Experimental study of counter-current gas–droplet flow limitation in a 30 cm pipe

In the present study, gas–liquid two-phase flow at the counter-current flow limitation (CCFL) condition in a relatively large pipe is investigated analytically and experimentally. Droplet behavior and stable counter-current flow criteria are analyzed by studying the interaction between downward moving liquid droplets and upward gas flow. An analytical model based on the Drift Flux Model was developed to predict the onset of CCFL phenomena. The model takes into account various factors that may be encountered in the industry including gas velocity profile, droplet fraction profile, and velocity fluctuation factor. Analyses show that maintaining a uniform gas velocity profile and a stable gas flow rate is the key to prevent droplet carry-over and hence delaying the CCFL condition. For droplet–gas interaction, droplet size in the distorted particle regime is the major contribution. An experimental facility consisting of a 30 cm test section pipe was designed and constructed to perform a fundamental study of counter-current droplet–gas flow. A dataset for the onset of CCFL at varying operating conditions was established. The proposed model showed the ability to predict the onset of CCFL in the counter-current two-phase flow.

► Gas–droplet counter-current two-phase flow facility was designed. ► CCFL and flow reversal dataset were obtained from the experiment. ► Newly developed analytical model to predict the CCFL condition is presented. ► The model prediction and experimental data are comparable within ±20%.