleation to lift-off phenomena for a subcooled boiling flow in a vertical annulus channel. A high speed digital video camera was used to capture the dynamics of the bubble nucleation to lift-off process. A total of 148 recordings were made, and the bubble lift-off diameter and the bubble nucleation frequency were evaluated for 118 recordings up to now. The basic features of the lift-off diameter and nucleation frequency were addressed based on the present observation. A database for the bubble lift-off diameter was built by gathering and summarizing the data of Prodanovic et al., Situ et al., and the present work. The prediction capability of Unal’s model, Situ et al.’s model, and Prodanovic et al.’s correlation was evaluated against the database. The best prediction results were obtained by modifying the wall superheat correlation in Unal’s model.