Development of force balance model for prediction of bubble departure diameter and lift-off diameter in subcooled flow boiling

Abstract

Visualization experiments are carried out and bubble departure diameter is obtained for subcooled flow boiling in a vertical narrow rectangular channel. Force balance analysis of a growing bubble is performed to determine the criteria for bubble departure and lift-off. A new mechanistic force balance model for predicting bubble departure and lift-off diameter is developed by modifying the bubble growth rate, bubble contact diameter and bubble contact angles. A detailed variation of forces with bubble size is presented, which is used to explain the bubble behaviors intuitively. Compared with Klausner's and Yun's force balance models, the present model shows a good agreement with experimental data by Zhou, Guan, Okawa and Ren. The results also show that the new model can be used to predict bubble diameters in various geometric channels.