Minimum entropy production principle-based semi-empirical model for void fraction prediction in vertical upward dispersed gas-liquid flows

In various energy transport systems, the void fraction of gas-liquid two-phase flow serves as one of the critical parameters. This study develops a theoretical framework based on the principle of minimum entropy production to predict the void fraction in gas-liquid dispersed flow, explicitly incorporating the contributions of two-phase frictional pressure drop and acceleration pressure drop to energy flux. By integrating the bubble layer thickness model with a modified energy flux equation, a novel semi-empirical model is proposed. The model is calibrated and validated using extensive experimental data from vertical upward flow conditions. Results indicate that accounting for the contributions of both frictional and acceleration pressure drops in the energy flux equation is both rational and necessary. Compared with existing models such as the drift-flux model, slip ratio model, and homogeneous flow model, the present model exhibits superior predictive accuracy and stability when validated against experimental data from both non-boiling and boiling flow regimes. Furthermore, the model is also applicable to rod bundle channel.