A full-flow-range drift-flux model for adiabatic and boiling two-phase flows in vertical narrow rectangular flow channels

This study has reviewed the past research for adiabatic and boiling GLTP (gas-liquid two-phase) flows in VNR (vertical narrow rectangular) flow channels. 1758 void fraction experimental data have been collected from 13 available databases of various researchers. The underlying distribution parameter and drift velocity features have been obtained by analyzing the experimentally-measured data in the classical Zuber-Findlay plots. Existing seven DF (drift-flux) correlations for the VNR flow channels have been examined with the obtained distribution parameter and drift velocity features from Zuber-Findlay plots and the collected 1758 void fraction data and their predictions are found to be unsatisfactory. So, this study has analyzed the dependencies of the distribution parameter and drift velocity on two-phase density ratio, flow channel separation and width, and local flow conditions, and developed new flow-regime-independent full-flow-range distribution parameter and the drift velocity correlations for the VNR flow channels. These newly-developed correlations have been examined with the obtained distribution parameter and drift velocity features from Zuber-Findlay plots and their agreement has been confirmed. The DF model closed by the newly-developed distribution parameter and the drift velocity correlations has also been verified by the collected 1758 void fraction data, and their relative error is 13.1 %.