Experimental Study on the Behavior of Single Rising Bubbles in a Confined Rectangular Channel

Sirino, Thiago; Mancilla, Ernesto; Morales, Rigoberto E. M.

doi:10.1016/j.ijmultiphaseflow.2021.103818

Cited by 8 publications

(3 citation statements)

References 54 publications

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“…For bubble columns with small inner diameter, the interaction between the rising bubbles and the reactor walls has to be considered. [ 42,43 ] For this purpose, Clift et al [ 43 ] suggest the multiplication of the bubble rise velocity with a wall factor WF. As no coalescence is considered in the model, bubbles comply over the entire length of the reactor with the range of validity given by Clift et al [ 43 ] The bubble Eotvos number

{Eo}_{normalB}

is smaller than 40 and the ratio of the equivalent bubble diameter and the inner reactor diameter

λ = \frac{d_{normalB}}{d_{normalR}}

yields values <0.6.…”

Section: Mathematical Modelingmentioning

confidence: 99%

Methane Pyrolysis in a Liquid Metal Bubble Column Reactor: A Model Approach Combining Bubble Dynamics with Byproduct and Soot Formation

et al. 2022

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Methane pyrolysis is a promising bridging technology to mitigate the effects of climate change. By decarbonizing natural gas, hydrogen can be produced from fossil fuels without creating CO2 emissions. The focus of future process optimization should not only be on the hydrogen yield and the energy efficiency but also on the carbon products and possible byproduct formation. During methane pyrolysis in a liquid metal (LM) bubble column reactor, at least two very distinct types of carbon are synthesized: soot particles and graphene‐like carbon sheets. A model is presented that couples a description of bubble dynamics in a LM bubble column reactor with a kinetic mechanism, originally developed for the combustion of natural gas that includes byproduct and soot formation. The model is validated by comparing it with an experimental dataset that covers a broad range of process conditions and the implications for carbon and byproduct formation are discussed. The good agreement of model results and experimental data shows that the combustion kinetic mechanism may be applied to methane pyrolysis and that the selected way of modeling bubble fluid dynamics in LM results in a good estimation of the actual bubble residence time in the optically nonaccessible liquid.

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{Eo}_{normalB}

is smaller than 40 and the ratio of the equivalent bubble diameter and the inner reactor diameter

λ = \frac{d_{normalB}}{d_{normalR}}

yields values <0.6.…”

Section: Mathematical Modelingmentioning

confidence: 99%

Methane Pyrolysis in a Liquid Metal Bubble Column Reactor: A Model Approach Combining Bubble Dynamics with Byproduct and Soot Formation

et al. 2022

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“…2014; Zhang et al. 2016; Madec 2021; Sirino, Mancilla & Morales 2021). A key result from these studies is that there is only one stable single-bubble solution for a channel of constant rectangular cross-section.…”

Section: Introductionmentioning

confidence: 99%

“…The propagation of finite air bubbles in a Hele-Shaw channel of uniform depth is a classical problem in fluid dynamics with a long and rich history. Transient behaviour and steady propagation modes have been investigated extensively in the case of a single bubble using a mixture of analytical and numerical techniques (see, for example Taylor & Saffman 1959;Tanveer 1987;Tanveer & Saffman 1987;Khalid, McDonald & Vanden-Broeck 2015;Green, Lustri & McCue 2017;Lustri, Green & McCue 2020) and experiments (see, for example Maxworthy 1986;Kopf-Sill & Homsy 1988;Wang et al 2014;Zhang et al 2016;Madec 2021;Sirino, Mancilla & Morales 2021). A key result from these studies is that there is only one stable single-bubble solution for a channel of constant rectangular cross-section.…”

Section: Introductionmentioning

confidence: 99%

The interaction of multiple bubbles in a Hele-Shaw channel

et al. 2022

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We study the dynamics of two air bubbles driven by the motion of a suspending viscous fluid in a Hele-Shaw channel with a small elevation along its centreline via physical experiment and numerical simulation of a depth-averaged model. For a single-bubble system we establish that, in general, the bubble propagation speed monotonically increases with bubble volume so that two bubbles of different sizes, in the absence of any hydrodynamic interactions, will either coalesce or separate in a finite time. However, our experiments indicate that the bubbles interact and that an unstable two-bubble state is responsible for the eventual dynamical outcome: coalescence or separation. These results motivate us to develop an edge-tracking routine and to calculate these weakly unstable two-bubble steady states from the governing equations. The steady states consist of pairs of ‘aligned’ bubbles that appear on the same side of the centreline with the larger bubble leading. We also discover, through time-dependent simulations and physical experiment, another class of two-bubble states that, surprisingly, are stable. In contrast to the ‘aligned’ steady states, these bubbles appear on either side of the centreline and are ‘offset’ from each other. We calculate the bifurcation structures of both classes of steady states as the flow rate and bubble volume ratio are varied. We find that they exhibit intriguing similarities to the single-bubble bifurcation structure, which has implications for the existence of $n$ -bubble steady states.

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