The Effect of Gas Injection Configuration on Two-Phase Countercurrent Flow Limitation in Short Vertical Channels

Countercurrent flow limitation in channels with evaporation taking place inside them is examined. Countercurrent flow limitation in short, small-diameter channels subject to purely axial, purely radial, and combined axial and radial gas injection is studied. Experiments were performed using air and water, with channel diameters 0.475 to 1.91 cm and channel lengths 1.27 to 5.72 cm. Purely axial gas injection data are shown to agree with Wallis’s correlation but with coefficients that strongly depend on channel dimensions. Purely radial gas injection data and data obtained with combined axial and radial gas injection result in flooding curves significantly different from those representing the purely axial gas injection data and indicate that near complete flooding (zero liquid penetration) can occur in small-diameter and short channels due to relatively small radial gas injection rates. Flooding curves for long or large-diameter channels are insensitive to the gas injection configuration, however.