Homogenization of current density of PEM fuel cells by in-plane graded distributions of platinum loading and GDL porosity

Lü, Xing; Wang, Yan; Das, Prodip K.; Scott, Keith; Shi, Weidong

doi:10.1016/j.ces.2018.08.029

Cited by 84 publications

(42 citation statements)

References 47 publications

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“…The conservation equations of mass, charge and energy at steady state can be described by the following general convection‐diffusion equation:

\nabla \cdot ((), \overset{ρ}{true} u^{g} φ) = \nabla \cdot ((), F_{φ} \nabla φ) + S_{φ}

where φ is the general variable to be solved,

\overset{ρ}{true}

is the nominal density, F φ is the generalized diffusion coefficient of variable φ , u g is the velocity of gas phase, and S φ is the source term. The detailed expression of φ ,

\overset{ρ}{true}

, F φ , and S φ for various processes were given elsewhere . Equation can be used to represent the transport of gas species, heat, ion, and electron.…”

Section: Model Development and Validationmentioning

confidence: 99%

“… ρ g is the density of gas mixture, M n is the mean molecular weight of gas mixture, S i is the source/sink term for species i . The detailed expressions were listed elsewhere . The effective diffusion coefficient of species i ,

D_{i}^{eff}

, must be corrected by the porosity of the electrode and water saturation, where Bruggeman correlation is typically used.

D_{i}^{eff} = {(ε_{s} - s ε_{italicCL})}^{1.5} D_{i}^{0}

where ε s and ε CL are the porosity of the secondary pores and the entire catalyst layer, respectively.…”

Section: Model Development and Validationmentioning

confidence: 99%

“…

k_{r}^{g}

and

k_{r}^{l}

are the relative permeability of gas phase and liquid phase, respectively.

S_{w}^{l}

is the source term of liquid water, details can be found elsewhere . D c is the capillary diffusion coefficient, defined as follow:

D_{c} = - \frac{k_{r}^{l}}{μ_{w}^{l}} σ \cos ((), θ_{c}) \sqrt{(ε k_{p})} \frac{italicdJ ((), s)}{ds}

where σ is surface tension of water, θ c is contact angle, J ( s ) is the Leverett function, ε and k p are the porosity and permeability of the porous electrode, respectively.…”

Section: Model Development and Validationmentioning

confidence: 99%

“…The migration of dissolved water through the membrane under electro‐osmotic drag (EOD), back diffusion and hydraulic permeation are described by a diffusive approach shown as follow:

\nabla \cdot ((), n_{d} \frac{i_{M}}{F}) - \nabla \cdot ((), D_{w} \nabla c_{w}^{d}) - \nabla \cdot ((), \frac{k_{p}^{M} c_{w}^{d}}{μ_{w}^{l}} \nabla p) = S_{w}^{d}

where n d is the EOD coefficient, i M is the electrolyte current density, D w is the diffusion coefficient of dissolved water migration through the membrane,

k_{p}^{M}

is the membrane permeability, and

S_{w}^{d}

is the source term of dissolved water, details can be found elsewhere .

c_{w}^{d}

is the concentration of the dissolved water, determined by the membrane water‐uptake mechanism associated with the dynamic and equilibrium membrane water content, respectively.…”

Section: Model Development and Validationmentioning

confidence: 99%

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A novel flow field with controllable pressure gradient to enhance mass transport and water removal of PEM fuel cells

Lü

Penga

et al. 2020

AIChE Journal

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An easily machined novel flow field with controllable pressure gradient across adjacent channels was designed and a two dimensional, across-the-channel, twophase model was developed to study the gas transport and water removal of the novel configuration. The effect of channel-rib width ratio, GDL thickness and pressure gradient on the profiles of oxygen concentration and water saturation within the GDL were investigated. Special attention was paid to the mechanisms of the promoted mass transport and water removal rates under a pressure gradient. The model was validated by experiments with various channel-rib ratios and GDL thicknesses at different operating pressure. The results revealed that, oxygen concentration was increased, and the water saturation was reduced under the rib with a pressure gradient generated across the adjacent channels. The optimal pressure gradient is between 0.1 to 0.2 atm for the studied channel geometry and configuration. The mechanisms of the improved cell performance were elucidated. K E Y W O R D S bipolar plates, novel flow fields, PEM fuel cells, pressure gradient, water removal

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“…The conservation equations of mass, charge and energy at steady state can be described by the following general convection‐diffusion equation:

\nabla \cdot ((), \overset{ρ}{true} u^{g} φ) = \nabla \cdot ((), F_{φ} \nabla φ) + S_{φ}

where φ is the general variable to be solved,

\overset{ρ}{true}

is the nominal density, F φ is the generalized diffusion coefficient of variable φ , u g is the velocity of gas phase, and S φ is the source term. The detailed expression of φ ,

\overset{ρ}{true}

, F φ , and S φ for various processes were given elsewhere . Equation can be used to represent the transport of gas species, heat, ion, and electron.…”

Section: Model Development and Validationmentioning

confidence: 99%

D_{i}^{eff}

, must be corrected by the porosity of the electrode and water saturation, where Bruggeman correlation is typically used.

D_{i}^{eff} = {(ε_{s} - s ε_{italicCL})}^{1.5} D_{i}^{0}

where ε s and ε CL are the porosity of the secondary pores and the entire catalyst layer, respectively.…”

Section: Model Development and Validationmentioning

confidence: 99%

“…

k_{r}^{g}

and

k_{r}^{l}

are the relative permeability of gas phase and liquid phase, respectively.

S_{w}^{l}

is the source term of liquid water, details can be found elsewhere . D c is the capillary diffusion coefficient, defined as follow:

D_{c} = - \frac{k_{r}^{l}}{μ_{w}^{l}} σ \cos ((), θ_{c}) \sqrt{(ε k_{p})} \frac{italicdJ ((), s)}{ds}

where σ is surface tension of water, θ c is contact angle, J ( s ) is the Leverett function, ε and k p are the porosity and permeability of the porous electrode, respectively.…”

Section: Model Development and Validationmentioning

confidence: 99%

“…The migration of dissolved water through the membrane under electro‐osmotic drag (EOD), back diffusion and hydraulic permeation are described by a diffusive approach shown as follow:

\nabla \cdot ((), n_{d} \frac{i_{M}}{F}) - \nabla \cdot ((), D_{w} \nabla c_{w}^{d}) - \nabla \cdot ((), \frac{k_{p}^{M} c_{w}^{d}}{μ_{w}^{l}} \nabla p) = S_{w}^{d}

where n d is the EOD coefficient, i M is the electrolyte current density, D w is the diffusion coefficient of dissolved water migration through the membrane,

k_{p}^{M}

is the membrane permeability, and

S_{w}^{d}

is the source term of dissolved water, details can be found elsewhere .

c_{w}^{d}

is the concentration of the dissolved water, determined by the membrane water‐uptake mechanism associated with the dynamic and equilibrium membrane water content, respectively.…”

Section: Model Development and Validationmentioning

confidence: 99%

See 2 more Smart Citations

A novel flow field with controllable pressure gradient to enhance mass transport and water removal of PEM fuel cells

Lü

Penga

et al. 2020

AIChE Journal

Self Cite

View full text Add to dashboard Cite

show abstract

“…Generally, uniform distribution of the platinum-based catalysts across the common electrodes increases the cost. Furthermore, non-uniform distribution of the current density, poisoning of catalyst and corrosin of support layer decreases the lifetime of membrane and catalyst (Xing, Wang, Das et al (2018)). Methanol fuel cell has a high potential for using in electronic products.…”

Section: Abstract: Fuel Cell; Carbon Nanotube; Catalyst; Platinum-rutmentioning

confidence: 99%

Electrochemical Performance Improvement of the Catalyst of the Methanol Micro-Fuel Cell Using Carbon Nanotubes

Nasrabadi¹,

Ebrahimi‐Moghadam²,

Ahmadi³

et al. 2019

Preprint

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Due to low working temperature, high energy density and low pollution, proton exchange fuel cells have been investigated under different operating conditions in different applications. Using platinum catalysts in methanol fuel cells leads to increasing the cost of this kind of fuel cell which is considered as a barrier to the commercialism of this technology. For this reason, a lot of efforts have been made to reduce the loading of the catalyst Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted:

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Mathematical Modeling of Reactor for Water Remediation

Bagheri¹,

Mohebbi²,

Mirzaie³

et al. 2021

Applied Water Science

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Homogenization of current density of PEM fuel cells by in-plane graded distributions of platinum loading and GDL porosity

Cited by 84 publications

References 47 publications

A novel flow field with controllable pressure gradient to enhance mass transport and water removal of PEM fuel cells

A novel flow field with controllable pressure gradient to enhance mass transport and water removal of PEM fuel cells

Electrochemical Performance Improvement of the Catalyst of the Methanol Micro-Fuel Cell Using Carbon Nanotubes

Mathematical Modeling of Reactor for Water Remediation

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