Oxygen mass transport limitations at the cathode of polymer electrolyte membrane fuel cells

Benziger, J.; Kimball, Erin; Mejia-Ariza, Raquel; Kevrekidis, Ioannis G.

doi:10.1002/aic.12455

Cited by 51 publications

(29 citation statements)

References 58 publications

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“…In the numerical simulation of a whole cell, the y Oc distribution is calculated using a model describing mass transport primarily in the GDL and flow channel. 10 As y Oc is raised, the effects of oxygen convection appear greater. In the case of an air supply, a more typical y Oc value is 0.1-0.21, and F Conversely, a negative Peclet number represents an oxygen profile that is shifted toward the PEM side, resulting in an improved F ðCÞ e .…”

Section: Dimensionless Model Analysismentioning

confidence: 99%

Electrochemical reaction engineering of polymer electrolyte fuel cell

et al. 2016

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in Wiley Online Library (wileyonlinelibrary.com) Although fuel cells can be considered as a type of reactor, methods of kinetic analysis and reactor modeling from the viewpoint of chemical reaction engineering have not yet been established. The rate of an electrochemical reaction is a function of concentration, temperature, and interfacial potential difference (or electromotive force). This study examined the cathode reaction in a polymer electrolyte fuel cell, in which oxygen and protons react over platinum in the catalyst layer (CL). The effects of the oxygen partial pressure and the cathode electromotive force on the reaction rate were assessed. Resistance to proton transport increases the electromotive force and reducing the reaction rate. It was established that the effectiveness factor of the cathode CL is determined by competition between the reaction and mass transport of oxygen and protons. Two dimensionless moduli that govern the cathode behavior are proposed as a means of depicting the processes in the cell.

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Section: Dimensionless Model Analysismentioning

confidence: 99%

Electrochemical reaction engineering of polymer electrolyte fuel cell

et al. 2016

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“…46 Moreover, Benziger et al showed that for lower oxygen molar fractions in the cathode (which is the case with air feed) the dominant mode of transport is diffusion. 47 Nevertheless, this assumption needs to be revisited based on the operating condition and cell configuration. For instance, Weber et al found convective heat transfer to be significant.…”

Section: Mathematical Model Developmentmentioning

confidence: 99%

“…wv,GDL [47] At the membrane interface, the following conditions are imposed for the water vapor flow rate:…”

mentioning

confidence: 99%

Computationally Efficient Pseudo-2D Non-Isothermal Modeling of Polymer Electrolyte Membrane Fuel Cells with Two-Phase Phenomena

Goshtasbi

Pence

Ersal

2016

J. Electrochem. Soc.

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In this article, a computationally efficient pseudo-2D model for real-time dynamic simulations of polymer electrolyte membrane fuel cells (PEMFCs) is developed with a specific focus on water and thermal management. The model accounts for temperature dynamics, two-phase flow and flooding in the diffusion media, and membrane water crossover as well as absorption and desorption processes. Computational efficiency is achieved by leveraging the disparate time scales within the system dynamics, in addition to exploiting the large aspect ratio of the cell layers to create a spatio-temporal decoupling. Taking advantage of such decoupling, the model yields a computationally efficient solution while providing detailed information about the state of water and temperature throughout the cell. Through this approach, the current implementation of the model is found to be about twice faster than real time. Moreover, a case study is carried out where different mechanisms contributing to overall water balance in the cell are investigated. The results are shown to be in qualitative agreement with published experimental data, thereby providing a preliminary validation of the modeling approach. Finally, using the modeling results, an equivalent electrical circuit model is proposed to help elucidate water transport inside various cell layers. Real-time estimation, prediction, and control of cell hydration and temperature distribution is essential for optimizing the performance of polymer electrolyte membrane fuel cells (PEMFCs), as well as avoiding critical conditions and mitigating cell degradation. These applications necessitate mathematical models that not only run in real time, but also incorporate the important physical phenomena related to water transport and thermal management. However, including such phenomena comes at the cost of higher computational requirements, resulting in a trade-off between model accuracy and computational speed, which must be carefully balanced based on the desired application. As a result of these competing requirements, developing mathematical models that achieve a balance between the needs for high fidelity and low computational demand remains an active area of research.Within the context of this paper, a fuel cell model is considered to have high fidelity if it incorporates the following phenomena: i) 3-D effects including anisotropic material properties 1-3 to resolve transport phenomena in all physical directions; ii) transient behavior; iii) detailed multistep hydrogen oxidation reaction (HOR) and oxygen reduction reaction (ORR) kinetics; 4,5 iv) multiphase flow in gas channels and porous media; v) non-isothermal effects; 6 and vi) multicomponent diffusion.7,8 A more detailed explanation of these considerations follows.In terms of dimensionality, 3-D models are of highest fidelity, because they are capable of capturing transport in both through-themembrane and along-the-channel directions and also account for the channel-land effects in the third dimension. Moreover, these models can easily in...

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“…6), indicating an increase in mass-transport resistance in cathode. For a DMFC operated with O 2 , convection is the main way for oxygen transport across the GDL, while for the one operated with air, diffusion is the dominant way for oxygen transport [27]. As a consequence, the overall performance of the cell fed with air is more sensitive to the changes in pore structures resulting from freeze damage than that fed with O 2 .…”

Section: Reversible Loss In Performancementioning

confidence: 99%