Novel Identifier of Transitions in Bubble Columns Operated with Water and Aqueous Alcohol Solutions

Abstract

The accurate identification of the transition velocities U trans in bubble columns (BCs) is important for their effective design, operation, and scale-up. In this work, a novel parameter, namely, the new hybrid index (NHI), was developed and successfully applied to gas holdup and pressure fluctuations recorded in various BCs operated with water and aqueous solutions of alcohols (ethanol and propan-2-ol). The first U trans was identified on the basis of a well-pronounced local NHI minimum, whereas the second U trans was distinguished by the point from which the NHI profile levels off. It was concluded that the main U trans depend on the type of gas-liquid system and sparger used. A set of several U trans is reported.

Guidance for Measuring the Axial Gas Dispersion Coefficient in Bubble Columns via Gas Flow Modulation

“…17 A good estimate of this transition velocity helps in selecting operating conditions before the transition to heterogeneous flow regime, where GFM is well applicable. Clearly, more accurate methods are available for determining the transition velocity (for example, see Nedeltchev et al 18 ), however, the double linear fitting approach is one of the easiest to implement and it is sufficient for the scope of this preliminary characterization.…”