Two-group drift-flux model for dispersed gas-liquid flow in rectangular channel

Conservation equations of mass, momentum, and energy for the gas and liquid phases are utilized for the twofluid model with dynamic interactions. The transfer rates of heat and mass are determined by multiplying the heat and mass transfer coefficients, the interfacial area concentration (IAC), and the driving potentials. The interfacial area transport equation (IATE) is dynamically applied to estimate the IAC in the two-fluid model. Bubble shapes and sizes are used to classify bubbles into group-1 and-2 bubbles. The current IATE is classified as one-group IATE and two-group IATE, which are applicable to one-group bubbles and two-group bubbles, respectively. The two-group IATE requires the gas velocity of each group. The two-group drift-flux model is a simplified approach to calculate the gas velocity for each group without implementing two momentum equations of the gas phase. This study developed the two-group drift-flux model for two-phase flow in a rectangular channel. The experimental data for two-phase flow in a rectangular channel were collected in order to model and validate the two-group drift-flux model. The asymptotic distribution parameter was evaluated at 1.00 and 1.45 for the collected data of group-1 and-2 bubbles, respectively. The drift velocity correlation developed by Barati et al. was found to correlate the selected experimental data in a reasonable manner. The void fraction and gas velocity were estimated using the two-group drift-flux model developed in the present study, and they were compared with the collected experimental data. For the group-1 bubble data, the mean absolute relative errors for calculating void fraction and gas velocity by the model were 11.6 % and 11.5 %, respectively. For the group-2 bubble data, the mean absolute relative errors were 13.6 % and 15.0 % for the estimation of void fraction and gas velocity by the model, respectively.