Affordable Access

Publisher Website

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

Authors
Journal
Chemical Engineering Science
0009-2509
Publisher
Elsevier
Publication Date
Volume
66
Issue
14
Identifiers
DOI: 10.1016/j.ces.2011.01.027
Keywords
  • Multiphase Flow
  • Bubble Columns
  • Airlift
  • Non-Newtonian Fluids
  • Viscoelasticity
  • Boger Fluid

Abstract

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 holdup, 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 behavior was observed for the maximum stable gas holdup and gas–liquid mass transfer coefficient in BC. Viscosity enhances homogeneous regime stability for μ<4.25 mPa s, in BC, and μ<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.

There are no comments yet on this publication. Be the first to share your thoughts.