AMO Internships 2021 Summer Research Presentations, August 4, 2021 Thomas Nguyen Oak Ridge National Laboratory

1. ORNL is managed by UT-Battelle LLC for the US Department of Energy
Simulation of Electrochemical Processes in
Aluminum Smelting
AMO Internships 2021 Summer Research
Presentations,
August 4, 2021
Thomas Nguyen
Oak Ridge National Laboratory

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About me
• 4th year Undergraduate Student at California State University
Long Beach
• Majoring in Aerospace Engineering with a minor in Applied
Math
• Interning at Oak Ridge National Laboratory with the Thermal
Hydraulics group

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Internship Project
• Collaborator: Alcoa USA corp.
• Proposal Program: HPC4 Energy Innovation (USDOE-EERE*)
• Goal: Adapt existing models in computational fluid dynamics
(CFD) with high numerical accuracy in simulating thermal,
chemical, and electric effects in Alcoa’s proprietary smelting
technology, using US DOE’s high-performance computing
(HPC) resources
• Develop HPC capable CFD models to model Alcoa’s smelting
process
• Use the CFD simulation results to identify and recommend
improvements to Alcoa’s furnaces
*EERE - Office of Energy Efficiency and Renewable Energy

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A History of Aluminum
• Aluminum is the most abundant metal on earth
• Aluminum naturally does not naturally occur as a metal
• Historically aluminum was a very precious metal
• The Hall-Héroult process extracted aluminum from aluminum
ore making it a very cheap metal
• The availability of aluminum led to the flight and the space age

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Conventional Smelting | Hall-Héroult process
• 𝐴𝐴𝑙𝑙2𝑂𝑂3 + 3𝐶𝐶 → 2𝐴𝐴𝑙𝑙(𝑙𝑙) + 3𝐶𝐶𝑂𝑂(𝑔𝑔) or 2𝐴𝐴𝑙𝑙2𝑂𝑂3 + 3𝐶𝐶 → 4𝐴𝐴𝑙𝑙(𝑙𝑙) + 3 𝐶𝐶𝑂𝑂2(𝑔𝑔)
• Alumina (Al2O3) has a very high melting temperature (2,072°C)
and is dissolved in cryolite (NaF, AlF3) with a far lower melting
point (850°C)
• Aluminum fluoride (AlF3) is added to increase the bath’s
electrical conductivity
• Bath = Alumina + Cryolite

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Conventional Smelting | Hall-Héroult process
*Videos from YouTube

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Undesirable Effects of Conventional Smelting
• An excessive yield
alumina creates
sludge due to the
bath’s density being
greater than
aluminum’s
• An insufficient yield
alumina results in the
“anode effect”
forming additional
harmful greenhouse
gases (𝐶𝐶2𝐹𝐹6, 𝐶𝐶𝐹𝐹4),
causing over-
voltage, and
interruptions in
production
• High energy
consumption
Panicker, Nithin S., Rajneesh Chaudhary, Prashant K. Jain, Vivek M. Rao, and
Marc O. Delchini. "COMPUTATIONALMODELING AND SIMULATION OF ALUMINIUM
SMELTING PROCESS USING OPENFOAM." (2021). 5th–6thThermalFluids and
Engineering Conference

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Software
• OpenFOAM is an open-source CFD code (“FOAM”: field
operation and manipulation)
• Access to the source code and easier to modify than
commercial CFD codes
• Has history of scalability on HPC
• Formulation of physics models can be modified at user-level

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Multiphysics Models
• Interactions
between phases
(gas, solid, liquid)
• Turbulent flow
• Electromagnetism
• Electrochemistry
Panicker, Nithin S., Rajneesh Chaudhary, Prashant K. Jain, Vivek M. Rao, and
Marc O. Delchini. "COMPUTATIONALMODELING AND SIMULATION OF ALUMINIUM
SMELTING PROCESS USING OPENFOAM." (2021). 5th–6thThermalFluids and
Engineering Conference

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Benefits of CFD simulations
• Evaluate new designs at a lower cost
• Investigate different operating conditions
• Reduce negative effects of smelting such as excessive energy
consumption and emissions

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Geometry of Smelting Domain
Top View
Side View
Front View
Anode (+)
Cathode (-)
Cathode (-) Cathode (-)
Anode (+)
Wall
Bath Surface
Wall
Wall
Wall
Isometric View

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Simulation of CO2 Formation
• The formation of aluminum and carbon
dioxide are dependent on the electrical
current
• CO2 bubbles are added to the system at the
anodes based on the electrical current using a
source
• The CO2 bubbles rise and cause the bath to
circulate
• 𝑂𝑂2−
+ 𝐶𝐶 → 𝐶𝐶𝑂𝑂(𝑔𝑔) + 2𝑒𝑒−
or 2𝑂𝑂2−
+ 𝐶𝐶 → 𝐶𝐶𝑂𝑂2(𝑔𝑔) + 4𝑒𝑒−
CO2 Formation on the Anode
Anode (+)
Cathode (-)
Bath Surface Bath Surface
Wall
Wall
Wall
Wall

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Velocity Distribution
Bath circulation on a central plane cutting through the anode
Anode (+)
Cathode (-)
Bath Surface Bath Surface
Wall
Wall
Wall
Wall
Anode (+)
Cathode (-)
Bath Surface Bath Surface
Wall
Wall
Wall
Wall

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Electric Current Density
Electric current density on a central plane cutting the anode
Anode (+)
Cathode (-)
Bath Surface Bath Surface
Wall
Wall
Wall
Wall
Anode (+)
Cathode (-)
Bath Surface Bath Surface
Wall
Wall
Wall
Wall

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Profiles in Anode-Cathode Distance (ACD)
Velocity profiles on a plane bisecting the ACD
Anode (+)
Cathode (-)

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Profiles in Anode-Cathode Distance (ACD)
Electric current density on a plane bisecting the ACD
Anode (+)
Cathode (-)

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Profiles on Anode Surface
CO2 evolution on anode surface Electric current density on anode surface
Anode Anode

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Scope of Work for Internship
• Travel to ORNL (August 9-10, 2021)
• Workshop on GPU basics at ORNL
• Advanced CAD modeling strategies
• Improve analytical skills with advanced CFD applications
• Gain proficiency with batch scripting for HPC systems
• Extend statistical tools to coursework
• Apply internship experience to Honors thesis

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Acknowledgements
• US DOE – EERE for internship opportunity
• ORISE for mediating internship
• ORNL Thermal Hydraulics Group (Host: Marc-Olivier G.
Delchini, PhD)
• NREL for access to Eagle HPC

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Q&A