Effect of spheroid bubble interface contamination on gas-liquid mass transfer at intermediate Reynolds numbers: From DNS to Sherwood numbers

• DOI: 10.1016/j.ces.2021.116979
• Publication Date: 2021-08-27T14:41:41Z
• Authors: Adil Dani; Arnaud Cockx; Dominique Legendre; Pascal Guiraud
• Keywords: Sherwood number; Schmidt number; Mass transfer coefficient

Abstract Gas–liquid mass transfer from spherical bubbles is studied by DNS for various Reynolds numbers ( 1 ⩽ Re ⩽ 300 ), Schmidt numbers ( 1 ⩽ Sc ⩽ 500 ) and bubble surface contamination degrees ( 0 ° ⩽ θ cap ⩽ 180 ° ). Computed separation angles, drag coefficients and average Sherwood numbers for both clean and fully contaminated bubbles are favorably compared to literature. For partially contaminated bubbles, a correlation giving the separation angle versus Re and θ cap is proposed. Local Sherwood numbers along the bubble interface shows a transition between clean and contaminated zones closed to the separation angle. At low Re , for θ cap 40 ° , mass transfer of the contaminated bubble can be estimated by correlations for spherical solid particles, meanwhile for θ cap > 160 ° , bubbles can be assimilated to clean bubbles. For intermediate contamination levels, a normalized Sherwood number Sh ∗ from the drag Sadhal(1983) model can be used. For intermediate Re and high Sc , Sh ∗ converges to a function well correlated to the normalized drag coefficient C D ∗ by Sh lower ∗ = 1 - ( 1 - ( C D ∗ ) 2 ) 0.5 .