Modeling flow distribution and pressure drop in redox flow batteries

Macdonald, Malcolm; Darling, Robert M.

doi:10.1002/aic.16330

Cited by 36 publications

(34 citation statements)

References 34 publications

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“…Portions of the electrode where | v |/ v R < 0.4 are deemed to be inactive. This criterion matches our previous work . Inactive fractions were calculated for an expansive set of ( h/w, r/w, α ) and then results for different values of α were averaged to give mean inactive area as a function of h/w and r/w .…”

Section: Resultsmentioning

confidence: 67%

“…The governing equations, types of boundary conditions, and numerical implementation schemes comprising the CFD model are essentially identical to those in our previous work . The 3D domain was created with ANSYS Design Modeler and meshed using ANSYS Meshing.…”

Section: Model Developmentmentioning

confidence: 99%

“…A density of 1,350 kg m −3 and a viscosity of 2.5 × 10 −3 kg m −1 s −1 were used in the simulations. The density and viscosity are representative of electrolyte solutions in vanadium flow batteries, while the permeability is typical of a carbon paper with 7 μm diameter fibers and 70% porosity …”

Section: Model Developmentmentioning

confidence: 99%

“…Furthermore, the dramatic reduction in the number of variables afforded by this uncoupling simplifies the display and correlation of results for an expansive range of parameters. Macdonald and Darling published a comprehensive evaluation of FT, PFF, and IDFF using CFD and analytical models . We augment that work by developing similar tools for SFFs and comparing the resulting velocity distributions and pressure losses to the other designs.…”

Section: Introductionmentioning

confidence: 99%

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Comparing velocities and pressures in redox flow batteries with interdigitated and serpentine channels

Macdonald¹,

Darling²

2019

AIChE Journal

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Serpentine channels adjacent to a thin, porous medium are a potentially attractive alternative to a conventional thick flow‐through electrode for redox flow batteries. The hydrodynamics of serpentine flow fields were investigated with computational fluid dynamics, a two‐dimensional model of the porous electrode based on Darcy's law, and a resistance network model at the scale of the active area. Predictions from the three models were used to map the available design space. The optimal electrode thickness, in terms of minimizing nonuniformity, was identified and compared to the result for an interdigitated flow field. Serpentine favors thicker electrodes and higher flows than interdigitated, in qualitative agreement with experimental findings. Furthermore, interdigitated designs deliver more uniform intraelectrode velocities and lower overall pressure drops than serpentine flow fields.

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Section: Resultsmentioning

confidence: 67%

Section: Model Developmentmentioning

confidence: 99%

Section: Model Developmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Comparing velocities and pressures in redox flow batteries with interdigitated and serpentine channels

Macdonald¹,

Darling²

2019

AIChE Journal

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“…31 However, the flow in an interdigitated flow field (IDFF) is complicated, and the geometry must be carefully designed to ensure enhanced velocities and flow distribution in order to realize the full potential of this type of flow field. [42][43][44] Further, in the process of modifying the surface of different carbon papers and cloths via a KOH treatment, Zhou et al observed differences in performance based on the electrode microstructure. 23,45,46 The authors attributed the improved performance in the woven electrodes to the broad pore size distribution, in particular the large, low tortuosity pores responsible for low pressure drop and high ionic conductivity.…”

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confidence: 99%

Exploring the Role of Electrode Microstructure on the Performance of Non-Aqueous Redox Flow Batteries

Forner‐Cuenca

Penn

Oliveira

et al. 2019

J. Electrochem. Soc.

132

259

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Redox flow batteries are an emerging technology for long-duration grid energy storage, but further cost reductions are needed to accelerate adoption. Improving electrode performance within the electrochemical stack offers a pathway to reduced system cost through decreased resistance and increased power density. To date, most research efforts have focused on modifying the surface chemistry of carbon electrodes to enhance reaction kinetics, electrochemically active surface area, and wettability. Less attention has been given to electrode microstructure, which has a significant impact on reactant distribution and pressure drop within the flow cell.Here, drawing from commonly used carbon-based diffusion media (paper, felt, cloth), we systematically investigate the influence of electrode microstructure on electrochemical performance. We employ a range of techniques to characterize the microstructure, pressure drop, and electrochemically active surface area in combination with in-operando diagnostics performed in a single electrolyte flow cell using a kinetically facile redox couple dissolved in a non-aqueous electrolyte. Of the materials tested, the cloth electrode shows the best performance; the highest current density at a set overpotential accompanied by the lowest hydraulic resistance. We hypothesize that the bimodal pore size distribution and periodic, well-defined microstructure of the cloth are key to lowering mass transport resistance.

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