Article
Engineering, Chemical
Lian Zhang, Kai Yang, Meng Li, Qingtai Xiao, Hua Wang
Summary: In this work, a novel stirring strategy called chaotic-speed with Logistic-Logistic cascade sequence (CS-LLCS) was proposed to enhance the quality of solid-liquid mixing state. The effects of stirring strategy, peak level (n(pvcs)), and speed changing time (t(sct)) of CS-LLCS stirring on the mixing state quality were investigated. Results showed that CS-LLCS stirring significantly reduced mixing time and power consumption compared to bidirectional-speed stirring (BS stirring) and constant speed stirring (CS stirring). The optimal stirring performance was achieved at a peak level of 140 r/min and a speed changing time of 3 s. The CS-LLCS stirring disrupted the periodic motion of vortices and increased the interfacial area of immiscible liquids, leading to improved mixing state quality. A chaotic indicator, K-c*(n), was proposed to accurately characterize the difference changes of chaos degree in various chaos mixing processes. The chaotic-speed stirring strategy with Logistic-Logistic cascade sequence enhanced energy transfer efficiency.
Review
Engineering, Chemical
Qianqian Kang, Jinfan Liu, Xin Feng, Chao Yang, Jingtao Wang
Summary: This study reviews the research on IMRs, enhancement of laminar mixing, and particle clustering within IMRs. The majority of studies aim to destroy IMRs and improve chaotic mixing, using methods such as off-centered agitation and dynamic mixing protocol. Techniques to characterize the shape and size of IMRs and mixing effect are summarized using experiments and simulations.
CHINESE JOURNAL OF CHEMICAL ENGINEERING
(2022)
Article
Engineering, Chemical
Deyin Gu, Ye Mei, Li Wen, Xingmin Wang, Zuohua Liu
Summary: Fractal impeller showed better gas holdup, smaller bubble size and gas-liquid dispersion performance compared to pitched-blade impeller, leading to an increase in volume mass transfer coefficient. The experimental results provide theoretical guidance for the optimal design of gas-liquid stirred tanks.
JOURNAL OF THE TAIWAN INSTITUTE OF CHEMICAL ENGINEERS
(2021)
Article
Materials Science, Multidisciplinary
Adam B. Cahaya, Rico M. Sitorus, Anugrah Azhar, Ahmad R. T. Nugraha, Muhammad Aziz Majidi
Summary: In a magnetic multilayer, the spin transfer between localized magnetization dynamics and itinerant conduction spin arises from the interaction between a normal metal and an adjacent ferromagnetic layer. In this work, using the generalized Anderson model, we estimate the spin-mixing conductance that arises from the orbital hybridization and find that it increases the magnitude of the spin-mixing conductance.
Article
Engineering, Chemical
Mengke Guo, Zhuotai Jia, Shuaifeng Zhang, Bo Kong, Minghui Xie, Qinghua Zhang, Chao Yang
Summary: The study focuses on the application of V-shaped punched baffle in gas-liquid systems and compares its performance with standard baffles. The results indicate that V-shaped baffles can enhance fluid mixing and improve gas dispersion and turbulence, especially VSPB-2.
JOURNAL OF THE TAIWAN INSTITUTE OF CHEMICAL ENGINEERS
(2023)
Article
Engineering, Chemical
A. Zak, F. Alberini, F. Maluta, T. Moucha, G. Montante, A. Paglianti
Summary: This study investigates a gas-liquid stirred tank of high aspect ratio that replicates the geometry of typical industrial aerated fermenters. The liquid phase homogenization dynamics and gas phase spatial distribution are determined using Electrical Resistance Tomography. The reliability of the collected data is quantitatively evaluated by comparing results obtained from vertical and horizontal arrangements of electrodes.
CHEMICAL ENGINEERING RESEARCH & DESIGN
(2022)
Article
Materials Science, Multidisciplinary
R. G. Gontijo, A. B. Guimaraes
Summary: This study numerically investigates the effect of a rotating magnetic field on heat dissipation in magnetic hyperthermia. A validated code based on Langevin Dynamics is used to simulate the problem. The results show nonlinear response of the magnetic suspension to the amplitude and frequency of the field. The relaxation time and volume fraction of particles also influence the thermal response. The analysis provides insights into the system's behavior based on timescales and micro-structural features of the suspension.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
Article
Chemistry, Physical
Wenchuan Liu, Dengwei Jing
Summary: It is proposed to use a rotating electric field to stretch a droplet into a liquid film pinned to the channel inner wall as an active liquid valve. Molecular dynamics simulations prove that droplets in nanochannels can be stretched and expanded into closed liquid films under the action of rotating electric fields. The formation of the liquid film occurs through gradual expansion and liquid column rotation, with increased electric field strength and angular frequency favoring liquid film closing.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Physics, Applied
Min Xu, Guiqian Jiang, Zhiyu Zhang, Jinyu Zhang, Changjing Hu, Wenlong Chen, Yuliang Chen
Summary: Irreversible vortex core switching in Pac-man disks has been investigated using micromagnetic simulations. The switching process is related to the evolution of energy densities, particularly a sharp peak in the local exchange energy density. The weak interaction between reversed vortex and rotating magnetic field enables the realization of irreversible switching. The work also explores the motion behavior of vortex and the impact of rotating magnetic fields on the switching time.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Engineering, Electrical & Electronic
Zhezai Hu, Chengqian Zhang, Haonan Sun, Xuejiao Ma, Peng Zhao
Summary: In this study, a method for controlling the length of hard magnetic particle chains using a rotating magnetic field was proposed. The results show that changing the frequency of the rotating magnetic field can effectively control the length of the magnetic particle chains. This convenient and stable method can be applied to manufacturing magnetic soft robots with more complex structures and diversified functions.
SENSORS AND ACTUATORS A-PHYSICAL
(2023)
Article
Computer Science, Artificial Intelligence
Giuseppe Forte, Federico Alberini, Mark Simmons, Hugh E. Stitt
Summary: This study developed a method to evaluate gas-liquid mixing regimes using acoustic emission data, and successfully identified different operating conditions with high accuracy in various flow regimes.
JOURNAL OF INTELLIGENT MANUFACTURING
(2021)
Article
Physics, Fluids & Plasmas
Baoming Ren, Jiadong Zhang, Zhida Yang, Guanghui Zhu, Haiyang Zhou, Jian Zheng, Xuan Sun
Summary: A novel method using rotating magnetic field to control plasma rotation speed was reported in this study, where electron-ion collisions are found to drive rotation. The experiment showed that plasma rotation speed is primarily determined by the RMF strength, with the rotation starting from the outside and developing sheared flow in the core region.
PLASMA PHYSICS AND CONTROLLED FUSION
(2021)
Article
Engineering, Multidisciplinary
Zhengyang Liu, Yongxing Song, Jizhou Liu, Linhua Zhang, Bin Huang, Dazhuan Wu, Jingting Liu
Summary: This study investigates the multi-physical instabilities of rotating machines under air-gap eccentricity fault using numerical and experimental methods. Electromagnetic simulations are carried out to calculate magnetic flux density and unbalanced magnetic pull. Signal acquisition and demodulation methods are employed to extract the modulation characteristics. The results show that the instabilities can be monitored and diagnosed using the modulation characteristics of multi-physical field signals.
ALEXANDRIA ENGINEERING JOURNAL
(2023)
Article
Materials Science, Multidisciplinary
Rong Cheng, Liangjin Zhang, Yanbin Yin, Jiongming Zhang
Summary: Research on gas agitation characteristics of side blowing in a 1:3 scale model ladle of a 150 t industrial gas-stirred ladle shows that side blowing with more than two plugs near the ladle bottom enhances water flow velocity and agitation power, improves uniformity of water velocity distribution, reduces stagnant regions, and shortens mixing time compared to bottom blowing.
Article
Engineering, Mechanical
Kai Yang, Xue Zhang, Meng Li, Qingtai Xiao, Hua Wang
Summary: In this study, a new method is proposed to measure the mixing state quality of gas-liquid two-phase flow stirred by top-blown air using electrical capacitance tomography (ECT)-based visualization experiments. The ECT measurement system successfully visualizes the thermal condition of the flow and accurately estimates the mixing time using chaos detection and logistic regression methods. Experimental and calculated results demonstrate the accuracy of ECT in visualizing the flow pattern and provide theoretical basis for the actual production process.
FLOW MEASUREMENT AND INSTRUMENTATION
(2022)
Article
Physics, Condensed Matter
M. Ziauddin, E. Schleicher, P. Trtik, L. Knuepfer, A. Skrypnik, T. Lappan, K. Eckert, S. Heitkam
Summary: The liquid fraction of foam is crucial for engineering process control and foam rheology interpretation. Existing measurement tools, such as optical measurement and radiography techniques, are mostly limited to laboratory settings, while conductivity-based measurements lack detailed spatial information. In this study, we compare the conductivity-based wire-mesh sensor with neutron radiography and find a linear relationship between the liquid fraction and wire-mesh readings with a deviation of less than 15%. However, the wire-mesh sensor systematically overestimates the liquid fraction due to liquid bridge formation between the wires.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Review
Chemistry, Multidisciplinary
Mariya E. Ivanova, Ralf Peters, Martin Mueller, Stefan Haas, Martin Florian Seidler, Gerd Mutschke, Kerstin Eckert, Philipp Roese, Sonya Calnan, Rory Bagacki, Rutger Schlatmann, Cedric Grosselindemann, Laura-Alena Schaefer, Norbert H. Menzler, Andre Weber, Roel van de Krol, Feng Liang, Fatwa F. Abdi, Stefan Brendelberger, Nicole Neumann, Johannes Grobbel, Martin Roeb, Christian Sattler, Ines Duran, Benjamin Dietrich, M. E. Christoph Hofberger, Leonid Stoppel, Neele Uhlenbruck, Thomas Wetzel, David Rauner, Ante Hecimovic, Ursel Fantz, Nadiia Kulyk, Jens Harting, Olivier Guillon
Summary: Hydrogen produced from renewables will have a growing impact on global energy dynamics towards sustainability and carbon neutrality. However, the current share of green hydrogen is too low, and there is a rising demand for high-quality hydrogen. This highlights the need for economically viable hydrogen generation technologies. This article evaluates existing technologies for high-quality hydrogen production based on solar energy, considering their current development level, technical limitations, and future potential.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Physical
Hannes Rox, Aleksandr Bashkatov, Xuegeng Yang, Stefan Loos, Gerd Mutschke, Gunter Gerbeth, Kerstin Eckert
Summary: A novel 3-electrode cell is used to investigate H2 evolution on porous electrodes in an alkaline electrolyte. Electrochemical methods and high-speed optical measurement are applied to characterize the electrodes and bubble dynamics. The size of detached bubbles and the surface coverage of the electrode are significantly influenced by the applied current density. Forced flow reduces the bubble size, while the initial transient is less affected by flow-through.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Chemistry, Multidisciplinary
Tobias Lappan, Dominic Herting, Muhammad Ziauddin, Julian Stenzel, Natalia Shevchenko, Sven Eckert, Kerstin Eckert, Sascha Heitkam
Summary: In mineral processing, froth flotation is used to recover valuable mineral particles through overflowing froth. However, the velocity profile of the overflowing froth beneath its free surface cannot be observed optically. This study combines X-ray radiography and particle tracking velocimetry to measure local flow velocities within an optically opaque foam at a weir. Tracer particles were used to trace the flow in X-ray image sequences, and the velocity profile above the weir crest was determined.
APPLIED SCIENCES-BASEL
(2023)
Article
Nanoscience & Nanotechnology
Lukas Krause, Katarzyna Skibinska, Hannes Rox, Robert Baumann, Mateusz M. Marzec, Xuegeng Yang, Gerd Mutschke, Piotr Zabinski, Andres Fabian Lasagni, Kerstin Eckert
Summary: Emerging manufacturing technologies allow for the design of electrocatalyst morphology on the nanoscale to improve efficiency in electrolysis processes. This study investigates the impact of electrode-attached hydrogen bubbles on electrode performance, depending on surface morphology and wettability. Nickel-based electrocatalysts with hydrophilic and hydrophobic nanostructures are manufactured and their surface properties are characterized. Despite a larger electrochemically active surface area, electrochemical analysis shows that samples with more pronounced hydrophobic properties perform worse at industrially relevant current densities. High-speed imaging reveals larger bubble detachment radii with higher hydrophobicity, indicating that gas blockage outweighs the benefits of nanostructuring. Additionally, a slight decrease in bubble size of 7.5% is observed with an increase in current density in 1 M KOH.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Engineering, Chemical
Aliyar Javadi, Majede Nourizade, Mohammad Rahmani, Kerstin Eckert
Summary: In photocatalytic processes for wastewater treatment, understanding the interactions between the catalyst and pollutant is crucial. This study uses drop profile analysis tensiometry (PAT) to analyze the surface tension and elasticity of dye solutions mixed with catalyst nanoparticles at different pH conditions. The results show that the surface activity of the dye Malachit Green (MG) increases at pH 9 when TiO2 nanoparticles are added. This indicates significant attraction and attachment of MG molecules to the surface of TiO2 nanoparticles, leading to higher degradation efficiency. The same trend is observed for the anionic dye Eriochrom Black-T (EBT) at pH 3.
CHEMICAL ENGINEERING SCIENCE
(2023)
Article
Mechanics
A. Bashkatov, A. Babich, S. S. Hossain, X. Yang, G. Mutschke, K. Eckert
Summary: The dynamics of hydrogen bubbles produced by water electrolysis in an acidic electrolyte are investigated using electrochemical and optical methods. Controlled production of interacting pairs of H2 bubbles is achieved through cyclic modulation of electric potential at a microelectrode. Three scenarios of bubble interactions are identified, with the most prominent one involving a sudden motion reversal of the first detached bubble, its return to the electrode, and eventual coalescence with the second bubble. Contactless motion reversal is explained by the competition between buoyancy and thermocapillary effects, as confirmed by Toepler's schlieren technique.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Yorgos Stergiou, Paszkal Papp, Dezso Horvath, Agota Toth, Kerstin Eckert, Karin Schwarzenberger
Summary: We investigated a convective buoyancy-driven instability that occurs when a denser miscible fluid is injected into a less dense one in a rectilinear geometry. The instability was visualized using shadowgraph technique and quantitative information was obtained using micro-Particle Image Velocimetry. Numerical simulations provided insights into the three-dimensional velocity field. We found that the instability occurs only above a certain Peclet number, depending on the Rayleigh and Schmidt numbers. Scaling laws for the critical time and dimensionless wavelength of the instability were proposed, showing their dependence on Pe and Ra. The interaction of the instability vortices with each other and the geometry boundaries was also investigated.
Article
Chemistry, Analytical
Piotr Piechota, Piotr Synowiec, Artur Andruszkiewicz, Wieslaw Wedrychowicz, Elzbieta Wroblewska, Andrzej Mrowiec
Summary: The aim of this work is to experimentally determine and evaluate the value of the correction factor for ultrasonic flow meters in order to improve their accuracy. This article discusses the measurement of flow velocity using clamp-on ultrasonic flow meters in the area of disturbed flow behind the distorting element. Water flow velocity tests were performed at different Reynolds numbers and distances from the source of interference. The results indicate that compensation error of measurement performed behind the disturbance without keeping the required straight sections of the pipeline is possible by using the correction factor.
Article
Engineering, Chemical
Sameh Alsaqoor, Piotr Piechota, Ali Alahmer, Samer As'ad, Nabil Beithu, Wieslaw Wedrychowicz, Artur Andruszkiewicz, Patryk Kotomski
Summary: This study examines the impact of changes in velocity profiles on the measurement inaccuracies of gas flow detected by an ultrasonic flowmeter. Variations in the shape factor coefficient are caused by changes in the downhill flow rate, affecting the cross-sectional velocity profile. The processing equation used in the flowmeter should take into account these variations to avoid inaccuracies in flow measurement.
Correction
Physics, Multidisciplinary
Felix Schindler, Sven Eckert, Till Zuerner, Jorg Schumacher, Tobias Vogt
PHYSICAL REVIEW LETTERS
(2023)
Article
Chemistry, Analytical
Sylvie Su, Tianyi Niu, Tobias Vogt, Sven Eckert
Summary: The capabilities of Fiber Bragg Grating (FBG) sensors to measure temperature variations in liquid flows without encapsulation were investigated in this study. Experimental tests were conducted using thin glass fibers placed under defined tension to improve their stiffness and immobility. The results showed that the FBG sensors can accurately measure relative temperature and obtain absolute temperature readings through appropriate correction. The study discusses the capabilities and limitations of this measurement technique for detecting temperature fields in liquid flows.
Article
Chemistry, Physical
Milad Eftekhari, Karin Schwarzenberger, Stoyan I. Karakashev, Nikolay A. Grozev, Kerstin Eckert
Summary: This article focuses on the interaction between oppositely charged nanoparticles and surfactants and their influence on interfacial properties. The findings suggest that the surfactant/nanoparticle ratio primarily determines the interfacial properties, affecting the rheological properties of the interface while not significantly impacting surface tension.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2024)
