A heat and mass transfer problem for the dissolution of an alumina particle in a cryolite bath

Kovács, Attila; Breward, Christopher; Einarsrud, Kristian Etienne; Halvorsen, Svenn Anton; Nordgård-Hansen, Ellen; Manger, Eirik; Münch, Andreas; Oliver, James M.

doi:10.1016/j.ijheatmasstransfer.2020.120232

Cited by 18 publications

(3 citation statements)

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“…The list of publications devoted to the alumina feeding problem is rather extensive, showing various approaches; see [16][17][18][19][20][21][22] in addition to those already covered in the Introduction. Practical usability of the complex mathematical modelling setups and the need for expensive computer Fig.…”

Section: The Theory Coupling Concentration Field and Raft Particle Mo...mentioning

confidence: 99%

Advanced Alumina Dissolution Modelling

Bojarevics

Dupuis²

2022

Light Metals 2022

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Alumina feeding requires optimization for the feed amount, timing, and point feeder locations. The alumina raft formation and dispersion are the essential stages leading to the particles of various sizes travel with the bath flow along anodes in the central channel, in the bath volume beneath the anodes, and gradually dissolving. The raft motion and particles are traced accounting for their inertia, drag in the turbulent flow, the dome-shaped anode bottom shape. Large-scale MHD-driven circulation in the cell is modelled using specific inputs corresponding to real commercial cells of various types. The feed material forming rafts and particles is added periodically, moves with the flow, and gradually dissolves depending on the local turbulence and instantaneous concentration in a location. The newly developed modelling technique is applied to illustrate possible optimization of the feeder locations, the variable mass, and feeding time intervals for possible adjustments suitable for commercial cells.

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Section: The Theory Coupling Concentration Field and Raft Particle Mo...mentioning

confidence: 99%

Advanced Alumina Dissolution Modelling

Bojarevics

Dupuis²

2022

Light Metals 2022

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“…Here, a chemical contaminant within the porespace is neutralised by a cleanser fluid, with the neutralisation reaction occurring at the interface between the two immiscible fluids. Stefan problems within porous media also fall into this category of interface-driven behaviour, for example those involving the freezing or melting of a liquid within a porous structure [11,15,17]. While the homogenised PDEs for the macroscale flow and transport of material through porous media incorporate the microscale processes and structure through effective parameters, it is not clear how and if the microstructure affects the interface conditions.…”

Section: Introductionmentioning

confidence: 99%

A homogenised model for the motion of evaporating fronts in porous media

et al. 2023

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Evaporation within porous media is both a multiscale and interface-driven process, since the phase change at the evaporating interfaces within the pores generates a vapour flow and depends on the transport of vapour through the porous medium. While homogenised models of flow and chemical transport in porous media allow multiscale processes to be modelled efficiently, it is not clear how the multiscale effects impact the interface conditions required for these homogenised models. In this paper, we derive a homogenised model, including effective interface conditions, for the motion of an evaporation front through a porous medium, using a combined homogenisation and boundary layer analysis. This analysis extends previous work for a purely diffusive problem to include both gas flow and the advective–diffusive transport of material. We investigate the effect that different microscale models describing the chemistry of the evaporation have on the homogenised interface conditions. In particular, we identify a new effective parameter, $\mathcal{L}$ , the average microscale interface length, which modifies the effective evaporation rate in the homogenised model. Like the effective diffusivity and permeability of a porous medium, $\mathcal{L}$ may be found by solving a periodic cell problem on the microscale. We also show that the different microscale models of the interface chemistry result in fundamentally different fine-scale behaviour at, and near, the interface.

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“…The Hall-Héroult process used almost exclusively in the aluminum industry suffers from relatively high heat loss from the electrolytic cells and increased CO2 emissions from the anodes, even though manufacturers have gradually improved their production processes (Kovács et al, 2020). In 2001, Jomar Thonstad, professor of Electrochemistry at the Norwegian university of science and technology (NTNU), and his colleagues, in their book (Thonstad, 2001), mentioned that "the Hall-Héroult process remains the only modern method of producing aluminum today, having withstood many attempts to replace it.…”

Section: Introductionmentioning

confidence: 99%