Parameters Affecting Bubble Formation and Size Distribution From Porous Media

This paper describes the experiments designed to control bubble size during gas injection through porous media into liquid cross flow. A parametric study examined the effect of control variables on average bubble size and standard deviation. Results showed that for a given air and liquid flow rate, changing liquid channel height at the air injection site had the largest effect on bubble size and size distribution while varying porous media grade and electrolyte concentration had smaller, though significant, effects. In this study, the channel height was varied from 0.8 to 8 mm, porous media grade from 0.5 to 100 and salt concentration varied from zero to 3%. The resulting average bubble diameters were 0.085–2.5 mm.

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Bubble Formation From Porous Plates in Liquid Cross-Flow

Volume 1: Flow Manipulation and Active Control; Bio-Inspired Fluid Mechanics; Boundary Layer and High-Speed Flows; Fluids Engineering Education; Transport Phenomena in Energy Conversion and Mixing; Turbulent Flows; Vortex Dynamics; DNS/LES and Hybrid RANS/LES Methods; Fluid Structure Interaction; Fluid Dynamics of Wind Energy; Bubble, Droplet, and Aerosol Dynamics ◽

10.1115/fedsm2018-83221 ◽

2018 ◽

Author(s):

Thomas Shepard ◽

Eric Ruud ◽

Henry Kinane ◽

Deify Law ◽

Kohl Ordahl

Keyword(s):

Size Distribution ◽

Bubble Size ◽

Bubble Diameter ◽

Bubble Formation ◽

Cross Flow ◽

Rectangular Channels ◽

Gas Liquid Flow ◽

Liquid Flows ◽

Processing Techniques ◽

The Impact

Controlling bubble diameter and bubble size distribution is important for a variety of applications and active fields of research. In this study the formation of bubbles from porous plates in a liquid cross-flow is examined experimentally. By injecting air through porous plates of various media grades (0.2 to 100) into liquid flows in rectangular channels of varying aspect ratio (1–10) and gas/liquid flow rates the impact of the various factors is presented. Image processing techniques were used to measure bubble diameters and capture their formation from the porous plates. Mean bubble diameters ranged from 0.06–1.21 mm. The present work expands upon the work of [1] and further identifies the relative importance of wall shear stress, air injector pore size and gas to liquid mass flow ratio on bubble size and size distribution.

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Bubble formation regimes during gas injection into a liquid cross flow in a conduit

The Canadian Journal of Chemical Engineering ◽

10.1002/cjce.22680 ◽

2016 ◽

Vol 95 (2) ◽

pp. 372-385 ◽

Cited By ~ 5

Author(s):

Miguel A. Balzán ◽

R. Sean Sanders ◽

Brian A. Fleck

Keyword(s):

Bubble Formation ◽

Gas Injection ◽

Cross Flow

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The Effect of Nozzle Shape and Configuration on Bubble Formation in a Liquid Cross Flow

Volume 1: Symposia, Parts A and B ◽

10.1115/fedsm2012-72313 ◽

2012 ◽

Author(s):

Mona Hassanzadeh Jobehdar ◽

Aly H. Gadallah ◽

Kamran Siddiqui ◽

Wajid A. Chishty

Keyword(s):

Liquid Flow ◽

Bubble Size ◽

High Speed ◽

Waste Water Treatment ◽

Bubble Formation ◽

Cross Flow ◽

Bubble Velocity ◽

Two Dimensional ◽

Flow Rates ◽

Nozzle Shape

Gas injection into a liquid cross flow from a nozzle causes bubble formations which have potential applications in industry such as chemical plants, waste water treatment and bio- and nuclear-reactors. The purpose of this study is to experimentally investigate the effects of nozzle shape and configuration with respect to the liquid cross-flow direction, on the bubbly flow characteristics such as bubble formation, detached bubble size and frequency at different gas and liquid flow rates. The experiments were conducted in a Plexiglas two-dimensional rig using a high speed camera. High speed imaging and an image processing algorithm were used to track each individual bubble and to quantify the bubble growth as well as the detachment frequency and the bubble velocity. Back light shadowgraphy which utilizes a low intensity diffuse light source to illuminate the background was used to image bubbles. Nozzles were mounted in the test section which was designed such that the flow in this section has a two-dimensional profile. The results showed that the bubble size increases with an increase in GLR (gas to liquid flow rates ratio). Furthermore, the bubble formations and detached bubble size were strongly influenced by the nozzle shape and configuration.

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A Review of Bubble Dynamics in Liquid Metals

Metals ◽

10.3390/met11040664 ◽

2021 ◽

Vol 11 (4) ◽

pp. 664

Author(s):

Tim Haas ◽

Christian Schubert ◽

Moritz Eickhoff ◽

Herbert Pfeifer

Keyword(s):

Size Distribution ◽

Bubble Size ◽

Bubble Dynamics ◽

Liquid Metals ◽

Bubble Formation ◽

Bubble Size Distribution ◽

The State ◽

Open Questions ◽

Casting Ladle ◽

Metallurgical Processes

Gas bubbles are of major importance in most metallurgical processes. They promote chemical reactions, homogenize the melt, or float inclusions. Thus, their dynamics are of crucial interest for the optimization of metallurgical processes. In this work, the state of knowledge of bubble dynamics at the bubble scale in liquid metals is reviewed. Measurement methods, with emphasis on liquid metals, are presented, and difficulties and shortcomings are analyzed. The bubble formation mechanism at nozzles and purging plugs is discussed. The uncertainty regarding the prediction of the bubble size distribution in real processes is demonstrated using the example of the steel casting ladle. Finally, the state of knowledge on bubble deformation and interfacial forces is summarized and the scalability of existing correlations to liquid metals is critically discussed. It is shown that the dynamics of bubbles, especially in liquid metals, are far from understood. While the drag force can be predicted reasonably well, there are large uncertainties regarding the bubble size distribution, deformation, and lift force. In particular, the influence of contaminants, which cannot yet be quantified in real processes, complicates the discussion and the comparability of experimental measurements. Further open questions are discussed and possible solutions are proposed.

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Mapping Bubble Formation and Coalescence in a Tubular Cross-Flow Membrane Foaming System

Membranes ◽

10.3390/membranes11090710 ◽

2021 ◽

Vol 11 (9) ◽

pp. 710

Author(s):

Boxin Deng ◽

Tessa Neef ◽

Karin Schroën ◽

Jolet de Ruiter

Keyword(s):

Bubble Size ◽

Bubble Formation ◽

Cross Flow ◽

Continuous Phase ◽

Convective Transport ◽

Process Conditions ◽

Fundamental Study ◽

Promising Alternative ◽

Fluid Properties ◽

And Control

Membrane foaming is a promising alternative to conventional foaming methods to produce uniform bubbles. In this study, we provide a fundamental study of a cross-flow membrane foaming (CFMF) system to understand and control bubble formation for various process conditions and fluid properties. Observations with high spatial and temporal resolution allowed us to study bubble formation and bubble coalescence processes simultaneously. Bubble formation time and the snap-off bubble size (D0) were primarily controlled by the continuous phase flow rate (Qc); they decreased as Qc increased, from 1.64 to 0.13 ms and from 125 to 49 µm. Coalescence resulted in an increase in bubble size (Dcoal>D0), which can be strongly reduced by increasing either continuous phase viscosity or protein concentration—factors that only slightly influence D0. Particularly, in a 2.5 wt % whey protein system, coalescence could be suppressed with a coefficient of variation below 20%. The stabilizing effect is ascribed to the convective transport of proteins and the intersection of timescales (i.e., μs to ms) of bubble formation and protein adsorption. Our study provides insights into the membrane foaming process at relevant (micro-) length and time scales and paves the way for its further development and application.

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