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Franck Pigeonneau - One of the best experts on this subject based on the ideXlab platform.
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Mass transfer around a rising bubble in a glass-forming liquid involving Oxidation-Reduction Reaction: Numerical computation of the Sherwood number
Chemical Engineering Science, 2020Co-Authors: Franck Pigeonneau, Luiz Pereira, Annabelle LaplaceAbstract:The mass transfer of a rising bubble in creeping flow regime is numerically investigated. A reversible Oxidation-Reduction Reaction is taken into account. Two coupled equations are needed to study the oxygen and reduced species transport. Three dimensionless numbers are involved: the Péclet and Damköhler numbers and the ratio of the diffusion coefficient of the reduced species to the diffusion coefficient of oxygen. Numerical computations are applied to a soda-lime-silica and a borosilicate glass-forming liquids. Results are focused on the determination of the Sherwood number. The mass transfer enhances strongly when the chemical Reaction is very fast, i.e. at large value of Damköhler number. Correlations to determine the enhancement factor are proposed in the two limits of small and large Péclet numbers. The Sherwood number enhances when the diffusion coefficient of the reduced species increases. A correlation of the Sherwood number is proposed taking into account advection and Reaction.
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Mass transfer of rising O2 bubble in molten glass coupled with the Oxidation-Reduction Reaction of iron
2016Co-Authors: Franck PigeonneauAbstract:Glass melting process involves two-phase flow for which bubbles are dispersed in a high viscous fluid. Due to the quality requirement, the bubble removal is needed. This stage is achieved by the bubble rising due to the buoyancy forces. The efficiency of the last effect is improved by increasing temperature and by bubble growth. In order to increase the bubble size, few chemical species are added which release gaseous species such as O2, SO2, by chemical Reactions. The modeling of mass transfer of bubble in a molten glass has been studying since many years. Nevertheless, the modifications in mass transfer due to chemical Reactions between bubbles and the molten glass are seldom. Since iron is an major element present in industrial glass coming from the raw materials and also add to change the glass color as a function of its Reduction state, we investigate the particular role of the iron by taking into account the Oxidation-Reduction Reaction of iron to describe the mass transfer around of oxygen bubble. The dimensionless mass transfer coefficient, Sherwood number, is determined as a function of the Péclet number based on the terminal rising velocity of the bubble. Two different techniques are used: the first based on the boundary layer theory and the second using a finite element method. The Sherwood number, taking into account the Oxidation-Reduction Reaction, increases with iron content as well as with Reduction state of iron [1]. The behavior of an isolated rising bubble in a molten glass is investigated both experimentally and numerically. The theoretical model to describe bubble shrinkage is based on the preceding results. We show that the bubble shrinkage increases with the reduced iron content. The behavior is very well established with the new developments on Sherwood number described above [2]. [1] F. Pigeonneau. " Mass transfer of rising bubble in molten glass with instantaneous Oxidation Reduction Reaction ". Chem. Eng. Sci., 64:3120-3129, 2009. [2] F. Pigeonneau, D. Martin and O. Mario. " Shrinkage of oxygen bubble rising in a molten glass ". Chem. Eng. Sci., 65:3158-3168, 2010.
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the impact of iron content in Oxidation front in soda lime silicate glasses an experimental and comparative study
Journal of Non-crystalline Solids, 2013Co-Authors: Franck Pigeonneau, S MullerAbstract:Abstract Experiments on the Oxidation front in two soda-lime silicate glasses melted at 1400 °C are first reported. The length of the Oxidation front is proportional to the square root of time and the kinetics is three times slower when the iron content changes from 0.08 to 0.64 wt.%. A theoretical model is drawn assuming that the Oxidation process is driven by the diffusion of oxygen coupled to the Oxidation–Reduction Reaction of iron. From scaling analysis, numerical and self-similar solutions, the length of the Oxidation front as a function of time is rescaled taking into account the iron content and the oxygen saturation in molten glass. The experimental results of Oxidation front merge in a master curve demonstrating the relevance of the theoretical developments.
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Shrinkage of an oxygen bubble rising in a molten glass
Chemical Engineering Science, 2010Co-Authors: Franck Pigeonneau, D Martin, O. MarioAbstract:Abstract The mechanisms controlling the evolution of a bubble surrounded by molten glass are important to understand in order to improve melting in glass furnaces, particularly during a change in composition. In order to provide insight into this phenomenon, the behavior of an isolated bubble rising in molten glass is examined both experimentally and numerically. An experimental procedure developed specifically to observe, in situ, a rising bubble is described. Two soda-lime-silica compositions are tested, with low and high iron content, respectively. The numerical model used to describe bubble shrinkage is based on the results recently proposed in Pigeonneau (2009) . A specific mass transfer coefficient is used for oxygen where the Oxidation–Reduction Reaction of iron oxides is taken into account. A comparison between the experimental and numerical results shows the importance of the Oxidation–Reduction Reaction of iron in the mass transfer of oxygen. The shrinkage rate of a pure O2 bubble is enhanced with reduced molten glass iron content.
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mass transfer of a rising bubble in molten glass with instantaneous Oxidation Reduction Reaction
Chemical Engineering Science, 2009Co-Authors: Franck PigeonneauAbstract:Abstract The mass transfer around a rising bubble has been studied within the field of glass melting processes. Due to the large value of liquid viscosity, creeping flow was used. The rising bubble is assumed to have a clean interface with a total mobility and the exact solution of Hadamard or Rybczynski was used to define the velocity field around the bubble. The mass transfer of oxygen in the soda–lime–silica glass melt where Oxidation–Reduction Reactions of iron oxides occur is also described. The dimensionless mass transfer coefficient, Sherwood number, was determined as a function of the Peclet number based on the terminal rise velocity of the bubble. Two different techniques have been used: the first based on the boundary layer theory and the second using a finite element method. In order to take into account the Oxidation–Reduction Reaction in a unified framework, a modified Peclet number has been defined as a function of two dimensionless numbers. The first is strongly linked to the equilibrium constant of the chemical Reaction and the second is the glass saturation, defined as the ratio of oxygen concentration in the bulk to that at the bubble surface. The Sherwood number, taking into account the chemical Reactions, increases with iron content as well as with glass Reduction (i.e. small saturation level). From an application point of view, the determination of a modified Peclet number is important because it is possible to use a similar expression (determined without the Reaction) by replacing the classical Peclet number by the modified one proposed herewithin.
Akira Yamaguchi - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of MgAl{sub 2}O{sub 4} whiskers by an Oxidation-Reduction Reaction
Journal of the American Ceramic Society, 1996Co-Authors: Shinobu Hashimoto, Akira YamaguchiAbstract:Magnesium aluminate whiskers were synthesized by an Oxidation-Reduction Reaction between MgO, C, and Al in a CO and CO{sub 2} atmosphere. The oxygen partial pressure suitable for MgAl{sub 2}O{sub 4} whisker growth ranged from 10{sup {minus}12.1} to 10{sup {minus}11.5} MPa. The average whisker diameter and length formed at 1,500 C for 8 h were {approximately} 3.1 {micro}m and {approximately} 4 mm, respectively. The whiskers grew in the [111] direction.
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Synthesis of MgAl2O4 whiskers by an Oxidation-Reduction Reaction
Journal of the American Ceramic Society, 1995Co-Authors: Shinobu Hashimoto, Akira YamaguchiAbstract:Magnesium orthosilicate (forsterite) whiskers were synthesized by an Oxidation-Reduction Reaction in the present investigation. These whiskers were rectangular parallelepipeds, with long sides in a cross-sectional view from two to ten times as long as the short sides, and measuring from several micrometers to 200 μm wide and ∼15 mm in the elongated direction. The Mg2SiO4 elongation was on the c-axis. The growth mechanism of the whiskers was investigated on the basis of chemical thermodynamics, and the present study revealed that the Mg2SiO4 whiskers grew by a VS (vapor-solid) mechanism.
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Synthesis of MgAl2O4 Whiskers by an Oxidation‐Reduction Reaction
Journal of the American Ceramic Society, 1995Co-Authors: Shinobu Hashimoto, Akira YamaguchiAbstract:Magnesium orthosilicate (forsterite) whiskers were synthesized by an Oxidation-Reduction Reaction in the present investigation. These whiskers were rectangular parallelepipeds, with long sides in a cross-sectional view from two to ten times as long as the short sides, and measuring from several micrometers to 200 μm wide and ∼15 mm in the elongated direction. The Mg2SiO4 elongation was on the c-axis. The growth mechanism of the whiskers was investigated on the basis of chemical thermodynamics, and the present study revealed that the Mg2SiO4 whiskers grew by a VS (vapor-solid) mechanism.
Annabelle Laplace - One of the best experts on this subject based on the ideXlab platform.
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Mass transfer around a rising bubble in a glass-forming liquid involving Oxidation-Reduction Reaction: Numerical computation of the Sherwood number
Chemical Engineering Science, 2020Co-Authors: Franck Pigeonneau, Luiz Pereira, Annabelle LaplaceAbstract:The mass transfer of a rising bubble in creeping flow regime is numerically investigated. A reversible Oxidation-Reduction Reaction is taken into account. Two coupled equations are needed to study the oxygen and reduced species transport. Three dimensionless numbers are involved: the Péclet and Damköhler numbers and the ratio of the diffusion coefficient of the reduced species to the diffusion coefficient of oxygen. Numerical computations are applied to a soda-lime-silica and a borosilicate glass-forming liquids. Results are focused on the determination of the Sherwood number. The mass transfer enhances strongly when the chemical Reaction is very fast, i.e. at large value of Damköhler number. Correlations to determine the enhancement factor are proposed in the two limits of small and large Péclet numbers. The Sherwood number enhances when the diffusion coefficient of the reduced species increases. A correlation of the Sherwood number is proposed taking into account advection and Reaction.
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Mass transfer around a rising bubble in a glass-forming liquid involving Oxidation-Reduction Reaction: Numerical computation of the Sherwood number
Chemical Engineering Science, 1Co-Authors: Franck Pigeonneau, Luiz Pereira, Annabelle LaplaceAbstract:Abstract The mass transfer of a rising bubble in creeping flow regime is numerically investigated. A reversible Oxidation-Reduction Reaction is taken into account. Two coupled equations are needed to study the oxygen and reduced species transport. Three dimensionless numbers are involved: the Peclet and Damkohler numbers and the ratio of the diffusion coefficient of the reduced species to the diffusion coefficient of oxygen. Numerical computations are applied to a soda-lime-silica and a borosilicate glass-forming liquids. Results are focused on the determination of the Sherwood number. The mass transfer enhances strongly when the chemical Reaction is very fast, i.e. at large value of Damkohler number. Correlations to determine the enhancement factor are proposed in the two limits of small and large Peclet numbers. The Sherwood number enhances when the diffusion coefficient of the reduced species increases. A correlation of the Sherwood number is proposed taking into account advection and Reaction.
Wei Du - One of the best experts on this subject based on the ideXlab platform.
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compressive strain in core shell au pd nanoparticles introduced by lateral confinement of deformation twinnings to enhance the Oxidation Reduction Reaction performance
ACS Applied Materials & Interfaces, 2019Co-Authors: Chenshuo Wu, Hong Li, Hongpeng He, Yahui Song, Cuixia Bi, Wei DuAbstract:In this work, quasi-spherical, uniform gold nanoparticles with rich deformation twinning (Audt NPs) were first synthesized with the assistance of copper(II) ions. Then, these Audt NPs were used as the cores for the fabrication of core–shell (CS) Audt–Pd NPs with ultrathin Pd layers, which also can bear compressive strain because of the formation of corrugated structured Pd shells led by the lateral confinement imposed by deformation twinning in the Au cores. The presence of compressive strain in the CS Audt–Pd NPs can result in the widening of the d-band width of the Pd shell and further the downshift of their d-band center, which can then improve the desorption ability of intermediates and still maintain the adsorption ability of the reactants because of the broad adsorption potential range. Taking the Oxidation Reduction Reaction and the ethanol Oxidation Reaction as examples, the as-prepared Audt–Pd NPs indeed exhibited superior catalytic performances because of the synergism of compressive strain and ...
Shinobu Hashimoto - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of MgAl{sub 2}O{sub 4} whiskers by an Oxidation-Reduction Reaction
Journal of the American Ceramic Society, 1996Co-Authors: Shinobu Hashimoto, Akira YamaguchiAbstract:Magnesium aluminate whiskers were synthesized by an Oxidation-Reduction Reaction between MgO, C, and Al in a CO and CO{sub 2} atmosphere. The oxygen partial pressure suitable for MgAl{sub 2}O{sub 4} whisker growth ranged from 10{sup {minus}12.1} to 10{sup {minus}11.5} MPa. The average whisker diameter and length formed at 1,500 C for 8 h were {approximately} 3.1 {micro}m and {approximately} 4 mm, respectively. The whiskers grew in the [111] direction.
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Synthesis of MgAl2O4 whiskers by an Oxidation-Reduction Reaction
Journal of the American Ceramic Society, 1995Co-Authors: Shinobu Hashimoto, Akira YamaguchiAbstract:Magnesium orthosilicate (forsterite) whiskers were synthesized by an Oxidation-Reduction Reaction in the present investigation. These whiskers were rectangular parallelepipeds, with long sides in a cross-sectional view from two to ten times as long as the short sides, and measuring from several micrometers to 200 μm wide and ∼15 mm in the elongated direction. The Mg2SiO4 elongation was on the c-axis. The growth mechanism of the whiskers was investigated on the basis of chemical thermodynamics, and the present study revealed that the Mg2SiO4 whiskers grew by a VS (vapor-solid) mechanism.
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Synthesis of MgAl2O4 Whiskers by an Oxidation‐Reduction Reaction
Journal of the American Ceramic Society, 1995Co-Authors: Shinobu Hashimoto, Akira YamaguchiAbstract:Magnesium orthosilicate (forsterite) whiskers were synthesized by an Oxidation-Reduction Reaction in the present investigation. These whiskers were rectangular parallelepipeds, with long sides in a cross-sectional view from two to ten times as long as the short sides, and measuring from several micrometers to 200 μm wide and ∼15 mm in the elongated direction. The Mg2SiO4 elongation was on the c-axis. The growth mechanism of the whiskers was investigated on the basis of chemical thermodynamics, and the present study revealed that the Mg2SiO4 whiskers grew by a VS (vapor-solid) mechanism.
