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Modelling and simulation of H2-H2O bubbly flow through a stack of three cells in a pre-pilot filter press electrocoagulation reactor

Modelling and simulation of H2-H2O bubbly flow through a stack of three cells in a pre-pilot filter press electrocoagulation reactor
Modelling and simulation of H2-H2O bubbly flow through a stack of three cells in a pre-pilot filter press electrocoagulation reactor
Computational fluid dynamics simulations were carried out to describe the hydrodynamic characteristics of a two-phase bubbly flow in a filter-press flow reactor stack of three cells, which is typically used in electrocoagulation (EC). The hydrogen evolution reaction (HER) took place at the cathode; dissolution of aluminium occurred at the anode. The fundamental transport equations of momentum and electrical potential were simultaneously were solved to simulate the H2-H2O flow. Continuous (H2O) and dispersed phase (H2) velocity fields were modelled via the Euler-Eulerian approach, using the biphasic Reynolds Averaged Navier-Stokes (RANS) equations and the standard k turbulence model. The influence of volumetric flow rate (1.7 ≤ Q ≤ 15 cm3 s–1) and applied current density (–28 ≤ j ≤ –5 mA cm–2) was systematically addressed to calculate the fraction of dispersed phase and current distribution along the electrodes. The evolved H2 bubbles were transported away from the electrode by the liquid flow. The dispersion of H2 through the electrode gap showed a modest bubble curtain profile due to the liquid flow rate. A homogeneous current distribution along the electrode length was experienced due to the geometrical design of the electrochemical cell and the low degree of H2 dispersion. The velocity profiles of the H2-H2O mixture were different in each cell due to the change of flow direction. H2 bubbles increased the velocity of the liquid phase but the gas fraction of such bubbles resulted in a higher pressure drop. Good agreement between theoretical and experimental residence time distribution curves was achieved; the experimental aluminium dose released by the anode agreed well with the simulations.
biphasic turbulent flow, current distribution, euler-eulerian approach, hydrogen evolution reaction, multi-electrode stack
1383-5866
Sandoval, Miguel A.
ee1d580e-9443-4370-b2bf-e71da72cf1ef
Fuentes, Rosalba
eb7b9157-273e-42ce-999c-2996ef3cf6f3
Pérez, Tzayam
7c1c644e-d97d-4a4f-9384-0803b62a2d73
Walsh, Frank
309528e7-062e-439b-af40-9309bc91efb2
Nava, Jose L.
266d748b-426f-4300-9306-0a2fe549bd15
Ponce De Leon Albarran, Carlos
508a312e-75ff-4bcb-9151-dacc424d755c
Sandoval, Miguel A.
ee1d580e-9443-4370-b2bf-e71da72cf1ef
Fuentes, Rosalba
eb7b9157-273e-42ce-999c-2996ef3cf6f3
Pérez, Tzayam
7c1c644e-d97d-4a4f-9384-0803b62a2d73
Walsh, Frank
309528e7-062e-439b-af40-9309bc91efb2
Nava, Jose L.
266d748b-426f-4300-9306-0a2fe549bd15
Ponce De Leon Albarran, Carlos
508a312e-75ff-4bcb-9151-dacc424d755c

Sandoval, Miguel A., Fuentes, Rosalba, Pérez, Tzayam, Walsh, Frank, Nava, Jose L. and Ponce De Leon Albarran, Carlos (2021) Modelling and simulation of H2-H2O bubbly flow through a stack of three cells in a pre-pilot filter press electrocoagulation reactor. Separation and Purification Technology, 261, [118235]. (doi:10.1016/j.seppur.2020.118235).

Record type: Article

Abstract

Computational fluid dynamics simulations were carried out to describe the hydrodynamic characteristics of a two-phase bubbly flow in a filter-press flow reactor stack of three cells, which is typically used in electrocoagulation (EC). The hydrogen evolution reaction (HER) took place at the cathode; dissolution of aluminium occurred at the anode. The fundamental transport equations of momentum and electrical potential were simultaneously were solved to simulate the H2-H2O flow. Continuous (H2O) and dispersed phase (H2) velocity fields were modelled via the Euler-Eulerian approach, using the biphasic Reynolds Averaged Navier-Stokes (RANS) equations and the standard k turbulence model. The influence of volumetric flow rate (1.7 ≤ Q ≤ 15 cm3 s–1) and applied current density (–28 ≤ j ≤ –5 mA cm–2) was systematically addressed to calculate the fraction of dispersed phase and current distribution along the electrodes. The evolved H2 bubbles were transported away from the electrode by the liquid flow. The dispersion of H2 through the electrode gap showed a modest bubble curtain profile due to the liquid flow rate. A homogeneous current distribution along the electrode length was experienced due to the geometrical design of the electrochemical cell and the low degree of H2 dispersion. The velocity profiles of the H2-H2O mixture were different in each cell due to the change of flow direction. H2 bubbles increased the velocity of the liquid phase but the gas fraction of such bubbles resulted in a higher pressure drop. Good agreement between theoretical and experimental residence time distribution curves was achieved; the experimental aluminium dose released by the anode agreed well with the simulations.

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More information

Accepted/In Press date: 16 December 2020
e-pub ahead of print date: 25 December 2020
Published date: 15 April 2021
Keywords: biphasic turbulent flow, current distribution, euler-eulerian approach, hydrogen evolution reaction, multi-electrode stack

Identifiers

Local EPrints ID: 446978
URI: http://eprints.soton.ac.uk/id/eprint/446978
ISSN: 1383-5866
PURE UUID: e1638361-db44-4b19-a278-d3bf06264021
ORCID for Carlos Ponce De Leon Albarran: ORCID iD orcid.org/0000-0002-1907-5913

Catalogue record

Date deposited: 01 Mar 2021 17:31
Last modified: 26 Nov 2021 02:49

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Contributors

Author: Miguel A. Sandoval
Author: Rosalba Fuentes
Author: Tzayam Pérez
Author: Frank Walsh
Author: Jose L. Nava

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