| 1. |
- Tilliander, Anders, et al.
(author)
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A mathematical model of the heat transfer and fluid flow in AOD nozzles and its use to study the conditions at the gas/steel interface
- 2001
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In: ISIJ International. - : Iron and Steel Institute of Japan. - 0915-1559 .- 1347-5460. ; 41:10, s. 1156-1164
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Journal article (peer-reviewed)abstract
- Knowledge of process gas parameters in the area where the gas leaves the nozzle and then enters the molten steel in AOD converters is necessary in order to determine the boundary conditions needed to model the converter process. Using a newly developed mathematical model for an AOD nozzle verified by comparison against laser Doppler anemometer measurements, the objective of this study was to predict characteristics of non-isothermal heat transfer and fluid flow at the nozzle for pure oxygen gas injected into an AOD converter. The inlet boundary conditions for the nozzle simulation were taken from plant data. The investigation showed that the thermodynamic and physical phenomena in the region where the gas enters the steel melt cannot be determined if the transformation of kinetic energy of gas into heat is not considered because this would amount to oversight of the influences of bubble frequency, temperature, etc. on the process. The possible ranges of bubble frequency and temperature for the nozzle conditions in the study were also determined.
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| 2. |
- Tilliander, Anders, et al.
(author)
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Effect of Ar/O-2 gas mixtures on heat-transfer and fluid-flow characteristics in AOD nozzles
- 2000
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In: Steel research. - : Wiley. - 0177-4832. ; 71:11, s. 429-434
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Journal article (peer-reviewed)abstract
- A model of fluid flow and heat transfer in a nozzle used for injection of argon and oxygen in AOD converters was developed earlier. In this study the model was used to determine the effect of changes in the ratio of argon to oxygen in argon-oxygen gas mixtures injected through the nozzle on fluid flow and heat transfer. It was found, for the studied conditions, that the temperature and laminar kinematic viscosity at the nozzle outlet were not dependent on the gas composition. However, the velocity, density, turbulent kinetic energy and dissipation of kinetic energy varied with a change in the fraction of oxygen injected. It is therefore concluded that for use as boundary-condition input data for an AOD converter model (under development), it is important to be able to calculate reliable velocity and turbulence parameter data for gas mixtures of different argon/oxygen ratios.
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| 3. |
- Ahnström, Eva-Lisa, et al.
(author)
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The profession of research management and administration in Sweden
- 2023
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In: The Emerald Handbook of Research Management and Administration Around the World. - : Emerald Group Publishing Ltd.. - 9781803827018 - 9781803827025 ; , s. 751-757
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Book chapter (other academic/artistic)abstract
- This chapter outlines the development of the Swedish Higher Education System that led to the evolution of the profession of research management and administration (RMA) in Sweden. Evolution from an informal network towards more formalised and structured work within the Swedish RMA community is highlighted. Discussion on the level of salaries development depending on the education level, gender, experience and roles are elaborated too. The majority of the Swedish RMA community are women, which does not differ from most other RMA communities around the world. Swedish Association of Research Managers and Administrators (SWARMA) is the bridge between national research and innovation funding agencies and researchers. SWARMA selected members actively participate in the reference groups for EU R&I programmes. The future for RMAs in Sweden looks bright!.
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| 4. |
- Aidas, Kestutis, et al.
(author)
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The Dalton quantum chemistry program system
- 2014
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In: Wiley Interdisciplinary Reviews. Computational Molecular Science. - : Wiley. - 1759-0876. ; 4:3, s. 269-284
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Journal article (peer-reviewed)abstract
- Dalton is a powerful general-purpose program system for the study of molecular electronic structure at the Hartree-Fock, Kohn-Sham, multiconfigurational self-consistent-field, MOller-Plesset, configuration-interaction, and coupled-cluster levels of theory. Apart from the total energy, a wide variety of molecular properties may be calculated using these electronic-structure models. Molecular gradients and Hessians are available for geometry optimizations, molecular dynamics, and vibrational studies, whereas magnetic resonance and optical activity can be studied in a gauge-origin-invariant manner. Frequency-dependent molecular properties can be calculated using linear, quadratic, and cubic response theory. A large number of singlet and triplet perturbation operators are available for the study of one-, two-, and three-photon processes. Environmental effects may be included using various dielectric-medium and quantum-mechanics/molecular-mechanics models. Large molecules may be studied using linear-scaling and massively parallel algorithms. Dalton is distributed at no cost from for a number of UNIX platforms.
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| 5. |
- Andersson, Margareta, et al.
(author)
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Some Aspects on Grain Refining Additions with Focus on Clogging during Casting
- 2006
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In: ISIJ International. - : Iron and Steel Institute of Japan. - 0915-1559 .- 1347-5460. ; 46:6, s. 814-823
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Journal article (peer-reviewed)abstract
- Some ideas of how to study optimum conditions for implementation of grain refining in liquid steel processing with focus on how to avoid clogging are discussed. It is assumed that the inclusions most beneficial for grain refining are known from studies by physical metallurgists. The challenge for a process metallurgist is how to provide a homogeneous distribution of grain refiners at the onset of solidification. Four different ways of providing information to succeed with this are discussed. Thermodynamic modeling can be used to predict what additions to make to create potential grain refiners, if relevant thermodynamic data is available. Mathematical fluid-flow modeling can be used to study where to add potential grain refiners. It is discussed that the tundish is the most appropriate reactor to add grain refiners, since enough time is given to a complete mixing of the grain refiner into the steel before the steel enters the mold. By using the scanning laser microscopy technique it is possible to study which potential grain refiners has the lowest attraction forces between each other. This is important in order to minimise growth of inclusions when they collide during transport in the tundish, which can lead to the formation of larger inclusions that do not serve as useful grain refiners. Finally, it is suggested that laboratory experiments are carried out in order to study the tendency for nozzle clogging, before the use of grain refiners is tested in industrial scale.
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| 6. |
- Andersson, Nils, et al.
(author)
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Fundamental decarburisation model of AOD process
- 2013
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In: Ironmaking & steelmaking. - 0301-9233 .- 1743-2812. ; 40:5, s. 390-397
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Journal article (peer-reviewed)abstract
- A mathematical fluid flow model of gas injection in an argon–oxygen decarburisation (AOD) converter process has been coupled with a high temperature thermodynamic model. The current model is a further enhancement of an earlier developed three-dimensional, three-phase model, to also include some thermodynamics of the process. The model is based on fundamental transport equations and includes separate solutions for the steel, slag and the gas phases and their coupling by friction. The AOD model has been used to predict the first injection stage of decarburisation in an AOD converter. The predictions have been found to agree well with the corresponding results from an industrial process control model. One of the important observations from the simulations was that large concentration gradients of carbon exist in the AOD at an early stage and as the first injection step approaching its end the carbon gradients diminish. Also, the results show, in accordance with theory, that the local decarburisation rate is decreased at elevated pressures.
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| 7. |
- Andersson, Nils, et al.
(author)
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Investigating the effectof slag on decarburization in an AOD converter using a fundamental model
- 2013
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In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 84:2, s. 169-177
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Journal article (peer-reviewed)abstract
- A high-temperature thermodynamics model has been coupled with a fundamental mathematical model describing the fluid flow, where boundary conditions were chosen based on data for an industrial AOD converter. Using this model, the effect of both slag phases (a liquid part and a solid part) on the decarburization was studied. More specifically, the separation of chromium oxide to liquid slag as well as the effect of the amount of rigid top slag (solid)on the decarburization was investigated. The liquid slag was considered with respect to the uptake of chromium oxide, while the rigid top slag was only considered with respect to the increase of the metallostatic pressure in the steel melt. The results suggest that separation of chromium oxide to liquid slag results in a decreased decarburization rate. The same conclusion can be drawn with respect to the amount of solid top slag.
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| 8. |
- Andersson, Nils, et al.
(author)
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Preliminary investigation of influence of temperature on decarburisation using fundamental AOD model
- 2013
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In: Ironmaking & steelmaking. - 0301-9233 .- 1743-2812. ; 40:7, s. 551-558
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Journal article (peer-reviewed)abstract
- A high temperature thermodynamics model was earlier coupled with a fundamental mathematical model describing the fluid flow in an argon–oxygen decarburisation (AOD) converter and was initially validated for an idealised temperature description. More specifically, a linear average temperature relation was used such that the temperature would be isolated from other effects such as reactions and mixing. Thereafter, the effect of the starting temperature on the decarburisation was studied. The purpose is to provide some initial knowledge about how temperature affects the decarburisation in an AOD converter. The results suggest that the thermodynamic limit for carbon concentration after reaching the carbon removal efficiency (CRE) maxima is vertically translated downwards at higher temperatures. Furthermore, when plotting the mass ratio between CO and CO2, there is an indication of a point that may relate to a CRE maximum.
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| 9. |
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| 10. |
- Andersson, Nils Å. I., et al.
(author)
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An in-Depth Model-Based Analysis of Decarburization in the AOD Process
- 2012
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In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 83:11, s. 1039-1052
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Journal article (peer-reviewed)abstract
- A previously reported flow and reaction model for an argon-oxygen decarburization converter was extended to also include a thermodynamic description. An in-depth study of the model results has been conducted to answer how concentrations of elements and species in the converter at different locations change with time. This may contribute to the understanding of the mechanisms of the refining procedure in the argon-oxygen decarburization process. The refining procedure includes several step-wise changes of an injected gas composition to higher and higher inert gas ratio, called step changes. A step change leads to a decreased partial pressure of carbon monoxide and maintains the decarburization at a higher efficiency. The results shows early and late concentration profiles for the first injection step and suggests a way to determine when a step change should be made. Moreover, the step change could be determined by calculating the carbon concentration profiles and deciding when the carbon concentration gradients start to diminish.
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