Computational design and optimization of fuel cells and fuel cell systems: A review

Secanell, Marc; Wishart, Jeffrey; Dobson, Peter J.

doi:10.1016/j.jpowsour.2010.12.011

Cited by 119 publications

(43 citation statements)

References 106 publications

(242 reference statements)

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“…0-D models are used to determine kinetic and net ohmic resistance parameters from a polarization performance curve. [15][16][17][18][19][20][21][22] A typical 0-D model equation for a polarization curve is V = U + b log (i 0 ) − b log (i) − R i + b log 1 − i i lim [7] and accounts for the major losses as shown in Figure 1. The first term on the right corresponds to the thermodynamic cell potential.…”

Section: Model Dimensionalitymentioning

confidence: 99%

“…The reversible potential is often determined empirically from the open-circuit voltage or by a thermodynamic expression. The kinetic overpotentials can be determined based on experimental measurements of Tafel slopes (see equation 7). With regard to transport, researchers are focused on quantifying and modeling the last three transport terms in equation 8, which can be compared to the associated expressions given by equation 7.…”

Section: Empirical-based Modelingmentioning

confidence: 99%

“…While there have been various reviews over the years of PEFC modeling [1][2][3][4][5][6][7] and issues, [8][9][10][11][12][13][14] as well as numerous books and book chapters, there is a need to examine critically the field in terms of what has been done and what needs to be done. This review serves that purpose with a focus on transport modeling of PEFCs.…”

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confidence: 99%

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A Critical Review of Modeling Transport Phenomena in Polymer-Electrolyte Fuel Cells

Weber

Borup

Darling³

et al. 2014

J. Electrochem. Soc.

509

394

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Polymer-electrolyte fuel cells are a promising energy-conversion technology. Over the last several decades significant progress has been made in increasing their performance and durability, of which continuum-level modeling of the transport processes has played an integral part. In this review, we examine the state-of-the-art modeling approaches, with a goal of elucidating the knowledge gaps and needs going forward in the field. In particular, the focus is on multiphase flow, especially in terms of understanding interactions at interfaces, and catalyst layers with a focus on the impacts of ionomer thin-films and multiscale phenomena. Overall, we highlight where there is consensus in terms of modeling approaches as well as opportunities for further improvement and clarification, including identification of several critical areas for future research. Fuel cells may become the energy-delivery devices of the 21 st century. Although there are many types of fuel cells, polymer-electrolyte fuel cells (PEFCs) are receiving the most attention for automotive and small stationary applications. In a PEFC, fuel and oxygen are combined electrochemically. If hydrogen is used as the fuel, it oxidizes at the anode releasing proton and electrons according toThe generated protons are transported across the membrane and the electrons across the external circuit. At the cathode catalyst layer, protons and electrons recombine with oxygen to generate waterAlthough the above electrode reactions are written in single step, multiple elementary reaction pathways are possible at each electrode. During the operation of a PEFC, many interrelated and complex phenomena occur. These processes include mass and heat transfer, electrochemical reactions, and ionic and electronic transport. * Electrochemical Society Active Member. z E-mail: azweber@lbl.govOver the last several decades significant progress has been made in increasing PEFC performance and durability. Such progress has been enabled by experiments and computation at multiple scales, with the bulk of the focus being on optimizing and discovering new materials for the membrane-electrode-assembly (MEA), composed of the proton-exchange membrane (PEM), catalyst layers, and diffusionmedia (DM) backing layers. In particular, continuum modeling has been invaluable in providing understanding and insight into processes and phenomena that cannot be resolved or uncoupled through experiments. While modeling of the transport and related phenomena has progressed greatly, there are still some critical areas that need attention. These areas include modeling the catalyst layer and multiphase phenomena in the PEFC porous media.While there have been various reviews over the years of PEFC modeling 1-7 and issues, [8][9][10][11][12][13][14] as well as numerous books and book chapters, there is a need to examine critically the field in terms of what has been done and what needs to be done. This review serves that purpose with a focus on transport modeling of PEFCs. This is not meant to be an exhaustive review...

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Section: Model Dimensionalitymentioning

confidence: 99%

Section: Empirical-based Modelingmentioning

confidence: 99%

See 1 more Smart Citation

A Critical Review of Modeling Transport Phenomena in Polymer-Electrolyte Fuel Cells

Weber

Borup

Darling³

et al. 2014

J. Electrochem. Soc.

509

394

View full text Add to dashboard Cite

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“…Fuel cell optimization is a relatively new area of research since published articles on fuel cell optimization were practically non-existent before the year 2000, and are singleobjective and multi-objective constrained optimization problems because these are the problems most commonly encountered in fuel cell design [8]. The optimization studies found in the literature are conducted for several levels: the single cell (components and entire cell), the stack, and a system with the stack and ancillary equipment (e.g., compressor, humidifier, cooler), and have mostly addressed the proton-exchange membrane fuel cell (PEMFC) [9].…”

Section: Introductionmentioning

confidence: 99%

Constructal alkaline membrane fuel cell (AMFC) design

Sommer¹,

Vargas²,

Martins³

et al. 2016

IJHT

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This paper introduces a structured procedure to optimize the internal structure (relative sizes, spacing) and external shape (aspect ratios) of a single alkaline membrane fuel cell so that net power is maximized. The optimization of flow geometry is conducted for the smallest (elemental) level of a fuel cell stack, i.e., the single alkaline membrane fuel cell, which is modeled as a unidirectional flow system. The polarization curve, total and net power, and efficiency are obtained as functions of temperature, pressure, electrolyte solution concentration (KOH), geometry and operating parameters. The optimization is subjected to fixed total volume. There are two levels of optimization: (i) the internal structure, which basically accounts for the relative thicknesses of two reaction and diffusion layers and the membrane space, and (ii) the external shape, which accounts for the external aspect ratios of a square section plate that contains all single alkaline membrane fuel cell components. The available volume is distributed optimally through the system so that the net power is maximized. Temperature and pressure gradients play important roles, especially as the fuel and oxidant flow paths increase. The optimized internal structure and external shape are a result of an optimal balance between electrical power output and pumping power required to supply fuel and oxidant to the fuel cell through the gas channels. In the process, a third level of optimization was found with respect to the KOH concentration in the electrolyte solution that leads to a 3-way maximized net power output. The numerical results show that the maxima found are sharp, since a variation of up to 600% in net power was observed within the tested range of AMFC external aspect ratios, what emphasizes the importance of finding the optimal AMFC parameters, no matter how complex the actual design might be. It is also shown that the three times maximized net power increases monotonically with total volume raised to the power 0.7 (~3/4), similarly to metabolic rate and mass in animal design. Due to the fact that precision and low computational time are combined, it is expected that the model could be used as an important tool for AMFC design, control and optimization at the fuel cell stack level.

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“…Understanding the role of liquid water and its impact on fuel cell operation has been a longstanding challenge for the industry. [1][2][3] Complete water removal from the cell is not an option because the currently used membrane materials must be hydrated to function.…”

mentioning

confidence: 99%

Simulation of a Full Fuel Cell Membrane Electrode Assembly Using Pore Network Modeling

Aghighi

Hoeh

Lehnert

et al. 2016

J. Electrochem. Soc.

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A pore network model has been applied to a both sides of a fuel cell membrane electrode assembly. The model includes gas transport in the gas diffusion layers and catalyst layers, proton transport in the catalyst layers and membrane, and percolation of liquid water. This paper presents an iterative algorithm to simulate a steady state isothermal cell with a 3D pore network model for constant voltage boundary condition. The proposed algorithm provides a simple method to couple the results of the anode and the cathode sides by iteratively solving the uncoupled equations of the transport processes. It was found that local water blockages at the GDL/CL interface not only affect concentration polarization, but also might change ohmic polarization of the cell. Depending on the liquid water configuration in the porous electrodes, the protons generated in the anode need to travel longer paths to reach the active sites of the cathode; consequently, the IR loss will be increased in the presence of liquid water. This finding highlights the strength of pore network models which resolve discrete water blockages in the electrodes. Polymer electrolyte membrane fuel cells are one of the key technologies required to realize a sustainable energy economy because they provide energy storage. A typical PEMFC is a stack of electrochemical cells, and the heart of each is a sandwich of several porous layers around a thin polymer electrolyte membrane, referred to as a membrane-electrode assembly (MEA). In the typical arrangement each side consists of a gas diffusion layer (GDL), and a catalyst layer (CL). The GDL is usually a carbon-fiber based paper and acts as a spacer to allow gaseous reactants to reach regions of the catalyst layer under the flow field ribs, and as a bridge to allow electron access to catalyst sites over the flow field channels. The CL is composed of a mixture of ionomer such as Nafion and carbon-supported platinum catalyst particles, and is adhered to the surface of the membrane as a porous coating around 10-20 μm thick. The ionomer phase in the CL allows protons to reach the catalyst sites, while the carbon particles provide pathways for electrons, and the porosity allows transport of gaseous reactants (oxygen and hydrogen) and product (water). Under some conditions the cathode produces liquid water, which can accumulate in the pore spaces, blocking the access to the reaction sites. Liquid water can also be found on the anode side, for instance if temperature fluctuations occur since the hydrogen is humidified. Understanding the role of liquid water and its impact on fuel cell operation has been a longstanding challenge for the industry.1-3 Complete water removal from the cell is not an option because the currently used membrane materials must be hydrated to function.When electrical current is drawn, several sources of voltage loss are incurred due to the inefficiencies of current generation and transport processes. Voltage losses can be broken into three categories: activation polarization η act , ohmic polarizat...

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Computational design and optimization of fuel cells and fuel cell systems: A review

Cited by 119 publications

References 106 publications

A Critical Review of Modeling Transport Phenomena in Polymer-Electrolyte Fuel Cells

A Critical Review of Modeling Transport Phenomena in Polymer-Electrolyte Fuel Cells

Constructal alkaline membrane fuel cell (AMFC) design

Simulation of a Full Fuel Cell Membrane Electrode Assembly Using Pore Network Modeling

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