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  • 1.
    Chen, Chao
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Some Aspects on Macroscopic Mixing in a Tundish2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Two aspects on macroscopic mixing in a continuous flow system – metallurgical tundish were studied. Specifically, 1) the first focus was on salt solution tracer mixing, which is important for tundish design from perspectives of tracer technology and Residence Time Distributions (RTD) as well as for the understanding of the macroscopic mixing in tundishes. The different amounts of salt solution tracer mixing in a tundish were studied by using both physical models and mathematical models. The disturbance of KCl salt tracer on the flow in the tundish with respect to different amounts is like the “butterfly effect”, i.e. only a slight increase of the amount of tracer, the flow field might be disturbed. This, in turn, will result in a shifted RTD curve. 2) The second focus was on Eulerian modeling of inclusions macroscopic transport and removal, which is important for tundish design from perspectives of inclusions removal and to provide information of macroscopic removal of inclusions. In the study, an approach that combined the meso-scale inclusions deposition at turbulent boundary layers of steel-slag interface and the macroscopic transport of inclusions in the tundish was used. The theoretical calculation results showed that the effect of the roughness on the deposition velocity of small inclusions (radius of 1 μm) were more pronounced than that for the big inclusions (up to the radius of 9 μm). The dynamic inclusions removal studies showed that the tundish with a weir and a dam exhibited a better performance with respect to the removal of bigger inclusions (radii of 5 μm, 7 μm and 9 μm) than that of the case without weirs and dams. However, the tundish without weirs and dams showed a higher removal ratio of smaller inclusions (radius of 1 μm).

  • 2.
    Chen, Chao
    et al.
    State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, China.
    Cheng, Guoguang
    State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, China.
    Sun, Haibo
    State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, China.
    Hou, Zibing
    State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Chaina.
    Wang, Xinchao
    State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing.
    Zhang, Jiaquan
    State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, China.
    Effects of Salt Tracer Amount, Concentration and Kind on the Fluid Flow Behavior in a Hydrodynamic Model of Continuous Casting Tundish2012In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 83, no 12, p. 1141-1151Article in journal (Refereed)
    Abstract [en]

    The hydrodynamic modeling method that widely used to simulate the fluid flow was reconsidered and discussed in this paper. The effects of injected salt tracer amount, concentration and kind on the fluid flow behavior in a hydrodynamic model tundish were investigated. The results were compared with the mathematical modeling calculation results, that the tracer density effect was eliminated. The residence time distribution (RTD) curve of tracer introduced deviated to the left side of the calculated curve, besides the deviation was increased as dimensionless tracer amount (the ratio of tracer amount to hydrodynamic model tundish volume) increased from 0.202 × 10−3 to 1.008 × 10−3. The results of tracer concentration study were similar, namely the deviation was increased with concentration increased; on the other hand, the deformation of a “stair-shape” RTD curve occurred when tracer concentration was much lower (at dimensionless tracer amount of 0.168 × 10−3 with converting to saturated solution). Besides, the effect of tracer kind on the accuracy of hydrodynamic modeling was also studied; the measurements of KCl solution with lower density than that of NaCl solution exhibited more of accuracy. Finally, the optimized tracer in hydrodynamic model tundish of present work is saturated KCl solution with dimensionless tracer amount of 0.202 × 10−3.

  • 3.
    Chen, Chao
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Illergård, Josefin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Effect of cationic polyelectrolytes in contact-active antibacterial layer-by-layer functionalization2017In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 71, no 7-8, p. 649-658Article in journal (Refereed)
    Abstract [en]

    Contact-active surfaces have been created by means of the layer-by-layer (LbL) modification technique, which is based on previous observations that cellulose fibers treated with polyelectrolyte multilayers with polyvinylamine (PVAm) are perfectly protected against bacteria. Several different cationic polyelectrolytes were applied, including PVAm, two different poly(diallyl dimethyl ammonium chloride) polymers and two different poly(allylamine hydrochloride) polymers. The polyelectrolytes were self-organized in one or three layers on cellulosic fibers in combination with polyacrylic acid by the LbL method, and their antibacterial activities were evaluated. The modified cellulose fibers showed remarkable bacterial removal activities and inhibited bacterial growth. It was shown that the interaction between bacteria and modified fibers is not merely a charge interaction because a certain degree of bacterial cell deformation was observed on the modified fiber surfaces. Charge properties of the modified fibers were determined based on polyelectrolyte titration and zeta potential measurements, and a correlation between high charge density and antibacterial efficiency was observed for the PVAm and PDADMAC samples. It was demonstrated that it is possible to achieve antibacterial effects by the surface modification of cellulosic fibers via the LbL technique with different cationic polyelectrolytes.

  • 4.
    Chen, Chao
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Royal Inst Technol KTH, Fibre & Polymer Technol, Stockholm, Sweden..
    Illergård, Josefin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Royal Inst Technol KTH, Fibre & Polymer Technol, Stockholm, Sweden..
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Royal Inst Technol KTH, Fibre & Polymer Technol, Stockholm, Sweden..
    Ek, Monica
    Royal Inst Technol KTH, Fibre & Polymer Technol, Stockholm, Sweden..
    Evaluation of Antibacterial functionalizations of CNF/PVAm multilayer modified cellulose fibre and surface studies on silica model surface2017In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 253Article in journal (Other academic)
  • 5.
    Chen, Chao
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. FOI, Swedish Defence Research Agency, Division of CBRN Defence and Security.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Cheng, Guoguang
    State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    A CFD Model Study of the Macroscopic Transport and Dynamic Removal of Inclusions at a Steel-Slag Interface for Different Tundish DesignsManuscript (preprint) (Other academic)
  • 6.
    Chen, Chao
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. FOI, Swedish Defence Research Agency, Division of CBRN Defence and Security.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Cheng, Guoguang
    State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    A Mathematical Modeling Study of the Influence of Small Amounts of KCl Solution Tracers on Mixing in Water and its Residence Time Distribution in a Continuous Flow Reactor-Metallurgical Tundish2015In: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 137, p. 914-937Article in journal (Other academic)
    Abstract [en]

    In an earlier research (Chen et al., 2015a) a mathematical model was established to simulate tracer mixing (a KCl solution). The predicted Residence Time Distribution (RTD) curves showed good agreements with experimental RID curves for larger amounts of tracer additions. However, for smaller additions (50 mL) of a KCl solution into water, the predicted RID curves tended to deviate from the experimental RTD curves for a tundish (a continuous flow reactor). The current paper focuses on the possibilities that the predictability for smaller additions could be resolved by using a suitable turbulence model. The performance of five different turbulence models representing different modeling techniques and levels of complexity were tested in combination with using a density-coupled mixed composition fluid model to simulate the mixing, i.e. the following models: LVEL, Chen-Kim k-epsilon, MMK k-epsilon, Explicit Algebraic Reynolds Stress Model (EARSM), and Large Eddy Simulation (LES): Wall-Adapting Local Eddy-viscosity (WALE). The results indicate that models that tend to resolve turbulence structures renders better predictions of the mixing process of smaller tracer amounts. In addition, the influence of different tracer amounts on the flow in tundish was assessed. The simulation results for 75 mL, 100 mL, 150 mL, and 250 mL KCl tracer additions were compared. The results showed that in an upward flow the tracer will, sooner or later (dependent on the tracer amount), sink to the bottom. This is due to the higher density of the tracer compared to the density of water. From a physical modeling perspective, this issue is like the "butterfly effect". It is showed that for a slight increase of the amount of tracer, the flow field might be disturbed. This, in turn, will result in a shifted RTD curve.

  • 7.
    Chen, Chao
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, China .
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. Swedish Def Res Agcy, FOI, Div CBRN Def & Secur, Sweden.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Cheng, Guoguang
    State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    A Mathematical Modeling Study of Tracer Mixing in a Continuous Casting Tundish2015In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 46, no 1, p. 169-190Article in journal (Refereed)
    Abstract [en]

    A mathematical model based on a water model was developed to study the tracer mixing in a single strand tundish. The mixing behavior of black ink and KCl solution was simulated by a mixed composition fluid model, and the data were validated by water modeling results. In addition, a model that solves the scalar transport equation (STE) without any physical properties of the tracer was studied and the results were compared to predictions using the density-coupled model. Furthermore, the mixing behaviors of different amounts of KCl tracers were investigated. Before the model was established, KCl tracer properties such as the KCl molecule diffusion (KMD), the water molecule self-diffusion (WSD) in KCl solution, and the KCl solution viscosity (KV) were evaluated. The RTD curve of 250 mL KCl for the KMD case was closer to the water modeling results than that of the case implemented with only density. Moreover, the ensemble average deviation of the RTD curves of the cases implemented with KMD+ WSD, KMD+ KV, and KMD+ WSD+ KV to the KMD case is less than 0.7 pct. Thus, the water self-diffusion and KV were neglected, while the KCl density and KMD were implemented in the current study. The flow pattern of black ink was similar to the STE result i. e., the fluid flowed upwards toward the top surface and formed a large circulating flow at the outlet nozzle. The flow behavior of the 100, 150, and 250 mL KCl cases exhibited a strong tendency to sink to the tundish bottom, and subsequently flow through the holes in the dam. Thereafter, it propagated toward the outlet nozzle. Regarding the KCl tracer amount, the tracer concentration propagated to the outlet nozzle much faster for the larger amount case than for the smaller amount cases. However, the flow pattern for the 50 mL KCl case was somewhat different. The fluid propagated to the top surface which acted like black ink during the initial injection, and subsequently the fluid flowed throughout the holes at a much slower pace. The breakthrough time and peak concentration of RTD curves of model predictions and water modeling results showed a good agreement (all difference within 12.5 pct) for the 100, 150, and 250 mL KCl cases.

  • 8.
    Chen, Chao
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing.
    Ni, Peiyuan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. FOI, Swedish Defence Research Agency, Division of CBRN Defence and Security.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Cheng, Guoguang
    State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Application of a Unified Eulerian Model to Study the Inclusions Deposition at a Steel-Slag Interface in a TundishManuscript (preprint) (Other academic)
  • 9.
    Chen, Chao
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Pettersson, Torbjörn
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Illergård, Josefin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Ek, Monica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Influence of Cellulose Charge on Bacteria Adhesion and Viability to PVAm/CNF/PVAm-Modified Cellulose Model Surfaces2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602Article in journal (Refereed)
    Abstract [en]

    A contact-active antibacterial approach based on the physical adsorption of a cationic polyelectrolyte onto the surface of a cellulose material is today regarded as an environment-friendly way of creating antibacterial surfaces and materials. In this approach, the electrostatic charge of the treated surfaces is considered to be an important factor for the level of bacteria adsorption and deactivation/killing of the bacteria. In order to clarify the influence of surface charge density of the cellulose on bacteria adsorption as well as on their viability, bacteria were adsorbed onto cellulose model surfaces, which were modified by physically adsorbed cationic polyelectrolytes to create surfaces with different positive charge densities. The surface charge was altered by the layer-by-layer (LbL) assembly of cationic polyvinylamine (PVAm)/anionic cellulose nanofibril/PVAm onto the initially differently charged cellulose model surfaces. After exposing the LbL-treated surfaces to Escherichia coli in aqueous media, a positive correlation was found between the adsorption of bacteria as well as the ratio of nonviable/viable bacteria and the surface charge of the LbL-modified cellulose. By careful colloidal probe atomic force microscopy measurements, it was estimated, due to the difference in surface charges, that interaction forces at least 50 nN between the treated surfaces and a bacterium could be achieved for the surfaces with the highest surface charge, and it is suggested that these considerable interaction forces are sufficient to disrupt the bacterial cell wall and hence kill the bacteria.

  • 10.
    Ek, Monica
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Illergård, Josefin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Chen, Chao
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Biointeractive fibers with antibacterial properties2016In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 251Article in journal (Other academic)
  • 11.
    Huang, Tianxiao
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Chen, Chao
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Li, Dongfang
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Ek, Monica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH Royal Inst Technol, Stockholm, Sweden..
    Hydrophobic and antibacterial textile fibres prepared by covalently attaching betulin to cellulose2019In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Article in journal (Other academic)
1 - 11 of 11
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