Gas-liquid mass transfer intensification for bubble generation and breakup in micronozzles

Abstract

The local gas-liquid mass transfer was characterized during bubble generation in T-contactors and in an adjacent micronozzle. A colorimetric technique with the oxygen sensitive dye resazurin was investigated to visualize gas-liquid mass transfer during slug flow, bubble deformation, as well as laminar and turbulent bubble breakup in the wake of a micronozzle. Two optimized nozzle geometries from previous studies were evaluated concerning volumetric mass transfer coefficients for low pressure loss, narrow residence time distribution, or high dispersion rates. Highest values in kla up to 60 s−1 were found for turbulent bubble breakup and an optimized micronozzle design in respect to pressure drop and dispersion rate. The achieved mass transfer coefficients were correlated with the energy dissipation rate within the micronozzles and with the inverse Kolmogorov time scale in vortex dissipation in good agreement for laminar and turbulent breakup regimes. Graphical abstract

Rapid prototyping of a modular optical flow cell for image-based droplet size measurements in emulsification processes

“…Previous investigations of the Laboratory of Equipment Design at TU Dortmund University focused on liquid-liquid microfluidic applications, multiphase flow, evaluation of different sensors for measurement in continuous capillary flow, and small-scale application [11][12][13][14][15][16]. Based on this, the current contribution describes a modular, optical measurement flow cell for improved optical access to an emulsification process and its design workflow.…”

Effects of bubble cutting dynamic behaviors on microalgal growth in bubble column photobioreactor with a novel aeration device

“…However, all enhancement methods above concentrated on the bubble formation phase and involved infinitely reducing the pore size to produce microbubbles, causing high breakthrough pressure to form microbubbles and gas pump operating costs. Although ultrasonication ( Wu et al, 2021a ; Wu et al, 2021b ; Qin et al, 2022 ), stirring ( Cheng et al, 2020 ; Naira et al, 2020 ; Wang et al, 2021a ), and turbulence ( Zhang et al, 2020 ; Wang et al, 2021b ; Reichmann et al, 2021 ) can improve the mass transfer coefficient at the gas-liquid interface during bubble rising by reducing bubble sizes and strengthening the interface disturbance, they involved high energy consumption. Adding surfactants can produce small bubbles without additional energy consumption; however, surfactants have recycling complications ( Li and Kang, 2020 ).…”