Effects of liquid properties on the hydrodynamics of gas-liquid systems were investigated in lab-scale bubble column (BC) and internal loop airlift (ILA). Alginate solutions, a glycerol solution and a Boger fluid were adopted to separately address the effects of viscosity and of surface tension for Newtonian fluids, and the effects of relaxation time for Non-Newtonian fluid characterized by approximately constant viscosity (low shear thinning). Hydrodynamic regimes were characterized in terms of overall gas hold-up, gas-liquid mass transfer coefficient, drift-flux and liquid circulation velocity. The superficial gas velocities at the transition between hydrodynamic regimes (homogenous regime – vortical-spiral regime – heterogeneous regime) as a function the liquid viscosity was characterized by a maximum. The same behaviour was observed for the maximum stable gas hold-up and gas-liquid mass transfer coefficient in BC. Viscosity enhances homogeneous regime stability for viscosity < 4.25 mPa•s, in BC, and viscosity < 7.68 mPa•s, in ILA. For Non-Newtonian fluids the transition velocity increases with liquid elasticity. The stabilization mechanism related to the relaxation time of Boger fluids has been discussed.

Effects of viscosity and relaxation time on the hydrodynamics of gas-liquid systems / Olivieri, Giuseppe; Russo, MARIA ELENA; Simeone, Marino; Marzocchella, Antonio; Salatino, Piero. - In: CHEMICAL ENGINEERING SCIENCE. - ISSN 0009-2509. - 66:(2011), pp. 3392-3399. [10.1016/j.ces.2011.01.027]

Effects of viscosity and relaxation time on the hydrodynamics of gas-liquid systems

OLIVIERI, GIUSEPPE;RUSSO, MARIA ELENA;SIMEONE, MARINO;MARZOCCHELLA, ANTONIO;SALATINO, PIERO
2011

Abstract

Effects of liquid properties on the hydrodynamics of gas-liquid systems were investigated in lab-scale bubble column (BC) and internal loop airlift (ILA). Alginate solutions, a glycerol solution and a Boger fluid were adopted to separately address the effects of viscosity and of surface tension for Newtonian fluids, and the effects of relaxation time for Non-Newtonian fluid characterized by approximately constant viscosity (low shear thinning). Hydrodynamic regimes were characterized in terms of overall gas hold-up, gas-liquid mass transfer coefficient, drift-flux and liquid circulation velocity. The superficial gas velocities at the transition between hydrodynamic regimes (homogenous regime – vortical-spiral regime – heterogeneous regime) as a function the liquid viscosity was characterized by a maximum. The same behaviour was observed for the maximum stable gas hold-up and gas-liquid mass transfer coefficient in BC. Viscosity enhances homogeneous regime stability for viscosity < 4.25 mPa•s, in BC, and viscosity < 7.68 mPa•s, in ILA. For Non-Newtonian fluids the transition velocity increases with liquid elasticity. The stabilization mechanism related to the relaxation time of Boger fluids has been discussed.
2011
Effects of viscosity and relaxation time on the hydrodynamics of gas-liquid systems / Olivieri, Giuseppe; Russo, MARIA ELENA; Simeone, Marino; Marzocchella, Antonio; Salatino, Piero. - In: CHEMICAL ENGINEERING SCIENCE. - ISSN 0009-2509. - 66:(2011), pp. 3392-3399. [10.1016/j.ces.2011.01.027]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/376628
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