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

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. (C) 2020 Elsevier Ltd. All rights reserved.