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  • 1.
    Akbarnejad, Shahin
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Mathematical and Experimental Study on Filtration of Solid Inclusions from Molten Aluminium and Steel2023Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Aluminium och stål har varit den mest producerade metallen respektive legeringen under många år. Deras omfattande användning i olika industrier, deras grundläggande roll i vårt vardagliga liv och deras utmärkta återvinningsegenskaper utgör de stora drivkrafterna för utvecklingen av en produktion mot mer hållbara processer. En framgångsrik integrering och tillämpning av smält metallfiltrering från oönskade inneslutningar i produktionsprocesser kan resultera i minskningar av skrot och omarbetning samt skulle ge en renare smält metall som kan leda till en produktion av metalliska material med förbättrade mekaniska egenskaper. Filtrering av aluminiumsmältor med keramiska skumfilter utgör en etablerad process inom aluminiumindustrin. Keramiska filter används också i stålgjuterier för att avlägsna inneslutningar från smältan före gjutning i en form. Användningen av keramiska filter är dock antingen begränsad till specifika typer av legeringar eller gjutgods eller till specifika filter med stora porer och öppningar. Som ett resultat av detta har användningen av keramiska filter i stålindustrin begränsningar när det gäller att fånga upp inneslutningar, där specifikt små inneslutningar inte kan fångas upp.

     Detta forskningsarbete syftar till att bidra till det globala arbetet med att utveckla processerna för tillverkning av smält metall för att bli mer hållbara och för att höja kvaliteten på slutprodukten. För att vara specifik syftar det till att sprida mer ljus gällande filtreringsapplikationer och användningen av keramiska filter för att avlägsna fasta icke-metalliska inneslutningar från smält aluminium och stål. Således bestämdes permeabilitetsegenskaper för enkla 30, 50 och 80 porer per tum (PPI) aluminiumoxid keramiska skumfilter (CFF) kvaliteter såväl som staplar av tre 30, tre 50 och tre 80 PPI aluminiumoxid CFF-kvaliteter baserat på experimentella och numeriska studier. Detta ger den information som behövs för att uppskatta det tryck som krävs för att grunda och/eller trycka det smälta aluminiumet genom filtren. Trycket kan antingen byggas upp av gravitationskrafter eller andra krafter. Det har nyligen visat sig att det är möjligt att grunda sådana filter med elektromagnetiska krafter och filtrera fasta inneslutningar från smält aluminium. Slutligen undersöktes och studerades fysisk raffinering av smält stål från fasta aluminiumoxidinneslutningar genom användande av ett monolitiskt extruderat fyrkantscelligt aluminiumoxidkeramiskt filter med en utvecklad matematisk Computational Fluid Dynamics (CFD) modell samt partikelbanorna för inneslutningar i storleksintervallet 1 till 100 [um].

     De experimentellt erhållna permeabilitetsegenskaperna såväl som de erhållna tryckgradientprofilerna för de enskilda 30, 50 och 80 PPI CFF:erna jämfördes med tidigare forskningsresultat från litteraturen. Överlag så var överensstämmelse mellan nuvarande och tidigare resultat god. Det visade sig också att det var viktigt att vätskan inte tog genvägar under permeabilitetsexperiment för att inte erhålla avvikelser så höga som 60 %. Det visade sig också att liknande permeabilitetsegenskaper för de staplade filtren som för de enskilda filtren kunde uppnås. Ett ungefär tre gånger högre tryckgradient eller tryck måste dock appliceras när man använder en stapel med tre identiska PPI-filter jämfört när enstaka filter används. De numeriska simuleringarna validerade också de experimentella resultaten från permeabilitetsexperimenten.

     CFD-simuleringarna och partikelbanorna för de fasta aluminiumoxidinneslutningarna i smält stål genom det monolitiska aluminiumoxidfiltret visade att det var möjligt att fånga upp alla partiklar större än 50 [µm]. Det var dock inte möjligt att fånga upp alla partiklar mindre än 50 [µm] på grund av den användande simuleringsmetoden samt de nuvarande simuleringsbegränsningar i programvaran.

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  • 2.
    Akbarnejad, Shahin
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Sheng, Dong-yuan
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    A Computational Fluid Dynamics Study on Physical Refining of Steel Melts by Filtration2023Ingår i: Metals, ISSN 2075-4701, Vol. 13, nr 6, artikel-id 1022Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, a previous experimental investigation on physical refining of steel melts by filtration was numerically studied. To be specific, the filtration of non-metallic alumina inclusions, in the size range of 1-100 & mu;m, was stimulated from steel melt using a square-celled monolithic alumina filter. Computational fluid dynamics (CFD) studies, including simulations of both fluid flow and particle tracing using the one-way coupling method, were conducted. The CFD predicted results for particles in the size range of & LE;5 & mu;m were compared to the published experimental data. The modeled filtration setup could capture 100% of the particles larger than 50 & mu;m. The percentage of the filtered particles decreased from 98% to 0% in the particle size range from 50 & mu;m to 1 & mu;m.

  • 3.
    Akbarnejad, Shahin
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Sheng, Dongyuan
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Jönsson, Pär Göran
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    A Computational Fluid Dynamics Study on Physical Refining of Steel Melts by FiltrationManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    In this paper, a previous experimental investigation on physical refining of steel melts by filtration was numerically studied. To be specific, filtration of non-metallic alumina inclusions, in the size range of 1 to 100 [μm], from steel melt by using a square-celled monolithic alumina filter was simulated. Computational fluid dynamics (CFD) studies, including simulations of both fluid flow and particle tracing using one-way coupling method, were conducted. The CFD predicted results for particles in the size range  5 [μm] were compared to the published experimental data. The modelled filtration setup could capture 100 % of the particles larger than 50 [μm]. The percentage of the filtered particles decreases from 98% to 0% in the particle size range of 50 [μm] to 1[μm].

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  • 4.
    Akbarnejad, Shahin
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Tilliander, Anders
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Sheng, Dongyuan
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Effect of Batch Dissimilarity on Permeability of Stacked Ceramic Foam Filters and Incompressible Fluid Flow: Experimental and Numerical Investigation2022Ingår i: Metals, ISSN 2075-4701, Vol. 12, nr 6, s. 1001-, artikel-id 1001Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ceramic foam filters (CFFs) are used to remove inclusions and/or solid particles from molten metal. In general, the molten metal poured on the top of a CFF should reach a certain height to form the pressure (metal head) required to prime the filter. For estimating the required metal head and obtaining the permeability coefficients of the CFFs, permeability experiments are essential. Recently, electromagnetic priming and filtration of molten aluminum with low and high grades of CFF, i.e., 30, 50 and 80 pore per inch (PPI) CFFs, have been introduced. Since then, there has been interest in exploring the possibility of obtaining further inclusion entrapment and aluminum refinement by using electromagnetic force to prime and filter with stacked CFFs. The successful execution of such trials requires a profound understanding concerning the permeability parameters of the stacked filters. Such data were deemed not to exist prior to this study. As a result, this study presents experimental findings of permeability measurements for stacks of three 30, three 50 and three 80 PPI commercial alumina CFFs from different industrial batches and compares the findings to numerically modelled data as well as previous research works. Both experimental and numerical findings showed a good agreement with previous results. The deviation between the experimentally and numerically obtained data lies in the range of 0.4 to 6.3%.

  • 5.
    Al-Saadi, Munir
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. R&D Metallurgy, AB Sandvik Materials Technology, SE-811 81 Sandviken, Sweden.
    Hulme-Smith, Christopher
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Sandberg, Fredrik
    R&D Metallurgy, AB Sandvik Materials Technology, SE-811 81 Sandviken, Sweden.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Hot Deformation Behaviour and Processing Map of Cast Alloy 825Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Alloy 825 is a nickel-based alloy that is commonly used in applications where both high strength and corrosion resistance are required. Applications include tanks in the chemical, food and petrochemical industries and oil and gas pipelines. Components made from Alloy 825 are often manufactured using hot deformation. However, there is no systematic study to optimise the processing conditions reported in literature. In this study, a processing map for as-cast Alloy 825 is established to maximise the power dissipation efficiency of hot deformation and correlate the processing conditions to final materials properties. The hot deformation behaviour of equiaxed Alloy 825 is characterized on the basis of the dynamic materials model and compression data in the temperature range of 950 °C to 1250 °C at an interval of 50°C and strain rate range of 0.01 s-1 to 10 s-1 to a true strain of 0.7 using a Gleeble-3500 thermomechanical simulator. Flow stress is modelled by the constitutive equation based on a hyperbolic sine function. The deformed material is characterized using Vickers hardness, optical microscopy and scanning electron microscopy, including electron backscattered diffraction. The true stress-true strain curves exhibit peak stresses followed by softening due to occurrence of dynamic recrystallization. The value of stress exponent in the hyperbolic sine-based constitutive equation, n=5.0. This suggests that the rate-limiting mechanism of deformation is climb (diffusion)-mediated dislocation glide. The activation energy for plastic flow in the temperature range tested is about 450 kJ mole-1, and the relationship between flow stress and temperature-compensated strain rate (via the Zener-Hollomon parameter) was found to be valid across this temperature range. The maximum power dissipation efficiency is over 35%. The highest efficiency is observed over temperature range of 1100 °C – 1250 °C and a strain rate of 0.01 s-1 – 0.1s-1. These are the optimum conditions for hot working. The optimum processing parameters for good strain hardening are obtained in the temperature range of between  950 °C  and  1100 °C with a strain rate between  0.3/s  and 10.0/s. 

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  • 6.
    Al-Saadi, Munir
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Hulme-Smith, Christopher
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Sandberg, Fredrik
    AB Sandvik Materials Technology.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Hot Deformation Behaviour and Processing Map of Cast Alloy 8252021Ingår i: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Alloy 825 is a nickel-based alloy that is commonly used in applications where both high strength and corrosion resistance are required, such as tanks in the chemical, food and petrochemical industries and oil and gas pipelines. Components made from Alloy 825 are often manufactured using hot deformation. However, there is no systematic study to optimise the processing conditions reported in literature. In this study, a processing map for as-cast Alloy 825 is established to maximise the power dissipation efficiency of hot deformation in the temperature range of 950 to 1250 °C at an interval of 50 °C and strain rate range of 0.01s−1 to 10.0s−1 to a true strain of 0.7 using a Gleeble-3500 thermomechanical simulator. The processing conditions are also correlated to the Vickers hardness of the final material, which is also characterised using optical microscopy and scanning electron microscopy, including electron backscattered diffraction. The true stress-true strain curves exhibit peak stresses followed by softening due to occurrence of dynamic recrystallization. The activation energy for plastic flow in the temperature range tested is approximately 450 kJ mol−1, and the value of the stress exponent in the (hyperbolic sine-based) constitutive equation, n=5.0, suggests that the rate-limiting mechanism of deformation is dislocation climb. Increasing deformation temperature led to a lower Vickers hardness in the deformed material, due to increased dynamic recrystallization. Raising the strain rate led to an increase in Vickers hardness in the deformed material due to increased work hardening. The maximum power dissipation efficiency is over 35%, obtained for deformation in the temperature range 1100-1250 °C and a strain rate of 0.01s−1-0.1s−1. These are the optimum conditions for hot working.

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  • 7.
    Al-Saadi, Munir
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer. Sandvik Materials Technology AB.
    Mu, Wangzhong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Strukturer.
    Hulme-Smith, Christopher
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Sandberg, Fredrik
    Sandvik Materials Technology AB.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Effect of Trace Magnesium Additions on the Dynamic Recrystallization in Cast Alloy 825 after One-Hit Hot-Deformation2021Ingår i: Metals, ISSN 2075-4701, Vol. 11, nr 1, artikel-id 36Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Alloy 825 is widely used in several industries, but its useful service life is limited by both mechanical properties and corrosion resistance. The current work explores the effect of the addition of magnesium on the recrystallization and mechanical behavior of alloy 825 under hot compression. Compression tests were performed under conditions representative of typical forming processes: temperatures between 1100 and 1250 °C and at strain rates of 0.1–10 s−1 to a true strain of 0.7. Microstructural evolution was characterized by electron backscattered diffraction. Dynamic recrystallization was found to be more prevalent under all test conditions in samples containing magnesium, but not in all cases of conventional alloy 825. The texture direction ⟨101⟩ was the dominant orientation parallel to the longitudinal direction of casting (also the direction in which the samples were compressed) in samples that contained magnesium under all test conditions, but not in any sample that did not contain magnesium. For all deformation conditions, the peak stress was approximately 10% lower in material with the addition of magnesium. Furthermore, the differences in the peak strain between different temperatures are approximately 85% smaller if magnesium is present. The average activation energy for hot deformation was calculated to be 430 kJ mol−1 with the addition of magnesium and 450 kJ mol−1 without magnesium. The average size of dynamically recrystallized grains in both alloys showed a power law relation with the Zener–Hollomon parameter, DD~Zn, and the exponent of value, n, is found to be 0.12. These results can be used to design optimized compositions and thermomechanical treatments of alloy 825 to maximize the useful service life under current service conditions. No experiments were conducted to investigate the effects of such changes on the service life and such experiments should now be performed.

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  • 8.
    Al-Saadi, Munir
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. R&D, AB Sandvik Materials Technology, SE-811 81Sandviken, Sweden..
    Sandberg, Fredrik
    R&D, AB Sandvik Materials Technology, SE-811 81Sandviken, Sweden..
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Hulme-Smith, Christopher
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Influence of Strain Magnitude on Microstructure, Texture and Mechanical Properties of Alloy 825 during hot-forgingManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Alloy 825 is a nickel-base alloy that is common in applications with high stresses and corrosive environments. It is commonly processed by hot forging, but there are few data about how hot forging affects the microstructure, which is critical for both mechanical and corrosion performance. Here, the alloy was hot forged in a commercial thermomechanical process to three industrially-relevant strains and the microscture was examined using scanning electron microscopy and EBSD. The tensile properties were also measured after thermomechanical treatment. Dynamic recrystallization was prevalent during the process, so increasing the forging strain leads to smaller grains and also higher dislocation density. Data were combined to allow the 0.2% proof stress to be calculated as a function of forging strain. All forging strains were sufficient to meet the criteria of the relevant industrial standard for this material. The maximum yield strength and ultimate tensile strength were obtained after forging to a true strain of 0.9 were 413 MPa and 622 MPa, respecitvely, with a ductlity of 40%. This may be used to tailor thermomechanical treatments to achieve precise mechanical properties and serve as a basis for future studies into the corrosion performance of this alloy as a function of forging strain.

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  • 9.
    Aragon-Briceno, Christian
    et al.
    Univ Twente, Dept Thermal & Fluid Engn, Drienerlolaan 5, NL-7522 NB Enschede, Netherlands..
    Pozarlik, Artur
    Univ Twente, Dept Thermal & Fluid Engn, Drienerlolaan 5, NL-7522 NB Enschede, Netherlands..
    Bramer, Eddy
    Univ Twente, Dept Thermal & Fluid Engn, Drienerlolaan 5, NL-7522 NB Enschede, Netherlands..
    Brem, Gerrit
    Univ Twente, Dept Thermal & Fluid Engn, Drienerlolaan 5, NL-7522 NB Enschede, Netherlands..
    Wang, Shule
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Wen, Yuming
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Yang, Weihong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Pawlak-Kruczek, Halina
    Wroclaw Univ Sci & Technol, Wybrzeze Wyspianskiego 27, PL-50370 Wroclaw, Poland..
    Niedzwiecki, Lukasz
    Wroclaw Univ Sci & Technol, Wybrzeze Wyspianskiego 27, PL-50370 Wroclaw, Poland..
    Urbanowska, Agnieszka
    Wroclaw Univ Sci & Technol, Wybrzeze Wyspianskiego 27, PL-50370 Wroclaw, Poland..
    Moscicki, Krzysztof
    Wroclaw Univ Sci & Technol, Wybrzeze Wyspianskiego 27, PL-50370 Wroclaw, Poland..
    Ploszczyca, Michal
    Wroclaw Univ Sci & Technol, Wybrzeze Wyspianskiego 27, PL-50370 Wroclaw, Poland..
    Integration of hydrothermal carbonization treatment for water and energy recovery from organic fraction of municipal solid waste digestate2022Ingår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 184, s. 577-591Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Anaerobic digestion is an efficient way of using a wet fraction of municipal solid waste (MSW) for energy purposes as it can produce biogas. The moisture content of the digestate after application of mechanical dewatering is still high, and the amount of heat needed for drying is significant. Hydrothermal carbonization (HTC) is a process that can potentially offer great benefits by improved mechanical dewatering and valorization of the digestate into a better quality solid fuel. This study focuses on the determination of the optimum HTC process conditions to recover water from the MSW digestate. Different process conditions as temperature (180, 200, and 230 °C) and residence time (30, 60, and 120 min) were tested. Furthermore, a mass and energy balance was carried out and a process model in Aspen Plus was built. Results showed that HTC treatment increased the water recovery (40–48%) during the dewatering process compared with the original feedstock (18%). The process model showed a positive energy balance of 110 kWh per ton of MSW digestate treated with an electrical efficiency of 23.9%.

  • 10.
    Aula, M.
    et al.
    Process Metallurgy Research Group, University of Oulu, P.O. Box 4300, FI-90014, Finland.
    Pauna, H.
    Process Metallurgy Research Group, University of Oulu, P.O. Box 4300, FI-90014, Finland.
    Andersson, Nils A. I.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Jonsson, Carrie
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Fabritius, Timo
    Process Metallurgy Research Group, University of Oulu, P.O. Box 4300, FI-90014, Finland.
    Arc plasma emerging from foaming slag - Plasma diagnostics and visual observations2018Ingår i: ICS 2018 - 7th International Congress on Science and Technology of Steelmaking: The Challenge of Industry 4.0, Associazione Italiana di Metallurgia , 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Slag is foamed in electric arc furnace during steelmaking to reduce the amount of energy emitted to the furnace walls. The behavior of the electric arc plasma during slag foaming is not very well understood, since it is very hard to obtain empirical data about arc plasma from industrial furnaces. In this work the effect of foaming on the arc plasma is studied by generating electric arc plasma over a foaming slag in laboratory scale. The arc was generated on top of the slag with a system modified from a welding power supply and the foaming of slag was induced by blowing oxygen gas into the slag. The electric arcs were monitored with two cameras filtered to measure different wavelengths and three spectrometers measuring different spectral regions with varying spectral resolution. The first camera was able to detect only the light emitted directly from the arc plasma while the second can detect the high temperature slag surrounding the submerged arc. By comparing the two images, it was possible to differentiate between arc burning inside the foaming slag and free burning arc. The use of plasma diagnostics with optical emission spectrometry provided information about electron temperature and density of the arc plasma. The plasma diagnostics and camera pixel intensities indicate that the arc burning inside foaming slag is constricted and has high plasma temperature. Comparing the free-burning arc on top of the foaming slag and non-foaming slag show that the CO bubbles cause the plasma temperature to fluctuate significantly.

  • 11.
    Ben Khedher, Nidhal
    et al.
    Univ Hail, Coll Engn, Dept Mech Engn, Hail 81451, Saudi Arabia.;Univ Monastir, Natl Sch Engn Monastir, Lab Thermal & Energet Syst Studies LESTE, Monastir 5000, Tunisia..
    Shahabadi, Mohammad
    Univ Oklahoma, Sch Aerosp & Mech Engn, Norman, OK 73019 USA..
    Alghawli, Abed Saif
    Prince Sattam Bin Abdulaziz Univ, Comp Sci Dept, Al Aflaj 11912, Saudi Arabia..
    Hulme-Smith, Christopher
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Mehryan, Seyed Abdollah Mansouri
    Islamic Azad Univ, Yasooj Branch, Young Researchers & Elite Club, Yasuj 7591493686, Iran..
    Numerical Study of the Flow and Thermomagnetic Convection Heat Transfer of a Power Law Non-Newtonian Ferrofluid within a Circular Cavity with a Permanent Magnet2022Ingår i: Mathematics, E-ISSN 2227-7390, Vol. 10, nr 15, artikel-id 2612Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this study is to analyze the thermo-magnetic-gravitational convection of a non-Newtonian power law ferrofluid within a circular cavity. The ferrofluid is exposed to the magnetic field of a permanent magnet. The finite element method is employed to solve the non-dimensional controlling equations. A grid sensitivity analysis and the validation of the used method are conducted. The effect of alterable parameters, including the power law index, 0.7 <= n <= 1.3, gravitational Rayleigh number, 10(4) <= Ra-T <= 10(6), magnetic Rayleigh number, 10(5) <= Ra-M <= 10(8), the location of the hot and cold surfaces, 0 <= lambda <= pi/2, and the length of the magnet normalized with respect to the diameter of the cavity, 0.1 <= L <= 0.65, on the flow and heat transfer characteristics are explored. The results show that the heat transfer rate increases at the end of both arcs compared to the central region because of buoyancy effects, and it is greater close to the hot arc. The location of the arcs does not affect the heat transfer rate considerably. An increase in the magnetic Rayleigh number contributes to stronger circulation of the flow inside and higher heat transfer. When the Kelvin force is the only one imposed on the flow, it enhances the heat transfer for magnets of length 0.2 <= L <= 0.3.

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  • 12.
    Bolívar Caballero, José Juan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Han, Tong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Svanberg, Rikard
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Zaini, Ilman Nuran
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Yang, Hanmin
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Gond, Ritambhara
    Department of Chemistry, Uppsala University, Lägerhyddsvägen 1, 751 21 Uppsala, Sweden, Lägerhyddsvägen 1.
    Cao, Pengcheng
    Kanthal AB, Sörkvarnsvägen 3, 734 27 Hallstahammar, Sweden, Sörkvarnsvägen 3.
    Lewin, Thomas
    Kanthal AB, Sörkvarnsvägen 3, 734 27 Hallstahammar, Sweden, Sörkvarnsvägen 3.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Yang, Weihong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Advanced application of a geometry-enhanced 3D-printed catalytic reformer for syngas production2023Ingår i: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 287, artikel-id 117071Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Catalyst research on reforming processes for syngas production has mainly focused on the active metals and support materials, while the effect of the catalyst's geometry on the reforming reactions has been poorly studied. The application of 3D-printed materials with enhanced geometries has recently started to be studied in heterogeneous catalysis and is of interest to be implemented for reforming biomass and plastic waste to produce H2-rich syngas. In this study, a geometry-enhanced 3D-printed Ni/Al2O3/FeCrAl-based monolithic catalyst with a periodic open cellular structure (POCS) was designed and fabricated. The catalyst was used for batch steam reforming biomass pyrolysis volatiles for syngas production at different parameters (temperature and steam-to-carbon ratio). The results showed complete reforming of pyrolysis volatiles in all experimental cases, a high H2 yield of ≈ 7.6 wt% of biomass was obtained at the optimized steam-to-carbon ratio of 8 and a reforming temperature of 800 °C, which is a higher yield compared to other batch reforming tests reported in the literature. Moreover, CFD simulation results in COMSOL Multiphysics demonstrated that the POCS configuration improves the reforming of pyrolysis volatiles for tar/bio-oil reforming and H2 production thanks to enhanced mass and heat transfer properties compared to the regular monolithic single-channel configuration.

  • 13.
    Bonechi, L.
    et al.
    INFN, Florence, Italy..
    Glaser, Björn
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Liu, Yu
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Rangavittal, Bharath Vasudev
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Viliani, L.
    INFN, Florence, Italy..
    et al.,
    BLEMAB European project: muon imaging technique applied to blast furnaces2022Ingår i: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 17, nr 04, s. C04031-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The BLEMAB European project (BLast furnace stack density Estimation through on-line Muon ABsorption measurements), evolution of the previous Mu-Blast European project, is designed to investigate in detail the capability of muon radiography techniques applied to the imaging of a blast furnace???s inner zone. In particular, the geometry and size of the so called ???cohesive zone???, i.e. the spatial zone where the slowly downward moving material begins to soften and melt, that plays an important role in the performance of the blast furnace itself. Thanks to the high penetration power of the natural cosmic ray muon radiation, muon transmission radiography represents an appropriate non-invasive methodology for imaging large high-density structures such as blast furnaces, whose linear size can be up to a few tens of meters. A state-of-the-art muon tracking system, whose design profits from the long experience of our collaboration in this field, is currently under development and will be installed in 2022 at a blast furnace on the ArcelorMittal site in Bremen (Germany) for many months. Collected data will be exploited to monitor temporal variations of the average density distribution inside the furnace. Muon radiography results will also be compared with measurements obtained through an enhanced multipoint probe and standard blast furnace models.

  • 14.
    Boström, M.
    et al.
    Centre of Excellence ENSEMBLE 3 Sp. z o. o., Wolczynska Str. 133, 01-919 Warsaw, Poland.
    Khan, M. R.
    Centre of Excellence ENSEMBLE 3 Sp. z o. o., Wolczynska Str. 133, 01-919 Warsaw, Poland.
    Gopidi, H. R.
    Centre of Excellence ENSEMBLE 3 Sp. z o. o., Wolczynska Str. 133, 01-919 Warsaw, Poland.
    Brevik, I.
    Department of Energy and Process Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
    Li, Y.
    Department of Physics, Nanchang University, Nanchang 330031, China; Institute of Space Science and Technology, Nanchang University, Nanchang 330031, China.
    Persson, Clas
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer. Centre for Materials Science and Nanotechnology, Department of Physics, University of Oslo, P. O. Box 1048 Blindern, NO-0316 Oslo, Norway.
    Malyi, O. I.
    Centre of Excellence ENSEMBLE 3 Sp. z o. o., Wolczynska Str. 133, 01-919 Warsaw, Poland.
    Tuning the Casimir-Lifshitz force with gapped metals2023Ingår i: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 108, nr 16, artikel-id 165306Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Casimir-Lifshitz interaction, a long-range force that arises between solids and molecules due to quantum fluctuations in electromagnetic fields, has been widely studied in solid-state physics. The degree of polarization in this interaction is influenced by the dielectric properties of the materials involved, which in turn are determined by factors such as band-to-band transitions, free carrier contributions, phonon contributions, and exciton contributions. Gapped metals, a new class of materials with unique electronic structures, offer the potential to manipulate dielectric properties and, consequently, the Casimir-Lifshitz interaction. In this study, we theoretically investigate the finite temperature Casimir-Lifshitz interaction in La3Te4-based gapped metal systems with varying off-stoichiometry levels. We demonstrate that off-stoichiometric effects in gapped metals can be used to control the magnitude and, in some cases, even the sign of Casimir-Lifshitz interactions. We predict measurable corrections due to stoichiometry on the predicted Casimir force between a La3Te4 surface and a gold sphere, attached to an atomic force microscopy tip.

  • 15.
    Boström, M.
    et al.
    Centre of Excellence ENSEMBLE3 Sp. z o. o., Wolczynska Str. 133, 01-919 Warsaw, Poland.
    Kuthe, Sudhanshu
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Carretero-Palacios, S.
    Departamento de Física de Materiales and Instituto de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, 28049 Madrid, Spain; Present address: Instituto de Ciencia de Materiales de Madrid, ICMM-CSIC, C/Sor Juana Inés de la Cruz, 3, 28049 Madrid, Spain.
    Esteso, V.
    Departamento de Física de la Materia Condensada, ICMSE-CSIC, Universidad de Sevilla, Apdo. 1065, Sevilla, Spain; European Laboratory for Non-Linear Spectroscopy (LENS), Via Nello Carrara 1, Sesto F.no 50019, Italy.
    Li, Y.
    Department of Physics, Nanchang University, Nanchang 330031, China; Institute of Space Science and Technology, Nanchang University, Nanchang 330031, China.
    Brevik, I.
    Department of Energy and Process Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
    Gopidi, H. R.
    Centre of Excellence ENSEMBLE3 Sp. z o. o., Wolczynska Str. 133, 01-919 Warsaw, Poland.
    Malyi, O. I.
    Centre of Excellence ENSEMBLE3 Sp. z o. o., Wolczynska Str. 133, 01-919 Warsaw, Poland.
    Glaser, Björn
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Persson, Clas
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Centre for Materials Science and Nanotechnology, Department of Physics, University of Oslo, P. O. Box 1048 Blindern, NO-0316 Oslo, Norway.
    Understanding ice and water film formation on soil particles by combining density functional theory and Casimir-Lifshitz forces2023Ingår i: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 108, nr 12, artikel-id 125434Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Thin films of ice and water on soil particles play crucial roles in environmental and technological processes. Understanding the fundamental physical mechanisms underlying their formation is essential for advancing scientific knowledge and engineering practices. Herein, we focus on the role of the Casimir-Lifshitz force, also referred to as dispersion force, in the formation and behavior of thin films of ice and water on soil particles at 273.16 K, arising from quantum fluctuations of the electromagnetic field and depending on the dielectric properties of interacting materials. We employ the first-principles density functional theory (DFT) to compute the dielectric functions for two model materials, CaCO3 and Al2O3, essential constituents in various soils. These dielectric functions are used with the Kramers-Kronig relationship and different extrapolations to calculate the frequency-dependent quantities required for determining forces and free energies. Moreover, we assess the accuracy of the optical data based on the DFT to model dispersion forces effectively, such as those between soil particles. Our findings reveal that moisture can accumulate into almost micron-sized water layers on the surface of calcite (soil) particles, significantly impacting the average dielectric properties of soil particles. This research highlights the relevance of DFT-based data for understanding thin film formation in soil particles and offers valuable insights for environmental and engineering applications.

  • 16.
    Carlsson, Leo
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Applied Machine Learning in Steel Process Engineering: Using Supervised Machine Learning Models to Predict the Electrical Energy Consumption of Electric Arc Furnaces2021Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Stålindustrin är i ständigt behov av att förbättra sina produktionsprocesser. Detta beror dels på ökad konkurrens och dels på miljöhänsyn. En vanligt förekommande metod för att förbättra dessa processer är genom modellering. Modeller representerar verkligheten och kan därmed användas för att undersöka effekten av nya processer och strategier utan kostsamma interventioner. Under de senaste åren har maskininlärning (ML) framhävts som en lovande modelleringsmetod för stålindustrin. Detta har delvis drivits på av Industri 4.0, som lyfter fram ML som en av sina nyckelteknologier. Dessa modeller är dock ofta svåra att tolka, vilket gör det opraktiskt att validera om modellen representerar verkligheten. Detta kan leda till brist på förtroende för ML-modeller som modelleringsverktyg inom stålindustrin. Målet med denna studie är att undersöka om ML modeller är praktiskt användbart inom stålprocessteknik. För att besvara denna forskningsfråga har förbrukningen av elektrisk energi (EE) för ljusbågsugnen valts som inriktning. Processen valdes på grund av dess omfattande användning inom stålindustrin och på grund av svårigheten att exakt modellera EE-förbrukningen med hjälp av metallurgi och termodynamik. I den aktuella litteraturen används vanligtvis linjära statistiska modeller även om EE-konsumtionen är icke-linjärt beroende av flera viktiga processvariabler. Dessutom undersöker inte studierna i litteraturen korrelationerna mellan invariablerna eller försöker hitta den mest optimala modellen med avseende på modellkomplexitet, prediktiv prestanda, stabilitet och generaliserbarhet. Dessutom saknas en konsekvent rapportering av prediktiva prestandamätvärden och tolkning av icke-transparenta modeller. Dessa brister motiverade utvecklingen av en metodik för att skapa ML modeller och en metodik för att utvärdera ML modeller. De båda metodikerna eliminerar dessa brister genom att beakta både de processmetallurgiska aspekterna samt de utmaningar som ML modelleringen medför. Genom användadet av de två metoderna kunde flera viktiga slutsatser dras från de modeller som skapades baserat på data från två olika ljusbågsugnar. I motsats till vad man tidigare trott är en hög modellkomplexitet, styrd av ett förhöjt antal invariabler och modellkoefficienter, inte nödjvändigt för att uppnå bäst prediktiv prestanda på testdata. Detta bekräftades både av det omfattande antalet skapade modeller och av jämförelsen mellan de utvalda modellerna och de modeller som rapporterats i litteraturen. För att förbättra modellernas prediktiva prestanda bör fokus istället läggas på datakvalitetsförbättringar. Kompetens från experter inom både processmetallurgi och den specifika processer som studeras måste användas när man utvecklar praktiskt användbara ML-modeller. Expertenas kompetens stödjer både valet av invariabler och tolkningen av effekterna invariablerna har på på EE-förbrukningen i förhållande till etablerade fysikaliska lagar och erfarenheter om den specifika ljusbågsugn som studerats. Dessutom resulterade en datarensning utförd av en expert på en av de två studerade ljusbågsugnarna i den bäst presterande modellen. Skrotsmältningsprocessen i ljusbågsugnen är komplicerad och därför utmanande att modellera med fysikalisk modellering. Med hjälp av ML-modellering visades det att en skrotkategorisering baserad på skrotets yta-till-volymsförhållande skapade ML-modeller med högst prediktiv prestanda. Detta stämmer väl med de fenomen som styr smältningen av skrot och som är proportionellt mot skrotets yta-till-volymsförhållande; temperaturgradienter, legeringsämnesgradienter, omrörningshastighet och frysningseffekten. Flera olika praktiska användningsfall har exemplifierats i denna avhandling eftersom modellutvärderingsmetoden påvisade de verkliga effekterna av varje invariabel på EE-förbrukningen. Det mest framträdande exemplet var effekten av olika skrotkategorier på EE-konsumtionen. Tre av dessa skrotkategorier tolkades korrekt av ML modellen enligt stålverkets processingenjörer. För att kunna dra specifika slutsatser krävs dock en mycket högre prediktiv prestanda hos modellerna. Detta kan bara förverkligas efter betydande förbättringar av datakvaliteten. I sin tur kan detta endast genomföras av utvecklarna på det stålverk som ligger till grund för det data som användes för att skapa modellerna. Slutligen är den utvecklade metoden inte begränsad till den inriktning som används i detta arbete. Metoden kan användas för att utveckla ML-modeller för andra processer inom stålindustrin. Detta är värdefullt för stålindustrins utveckling av Industri 4.0.

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  • 17.
    Carlsson, Leo
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Samuelsson, Peter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    A Proposed Methodology to Evaluate Machine Learning Models at Near-Upper-Bound Predictive Performance—Some Practical Cases from the Steel Industry2023Ingår i: Processes, ISSN 2227-9717, Vol. 11, nr 12, artikel-id 3447Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The present work aims to answer three essential research questions (RQs) that have previously not been explicitly dealt with in the field of applied machine learning (ML) in steel process engineering. RQ1: How many training data points are needed to create a model with near-upper-bound predictive performance on test data? RQ2: What is the near-upper-bound predictive performance on test data? RQ3: For how long can a model be used before its predictive performance starts to decrease? A methodology to answer these RQs is proposed. The methodology uses a developed sampling algorithm that samples numerous unique training and test datasets. Each sample was used to create one ML model. The predictive performance of the resulting ML models was analyzed using common statistical tools. The proposed methodology was applied to four disparate datasets from the steel industry in order to externally validate the experimental results. It was shown that the proposed methodology can be used to answer each of the three RQs. Furthermore, a few findings that contradict established ML knowledge were also found during the application of the proposed methodology.

  • 18.
    Chanouian, Serg
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer. KTH, Royal Institute of Technology.
    Mixing Time and Decarburization Reactions in Side-blown Metallurgical Converters: A Practical Approach using CFD and Thermodynamics2023Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    AOD konvertern, känd för sin intensiva gasomrörning och turbulenta natur, ställer komplexautmaningar inom fluidmekanik och termodynamik. Modellering har spelat en betydande roll iutvecklingen av metallurgiska konvertrar, särskilt för att förstå jetbeteende, omrörning, flödesmönsteroch kemiska reaktioner. Flödesegenskaper och omrörningstid betraktas som avgörande faktorer somförbättrar effektiviteten och kolfärskningshastigheten i metallurgiska reaktorer. Men enligtförfattarens kännedom har ingen tidigare studie undersökt effekten av omrörningstid på kolfärskning.Även om de flesta studier föreslår att en minskning av omrörningstiden är fördelaktig, är det rimligtatt anta att det kan finnas en punkt där ytterligare minskning av omrörningstiden inte leder till enökning av reaktionshastigheten. Justeringar som att luta konvertern eller omplacera dysorna kanförbättra kolfärskningseffektiviteten genom att ändra tryckförhållandena och omrörningen. Måletmed denna studie är att utforska hur dessa faktorer påverkar kolfärskningsreaktionen i sidoblåstakonvertrar genom modellering. Arbetet har utförts i flera steg med olika tillägg.Experiment med vattenmodeller av sidoblåst gas utfördes för att undersöka hur en lutning avbehållaren skulle påverka omrörningstiden. Resultaten visade tydligt en ökning av omrörningstidennär högre lutningsvinklar (14°) användes. Dock kunde studier av icke-reaktiva vattenmodeller bara geinsikt om omrörningseffektivitet och inte ge information om hur effektiv kolfärskningen är.En numerisk modell som kan integrera mass- och värmetransport med kemiska reaktioner vid högatemperaturer utvecklades för att hjälpa till med denna undersökning. Först tillämpades modellen påen stigande gasbubbla i smält stål. Effekten av trycket undersöktes genom att injicera bubblan på olikabadnivåer. Det visades att en enkel bubbla injicerad vid dys positionen under industriella förhållandeninte kolfärskade effektivt, utan löstes in i stålet. Endast trycknivåer vid badytan kunde behålla gasensom en stabil fas och kolfärska effektivt.Med hög upplösning på beräknings celler krävde modellen mycket tid för att beräkna jämvikt lokalt ivarje cell med gas och vätska närvarande. Därför användes ett mer praktiskt tillvägagångssätt för attstudera AOD-konvertern, som visade bra överensstämmelse med det första färsknings stegetgentemot två industriella charger. Det visades att med grova lösningar inom beräkningsfluidmekanikkunde modellen vara praktisk men grundläggande. Resultaten visade även att Ingen kromoxidationhittades i en av omgångarna i början av processen när den initiala kolhalten var hög. Trendernajämfördes med en industriell online-processmodell och visade liknande beteende.Med ytterligare utveckling testades modellen med olika behandlingar av termodynamisk koppling,inklusive reaktioner begränsade av turbulens i en intensivt omrörd sidoblåst reaktor. Omrörningstidenvisade sig ha en obetydlig effekt på kolfärsknings hastigheten; istället styrdes systemet avtermodynamik och gasleveranshastighet.Sammanfattningsvis utvecklades en generell modell i detta arbete som kan koppla samman kemiskareaktioner med fluiddynamiska beräkningar. Användningen av denna modell ledde till slutsatsen atten lutning av behållaren inom praktiska driftsvinklar inte skulle gynna färskningshastigheten i detidiga stadierna av kolfärskning. Med ökade omrörningstider och små tryckvariationer från sänktbadnivå skulle fördelarna med kolfärskning vara små jämfört med de tekniska utmaningar somsådana förändringar medför. Även omplacering av dysan skulle kräva stora och opraktiskahöjdskillnader för att uppnå den trycksänkning som behövs för att gynna termodynamiken.

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  • 19.
    Chanouian, Serg
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Ahlin, Björn
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Tilliander, Anders
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    A Fundamental Investigation of Decarburization Reactions in the Argon–Oxygen Decarburization Converter Using Coupled Computational Fluid Dynamics and Thermodynamics Databases2022Ingår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 93, nr 12, artikel-id 2200156Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Metallurgical converters such as the argon–oxygen decarburization (AOD) converter generally utilize gas blowing for the mixing and refinement of liquid steel. Due to the harsh environment of the complex and opaque system, it is common practice to study the stirring of the process through physical and numerical models. Effective mixing in the bath has an important role in refinement such as decarburization and has been vividly studied before. However, high-temperature chemical reactions that also play a major role are sparsely investigated. With the help of modeling, a computational fluid dynamics model coupled with chemical reactions is developed, allowing the study of both dynamic fluid transport and chemical reactions. Herein, the chemical reactions for a single gas bubble in the AOD are investigated. The study shows that a 60 mm oxygen gas bubble rapidly reacts with the melt and is saturated with carbon in 0.2–0.25 s at low-pressure levels. The saturation time is affected by the pressure and the composition of the injected gas bubble. The impact of ferrostatic pressure on the reactions is more significant at larger depth differences. 

  • 20.
    Chanouian, Serg
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Ahlin, Björn
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Tilliander, Anders
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Inclination Effect on Mixing Time in a Gas–Stirred Side–Blown Converter2021Ingår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 92, nr 10, s. 2100044-, artikel-id 2100044Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Small-scale physical models are commonly used to investigate gas-stirred processes in steelmaking practice. The argon oxygen decarburization (AOD) converter is among various processes widely used in the metallurgy field and utilizes side blowing of oxygen and inert gas for mixing in the bath. Herein, the effect of the converter inclination on mixing time and jet-penetration length with a side-blown physical model is investigated. Scaling with the modified Froude number is applied on data from a real industrial AOD converter to achieve a system with reasonable gas flow rates. During the experiments, water is used to simulate liquid steel and air is blown through side-mounted nozzles for stirring. A NaCl tracer is added and subsequent conductivity measurements are used to measure mixing time. Overall, the penetration length is shown to be independent of inclination angle. The mixing time is found to be influenced by the change of bath height to diameter ratio, change of geometry in the bath volume, gas flow rate, and the intensified wave motion at the interface caused by the inclination of the vessel. The mixing time increase with 14% when 14° angle is applied.

  • 21.
    Chanouian, Serg
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Larsson, Henrik
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Strukturer.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    The Importance of Mixing Time in Intensely Stirred Metallurgical Reactors: Applied on Decarburization Reactions2023Ingår i: Metals, ISSN 2075-4701, Metals, E-ISSN 2075-4701, Vol. 13, nr 10, artikel-id 1694Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In metallurgical converter processes, numerical modeling is a useful tool for understanding the complexity of the systems. In this paper, we present a practical model that couples fluid dynamics and chemical reactions to explore the impact of mixing time on decarburization. Using computational fluid dynamics (CFD), in this study, we investigate an arbitrary metallurgical reactor with continuous oxygen supply, focusing on the Fe–C–O system. The model employs local equilibrium, a turbulence limiter, and finite volume method for mass, momentum, and energy transfer. Tracer injection points in the gas plume’s rising region exhibit faster mixing, and a comparison of reaction cases reveals distinct decarburization rates based on oxygen injection distribution and the influence of turbulence on reactions. Overall, while mixing time matters, the results show that this system is primarily governed by thermodynamics and oxygen supply, and a 270% increase in mixing time increase had a small impact on the end carbon content.

  • 22.
    Chanouian, Serg
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Pitkala, Jyrki
    Outokumpu Stainless AB.
    Larsson, Henrik
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Strukturer.
    Ersson, Mikael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Modelling Decarburization in the AOD Converter: A Practical CFD-Based Approach with Chemical ReactionsManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Gas blowing technology is widely used in converter steelmaking to homogenize liquid steel and accelerate chemical reactions, with Argon oxygen decarburization (AOD) being the dominant process for stainless steelmaking. Due to the harsh environment, it is advisable to study the phenomenon using small-scale physical models and numerical simulations before conducting industrial-scale trials. This paper presents a practical computational fluid dynamics (CFD) approach for simulating the AOD process, with chemical reactions considered. This approach can simulate the entire process in a reasonable time using a standard workstation. The simulation employs a Finite Volume Method CFD approach to handle mass, momentum and energy transfer, and a local equilibrium assumption is utilized. The study shows that a practical approach can be used to model the initial stage of decarburization in the AOD process with a reduced accuracy in mass transport calculations. The accuracy of the simulation is validated using industrial data, and good agreement is found.

  • 23.
    Chipakwe, Vitalis
    et al.
    Luleå Tekniska Universitet.
    Hulme-Smith, Christopher
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Karlkvist, Tommy
    Luleå Tekniska Universitet.
    Rosenkranz, Jan
    Luleå Tekniska Universitet.
    Chelgani, Saeed Chehreh
    Luleå Tekniska Universitet.
    Effects of Chemical Additives on Rheological Properties of Dry Ground Ore: A Comparative Study2021Ingår i: Mineral Processing and Extractive Metallurgy Review, ISSN 0882-7508, E-ISSN 1547-7401Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is well documented that chemical additives (grinding aid “GA”) during grinding can increase mill throughput, reduce water and energy consumption, narrow the particle size distribution of products, and improve material flowability. These advantages have been linked to their effects on the rheology, although there is a gap in understanding GA effectiveness mechanism on the flow properties. The present study aims to fill this gap using different GAs (Zalta™ GR20-587, Zalta™ VM1122, and sodium hydroxide) through batch grinding experiments of magnetite ore and addressing the mechanisms of their effects on the rheology by an FT4 Powder Rheometer as a unique system. Experimental results showed that GA improved grinding efficiency (energy consumption and product fineness), which were well-correlated with basic flow energy, specific energy, aerated basic flow energy, and aerated energy. Moreover, the rheometry measurement showed strong linear correlations between basic flow energy, specific energy, and the resulting work index when GAs was considered for grinding, which confirmed the effect of GA on ground particles’ flowability. Zalta™ VM1122, a polysaccharide-based grinding aid, showed the best performance with 38.8% reduction of basic flow energy, 20.4% reduction of specific energy, 24.6% reduction of aerated basic flow energy, and 38.3% reduction of aerated energy. It also showed the strongest correlation between the grinding parameters and flow parameters (r > 0.93). The present investigation shows a strong indication that the predominant mechanism of GAs is based on the alteration of rheological properties and identify Zalta™ VM1122 as the best GA.

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    fulltext
  • 24. Cho, J. H.
    et al.
    Martinsson, Johan
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Sichen, D.
    Park, Joo Hyun
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Desulfurization Behavior of Incoloy® 825 Superalloy by CaO-Al2O3-MgO-TiO2 Slag2021Ingår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 52, nr 6, s. 3660-3670Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ni-based superalloy, which has excellent high-temperature strength and corrosion resistance, is mainly used in aviation materials, high-performance internal combustion engines, and turbines for thermal and nuclear power generation. For this reason, refining the impurities in Ni-based superalloys is a very important technical task. Nevertheless, the original technology for the melting and refining of Ni-based superalloys is still insufficient. Therefore, in this study, the effect of the CaO-Al2O3-MgO-TiO2 slag on the removal efficiency of an impurity element sulfur in Incoloy® 825 superalloy, one of the representative Ni-based superalloys, was investigated. The desulfurization behavior according to the change of TiO2 content and CaO/Al2O3 (=C/A, basicity) ratio as experimental variables was observed at 1773 K (1500 °C). Although the TiO2 content in the slag increases to 15 mass pct, the mass transfer coefficient of sulfur in molten alloy showed a constant value. Alternatively, under the condition of C/A &gt; 1.0 of slag, the mass transfer coefficient of sulfur showed a constant value, whereas under the condition of C/A &lt; 1.0, the mass transfer coefficient of sulfur greatly decreased as CaO decreased. Hence, in the desulfurization of Incoloy® 825 superalloy using the CaO-Al2O3-MgO-TiO2 slag, the TiO2 content in the slag does not have a considerable effect on the desulfurization rate and desulfurization mechanism (metal phase mass transfer controlled regime), but the basicity of the slag has a significant effect on desulfurization mechanism. When the slag basicity decreases below the critical level, i.e., C/A &lt; 1.0, which is corresponding to sulfur distribution ratio, Ls &lt; 200, it was confirmed that the desulfurization mechanism shifts from the metal phase mass transfer-controlled regime to the slag phase mass transfer-controlled regime due to the variation in the physicochemical properties of the slag such as viscosity and sulfide capacity. In addition, the different desulfurization rates between steel and Ni alloy melts were discussed by employing the diffusivity of sulfur in both systems.

  • 25.
    Choi, Nuri
    et al.
    Hanyang Univ, Dept Mat Sci & Chem Engn, Ansan 15588, South Korea..
    Park, Nokeun
    Yeungnam Univ, Sch Mat Sci & Engn, Gyeongbuk 38541, South Korea..
    Kim, Jin-kyung
    Hanyang Univ, Dept Mat Sci & Chem Engn, Ansan 15588, South Korea..
    Karasev, Andrey
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer. KTH Royal Inst Technol, Dept Mat Sci & Engn, S-10044 Stockholm, Sweden..
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Park, Joo Hyun
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Hanyang Univ, Dept Mat Sci & Chem Engn, Ansan 15588, South Korea..
    Influence of Manufacturing Conditions on Inclusion Characteristics and Mechanical Properties of FeCrNiMnCo Alloy2020Ingår i: Metals, ISSN 2075-4701, Vol. 10, nr 10, artikel-id 1286Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Three CoCrFeMnNi high-entropy alloys (HEAs) were produced by vacuum induction melting, induction melting under inert gas atmosphere, and melting under inert gas atmosphere followed by air exposure, respectively. The different manufacturing conditions for the three investigated alloys resulted in different levels and types of inclusions. The alloys melted under vacuum or inert gas contained Al2O3 inclusions formed by impurity Al, due to its high oxidation tendency. The molten alloy exposed in air showed an excessive oxidation. During oxidation of the molten alloy in air, impurity Al was initially oxidized, and fine MnCr2O4 inclusions were formed rather than pure Al2O3 inclusions. This difference was analyzed based on thermodynamic calculations. Specifically, the influence of impurity content on the inclusion characteristics was investigated for the three HEAs. Moreover, the inclusion characteristics were found to have an influence on mechanical properties of the alloys also. In air-exposed HEA, smaller inclusions were formed, resulting in a higher dislocation density at the matrix/inclusion interface and thus strengthening of the HEA. Thus, it is proposed that atmospheric conditions could be an important factor to control the inclusion characteristics and to form fine inclusion particles, which could improve the mechanical properties of HEAs.

  • 26.
    Compañero, Reinol Josef
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Recirculation of scrapped resources: The role of material information in enhancing the sustainability of recycling2024Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Industrier bemöter klimatkrisen genom att positionera verksamheten i linje med begrepp såsom cirkulär ekonomi. Genom att förmedla idén om att optimera och cirkulera resurser på ett sätt som överensstämmer med principerna för hållbar utveckling har trycket för att genomföra åtgärder för cirkularitet ökat, samtidigt som det finns tydliga ekonomiska incitament. Företag som traditionellt har förbrukat både primära och antropogena resurser i produktionen av material som används inominfrastruktur, transport och för andra tekniska behov har en särskild ställning. Å ena sidan behövs deras produkter för samhällsutvecklingen. Men å andra sidan ger deras verksamheter upphov till betydande mängder växthusgaser.

    Stålindustrin är ett klassiskt exempel där besparingar av material- och energiresurser uppnås när produkterna återvinns i slutet av deras livscykel. De positiva effekterna är dock beroende av att skrotär en lämplig ersättning för malm-baserade resurser. Ersättningen av primära (dvs. renare) resurser med sekundära (dvs. förorenade) som råmaterial för produktionen är starkt beroende avåtervinningssystemets förmåga att hantera komplexiteten hos de järn- och stål-skrotströmmar som samhället genererar. Mer specifikt, behöver aktörerna i värdekedjan återställa materialets identitet genom karaktärisering och sortering som minskar eller undviker den nuvarande praxisen att antingen utspäda föroreningar eller kompensera för otillräcklig legering genom tillsats av primära resurser.

    Denna avhandling granskar användningen av skrot med uppfattningen att återvinning är en tekniskprocess som utförs av företag. Intrycket att återvinning följaktligen ersätter användningen av primära resurser granskas, med beaktande av skrot som ett karaktäristiskt lämpligt men samtidigt utmanande råmaterial att använda. Fallstudier som fokuserar på den svenska skrotbaserade produktionskontexten visade att aktörerna inom återvinningssystemet agerar baserat på skrotets kvalitet, vilket i sin tur tolkades som mångdimensionellt och beroende av varje aktörs preferenser. Samstämmigheten mellan ekonomiska och miljömässiga intressen kopplade till skrotanvändning visade sig vara begränsad, med företag som föredrog användningen av primära resurser när skrot inte längre var lämpligt.

    Tanken på lämplighet tillskrevs sedan kompositionell information om skrot och testades på tvånivåer: att ha tillgång till partiell eller fullständig information. Det förra är vad som uppnås genomden nuvarande hanteringen av skrot i den omvända loopen medan det senare är en idealiserad situation där den exakta kemin hos skrotet är känd. Ett optimeringsprogram användes sedan för att simulera stålåtervinning där de testade scenarierna var utformade för att fokusera på produktionsmodellens respons på skrotets kemiska sammansättning. De erhållna resultaten visade en övergripande minskning av produktionskostnaderna och en ökning av andelen skrot som används i produktionen. I de flesta fall tillskrevs detta flexibiliteten att tilldela skrot baserat på dess sammansättning till de närmast matchande målprodukterna.

    Slutligen klargjorde ytterligare intervjuer med branschutövare etablerade och företagsbaserade protokoll för att hantera bristen på information och gav insikter med avseende på möjligheter att öka skrotanvändningen. En analys av svaren antydde att det finns kontextuella skillnader när det gäller praxis från varje företag, och även attityder, gentemot antropogena resurser. Slutligen stöder insikterna från denna avhandling behovet för företag att hantera de kompromisser som är relaterade till skrotanvändning och leder till förbättrad hållbarhet inom stålåtervinning.

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    Compañero_kappa_2024
  • 27.
    Compañero, Reinol Josef
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Feldmann, Andreas
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekonomi och organisation (Inst.), Hållbarhet, Industriell dynamik & entreprenörskap.
    Samuelsson, Peter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Tilliander, Anders
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Gyllenram, Rutger
    Appraising the value of compositional information and its implications to scrap-based production of steel2023Ingår i: Mineral Economics, ISSN 2191-2203, E-ISSN 2191-2211Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The current nature of steel design and production is a response to meet increasingly demanding applications but without much consideration of end-of-life scenarios. The scrap handling infrastructure, particularly the characterization and sorting, is unable to match the complexity of scrapped products. This is manifested in problems of intermixing and contamination in the scrap flows, especially for obsolete scrap. Also, the segmentation of scrap classes in standards with respect to chemical compositions is based on tolerance ranges. Thus, variation in scrap composition exists even within the same scrap type. This study applies the concept of expected value of perfect information (EPVI) to the context of steel recycling. More specifically, it sets out to examine the difference between having partial and full information on scrap composition by using a raw material optimization software. Three different scenarios with different constraints were used to appraise this difference in terms of production and excess costs. With access to perfect information, production costs decreased by 8–10%, and excess costs became negligible. Overall, comparing the respective results gave meaningful insights on the value of reestablishing the compositional information of scrap at the end of its use phase. Furthermore, the results provided relevant findings and contribute to the ongoing discussions on the seemingly disparate prioritization of economic and environmental incentives with respect to the recycling of steel.

  • 28.
    Compañero, Reinol Josef
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Feldmann, Andreas
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekonomi och organisation (Inst.), Hållbarhet, Industriell dynamik & entreprenörskap.
    Tilliander, Anders
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Circular Steel: How Information and Actor Incentives Impact the Recyclability of Scrap2021Ingår i: Journal of Sustainable Metallurgy, ISSN 2199-3823Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recycling plays a vital role in preserving resources like steel and consequently in a circular economy. Scrap dealers and steel mills, the main business units in this system, often encounter opposing financial and sustainability incentives in using scrap as feedstock because regular sorting and scrap-preparation infrastructure cannot deal with the increasing complexity of steel scrap. Mismatches between the inputs and the target composition of the recycled steel result in trade-offs that favor the economics at the expense of resource efficiency. By examining literature and interviewing several actors, different scrap characteristics were identified as dimensions of scrap quality. Quality is typically associated with chemical composition, which is important, but this study aims to elaborate the concept of quality further and to connect it to the realities of scrapyard operations. Industry actors have different definitions for desired content, physical condition, shape and size, and homogeneity, based on their needs. Very few studies examine these details. Additionally, the relationship of quality and the level of information about the characteristics of the material was established. Having more definitive information on scrap increases opportunities for resource-efficient actions. This work offers an alternative perspective on how to address issues pertinent to recycling.

  • 29.
    Cui, Yuxiao
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Han, Tong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Svagan, Anna Justina
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Achieving carbonized minitablet-shaped structures from lignin: The importance of heating rate on shape2023Ingår i: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250X, Vol. 176, s. 106260-, artikel-id 106260Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Shape-anisotropic building blocks are vital in the creation of hierarchical materials in nature, as it enables directional alignment, property anisotropy and overall functionality improvement in biological materials. Likewise, the performance of carbonized superstructures could potentially be more precisely designed by using anisotropic building blocks. Lignin represents an important and sustainable alternative in the production of carbonized materials, which is due to its abundance and high carbon content (∼60%). However, to expand its utility, for producing carbonized shape-anisotropic materials, adequate synthesis and pyrolysis-protocols are essential. Here, a fractionated and acetylated Kraft lignin was used to successfully self-assemble shape-anisotropic microcapsules. Then a carbonization procedure (slow heating at 0.6 °C min−1), that retained the original shape-anisotropy after carbonization, was developed. The formation mechanism was discussed as a function of the heating rate. The overall strategy was template-free and the attained shape-anisotropies were well-defined and narrow in size distribution. This is a scalable route for achieving shape-anisotropic carbonized building blocks from lignin.

  • 30.
    De Colle, Mattia
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Experimental studies to overcome the recycling barriers of stainless-steel and BOF slags2022Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Denna avhandling presenterar flera studier som syftar till att förbättra återvinningen av stålslagger. Studierna är baserade på en första

    utvärdering av den senaste tekniken för återvinningsapplikationer både med avseende på möjligheter och begränsningar. Dessutom presenteras en

    studie som belyser flera egenskaper hos alla typer av järnslagger, såsom bulk-kemisk sammansättning och vanliga mineralfaser, för att underlätta

    diskussionen. Specifikt, så omfattar studierna som presenteras i denna avhandling två huvudämnen: en ny återvinningsapplikation för slagger

    från tillverkning av rostfritt stål och en teoretisk studie om hydrering av ferroperiklas, vilket är ett mineral som ofta förekommer i konverterslagger.

    De flesta av de studier som presenteras i denna avhandling fokuserar på utforskningen av en ny användning av slagger från tillverkning av rostfritt

    stål, i syfte att undersöka hur det är möjligt att öka deras återvinningsgrad. Faktum är att denna typ av material är de mest problematiska slaggerna

    att återvinna, eftersom de flesta inte kan behandlas med användandet av de flesta av de senaste slaggåtervinningsteknikerna. Därför undersöks

    deras potential att kunna användas som ersättning för kalk vid neutralisering av surt avloppsvatten. Studierna omfattar ett brett spektrum

    av försök, från laboratorietester till industriella tester med surt avloppsvatten som samlats från rostfria ståltillverkningsanläggningar, till

    mer grundläggande studier om hur upplösning av slaggmineraler sker i en sur miljö. Sammanfattningsvis, så visar resultaten att ersättningen av kalk

    med slagg av rostfritt stål är framgångsrik både med avseende på att slutliga pH-värden som erhållits samt med avseende på att erhålla ett

    effektivt avlägsnande av metalljoner som är lösta i vatten. I sista delen av avhandlingen så behandlas en teoretisk studie om

    hydrering av ferroperiklas. Denna studie föreslår en möjlig teknisk lösning för att minska den volymetriska expansionen av stålslagg som

    innehåller höga halter av periklas. Specifikt så visar resultaten att ferroperiklas med höga andelar FeO adsorberar mindre vatten och därför

    så expanderar dessa slagger mindre i jämförelse med vanlig ferroperiklas. Därför kan bildandet av en sådan fas under stelning av slagg ge en högre

    volymetrisk stabilitet, vilket är mycket fördelaktigt när materialet senare används i applikationer utomhus.

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    M. De Colle - Experimental studies to overcome the recycling barriers of stainless-steel and BOF slags
  • 31.
    De Colle, Mattia
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Karasev, Andrey
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Sohei, Sukenaga
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University.
    Mibu, Ko
    Department of Physical Science and Engineering, Graduate School of Engineering, Nagoya Institute of Technology.
    Kato, Yusuke
    Steel Research Laboratory, JFE Steel Corporation.
    Mastunaga, Hisahiro
    Steel Research Laboratory, JFE Steel Corporation.
    Shibata, Hiroyuki
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University.
    Study of the Hydration Behavior of Synthetic Ferropericlase with LowIron Oxide Concentrations to Prevent Swelling in Steel Slags2021Ingår i: Journal of Sustainable Metallurgy, ISSN 2199-3831Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Steel slags generally swell when subjected to water or humidity, which prevents proper recycling in the cement or asphaltindustries. The MgO and CaO phases in steel slags are responsible for this phenomenon, as both minerals easily absorb waterto form their respective hydroxides. MgO is often present in steel slags in a solid solution with several oxides, constitutingthe so-called RO phase. This study investigates the hydration rate of an RO phase consisting of FeO and MgO called ferropericlase.The material was synthesized in a laboratory furnace by sintering a FeO–MgO powder mixture with varying initialFeO contents (approximately 10, 15, and 20 wt%). Thereafter, electron probe micro-analyzer (EPMA) and X-ray diffraction(XRD) spectroscopies were used to characterize the structure of the samples, which were mainly composed of ferropericlaseand an exsolution of magnesioferrite. Also, Mössbauer spectra showed that the total ferrous iron proportion (Fe2+/ΣFe) ofthe sintered samples was in the range of 0.55–0.72. To measure the hydration behavior, the samples in powder form werecured in an autoclave at an H2Opartial pressure of 2 atm. Thereafter, thermal gravimetric analysis (TGA) was performed tomeasure the amount of water absorbed during the autoclave curing from the mass drop associated with the dehydration ofthe hydroxide. The study found a linear correlation between the initial FeO content and the weight loss after TGA, with areduction down to 6% in the sample with an initial FeO content of 20 wt% content compared to pure MgO.

  • 32.
    De Colle, Mattia
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Kielman, Ross
    KTH.
    Karlsson, Andreas
    Swedish Museum Nat Hist, SE-10405 Stockholm, Sweden..
    Karasev, Andrey
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Study of the Dissolution of Stainless-Steel Slag Minerals in Different Acid Environments to Promote Their Use for the Treatment of Acidic Wastewaters2021Ingår i: Applied Sciences, E-ISSN 2076-3417, Vol. 11, nr 24, artikel-id 12106Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Several stainless-steel slags have been successfully employed in previous studies as substitutes for lime in the treatment of industrial acidic wastewaters. This study deepens the knowledge of such application, by analyzing the neutralizing capacity of different slags related to their mineral compositions. To do so, firstly the chemical and mineral compositions of all the slag samples are assessed. Then, 0.5 g, 1 g, 2 g of each slag and 0.25 g and 0.5 g of lime are used to neutralize 100 g of 0.1 M HCl or HNO3 solutions. After the has neutralization occurred, the solid residues are extracted and analyzed using XRD spectroscopy. Then, the solubility of the minerals is assessed and ranked, by comparing the XRD spectra of the residues with the obtained pH values. The results show that minerals such as dicalcium silicate and bredigite are highly soluble in the selected experimental conditions, while minerals such as merwinite and akermanite, only partially. Moreover, Al-rich slags seem to perform poorly due to the formation of hydroxides, which generate extra protons. However, when the weight of slag is adequately adjusted, Al-rich slags can increase the pH values to higher levels compared to the other studied slags.

  • 33.
    De Colle, Mattia
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Puthucode, Rahul
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Karasev, Andrey
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    A Study of Treatment of Industrial Acidic Wastewaters with Stainless Steel Slags Using Pilot Trials2021Ingår i: Materials, E-ISSN 1996-1944, Vol. 14, nr 17, s. 4806-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Different stainless steel slags have been successfully employed in previous experiments, for the treatment of industrial acidic wastewaters. Although, before this technology can be implemented on an industrial scale, upscaled pilot experiments need to be performed. In this study, the parameters of the upscale trials, such as the volume and mixing speeds, are firstly tested by dispersing a NaCl tracer in a water bath. Mixing time trials are used to maintain constant mixing conditions when the volumes are increased to 70, 80 and 90 L, compared to the 1 L laboratory trials. Subsequently, the parameters obtained are used in pH buffering trials, where stainless steel slags are used as reactants, replicating the methodology of previous studies. Compared to laboratory trials, the study found only a minor loss of efficiency. Specifically, in previous studies, 39 g/L of slag was needed to buffer the pH of the acidic wastewaters. To reach similar pH values within the same time span, upscaled trials found a ratio of 43 g/L and 44 g/L when 70 and 90 L are used, respectively. Therefore, when the kinetic conditions are controlled, the technology appears to be scalable to higher volumes. This is an important finding that hopefully promotes further investments in this technology.

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    fulltext
  • 34.
    Du, Hongying
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Evaluations of Non-metallic Inclusionsin Ca-treated Steels and Their Effect on the Machinability2021Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Under de senaste decennierna har en stor utveckling av ståls prestande skett, vilken lett till stora utmaningar gällande bearbetningen av dessa stålsorter. Därför är det viktigt att göra en lämplig modifiering av icke-metalliska inneslutningar (NMI) vid ståltillverkningsprocessen och ha en god kontroll över dess egenskaper för att uppnå de önskade mekaniska egenskaperna och en god skärbarhet.

    Baserat på ett fall innefattande ett 316L-försök i rostfritt stål med en kalciummodifiering för att förbättra stålets bearbetbarhet diskuterades påverkan av olika NMI  på skärbarheten. Inledningsvis så användes Thermo-Calc-beräkningar för att bestämma ett lämpligt intervall för Ca-tillsats för stål som skulle produceras genom att utföra en kalciumbehandling vid slutet av skänkbehandlingen. För att utvärdera icke-metalliska inneslutningar och deras påverkan på skärbarhetstest, så samlades stålprover från valsade stänger som producerats genom användande av den konventionella produktionsvägen (316R) och ett försök med användande av en kalciumbehandling (316Ca). Metallspånorna som genererades under skärbarhetstesten samlades också in för utvärdering av spånbrytbarheten och NMI-egenskaperna efter den skärande bearbetningen. Dessutom så användes en elektrolytisk extraktionsteknik (EE) för att extrahera NMI från stål- och spånprover. Därefter utfördes en tredimensionell (3-D) studie på inneslutningar som samlats på ett membranfiltret efter filtrering, med användande av ett svepelektronmikroskop (SEM) utrustat med energidispersiv röntgenspektroskopi (EDS). Morfologin, storleken, antalet, frekvensen och sammansättningen hos de icke-metalliska inneslutningarna studerades. Fyra huvudtyper av inneslutningar hittades i 316Ca stålet: typ I (långsträckta MnS), typ II (oxisulfider med hårda oxidkärnor), typ III (mjuka långsträckta oxider) och typ IV (hårda odeformerade oxider).

    Resultaten visar att morfologin hos NMI i rostfria spån förändrades markant efter en skärnande bearbetning. Sammanlagt upptäcktes tre olika huvudtyper av NMI: i) Grupp I liknande former, ii) Grupp II sträckta inneslutningar med mycket tunna filmliknande (Grupp II-a) och utsträckta spruckna morfologier (Grupp II-b) och iii) Grupp III spröda inneslutningar. De totala ytorna för MnS- och SO-inneslutningarna i spånens sekundära deformationszon ökade signifikant (upp till 2-3 gånger) jämfört med det resultaten för referensstålprovet taget före skärbarhetstestet. Det visade sig att morfologin hos NMI under bearbetning beror på lokaliseringen av inneslutningen i spånan, provmaterialet samt den applicerade skärhastigheten. Detta resulterar i olika temperaturer och olika deformationsgrader av metallmatrisen under den skärande bearbetningen.

    Dessutom utvärderades spånbrytbarheten och kontaktlängden mellan spånan och verktyget för referensstålet och experimentstålet och resultaten jämfördes med karakteristiken hos NMI i de två stålen. En ny viktmätningsbaserade metod utvecklades. Resultaten visar att 316Ca-stålet i allmänhet har en bättre skärbarhet jämfört med referens 316R-stålet. Däremot så visar resultaten gällande kontaktlängden mellan spånan och verktyget att modifieringen av NMI för förbättringar av skärbarheten endast är fördelaktig i vissa bearbetningsprocesser. Specifikt, så är en användning av ett 316R-stål att föredra vid låga skärhastigheter, medan stålet 316Ca föredrogs vid höga skärhastigheter. De olika egenskaperna hos NMI för olika bearbetningsförhållanden och material leder till olika beteenden och funktioner hos NMI under skärande bearbetning.

    Slutligen så utvärderades den möjliga tillämpningen av PDA/OES i ståltillverkningsprocessen. Denna online-undersökningsmetod som utvecklats i branschen under de senaste åren erbjuder en stor möjlighet att åstadkomma en snabb bestämning av NMI-innehållet och visar en potential att kunna utveckla möjligheten för en kontroll av NMI under stålprocessen.

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  • 35.
    Du, Hongying
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Karasev, Andrey
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Influence of non-metallic inclusions in 316L stainless steels on machining using different cutting speedsIngår i: Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    This research focuses on providing a detailed characteristic of non-metallic inclusions (NMIs) in 316L stainless steels with and without Ca treatment after machining using different cutting speeds. The electrolytic extraction (EE) technique was used for three-dimensional determinations of the inclusion characteristics. Quantitative data from the fragile non-metallic inclusions (such as size, surface area, number) in chips obtained from different cutting speeds and materials were determined. The morphologies of NMIs in the chip samples were quite different compared to the original inclusions in the stainless steel samples before machining. It was proved that the deformation degree of soft inclusions such as MnS and CaO-SiO2-Al2O3-MgO-TiOx is dependent on the cutting speed as well as the temperatures and deformation degrees of the metal matrix during machining. The total surface areas of MnS inclusions increase from 2.8 to 3.8 times compared to the original total areas with an increased cutting speed. The total surface areas of soft oxide inclusions also increase from 1.1 to 3.5 times compared to the original total areas. In addition, the tool-chip contact lengths were also measured on the rake face of the tool, and the results were compared to the determined characteristics of the observed inclusions. It was found2that the modification of NMIs by Ca treatment in 316L stainless steels is preferred for high cutting speeds.

  • 36.
    Du, Hongying
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Karasev, Andrey
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Three-Dimensional Investigations of Non-Metallic Inclusions in Stainless Steels Before and After MachiningIngår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The focus of this study is to investigate non-metallic inclusions (NMIs) in stainless steels before (in steel samples) and after machining (in steel chips). In this study, the electrolytic extraction (EE) technique was used to extract non-metallic inclusions from steel samples. This makes it possible to investigate NMIs on film filters as three-dimensional objects by using SEM. The characteristics of NMIs in steel and chips have been systematically investigated and compared. Based on the results, it was found that the morphology of NMIs was significantly changed after machining. Overall, three different main shapes of NMIs were found: 1) a similar shape, 2) a stretched shape, and 3) a brittlely fractured shape. Furthermore, the degree of deformation of MnS and soft oxide NMIs in different zones of the chips depends on the distances from the contact zone of the tool and the chip. The total areas of MnS and soft oxides in the secondary deformation zone were increased by up to 2-3 times compared to that of the reference steel sample. This study also shows the advantages of the EE method in investigating NMIs in chips compared to using the conventional two-dimensional investigations of NMIs on the polished metal surface.

  • 37.
    Du, Hongying
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Karasev, Andrey
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Jönsson, Pär Göran
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Influence of Non-metallic Inclusions in 316L Stainless Steels on Machining Using Different Cutting Speeds2021Ingår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 61, nr 9, s. 2426-2434Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This research focuses on providing a detailed characteristic of non-metallic inclusions (NM's) in 316L stainless steels with and without Ca treatment after machining using different cutting speeds. The electrolytic extraction (EE) technique was used for three-dimensional determinations of the inclusion characteristics. Quantitative data from the fragile non-metallic inclusions (such as size, surface area, number) in chips obtained from different cutting speeds and materials were determined. The morphologies of NMIs in the chip samples were quite different compared to the original inclusions in the stainless steel samples before machining. It was proved that the deformation degree of soft inclusions such as MnS and CaO-SiO2-Al2O3-MgO-TiOx is dependent on the cutting speed as well as the temperatures and deformation degrees of the metal matrix during machining. The total surface areas of MnS inclusions increase from 2.8 to 3.8 times compared to the original total areas with an increased cutting speed. The total surface areas of soft oxide inclusions also increase from 1.1 to 3.5 times compared to the original total areas. In addition, the tool-chip contact lengths were also measured on the rake face of the tool, and the results were compared to the determined characteristics of the observed inclusions. It was found that the modification of NMIs by Ca treatment in 316L stainless steels is preferred for high cutting speeds.

  • 38.
    Du, Hongying
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Karasev, Andrey
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Jönsson, Pär Göran
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Three-dimensional Investigations of Non-metallic Inclusions in Stainless Steels before and after Machining2021Ingår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 61, nr 9, s. 2416-2425Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The focus of this study is to investigate non-metallic inclusions (NMIs) in stainless steels before (in steel samples) and after machining (in steel chips). In this study, the electrolytic extraction (EE) technique was used to extract non-metallic inclusions from steel samples. This makes it possible to investigate NMIs on film filters as three-dimensional objects by using SEM. The characteristics of NMIs in steel and chips have been systematically investigated and compared. Based on the results, it was found that the morphology of NMIs was significantly changed after machining. Overall, three different main shapes of NMIs were found: 1) a similar shape, 2) a stretched shape, and 3) a brittlely fractured shape. Furthermore, the degree of deformation of MnS and soft oxide NMIs in different zones of the chips depends on the distances from the contact zone of the tool and the chip. The total areas of MnS and soft oxides in the secondary deformation zone were increased by up to 2-3 times compared to that of the reference steel sample. This study also shows the advantages of the EE method in investigating NMIs in chips compared to using the conventional two-dimensional investigations of NMIs on the polished metal surface.

  • 39.
    Du, Hongying
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Karasev, Andrey
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Stavlid, Nils
    Swerea KIMAB, Dept Mat & Mfg, Isafjordsgatan 28A, S-16440 Kista, Sweden..
    Bjork, Thomas
    Swerea KIMAB, Dept Mat & Mfg, Isafjordsgatan 28A, S-16440 Kista, Sweden..
    Lovquist, Simon
    AB Sandvik Coromant, Dept Verificat Prod Characterist, Mossvagen 10, S-81181 Sandviken, Sweden..
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Using chip weight distribution as a method to define chip breakability during machining2018Ingår i: Proceedings 8th Swedish Production Symposium (SPS) / [ed] Onori, M Wang, L Wang, XV Ji, W, Elsevier BV , 2018, Vol. 25, s. 309-315Konferensbidrag (Refereegranskat)
    Abstract [en]

    Nowadays, the existing evaluation methods of chip breakability in industry are based on subjective visual evaluations of the chip formation during cutting or on a chip chart made after the tests. However, more sensitive methods are needed to provide more in-depth information. Thus, this study proposes a method to better evaluate the chip breakability. Based on a systematically study using the weight distribution measurement method, the results show that a great consistency and reliability to evaluate the chip breakability can be obtained. Overall, it is an objective, available and precise method to be applied in the academic and industrial research. (C) 2018 The Authors. Published by Elsevier B.V.

  • 40.
    Du, Hongying
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Yang, Annika
    SSAB Special Steels, 613 08, Oxelösund, Sweden.
    Karasev, Andrey
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Characterization of non-metallic inclusions in low-alloyed steels by using PDA/OES and off-line investigation methodsManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The characteristics of non-metallic inclusions(NMIs)in low-alloyed steel samples taken during ladle treatment beforeand after Ca-treatment were evaluated by using the Pulse Distribution AnalysisOptical Emission Spectroscopy (PDA/OES)method,INCA-Feature investigationsof inclusions on polished surfacesof steel samples, and three-dimensional investigations of NMIs after electrolytic extraction (EE) ofsteel samples. The investigation results of NMIs by using different methodswere compared.The PDA/OES resultsshow a clear tendency of achange in the average composition and quantity of NMIs during the ladle treatment, whichcorrelated well with the resultsobtainedfrom the other two methods. Overall, it was found that theapplication of the PDA/OES method is appropriate to enablea fast on-lineevaluation of inclusioncompositionsand their behaviors during steelmaking. This, in turn,provides the means for establishing an on-linecontrol and correction of technological operations of the ladle treatment to implement necessary modification of NMIsin order to improve the cleanliness of steelsand to avoid clogging problemsduring casting.

  • 41.
    Du, Hongying
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Yang, Annika
    Department of Process DevelopmentSSAB Special Steels613 08 Oxelösund, Sweden.
    Karasev, Andrey
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Characterization of Nonmetallic Inclusions in Low-Alloyed Steels Using Pulse Distribution Analysis Optical Emission Spectroscopy and Offline Investigation Methods2021Ingår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 92, nr 11, s. 2100223-, artikel-id 2100223Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The characteristics of nonmetallic inclusions (NMIs) in low-alloyed steel samples taken during ladle treatment before and after Ca treatment are evaluated using the pulse distribution analysis optical emission spectroscopy (PDA/OES) method, INCA-Feature investigations of inclusions on a polished surface of steel samples, and 3D investigations of NMIs after electrolytic extraction (EE) of steel samples. The investigation results of NMIs using the different methods were compared. The PDA/OES results show a clear tendency of a change in the average composition and quantity of NMIs during ladle treatment, which correlates well with the results obtained from the other two methods. Overall, it is found that the application of the PDA/OES method is appropriate to enable a fast online evaluation of inclusion compositions and their behaviors during steelmaking. This, in turn, provides the means for establishing an online control and correction of technological operations of the ladle treatment to implement necessary modification of NMIs to improve the cleanliness of steels and avoid clogging problems during casting.

  • 42.
    Fleuriault, Camille
    et al.
    Eramet Norway, Sauda, Norway.
    Steenkamp, Joalet D.
    Glencore XPS, Sudbury, ON, Canada.
    Gregurek, Dean
    RHI Magnesita Technology Center, Leoben, Austria.
    White, Jesse
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Reynolds, Quinn G.
    Mintek, Johannesburg, South Africa.
    Mackey, Phillip J.
    P. J. Mackey Technology Inc. Kirkland, QC, Canada.
    Hockaday, Susanna A.C.
    Curtain University, Perth, WA, Australia.
    Preface2023Ingår i: Minerals, Metals and Materials Series, Springer Nature , 2023Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 43.
    Forsberg, Kerstin
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Resursåtervinning.
    Hulme-Smith, Christopher
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Materials - a tangible challenge for the electrification of society2022Ingår i: Towards the energy of the future – the invisible revolution behind the electrical socket / [ed] Fredrik Brounéus & Christophe Duwig, Books on Demand , 2022Kapitel i bok, del av antologi (Övrig (populärvetenskap, debatt, mm))
  • 44.
    Franklin White, Jesse
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Skorodumova, Natalia
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Strukturer.
    Glaser, Björn
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Towards Bio-carbon Substitutes in the Manufacture of Electrodes and Refractories for the Metallurgical Industries: A Science and Technology Review2023Ingår i: Advances in Pyrometallurgy: Developing Low Carbon Pathways, Springer Nature , 2023, s. 151-152Konferensbidrag (Refereegranskat)
    Abstract [en]

    The unique structural versatility and chemical and thermophysical properties of carbon make it essentially irreplaceable for non-reductant uses in many high-temperature metallurgical processes. At present, bio-carbon substitutes are not technically feasible for large-scale use in electrode and refractory materials that are vital consumables in the steel, aluminum, and non-ferrous metal industries. Carbon electrodes of all types (including Soderberg, prebaked, and anodes/cathodes for Al) as well as carbon lining pastes are all similar in that they are comprised of a granular carbon aggregate and a carbon-based binder. Similarly, refractories such as MgO-C utilize both natural (mined) graphite and carbon-based binders. Replacements of fossil materials with equivalent bio-carbon substitutes have the potential to dramatically reduce the carbon footprints of these products. However, there are still considerable materials engineering challenges that must be surmounted. The properties of bio-carbon materials and technological obstacles are explored, including catalytic graphitization and development of bio-pitch materials.

  • 45.
    Frosin, C.
    et al.
    Department of Physics and Astronomy, University of Florence, Via Giovanni Sansone 1, 50019 Sesto Fiorentino, Italy, Via Giovanni Sansone 1; INFN Florence, Via Bruno Rossi, 1, 50019 Sesto Fiorentino, Italy, Via Bruno Rossi, 1.
    Glaser, Björn
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Rangavittal, Bharath Vasudev
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Vynnycky, Michael
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    et al.,
    Exploring the potential of muon radiography for blast furnace assessments: advancements in non-invasive imaging and structural analysis2024Ingår i: Journal of Instrumentation, E-ISSN 1748-0221, Vol. 19, nr 2, artikel-id C02041Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The BLEMAB European project (BLast furnace stack density Estimation through online Muon ABsorption measurements), the evolution of the previous Mu-Blast European project, is designed to investigate in detail the capability of muon radiography techniques applied to the imaging of the inner zone of a blast furnace. In particular, the goal of this collaboration is to characterize the internal region (so-called cohesive zone) where the slowly downward-moving material begins to soften and melt, which plays an important role in the performance of the blast furnace itself. In this contribution, we describe the state-of-the-art of the muon tracking system which is currently being developed and installed at a blast furnace on the ArcelorMittal site in Bremen (Germany). Moreover, we will present the GEANT4 simulation framework devised for this application together with the simulation results. Finally, we will show the possible contribution of multiple scattering effects to such peculiar applications.

  • 46.
    Ghadamgahi, Mersedeh
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik. Ovako Hofors AB, Hofors, Sweden .
    Ölund, P.
    Lugnet, A.
    Saffaripour, Mohsen
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Yang, Weihong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Design optimization of flameless-oxyfuel soaking pit furnace using CFD technique2014Ingår i: Energy Procedia, 2014, Vol. 61, s. 611-614Konferensbidrag (Refereegranskat)
    Abstract [en]

    The effect of the combustion chamber’s configuration on the characteristics of flow and combustion parameters has been numerically investigated for a multi injecting, LPG, Flameless Oxy-fuel burner in a real-size soaking pit furnace, using CFD simulation. The simulation has been performed on two different furnace configurations, namely; small and large chambers of 15 m3 and 27 m3, with a height to width ratios of 1.49 and 2.02 respectively and with corresponding burner capacities of 560 kW and 900 kW. A major experimental trial has been performed in order to validate the results and reasonable consistency has been observed. The predicted results, with particular focus on the temperature distribution and heat transfer rate of two cases have been studied in detail.

  • 47.
    Ghalambaz, Mohammad
    et al.
    Ton Duc Thang University.
    Mansouri Mehryan, Seyed Abdollah
    Islamic Azad University, Yasooj.
    Ayoubi Ayoubloo, Kasra
    Shahid Chamran University of Ahvaz.
    El Kadri, Mohamad
    Université Ferhat Abbas Sétif-1; Centre Scientifique et Technique du Bâtiment.
    Hajjar, Ahmad
    Université de Lyon.
    Younis, Obai
    Department of Mechanical Engineering, College of Engineering at Wadi Addwaser, Prince Sattam Bin Abdulaziz University.
    Saffari Pour, Mohsen
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Hulme-Smith, Christopher
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Thermal Energy Storage and Heat Transfer of Nano-Enhanced Phase Change Material (NePCM) in a Shell and Tube Thermal Energy Storage (TES) Unit with a Partial Layer of Eccentric Copper Foam2021Ingår i: Molecules, ISSN 1431-5157, E-ISSN 1420-3049, Vol. 26, nr 5, artikel-id 1491Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Thermal energy storage units conventionally have the drawback of slow charging response. Thus, heat transfer enhancement techniques are required to reduce charging time. Using nanoadditives is a promising approach to enhance the heat transfer and energy storage response time of materials that store heat by undergoing a reversible phase change, so-called phase change materials. In the present study, a combination of such materials enhanced with the addition of nanometer-scale graphene oxide particles (called nano-enhanced phase change materials) and a layer of a copper foam is proposed to improve the thermal performance of a shell-and-tube latent heat thermal energy storage (LHTES) unit filled with capric acid. Both graphene oxide and copper nanoparticles were tested as the nanometer-scale additives. A geometrically nonuniform layer of copper foam was placed over the hot tube inside the unit. The metal foam layer can improve heat transfer with an increase of the composite thermal conductivity. However, it suppressed the natural convection flows and could reduce heat transfer in the molten regions. Thus, a metal foam layer with a nonuniform shape can maximize thermal conductivity in conduction-dominant regions and minimize its adverse impacts on natural convection flows. The heat transfer was modeled using partial differential equations for conservations of momentum and heat. The finite element method was used to solve the partial differential equations. A backward differential formula was used to control the accuracy and convergence of the solution automatically. Mesh adaptation was applied to increase the mesh resolution at the interface between phases and improve the quality and stability of the solution. The impact of the eccentricity and porosity of the metal foam layer and the volume fraction of nanoparticles on the energy storage and the thermal performance of the LHTES unit was addressed. The layer of the metal foam notably improves the response time of the LHTES unit, and a 10% eccentricity of the porous layer toward the bottom improved the response time of the LHTES unit by 50%. The presence of nanoadditives could reduce the response time (melting time) of the LHTES unit by 12%, and copper nanoparticles were slightly better than graphene oxide particles in terms of heat transfer enhancement. The design parameters of the eccentricity, porosity, and volume fraction of nanoparticles had minimal impact on the thermal energy storage capacity of the LHTES unit, while their impact on the melting time (response time) was significant. Thus, a combination of the enhancement method could practically reduce the thermal charging time of an LHTES unit without a significant increase in its size.

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  • 48.
    Ghalambaz, Mohammad
    et al.
    Ton Duc Thang University.
    Mehryan, Seyed Abdollah Mansouri
    Islamic Azad University.
    Hajjar, Ahmad
    Université de Lyon.
    Younis, Obai
    Prince Sattam Bin Abdulaziz University; University of Khartoum.
    Sheremet, Mikhail
    Tomsk State University.
    Saffari Pour, Mohsen
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer. Shahid Bahonar University of Kerman.
    Hulme-Smith, Christopher
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Phase-Transition Thermal Charging of a Channel-Shape Thermal Energy Storage Unit: Taguchi Optimization Approach and Copper Foam Inserts2021Ingår i: Molecules, ISSN 1431-5157, E-ISSN 1420-3049, Vol. 26, artikel-id 1235Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Thermal energy storage is a technique that has the potential to contribute to future energy grids to reduce fluctuations in supply from renewable energy sources. The principle of energy storage is to drive an endothermic phase change when excess energy is available and to allow the phase change to reverse and release heat when energy demand exceeds supply. Unwanted charge leakage and low heat transfer rates can limit the effectiveness of the units, but both of these problems can be mitigated by incorporating a metal foam into the design of the storage unit. This study demonstrates the benefits of adding copper foam into a thermal energy storage unit based on capric acid enhanced by copper nanoparticles. The volume fraction of nanoparticles and the location and porosity of the foam were optimized using the Taguchi approach to minimize the charge leakage expected from simulations. Placing the foam layer at the bottom of the unit with the maximum possible height and minimum porosity led to the lowest charge time. The optimum concentration of nanoparticles was found to be 4 vol.%, while the maximu possible concentration was 6 vol.%. The use of an optimized design of the enclosure and the optimum fraction of nanoparticles led to a predicted charging time for the unit that was approximately 58% shorter than that of the worst design. A sensitivity analysis shows that the height of the foam layer and its porosity are the dominant variables, and the location of the porous layer and volume fraction of nanoparticles are of secondary importance. Therefore, a well-designed location and size of a metal foam layer could be used to improve the charging speed of thermal energy storage units significantly. In such designs, the porosity and the placement-location of the foam should be considered more strongly than other factors.

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  • 49.
    Ghalambaz, Soodabeh
    et al.
    Payame Noor Univ PNU, Dept Management, POB 19395-4697, Tehran, Iran..
    Hulme-Smith, Christopher
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    A Scientometric Analysis of Energy Management in the Past Five Years (2018-2022)2022Ingår i: Sustainability, E-ISSN 2071-1050, Vol. 14, nr 18, s. 11358-, artikel-id 11358Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Energy management is an essential part of the integration of renewable energy in energy systems, electric vehicles, energy-saving strategies, waste-heat recovery, and building energy. Although many publications considered energy management, no study addressed the connection between scientists, organizations, and countries. The present study provides a scientometric analysis that addresses the trend of publications and worldwide dynamic maps of connectivity and scientists, organizations, and countries and their contribution to energy management. The results showed that Javaid Nadeem published the most papers in the field of energy management (90) while Xiao Hu received the most citations (1394). The university with the highest number of publications in energy management is the Islamic Azad University (144 papers), while the Beijing Institute of Technology has received the most citations (2061 citations) and the largest h-index (28). China and the United States are in the first and second rank in terms of total publications, citations, and h-index. Pakistan has the most publications relative to the country's research and development investment level. The maps of co-authorship show islands of isolated groups of authors. This implies that the researchers in energy management are not well-connected. Bibliographic coupling of countries revealed China and USA are influential contributors in the field, and other countries were coupled mostly through these two countries.

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  • 50.
    Gomez-Rueda, Yamid
    et al.
    Dept Mech Engn, Celestijnenlaan 300, B-3001 Leuven, Belgium..
    Zaini, Ilman Nuran
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Processer.
    Yang, Weihong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Helsen, Lieve
    Dept Mech Engn, Celestijnenlaan 300, B-3001 Leuven, Belgium.;Energyville, Thor Pk, Waterschei, Belgium..
    Seashell waste-derived materials for secondary catalytic tar reduction in municipal solid waste gasification2020Ingår i: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 143, artikel-id 105828Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Catalytic tar removal from producer gas is critical for the economic feasibility of Municipal Solid Waste (MSW) gasification in the waste-to-energy(WtE) approach. Nickeland noble-metal catalysts have the highest tar cracking activities, but they increase costs, use scarce materials, and generate dangerous byproducts. To overcome these drawbacks, naturally occurring materials should be used for tar cracking. In this paper, two nanomaterials, synthesized from oyster and mussel waste shells respectively, are used to clean syngas from MSW in a secondary tar cracking unit. We observed that they reform class 1 tar (heavy tars that condense at high temperatures at very low concentrations) into class 3 tar (light hydrocarbons that are not important in condensation) and benzene. Although both catalysts' composition and textural properties were identical, crystallite size and especially specific surface area variation was enough to generate a change in product selectivity. A larger crystallite size and SSA shows a soot yield reduction of 95% with respect to the non-catalytic case, simultaneously increasing the H-2/CO at 1000 degrees C.

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