Diffusion of Water in Nafion 115 Membranes

Motupally, Sathya; Becker, Aaron J.; Weidner, John W.

doi:10.1149/1.1393879

Cited by 441 publications

(287 citation statements)

References 14 publications

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“…where D w = 4.17 × 10 −8 (1 + 161e − ) exp(−2436/T ) is the dissolved water diffusion coefficient [27] and = 22 is the water content of a liquid-saturated membrane. The liquid velocity, u l , is subject to an incompressibility constraint, ∇ · u l = 0, and is given by Schloegl's equation:…”

Section: Model Assumptions and Developmentmentioning

confidence: 99%

“…Bubbles flow outwards with the oxygen bubble velocity, u g and the pressure satisfies a pressure outlet condition, p = p out . At the inlets, the reactants enter with a prescribed bulk velocity and concentrations that depend on the pump rate, while the electrolyte is assumed to be Tables 2-7. free of bubbles: (27) Concentrations at the inlet boundaries vary with time depending on the movement of the electrolyte solution through the electrode and pump. By conservation of volume, the volumetric flow rate at the outlet boundaries is Q = v in A out , where A out = L t L w is the cross-sectional area of the outlet/inlet boundaries, L t is the electrode thickness and L w is the electrode width ( Table 6).…”

Section: Qamentioning

confidence: 99%

See 1 more Smart Citation

Modelling the effects of oxygen evolution in the all-vanadium redox flow battery

Al-Fetlawi

Shah

Walsh

2010

Electrochimica Acta

211

132

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a b s t r a c tThe impact of oxygen evolution and bubble formation on the performance of an all-vanadium redox flow battery is investigated using a two-dimensional, non-isothermal model. The model is based on mass, charge, energy and momentum conservation, together with a kinetic model for the redox and gas-evolving reactions. The multi-phase mixture model is used to describe the transport of oxygen in the form of gas bubbles. Numerical simulations are compared to experimental data, demonstrating good agreement. Parametric studies are performed to investigate the effects of changes in the operating temperature, electrolyte flow rate and bubble diameter on the extent of oxygen evolution. Increasing the electrolyte flow rate is found to reduce the volume of the oxygen gas evolved in the positive electrode. A larger bubble diameter is demonstrated to increase the buoyancy force exerted on the bubbles, leading to a faster slip velocity and a lower gas volume fraction. Substantial changes are observed over the range of reported bubble diameters. Increasing the operating temperature was found to increase the gas volume as a result of the enhanced rate of O 2 evolution. The charge efficiency of the cell drops markedly as a consequence.

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Section: Model Assumptions and Developmentmentioning

confidence: 99%

Section: Qamentioning

confidence: 99%

Modelling the effects of oxygen evolution in the all-vanadium redox flow battery

Al-Fetlawi

Shah

Walsh

2010

Electrochimica Acta

211

132

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show abstract

“…Most interesting studies in this area include the determination of water diffusion coefficient by Zawodzinski et al (1995) and water drag coefficient by Zawodzinski et al (1991) and investigating the diffusion of water in Nafion membranes by Motupally et al (2000).…”

Section: Numerical Modelmentioning

confidence: 99%

Numerical Investigation of Channel Geometry on the Performance of a Pem Fuel Cell

Khazaee¹,

Mohammadiun²

2013

International Journal of Applied Mechanics and Engineering

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A complete three-dimensional and single phase model for proton exchange membrane (PEM) fuel cells was used to investigate the effect of using different channels geometry on the performances, current density and gas concentration. The proposed model was a full cell model, which includes all the parts of the PEM fuel cell, flow channels, gas diffusion electrodes, catalyst layers and the membrane. Coupled transport and electrochemical kinetics equations were solved in a single domain; therefore no interfacial boundary condition was required at the internal boundaries between cell components. This computational fluid dynamics code was employed as the direct problem solver, which was used to simulate the three-dimensional mass, momentum, energy and species transport phenomena as well as the electron-and proton-transfer process taking place in a PEMFC. The results showed that the predicted polarization curves by using this model were in good agreement with the experimental results and a high performance was observed by using circle geometry for the channels of anode and cathode sides. Also, the results showed that the performance of the fuel cell improved when a rectangular channel was used.

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“…The term S w represents water production and S dl represents mass transfer between the liquid and dissolved phases (see Section 2.5). D d is the diffusion coefficient for dissolved water [39] …”

Section: Membrane and Carbon Phasesmentioning

confidence: 99%