In the concept of a microstructured bubble column reactor, meshes coated with catalyst can cut the bubbles, which in turn results in high interfacial area and enhanced interface hydrodynamics. In previous work, we developed a closure model for the fate of bubbles interacting with a wire mesh based on the outcomes of energy balance analysis. In this paper, the model is validated using Euler-Lagrange simulations against two experimental cases of microstructured bubble columns. Before validation of the model, the definition of the deceleration thickness, as used in the calculation of the virtual mass term, is refined to introduce the effects of liquid viscosity and wire thickness. Proceeding with the validation, the inclusion of our cutting closure model results in an excellent match of the bubble size reduction by the wire mesh with the experimental data. Consequently, the simulations produce a more accurate prediction of the reactor performance for the gaseous reaction in view of the pH and gas holdup profiles. The effect of liquid viscosity on the bubble size reduction by the wire mesh is replicated accurately as well. Noticeably, the significance of bubble coalescence and breakup in bubble dynamics overperforms the role of bubble cutting at high superficial gas velocities; thus, further improvement is needed there. Finally, based on the validated cutting model, we share some perspectives on the design of wire meshes to increase the bubble interfacial area.
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http://dx.doi.org/10.1021/acs.iecr.3c02352 | DOI Listing |
AAPS J
January 2025
Institute of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, China.
Freeze drying is one of the common methods to extend the long-term stability of biologicals. Biological products in solid form have the advantages of convenient transportation and stable long-term storage. However, long reconstitution time and extensive visible bubbles are frequently generated during the reconstitution process for many freeze-dried protein formulations, which can potentially affect the management efficiency of staff, patient compliance, and product quality.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
Department of Mechanical Engineering, Boston University, 110 Cummington Mall, Boston, Massachusetts 02215, United States.
Hydrogen bubble adhesion to the electrode presents a major obstacle for green hydrogen generation via the hydrogen evolution reaction (HER) as it would induce undesired overpotential and undermine the reaction efficiency by reducing reaction area, increasing transport resistance, and creating an undesired ion concentration gradient. While electrodes with aerophobic/hydrophilic surfaces have been developed to facilitate bubble detachment, they primarily rely on micro- and nanostructured catalyst surfaces to enhance buoyance-induced bubble departure. Here, we demonstrate that introducing nonreactive yet more hydrophilic surfaces can promote coalescence-induced bubble departure, thereby significantly reducing the transport overpotential and improving HER performance.
View Article and Find Full Text PDFSci Rep
January 2025
Udmurt Federal Research Center of the Ural Branch of RAS, Baramzina str. 34, Izhevsk, 426067, Russia.
Ultrasound can improve the quality of finished products by reducing porosity and enhancing microstructure in selective laser melting, directed energy deposition, and laser beam welding. This study evaluates the efficiency of ultrasound produced by a pulsed laser via the optoacoustic effect. A quantitative model of collapse of vapor-gas bubbles has been developed under the conditions of ultrasonic treatment at near resonance frequencies.
View Article and Find Full Text PDFMicromachines (Basel)
December 2024
Department of Mechanical Engineering, The University of Memphis, Memphis, TN 38152, USA.
Microbubbles, acting as cavitation nuclei, undergo cycles of expansion, contraction, and collapse. This collapse generates shockwaves, alters local shear forces, and increases local temperature. Cavitation causes severe changes in pressure and temperature, resulting in surface erosion.
View Article and Find Full Text PDFJ Chem Phys
December 2024
Baikov Institute of Metallurgy and Materials Science, Russian Academy of Sciences, 49 Leninsky Pr., 119334 Moscow, Russian Federation.
Copper and its alloys with transition metals (as good conductors of electricity and heat) are extensively used in electrical industry, electronics, and cooling systems and can be the subject of surface degradation by oxidation. In certain circumstances, surface degradation of copper occurs catastrophically. Predicting catastrophic oxidation kinetics and developing protective technology require understanding the mass transfer mechanisms in the solid/liquid/gas composite scale formed on the copper surface during catastrophic degradation.
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