Experimental study of the dominant frequency of pressure oscillations and condensing pattern in vertically upward steam bubbles jets under rolling conditions

Abstract

Steam bubbles direct jet condensing technology, known for their exceptional performance in both the transfers of heat or mass, is popular in static and marine industrial energy systems. Nevertheless, it causes intense pressure oscillations, which can be exacerbated by rolling motions in the marine environments. This can severely impact the safe operation of steam bubbles jet equipment. Therefore, the experimental study is carried out to study the effect of rolling motions on condensing pattern and pressure oscillation frequency of vertically upward bubbles jets. The results reveal that, firstly, the condensing pattern of the vapor bubbles changed, and the rolling motions force the vapor bubbles patterns to roll in the same direction as the rolling motions as compared to the static environment. This rolling behavior of the bubbles causes instability during necking and detachment of bubbles and enhances the heat transfers between the bubbles and the subcooled water, which expedites the condensation rate of the bubbles. This phenomenon explains the second finding: the condensing pressure oscillation dominant frequency of vapor bubbles under rolling conditions is larger than that under static conditions. Meanwhile, with a decrease in these rolling periods and an increasing of the maximum angles of rolling, this dominant frequency of bubbles condensing pressure oscillations increases gradually. Finally, a correlation equation is developed to predict dominant frequency of bubbles condensing pressure oscillations for rolling motions with a bias of ±25%.