Local and global hydrodynamics in a two-phase internal loop airlift

Two-phase hydrodynamic regimes establishing in a lab-scale internal circulation airlift operated at low superficial gas velocity have been investigated. The airlift was operated with air and bidistilled water at room temperature. The gas–liquid (G–L) behaviour was investigated by visual inspection of the system and by analysis of the time series of the pressure along the loop and of the thermal power exchanged between the G–L suspension and a hot film probe. Local and overall dynamical features have been investigated by analysing the time-resolved signals by means of advanced mathematical tools (Kolmogorov entropy, coherence, Hurst exponent).