Theoretical analysis on bubble radius and pressure fluctuation during steam bubble condensation

The pressure oscillation and condensation behavior of steam bubbles at low steam mass flux are experimentally and theoretically studied in this work. Based on the synchronous measurement system of bubble behavior and pressure oscillation, it is found that the steam bubble condenses first and then expands and contracts, the water pressure reaches the maximum (about 13 kPa) when the bubble condenses to the minimum radius (about 1 mm). Subsequently, taking into account the movement of the bubble and the change of internal pressure during the bubble condensation process, a theoretical model of heat and mass transfer in the bubble condensation process is established, which shows that the steam bubble collapse is caused by heat transfer and the bubble internal pressure fluctuation. In the early condensation process of steam bubble, the bubble internal pressure continues to increase, meanwhile, the influence of bubble internal pressure on bubble condensation continues to increase. During the later expansion and contraction process of the bubble, the bubble internal pressure decreases first and then increases, the bubble behavior is mainly controlled by the bubble internal pressure.