Gudrun SaevarsdottirReykjavik University · Mechanical and electrical engineering
Gudrun Saevarsdottir
Doctor of Philosophy
About
123
Publications
39,448
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776
Citations
Introduction
Additional affiliations
July 2018 - April 2021
Reykjavik University
Position
- Professor (Associate)
January 2012 - July 2018
Education
August 1996 - May 2002
September 1994 - June 1996
August 1991 - June 1994
Publications
Publications (123)
In this work, we studied the electrochemical behaviour of silicon ions in NaCl-KCl-KF molten salts containing K2SiF6 at 1003 K. Electrochemical techniques such as cyclic voltammetry, chronopotentiometry and chronoamperometry were used to study the kinetics of Si deposition on molybdenum working electrode. The diffusion coefficient and nucleation mo...
Electric arcs are a necessary heat source in many industrial processes that take place in Submerged Arc Furnaces (SAFs). Arcs exhibit non-linear electrical characteristics and behave in a complex manner. Therefore, an improved understanding of their behavior enables better control of furnace operation. Modeling of industrial arcs is a multiphysics...
The anodic behavior of Ni48Fe47Cu5 and Ni42Fe38Cu20 alloys in NaF-KF-AlF3-
Al2O3 electrolyte was studied using electrochemical methods, such as
chronopotentiometry, chronoamperometry, and linear sweep voltammetry at
770�C. The cryolite ratio and potassium ratio were 1.3 and 0.7, respectively.
The steady-state polarization curves were obtained befor...
To eliminate climate gas emissions from aluminum electrolysis, modifying a cryolite-based electrolyte partly replacing Na with K reduces liquidus, allowing a process temperature of 800°C. This enables the use of various metallic alloys for oxygen-evolving inert anode technology. This alternative process requires a higher energy efficiency to compen...
This study reports the direct production of aluminum–manganese alloys during the electrodeposition of aluminum in cryolitic melts. For the purpose of measuring current efficiency, experiments were conducted in a laboratory cell. The temperature was changed between 960 and 980 °C at a cryolite ratio (CR) of 2.2 and a cathodic current density (CCD) o...
There is a strong push towards developing an alternative low-carbon process for the primary production of aluminium. Electrolysis with inert, oxygen-evolving anodes is an attractive alternative, and alloys of Ni–Fe–Cu are promising. This paper describes results from electrochemical studies to examine the performance of such anodes for different sod...
The performance of low-temperature electrolytes in a 40 A laboratory oxygen-evolving aluminum electrolysis cell with vertical inert electrodes for two compositions of NaF-KF-AlF₃-based electrolyte was investigated. Two compositions of Cu-Ni-Fe alloy, single-phase homogenized, 20Cu-42Ni-38Fe wt% and 5Cu-48Ni-47Fe wt%, were evaluated as anodes. Titan...
Primary aluminium is produced by the Hall-Heroult process which is based on electrolysis in molten fluoride electrolyte, Na 3 AlF 6 -AlF 3 , at ~960 o C in which the raw material alumina is dissolved and decomposed into pure aluminium and CO 2 gas due to the use of carbon anodes. The current efficiency with respect to aluminium can be as high as 96...
Using inert anode technology to produce aluminium would substantially reduce the aluminium industry's carbon footprint. Replacing the Hall-Héroult process with an alternative process based on vertical electrode cell (VEC) design using inert anodes and wettable cathodes is a promising alternative, but must be developed to be economically viable at s...
To eliminate climate gas emissions from aluminum electrolysis, significant research and development efforts focus on non-consumable oxygen evolving anodes to replace the carbon anodes used in the Hall Héroult process. Modifying the cryolite-based electrolyte currently used, by partly replacing Na with K in the molten fluoride, opens up a range of m...
Replacing consumable carbon anodes with oxygen evolving inert anodes, in aluminium reduction cells, has long been a goal for the aluminium industry. Using inert anodes would have several advantages, one of them being the elimination of greenhouse gas emission during the electrolysis process. Metallic alloys have proven to be a promising category of...
The anodic behaviour of Ni42Fe38Cu20 alloy at different sodium-potassium-cryolite-based electrolyte compositions was examined by chronopotentiometry, chronoamperometry, and linear sweep voltammetry at 1098 K for different electrolyte compositions. Steady-state anodic polarisation curves show that the anodic overpotential in electrolytes with molar...
The formation of silicon carbide (SiC) and the energy distribution in the furnace are two important parameters in evaluating furnace operations. The energy distribution is determined by the resistivity of the materials in the furnace. This work aims to investigate the bulk resistivity of materials in the silicon (Si) furnace using both partially tr...
Due to environmental and economic concerns, carbon-free aluminium production has been an ultimate goal for aluminium industries. For the past few decades, a considerable amount of research has been conducted to find an inert anode material that could replace the consumable carbon anodes for aluminium electrolysis. Anodic materials such as metals, c...
The global community has set a goal of carbon neutrality by 2050. Almost one-fourth of the global emissionsEmissions, attributed to direct emissionsEmissions from industrial processes, must be addressed by developing zero-carbon alternatives for each process, including the production of aluminumAluminum. Several companies and research institutions...
Reducing CO2 emissions from aluminum smelters is of great interest to reach the goal of carbon neutrality. One possible approach is to implement carbon captureCarbon capture and sequestration techniques (CCS). This is already being done within the geothermal sector in Iceland, where captured CO2 is sequestered through the Carbfix method of minerali...
Haraldsson, Hákon ValurTraustason, HalldórTesfahunegn, Yonatan A.Tangstad, MereteSævarsdóttir, GurúnElectric arcs are necessary for high Si yield in submerged arc furnaces (SAFs) for Si/FeSi production, and a certain fraction of heat dissipation in the arc enables optimal operating conditions. Direct measurement of the arc characteristics is imposs...
Electrochemically produced Si in molten salts can be used to fabricate electronic and photovoltaic devices. The major factors influencing the structure and morphology of Si deposits are electrolyte composition, applied current densities and overpotentials, type of precursors, operating temperature, and electrodeposition duration. For Si electrodepo...
Primary aluminium is produced by the Hall-Heroult process which is based on electrolysis in molten fluoride electrolyte, Na 3 AlF 6 -AlF 3 , at ~960 o C in which the raw material alumina is dissolved and decomposed into pure aluminium and CO 2 gas due to the use of carbon anodes. Alloys are made by adding pure metals prior to the casting process. A...
Carbon dioxide and other greenhouse gases are emitted during the production of primary aluminium through the Hall-Heroult process. Moreover, the process requires specific energy consumption of as high as 14.685 kWh/tonne of Al. There is an urgency to replace the existing process with a more environmentally and economically friendly process. One suc...
The industrial process for Aluminium production is the Hall-Héroult process, an electrolysis process where the alumina raw material is dissolved in a cryolite based electrolyte, the aluminium is deposited at the cathode while the oxygen from the alumina reacts anodically with the carbon anodes, which are consumed in the process. The chemical energy...
The anodic behaviour of NixFeyCuz alloy at different sodium- and potassium-cryolite based electrolyte compositions was examined by chronopotentiometry, galvanostatic polarisation, and linear sweep voltammetry at 1098 K. Steady-state anodic polarisation curves show anodic overpotential in electrolyte with molar ratio CR=(NaF+KF)/AlF3=1.4 is signific...
Due to environmental and economic concerns, carbon-free
aluminium production has been an ultimate target for aluminium
industries. For the last few decades, a considerable amount of
research has been conducted to find a suitable inert anode that
could replace the consumable carbon anodes for aluminium
electrolysis. Material types such as metals, ce...
Primary aluminium is produced by the Hall-Heroult process which is based on electrolysis in molten fluoride electrolyte, Na 3 AlF 6 -AlF 3 , at ~960 o C in which the raw material alumina is dissolved and decomposed into pure aluminium and CO 2 gas due to the use of carbon anodes. Alloys are made by adding pure metals prior to the casting process. A...
In the Hall–Héroult aluminum production process, the amount of carbon consumed per ton of aluminum produced is an important metric. Deviations from ideal conditions in the reduction cells contribute to the discrepancy between the theoretical carbon consumption and the actual Net Carbon Consumption (NCC). Previous work from the authors, focused on p...
Titanium diboride (TiB 2 ) is considered a promising material for wettable cathodes in aluminum electrolysis. The demand for wettable cathodes is associated with the development of inert anode technologies to eliminate CO 2 emissions caused by the conventional aluminum reduction process. Titanium diboride has been given special attention due to its...
We report Ti concentration measurements in dilute Al-Ti alloys, acquired from direct analysis of the molten metal by laser-induced breakdown spectroscopy (LIBS). The LIBS analysis showed approximately constant Ti concentrations at melt temperatures above the liquidus, while at lower temperatures the measured concentration followed the L/(L + Al3Ti)...
ABS TRACT The work presents Computational Fluid Dynamic (CFD) analysis of two-phase flow in a geothermal wellbore with calcite scaling. The analysis uses Eulerian six-equation model for modeling two-phase flow. The model calculates velocities of each phase separately, thus taking into consideration the effect of slip velocity on heat transfer betwe...
Surface coatings can enhance the substrate material’s properties and increase its lifetime. HEA-based materials have been extensively investigated as coating materials due to their superior hardness, excellent oxidation and corrosion resistance, effective diffusion barrier properties and wear resistance. Magnetron sputtering has been regarded as on...
Aluminum smelters produce pure aluminum in reduction cells by the Hall-Héroult process but supply a variety of alloys to their customers. The alloys are produced in the cast house, as master alloys containing the desired alloying elements are added to the primary aluminum from the potroom before casting. In this work, the concept of producing silic...
Aluminum smelters produce pure aluminum in reduction cells by the Hall-Héroult process, however, aluminum is usually supplied as a variety of alloys to their customers. The alloys are produced in the casthouse, as desired alloying elements are added to the primary aluminum from the potroom before casting. In this work the concept of producing titan...
Although modern aluminium smelters using 100% green electrical energy generation can achieve on-site emissions of about 2 kg CO2 equivalents per tonne of aluminium produced (t CO2e/t Al), the total global average emissions from primary aluminium production from bauxite mine-to-metal ingot are much larger, about 16.5 t CO2e/t Al. Two thirds of the t...
Optimal current paths through the silicon furnace depend on the electrical properties of the charge materials. It is essential for good tapping conditions that sufficient current is supplied to the arc and lower part of the furnace. As such, the electrical resistivity of the charge mix as it is transformed in the furnace is investigated. Various ca...
This work presents a computational study to understand different heat transfer and phase transition processes of two-phase flow in a geothermal wellbore. The simulation uses a six-equation model with mass, momentum, and energy balance equations for the liquid and vapour phase, which is available in Ansys Fluent. The model considers the effect of ph...
This work addresses different characteristics of two-phase fluid flow and phase transition occurring during the flashing process, which affects the rate of calcite deposition in a geothermal wellbore. To achieve this, a two-phase flow CFD (Computational Fluid Dynamics) model available in Ansys Fluent is used for simulating a case study involving fl...
Particulate and acid gas scrubbing from geothermal steam can be achieved without considerable loss in the fluid superheat by using aqueous potassium carbonate solution with high boiling point elevation as a scrubbing medium. This work presents a discrete phase model using Euler-Lagrangian approach for simulating the behavior of aqueous potassium ca...
This paper presents a thermoeconomic analysis of power cycles proposed to utilize geothermal fluid in a superheated state with acid chloride impurities. A case study was performed where utilization models of the fluid from the well IDDP-1 proposing four different viable power cycles. Each cycle includes a technique to overcome or mitigate the chlor...
The paper presents application of Eulerian two phase flow Computational Fluid Dynamics (CFD) model for simulating flash boiling in a geothermal well. The simulation uses a six-equation model with separate mass, momentum, and energy balance equations for the liquid and vapor phases, and, is available in Ansys Fluent. The model takes into account the...
The boiling point elevation properties of certain aqueous salt solutions enable water droplets to stay in the liquid phase in superheated steam flow. This work describes how aqueous salt solutions with high boiling point elevation can be applied for scrubbing particulates and acid gas impurities from superheated geothermal steam. To demonstrate the...
The work presents the application of an advection-diffusion model for predicting precipitated silica transport and deposition occurring in superheated geothermal steam. The computational model takes into account the effect of Brownian and turbulent diffusion, turbophoresis, lift and drag force on particle motion. The simulation results were verifie...
Improved value generation and efficient use of resources are important steps national economies can implement to minimize the use of resources and mitigate the creation of waste and toxic emissions. The increase of resource efficiency is eminent to tackle the imminent challenges of depleting resources and the emerging environmental crisis. In this...
The world now pushes for a low-carbon future, and international goals for greenhouse gas emission reductions have been set. Industrial processes, including metallurgical processes, make up more than a fifth of the total global emissions, and those have been rising with infrastructure development and the expansion of the middle-class worldwide. This...
This work discusses the effect of electrode position on the electrical characteristics of a submerged arc furnace. A 3D model has been developed in ANSYS Maxwell using an eddy current solver that considers alternating current. The model includes flexibles, busbars, and the whole furnace. The furnace model contains electrodes, main arcs, craters, cr...
Direct production of aluminium-silicon alloy during aluminium electrolysis in fluoride-based melts was studied. Experiments were carried out in a laboratory cell dedicated to current efficiency measurements. Electrolysis was run at 960 °C, 970 °C, and 980 °C at a fixed cathodic current density (CCD) of 0.9 A cm ⁻² and a cryolite ratio (CR) of 2.2....
Direct production of aluminium-silicon alloy during aluminium electrolysis in fluoride-based melts was studied. Experiments were carried out in a laboratory cell dedicated to current efficiency measurements. Electrolysis was run at 960°C, 970°C, and 980°C at a fixed cathodic current density (CCD) of 0.9 A cm −2 and a cryolite ratio (CR) of 2.2. Sil...
This study reports the direct production of an aluminium−manganese alloy during aluminium electrolysis in fluoride-based melts. Experiments were conducted in a laboratory cell dedicated for current efficiency measurements. The temperature was varied from 965 to 980 ˚C at a cathodic current density (CCD) of 0.9 A/cm² and a cryolite ratio (CR) of 2.2...
This study reports the direct production of an aluminium–titanium alloy during aluminium electrolysis in fluoride-based melts. Experiments were conducted in a laboratory cell dedicated to current efficiency measurements. The temperature was varied from 960 to 980 ˚C at a cathodic current density (CCD) of 0.9 A/cm² and a cryolite ratio (CR) of 2.2....
In the aluminum electrolysis, the amount of carbon consumed per unit of metal produced is always higher than the theoretical one. Raw material variability, anode properties, and reduction cell operation and performance can influence this discrepancy. Linking these factors to each individual anode could help close this gap thus improving the environ...
The work presents computational modeling and an experimental investigation of silica deposition occurring in geothermal systems with superheated steam flows. An advection diffusion model was implemented for predicting silica particle transport and deposition in turbulent flows. The model includes the effect of Brownian diffusion, turbulent diffusio...
The paper describes a computational study and an experimental investigation of aqueous potassium carbonate droplets in superheated steam flow for potential applications in mitigation of superheated geothermal steam. The computational model included the boiling point elevation due to the droplet salt concentration as well as other concentration-depe...
The current method of producing aluminium-titanium master alloys is via melt mixing of pure titanium metal with primary molten aluminium prior to casting[1].The energy consumption and the production cost could be significantly lowered by the viable method of an in-situ electrochemical reduction of titania in fluoride-based melts which has been a su...
This work discusses 3D models of current distribution in a three-phase submerged arc furnace that contains several components, such as electrodes, central arcs, craters, crater walls, and side arcs that connect electrodes and crater walls. A complete modeling approach requires time-dependent modeling of the AC electromagnetic fields and current dis...
This paper addresses the global challenge of greenhouse gas emissions facing the aluminum industry. The demand, production and use of aluminum are increasing and so are the emissions. From bauxite mine to aluminum ingot, the total global average emissions vary somewhat in the literature, but most reported values are now between 12 and 17 metric ton...
A study on scrubbing of superheated steam containing silica impurities is performed using an aqueous potassium carbonate solution as a potential application in mitigation of superheated geothermal steam. An experimental setup aimed at testing a silica particle scrubbing technique was built. The setup consists of a superheated steam generating syste...
Most submerged arc furnaces used for the production of ferroalloys run on three-phase alternating current. This affects the electrical operation of the furnace and thus it is of interest to study alternating current distributions in the system. This work presents computations of alternating electric current distributions inside an industrial submer...
This thesis describes a study of the viability of using excess energy from the exhaust gases at the Alcoa Fjarðaál aluminium plant to provide residential heating and hot water for household use in Reyðarfjörður. The results of the study indicate that such a system would be technically viable as well as delivering social and environmental benefits t...
This work presents computations of electric current distributions inside an industrial submerged arc furnace. A 3D model has been developed in ANSYS Fluent that solves Maxwell’s equations based on scalar and vector potentials approach that are treated as transport equations. In this paper, the approach is described in detail and numerical simulatio...
This work presents computations of electrical current distribution inside an industrial submerged arc furnace for silicon production. A 3D model has been developed in ANSYS Fluent using an electrical potential solver. The electrode, arc, crater, crater wall, and side arcs that connect the electrode and crater wall are considered for each phase. The...
Current distribution is critical for good operation of Submerged Arc Furnaces for silicon production. Control systems do not offer this information as it is not directly measureable, but metallurgists operate furnaces based on experienced interpretation of available data. A number of recent dig-outs of industrial furnaces has expanded available inf...
Superheated geothermal systems represent two phase system consisting of precipitated silica in dispersed phase with the superheated steam. The work presents computational approach to predict silica transport and deposition in superheated geothermal systems. Advection diffusion model was implemented using OpenFoam. The model includes effect of Brown...
Around half of the energy consumed in aluminum production is lost as waste heat. Approximately 30–45% of the total waste heat is carried away by the exhaust gas from the smelter and is the most easily accessible waste heat stream. Alcoa Fjarðaál in east Iceland produces 350 000 tons annually, emitting the 110 °C exhaust gas with 88.1 MW of heat, wh...