Experimental Study of Bubble Dynamics of Direct Contact Condensation of Steam in Subcooled Water

A study on the relationship between hydraulic model and heat transfer characteristics of the direct contact condensation in an unstable bubbling condensation oscillation region during vertical upward steam injection into subcooled water pool has been conducted. Experiments were performed by injecting 0.5 g / s to 4.0 g / s of steam through a nozzle having an inner diameter of 10 mm into the water tank containing 70 to 95 C° of DI water. To obtain images of bubble dynamics, a high-speed camera was used. Bubble dynamic parameters such as collapsing frequency, departure frequency, bubble equivalent diameter, rising velocity, and heat transfer coefficient were calculated. The system dimensional analysis was performed, and the result was compared with existing bubble dynamics models developed from the subcooled pool boiling studies. As a result, a similarity was found that the product of the bubble departure frequency and the diameter is proportional to the bubble rising velocity. On the other hand, a difference was seen in the proportionality coefficient due to the phenomenological difference. Furthermore, the correlation between departure frequency in hydraulic dynamics model and heat transfer coefficient was investigated.