Hydrodynamics of gas-liquid systems: effects of liquid features

The hydrodynamics of gas-liquid apparatus - bubble columns, airlifts, … - is strongly affected by liquid properties as well as by reactor design and operating conditions. The present contribute reports on the effects of the liquid features on the hydrodynamics of gas-liquid apparatus. In particular, the effects of viscosity - Newtonian fluid – and of relaxation time – non-Newtonian fluid – were separately addressed in bubble columns (BCs). The experimental apparatus consisted of two lab scale BCs. The first BC was characterized by square cross section and was equipped with a single needle gas distributor to inject single bubbles and chains of bubbles. The second BC was characterized by circular cross section and was equipped with needles gas distributor. The units were equipped with gas flow controller, humidifier, diagnostic instrumentation, data acquisition unit, and a high-speed digital camera. The liquids investigated were: a) distilled water; b) aqueous solutions of sodium alginate; c) aqueous solutions of glycerol; d) aqueous solutions of glycerol and polyethylene oxide. The alginate solutions and glycerol solution are Newtonian fluids, the solutions d) are constant-viscosity elastic fluids (Boger fluids). Results highlighted the hydrodynamics of single- or chain-bubbles in Boger fluids as well as the behaviour of fully developed two-phase flow in BC.