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Electricity is the major component in the cost of hydrogen production via electrolysis. This study aims to reduce electric energy consumption in electrolysis and replace it with lower cost thermal energy. An idealized thermodynamic analysis of hydrogen production by electrolysis at higher temperatures is presented, with particular emphasis on isolating the work and thermal components of the required energy. There is significant advantage in using thermal energy from another complementary process to overheat the inlet steam to meet this need. The electricity demand for electrolysis, under reasonable conditions, can thus be reduced to 26.63 kWh kg−1. Introducing multiple stages can further reduce this to 25.22 kWh kg−1 and more significantly, greatly reduce the temperature of the thermal energy needed. At lower utilizations, it is possible to reduce the electrical requirement to below 20 kWh kg−1, which is less than half the most aggressive targets for electrolyzer improvements.

The authors present generalized finite-volume-based discretized loss functions integrated into pressure-linked algorithms for physics-based unsupervised training of neural networks (NNs). In contrast to automatic differentiation-based counterparts, discretized loss functions leverage well-developed numerical schemes of computational fluid dynamics (CFD) for tailoring NN training specific to the flow problems. For validation, neural network-based solvers (NN solvers) are trained by posing equations such as the Poisson equation, energy equation, and Spalart–Allmaras model as loss functions. The predictions from the trained NNs agree well with the solutions from CFD solvers while also providing solution time speed-ups of up to seven times. Another application of unsupervised learning is the novel hybrid loss functions presented in this study. Hybrid learning combines the information from sparse or partial observations with a physics-based loss to train the NNs accurately and provides training speed-ups of up to five times compared with a fully unsupervised method. Also, to properly utilize the potential of discretized loss functions, they are formulated in a machine learning (ML) framework (TensorFlow) integrated with a CFD solver (OpenFOAM). The ML-CFD framework created here infuses versatility into the training by giving loss functions access to the different numerical schemes of the OpenFOAM. In addition, this integration allows for offloading the CFD programming to OpenFOAM, circumventing bottlenecks from manually coding new flow conditions in a solely ML-based framework like TensorFlow.

The High Temperature Polymer Electrolyte Fuel Cell (HT-PEFC) converts chemical energy to electricity and heat. Operating at around 160°C, the heart of a HT-PEFC is a phosphoric-acid-doped polybenzimidazole membrane, which exhibits good protonic conductivity. HT-PEFCs may readily operate with either hydrogen or reformate as fuel. As is the case with most fuel cells, HT-PEFCs are operated in stacks in order to increase the overall electric potential. However, there are few comprehensive models of HT-PEFC stack performance. The results of this research program are among the first to obtain performance calculations for HT-PEFC at the stack scale with experimental validation. HT-PEFC stacks designed at the Forschungszentrum Jülich are actively cooled with polyalkyline glycol liquid (oil) coolant, flowing in internal passages within the solid bi-polar plates, upon the surfaces of which a complex pattern consisting of straight and serpentine passages have been machined, in order to supply the air and fuel to the cell. Because of the elevated temperature, liquid water is not generally found in the gas channels or porous layers. Considerable experimental data have been previously gathered, in-house, for a 5-cell stack based on this design. Two high temperature polymer electrolyte fuel cell (HT-PEFC) models of a HT-PEFC stack are described in detail: (i) A detailed cell-level model where a set of conformal meshes are body-fitted to all the different parts of the stack. The code typically runs, in parallel, on 1000-2000 cores at the Jülich Supercomputer Centre; and, (ii) A coarse-grid stack model based on a ‘distributed resistance analogy’ whereby rate equations supplant local diffusion terms in selected locations and directions to reduce computational requirements. A multiply-shared space (MUSES) method is employed to obtain simultaneous solutions for concentration, heat and momentum for the different phases occupying the ‘same’ global space. Both (i) detailed and (ii) MUSES methods are implemented by instantiating 5 distinct meshes corresponding to (i) air, (ii) fuel, (iii) oil (fluid), and (iv) membrane electrode assembly, (v) bipolar plate (solid) regions, and obtaining solutions of the governing equations on these meshes. For both methods a solution is obtained simultaneously for the stack manifolds, cell manifolds (entrance regions) as well as the ‘core’ of the fuel cell stack. Thermal equilibrium between the 3 fluid phases is not presumed, a priori. In both methods, the electric field potential is expressed as the ideal (Nernst) potential less activation, ohmic, and transport losses. Individual cell potentiostatic boundary conditions are iteratively corrected until the desired overall galvanostatic condition is obtained for all cells in the stack. Both codes are developed in the modern open-source object-oriented library, OpenFOAM. The results of the two models are compared with each other in terms of local current density and species partial pressure distributions. Both models are then compared with experimental data. The results show that the coarse-grid stack model (ii) agrees well, both quantitatively and qualitatively, with the detailed model (i) and experimental results and calculations are performed in two orders of magnitude less computation time. However, neither the experimental results nor the stack model (ii) are able to resolve local extrema in the current density and species mole fraction values that are observed with the detailed model (i). These are due to complex flow regimes associated with the meandering channels and flow bypassing in the porous transport layers. Importantly, these lead to significant local extrema in the local current density and other parameters of significance. These are among the first fully-comprehensive physicochemicohydrodynamic models of a HT-PEFC stack which allows calculations to be performed simultaneously for all the fluid and solids in the manifolds, entrance regions and stack core, together with experimental validation.

This work is among the first where the results of an extensive experimental research programme are compared to performance calculations of a comprehensive computational fluid dynamics model for a solid oxide fuel cell stack. The model, which combines electrochemical reactions with momentum, heat, and mass transport, is used to obtain results for an established industrial-scale fuel cell stack design with complex manifolds. To validate the model, comparisons with experimentally gathered voltage and temperature data are made for the Julich Mark-F, 18-cell stack operating in a test furnace. Good agreement is obtained between the model and experiment results for cell voltages and temperature distributions, confirming the validity of the computational methodology for stack design. The transient effects during ramp up of current in the experiment may explain a lower average voltage than model predictions for the power curve.

Summary As the polymer electrolyte membrane fuel cell (PEMFC) matures performance keeps increasing—mainly in terms of conversion rate rather than efficiency. Increased conversion results in increased heat release. Fuel cell performance and degradation is a delicate balance of heat and work manipulated significantly by the transport and the state of water in the system. With high heat release rates and low thermal conductivities the maximum temperature can be up to 20 °C warmer than the coolant. While much work has been done in understanding the thermal conductivity of fuel cell materials, even more is needed. Particular needs for continued research include: the thermal implications of material ageing, the nature and importance of the composite interface between the microporous layer and the porous transport layer, the impact of liquid water on thermal conductivity, a better understanding of phase change in electrodes and the heat capacities of fuel cell materials. Finally, the heat release in a fuel cell presents a significant opportunity to better understand the system and changes in the system. Fuel cell calorimetry has only begun to be used to explore heat and work in PEMFC and should be explored in greater detail.

A review is presented of the evolution of heat and mass transfer in modern fuel cells, and the role of computational fluid dynamics in the prediction of their performance. Both polymer electrolyte and solid oxide fuel cells are considered. The mathematical details of the mass transfer driving force and the transferred substance state, as well as the distributed resistance analogy, are derived. It is shown how the transferred substance state may be used to prescribe generalised convection–diffusion boundary conditions (inlet/outlet/wall). The combination of the mass transfer driving force and the application of the distributed resistance analogy concept to fuel cell stack models are explained in detail. In addition to the governing equations for thermofluids, the mathematical modelling of fuel cells requires additional thermodynamic, electrochemical kinetic and electric considerations to be taken into account (physicochemical hydrodynamics). Moreover, the results of original research conducted over two decades and culminating in very recent results are presented and explained. This work is research-in-motion and some future possibilities are outlined in the conclusion.

The demand for renewable energy storage systems and CO2-utilization technologies has become apparent in recent decades due to concerns related to the continuous emission of anthropogenic greenhouse gases. A promising technology that can help alleviate some of these concerns are solid oxide electrolyzers, since they have the ability to convert CO2 and steam into valuable chemicals and fuels from the electricity generated by renewable sources, including wind and solar energy. Furthermore, these devices can operate in fuel-assisted mode, wherein a reactant, such as methane, hydrogen, and/or carbon monoxide, is delivered to the anode in order to reduce its operating potential. This simple modification has been shown to decrease the operating potential by nearly one order of magnitude [1-3], and, in some instances, has enabled the cell to generate power and synthesis gas simultaneously [4-6]. Fuel-assisted solid oxide electrolyzers have therefore emerged as a compelling option for renewable energy storage and large-scale chemical production, and have begun to draw significant attention from researchers and designers. But despite previous efforts, an understanding of how to attain a desired product composition and efficiency remains unclear. The objective of the presented work, then, is to perform a scaling analysis of the transport phenomena pertinent to fuel-assisted cells, in order to develop a set of dimensionless ratios that characterize the interplay between chemical and electrochemical reactions, and advective and diffusive transport. These dimensionless ratios provide crucial information on how to control the contribution of chemical and electrochemical reactions, as well as strategies to mitigate concentration and temperature gradients within the electrodes and flow channels. This approach is intended to provide an enhanced understanding of how to increase the product selectivity and performance of fuel-assisted solid oxide electrolyzers, which will hopefully lead to enhanced electrode and cell designs. [1] A. Q. Pham, P. H. Wallman and R. S. Glass, US Patent 6,051,125 (2000). [2] F. Chen and Y. Wang, US Patent 9,574,274 (2017). [3] Y. Wang, T. Liu, S. Fang, G. Xiao, H. Wang and F. Chen, J. Power Sources, 277, 261 (2015). [4] H. Xu, B. Chen and M. Ni, J. Electrochem. Soc., 163, F3029 (2016). [5] Y. Patcharavorachot, S. Thongdee, D. Saebea, S. Authayanun and A. Arpornwichanop, Energy Convers. Manage., 120, 274 (2016). [6] H. Xu, B. Chen, J. Irvine and M. Ni, Int. J. Hydrogen Energy, 41, 21839 (2016).

In solid oxide electrolyzers, the transport of species to and from the electrochemical reaction sites plays an important role in governing their performance and efficiency. The competing effects between diffusive, advective, and reactive transport on such metrics, however, are seldom considered in their design and analysis. Additionally, these devices possess a wide range of design specifications and operating conditions, therefore making it difficult to draw meaningful comparisons between the results presented in different studies. Here, we introduce a comprehensive approach for the design, evaluation, and comparison of solid oxide electrolyzers. A scaling analysis of the transport phenomena is undertaken to develop dimensionless ratios that characterize the delivery and removal of species at the electrochemical reaction sites. These dimensionless ratios elucidate when certain transport mechanisms are inconsequential to the performance of solid oxide electrolyzers, and reveal how concentrations gradients and overpotentials scale with parameters such as flow velocity, reaction rates, and geometry. This analysis offers designers and researchers an effective approach to identify rate-limiting mechanisms that inhibit the performance of solid oxide electrolyzers, and allows for direct comparisons to be made between cells of varying geometry, operating conditions, reactant and product species, and catalytic materials.

This paper describes the development and application of a novel computational fluid dynamics model which allows the investigation of large solid oxide fuel cell stacks in practical computation times. Comparisons with a previously verified model match quantitatively to within 3% difference for all parameters of a benchmark case and solve within 1.5% the computation time for parallel flows of air and fuel in a cell, verifying the present model as a practical option in stack design. The model is used to demonstrate that the distribution of flow rates to each cell in a 100 cell stack significantly affects the temperature distribution and overall electrochemical performance. In a further analysis, it is quantitatively demonstrated that it would be misleading to attempt to predict performance or optimise manifold designs based on a model with uncoupled transport and electrochemistry.

It is important to ensure that the water content of a catalyst coated membrane (CCM) has equilibrated before it is used in the manufacturing of a proton exchange membrane (PEM) fuel cell stack. Equilibration is achieved when the water content in the CCM reaches equilibrium with controlled relative humidity (RH) and temperature conditions. A CCM consists of a membrane coated with a catalyst layer (CL) electrode on both sides. The ionomer, which is a component of both the membrane and the CLs, absorbs/desorbs water as the CCM equilibrates, and as such, the ionic conductivity of the CCM is directly impacted. The electronic conductivity is indirectly impacted as dimensional changes in the ionomer result in changes to the network of electronically conducting materials in the CLs. Alternating current (AC) and direct current (DC) methods were investigated to measure the through-plane ionic resistance and in-plane electronic resistance as the CCM equilibrated. When CCM is manufactured it is wound around a plastic core with an impermeable leader and trailer portion protecting the surface of the CCM from the core and from the environment. As such, only the two edges of the roll are exposed to environmental conditions. It is in this state that the CCM must equilibrate to the manufacturing environment. To simulate this, discrete 4 samples of a commercially available CCM (Ion Power) were tested in a sample holder with pressure applied to replicate the roll winding tension. The sample holder covered the top, bottom, and two sides (roll direction) of the CCM, leaving the other two sides exposed to controlled conditions in an environmental chamber. The measurements described below were taken as the samples equilibrated from 50% RH to 45% RH at a constant temperature. The first method is an AC technique used to measure the through-plane sample impedance. The correlation between the RH of ionomers and their ionic conductivity is well established in literature [Cooper 2009, Maréchal 2007, Anantaraman 1996]. To measure the ionic conductivity of the sample, a sinusoidal alternating voltage was applied to silver foil strips on the top and bottom of the sample. This results in an alternating current passing through the sample. Electrochemical impedance spectroscopy (EIS) was used to measure the impedance as a function of frequency. From this data it was possible to extract the conductivity of the membrane and the equilibration time was investigated by tracking the impedance of the samples at 1 kHz. The second method is a DC technique, which employs more readily available equipment and reduces the data analysis complexity compared to the AC technique. The DC setup used four probes made of gold plated foil strips contacting each corners of the sample: two probes to measure a voltage difference and two to apply current to the sample. Current flows through the CL via a carbon/platinum network, which is only indirectly affected by water content as the ionomer expands or contracts due to water absorption or desorption [Morris 2014]. A constant current was applied to the sample undergoing equilibration and the voltage difference was monitored to determine the equilibration time. Both methods showed sensitivity to changing RH and exhibited reasonably constant results after a sufficient time, indicating that the samples had equilibrated to the environment. Figure 1 shows the impedance (1 kHz) of a CCM initially equilibrated to 50% RH as it equilibrates to 45% RH. The impedance increased rapidly for the first few hours and then slowed down before eventually reaching an approximately constant value, indicating equilibrium with the environment was achieved after approximately 18 h. The results of the DC method were consistent with those of the AC method. The novelty of this research is in providing quantitative methods to determine when a CCM roll has equilibrated with its environment. Once equilibrated, the CCM roll can be used in the manufacturing of fuel cell stacks. This research will help increase the efficiency of the manufacturing process and improve the quality assurance of the final product. Research funding from both MITACS (Accelerate program) and NSERC (Engage Plus program) is gratefully acknowledged, as is early and significant work by Anne Moore and Jeff Laflamme. References Anantamaran, A. V.; Gardner, C. L. J. Electroanal. Chem., 414, 115 (1996) Cooper K. R. ECS Transactions, 25, 995 (2009) Maréchal, M; Souquet, J. -L.; Guindet, J; Sanchez, J. -Y. Electrochem. Comm., 9, 1023 (2007) Morris, D.; Liu, S.; Gonzalez, D.; & Gostick, J. ACS Applied Materials & Interfaces, 18609 (2014) Figure 1

Code stability is a matter of concern for three-dimensional (3D) fuel cell models operating both at high current density and at high cell voltage. An idealized mathematical model of a fuel cell should converge for all potentiostatic or galvanostatic boundary conditions ranging from open circuit to closed circuit. Many fail to do so, due to (i) fuel or oxygen starvation causing divergence as local partial pressures and mass fractions of fuel or oxidant fall to near zero and (ii) nonlinearities in the Nernst and Butler–Volmer equations near open-circuit conditions. This paper describes in detail, specific numerical methods used to improve the stability of a previously existing fuel cell performance calculation procedure, at both low and high current densities. Four specific techniques are identified. A straight channel operating as a (i) solid oxide and (ii) polymer electrolyte membrane fuel cell is used to illustrate the efficacy of the modifications.

A multi-scale analysis of the diffusion and reaction in the catalyst coating of a reformer is done based on virtual reconstructions of the porous catalyst coating. Pore structure can have significant impact on reaction and transport processes in the catalyst coating and consequently on the reformer performance. In this work, tomography-based simulation of the methane steam reforming in the microstructure of a nickel–alumina spinel coating is presented. X-ray nano- and micro-computed tomography are done to reconstruct the catalyst pore structure at different length scales and to consider the effect of both intra- and inter-particle pores on the reacting flow in the coating. Results of the reacting flow simulation in the coating microstructure based on tomographic imaging are compared with the simulation using numerically reconstructed microstructure based on a random packing of spheres with similar morphological characteristics. The comparison shows that the rate of hydrogen production, in general, is higher in the particle packing due to better inter-particle pore connectivity.

A systematic approach is presented to study the effect of a catalyst coating microstructure on its performance in a wall-coated steam methane reformer using response surface methodology. Three-dimensional simulation of diffusion and reaction are performed in several catalyst microstructures represented by packing of overlapping spheres. A surrogate model is developed based on Latin hypercube design of experiment and response surface methodology that relates the rate of hydrogen production in the catalyst coating microstructure to inter-particle porosity and average particle size. Two sets of simulations are done based on a kinetic model with two different sets of kinetic parameters and the results are compared. The comparison shows that the maximum rate of hydrogen production occurs at higher inter-particle porosity and smaller particle size, when the kinetics is faster and diffusion limitation is more severe.

While the development of new solid oxide fuel cell (SOFC) electrodes must fundamentally occur within a lab setting, computational models which aid in the initial characterization and selection process can help reduce the overall financial cost and development time. A computational performance model, which both evaluates the structural properties and predicts the performance (current production) within electrode microstructures, generated from either experimental or numerical techniques, is presented. The application of the model to investigate the effects of different initial powder manufacturing parameters on the electrode performance is also demonstrated. The first part of this work presents the aforementioned performance model, which was developed in a modified version of OpenFOAM, MicroFOAM (1). The model begins by evaluating the total TPB length and the normalized effective species transport of all three phases within the electrode microstructure. The model then predicts the current production within the electrode by coupling the three percolating transport regions (electron, ion and pore) at the electrochemically active triple phase boundary (TPB), with a Butler-Volmer type expression. The identification of the microstructure properties and performance will enable relationships between these properties to be established. A particle-based numerical reconstruction model (2) is employed in this study to generate the synthetic electrode microstructures. The generated microstructures consist of a random distribution of overlapping spherical particles placed using a drop-and-roll algorithm. The packing algorithm allows for user specification of the initial starting parameters and is ideal for studying microstructure with a wide range of properties. Among the modifiable initial parameters include; the solid volume faction, porosity, and particle size distribution. In the second part of the study the performance model, developed in the first section, and the packing algorithm, mentioned above, are used to study the effects of different manufacturing parameters on the structural properties and performance of a cermet anode active layer. Initially the structural properties and performance of anodes generated with different initial electron-ion phase volume fractions (solid volume fraction) and porosities will individually be examined to identify the microstructure settings which maximizes the current production. Once identified, the two optimal individual settings will be combined and varied again to explore what optimal balance maximizes current production. Once identified, conclusions about the microstructure properties and manufacturing settings will be reviewed and discussed. Further manufacturing parameters including the particle size, particle size distribution, and thickness may also be explore in this work. References Choi, H.-W., Berson, A., Pharoah, J.G., Beale, S.B. Proc. IMechE. J. Power & Energy, 225(2): 183-197 (2011). Kenney, B., Vadmanis, M., Baker, C., Pharoah, J.G., Karen, K. J. Power Sources, 189: 1051-1059 (2009).

The morphology of the active electrode in a solid oxide fuel cell has a strong impact on both the transport properties and the active triple phase boundary length and distribution. The performance of the electrode emerges from the interaction of these two parameters and is impacted strongly by the size and shape of the starting powders used to make the ionically and electronically conducting phases of the electrode as well as by the manufacturing method used and the sintering process post manufacture. This paper presents a numerical study over a range of electrode morphologies chosen to represent different manufacturing processes and presents comparisons of geometric characteristics, transport properties and electrode performance. Three different morphologies are generated from three different starting powders, spheres representing non aggregated powders, agglomerates of spheres and high aspect ratio cylinders modelling splats formed in plasma sprays. Of particular interest in this study is the effect of anisotropy of the base particles on the resulting electrode. For each base particle shape multiple stochastic realizations of densely packed particle systems are generated using a collective rearrangement algorithm. The structures are then analysed geometrically with methods from spatial statistics using our own Java-based software, and meshed, solved and analysed with respect to transport and performance using a custom modified version of the open source computational fluid dynamics package, openFOAM. Detailed comparisons are presented in terms of tortuosity of paths through each phase of the material, constrictivity and chord lengths in different directions, directional transport properties in each of the three phases, distribution of the triple phase boundary lines and electrode performance

Oxygen electrodes of Solid Oxide Electrolysis Cells (SOECs) have been manufactured using a spray deposition method with strictly controlled parameters to understand electrode transport, improve performance and extend electrolyser life time. The controlled parameters were the; particle size distribution, solid fraction of the ink, and spray deposition rate. The effect on physical properties; porosity, pore size, and the mass fraction of the individual ceramics in the solid phase as a function of distance from electrolyte, caused by controlling the above mentioned parameters was studied. The changes in performance of the cells with differing parameters were observed as; polarization responses, long term current-voltage behaviour, impedance spectroscopy and effective conductivities, measured with the van der Pauw method. The polarization responses gave valuable information to compare cells to those commercially available. The impedance spectroscopy of the cells allowed for the study of the changing physical properties effect on the electrochemical behaviour. Specifically the individual electrochemical processes; cell conductivity, oxygen gas diffusion, and oxygen evolution.

A process where power and biomass are converted to Fischer-Tropsch liquid fuels (PBtL) is compared to a conventional Biomass-to-Liquid (BtL) process concept. Based on detailed process models, it is demonstrated that the carbon efficiency of a conventional Biomass to Liquid process can be increased from 38 to more than 90% by adding hydrogen from renewable energy sources. This means that the amount of fuel can be increased by a factor of 2.4 with the same amount of biomass. Electrical power is applied to split water/steam at high temperature over solid oxide electrolysis cells (SOEC). This technology is selected because part of the required energy can be replaced by available heat. The required electrical power for the extra production is estimated to be 11.6 kWh per liter syncrude . By operating the SOEC iso-thermally close to 850 °C the electric energy may be reduced to 9.5 kWh per liter, which is close to the energy density of jet fuel. A techno-economic analysis is performed where the total investments and operating costs are compared for the BtL and PBtL. With an electrical power price of 0.05 $/kWh and with SOEC investment cost of the 1000 $/kW(el), the levelized cost of producing advanced biofuel with the PBtL concept is 1.7 $/liter, which is approximately 30% lower than for the conventional BtL. Converting excess renewable electric power to advanced biofuel in a PBtL plant is a sensible way of storing energy as a fuel with a relatively high energy density. © 2018 Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/BY/4.0/).

The present work suggests two concepts for producing hydrogen by reverse electrodialysis. Reverse electrodialysis is a technology that uses concentration differences to create electrical energy. In this work, the energy is utilised as direct hydrogen production within a closed-loop system. For both system alternatives, waste heat is used to set up the mentioned concentration differences. The first concept is evaporation, where heat is added to boil off excess water from a concentrated solution and thereby increase its concentration. The second concept removes heat in order to precipitate excess salt. For the precipitation concept to work, a salt where the solubility is highly dependent on temperature must be used. KNO3 fulfils this requirement. As part of a proof of concept, the conductivity of membranes soaked in KNO3 was investigated. The conductivity of the salt in two commercialised membranes, Fumatech FKE-50 and FAS-30, was measured and compared to NaCl in the same membranes. The conductivity of K+ in FKE-50 was found to be 4.5 and 6.6 mS cm−1 at 25◦C and 40◦C respectively. The conductivity of NO−3 in FAS-30 was found to be 4.3 mS cm−1 and 6.5 mS cm−1 at 25◦C and 40◦C respectively. Neither of the membranes change conductivity with soaking concentrations. The conductivity at 40◦C compared to 25◦C is significantly better in the FKE membrane, and seemingly better in the FAS membrane. Potential peak power densities for a RED unit cell is 1.29 W m−2 with the precipitation system, and 28.1 W m−2 when evaporation is used. © 2018. This is the authors' accepted and refereed manuscript to the article. The final authenticated version is available online at: http://dx.doi.org/10.1149/08513.0147ecst

A detailed model of a solid oxide fuel cell was developed with an object-oriented open-source computational fluid dynamics code based on a finite-volume method. The methodology is derived from a local Nernst equation with associated irreversible losses. Calculations were performed with the International Energy Agency benchmark case #1 with hydrogen as fuel, for co-flow, counter-flow, and cross-flow. While agreement with the results of previous workers was satisfactory, a number of shortcomings with the benchmark case were identified and highlighted. These include over-simplified electro-chemical kinetics, neglect of porous transport layers, and ambiguities associated with the very low flow rates prescribed for the benchmark case.

A fundamental study on the effective conductivity in random porous media is presented in this paper. Porous media are distinguished based on the convexity of the insulating porous phase: microstructures with convex porosity are representative of foams and sponges, while non-convex porosity includes granular and particulate materials. This distinction allows us to identify two limit cases within which the effective conductivity of an isotropic porous medium lies. The effective conductivity is evaluated through a random walk method, applied on structures numerically reconstructed with packing algorithms which use spheres to represent convex elements. Simulation results are compared with theoretical relations and experimental data in a range of 0–40% in porosity, wherein the solid phase is entirely connected and not suspended in the porous phase. This study shows that, given the porosity, structures with convex porosity are more conducting than structures with non-convex pores, because the bottlenecks for conduction are narrower in the second case. These situations identify two limit cases for the effective conductivity in a random isotropic porous medium, as confirmed by experimental data of structures with partly convex and partly non-convex porosity. In addition, for convex porosity the effective conductivity is larger when pores are isolated, attaining the Hashin–Shtrikman upper bound, while when pores are overlapped the effective conductivity is well described by the Archie power law.

A multiscale methodology is presented to analyze the transport and reaction processes in the catalyst coating of a microstructured reformer and to elucidate the effect of catalyst morphology on transport limitations and the reformer performance. This analysis includes three-dimensional simulations of methane steam reforming at both reactor level (macroscale) and catalyst microstructure level (microscale). Hypothetical catalyst microstructures are generated using an in-house particle packing code. Based on the generated structures, the effective transport properties of the porous catalyst and the average reaction rates in the microstructure are determined to be applied in the pseudohomogeneous model used in the macroscale simulation. Parametric study is done to demonstrate the significant effect of the catalyst intraparticle and interparticle porosity as well as the particle size on the reaction effectiveness factor and methane conversion. This study shows that an optimal catalyst coating has a decreasing porosity along the reformer length based on the difference in the degree of diffusion limitation. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2263–2274, 2014

A modified collective rearrangement algorithm, based on the sphere-assembly representation of the particle shape, is presented for simulating random packings of nonspherical particles and arbitrary shapes. Compared to other collective rearrangement methods, the modification introduced by this algorithm consists in i) avoiding the particle-to-container shrinking procedure by allowing particles to sequentially settle down and ii) in a stability constraint applied to all the particles in the packing. The coupling of these criteria ensures that all the particles are stable and contacting each other, allowing for an unambiguous detection of contacts, which is important in the evaluation of the effective properties desired in many engineering applications, such as percolation thresholds and effective conductivity. The effect of the internal parameters of the algorithm is investigated, showing that random close packings can be obtained. The algorithm is applied to simulate packings of rigid ellipsoids and cylinders with different aspect ratios, which are compared with simulation results provided by other packing algorithms, showing the consistency of our method. Simulations of inter-penetrating particles, mixtures of particles with different shapes and packings of agglomerates are shown, which confirm the applicability of the method to a broad range of packing problems of practical interest and, in particular, for fuel cell applications.

aLawrence Berkeley National Laboratory, Berkeley, California 94720, USA bLos Alamos National Laboratory, Los Alamos, New Mexico 87545, USA cUnited Technologies Research Center, East Hartford, Connecticut 06118, USA dSchool of Mechanical and Systems Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom eChemical and Biomolecular Engineering Department, University of California, Berkeley, California 94720, USA fFuel Cell Research and Development, General Motors, Pontiac, Michigan 48340, USA gBallard Power Systems, Burnaby, British Columbia V5J 5J8, Canada hFuel Cell Research Centre, Queens University, Kingston, Ontario K7L 3N6, Canada iDepartment of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA jDepartment of Mechanical Aerospace and Biomedical Engineering, University of Tennessee at Knoxville, Knoxville, Tennessee 37996, USA kDepartment of Mechanical Engineering Technology, SUNY Alfred State College, Alfred, New York 14802, USA lDepartment of Mechanical Engineering, University of Alberta, Edmonton, Alberta T6G 2G, Canada

Spacer-filled channels are employed in membrane modules in many industrial applications where feed-flow spacers (employed to separate membrane sheets and create flow channels) tend to enhance mass transport characteristics (and possibly) mitigate fouling and concentration polarization phenomena. In this work direct numerical simulation was performed for the flow in spacer-filled channels to obtain a better understanding of fluid flow phenomena in these assemblies. Reynolds numbers of 300, 500 and 800 were considered. The effect of spacer location was also studied for three different configurations: spacer at the centre of the channel, off-centre, and attached to the wall. Instantaneous velocity fields and flow structures, such as boundary layer separation on the walls and on the cylinder, eddies on the walls, recirculation regions and vortex shedding were investigated. A Fourier analysis was carried out on the time series velocity data. Using this analysis the Strouhal number was calculated and the development of the flow towards a broader turbulent state at higher Reynolds number was captured. Other statistical characteristics such as time-averaged velocities and wall shear rates are obtained and discussed. The average pressure loss was calculated for the channels and found to be highest for spacer at the centre of the channel and lowest for spacer attached to the wall.

Most analyses of fuel cell stacks consider either transport or electrochemical phenomena, but neglect the coupling between the two. An original mathematical model was developed to solve the transport equations coupled with heterogeneous electrochemical reactions for large stacks with internal/external manifolds. The code was used to determine the effect of utilization on electrochemical performance and temperature distribution. The results are presented in terms of fluid flow, pressure, temperature, voltage, and current density distributions. The discussion highlights the importance of manifold design on performance and thermal management.

Recently, the solid oxide electrolysis cell (SOEC) has gained great attention as it offers higher efficiencies compared to conventional low-temperature electrolysis. High-temperature SOEC systems takes advantage of excess steam from coal or nuclear power plants to reduce the required input energy, thus improving the overall efficiency for electrolysis. A novel three-dimensional computational fluid dynamics (CFD) model is developed to simulate the coupled physical phenomena occurring in SOECs. The computational model is based on the open-source CFD software package, OpenFOAM®. The novelty would be development and implementation of complicated thermo-electrochemical models of underlying governing equations for SOEC.

The thermal conductivity and the thickness change with pressure of several different micro porous layers (MPL) used for the polymer electrolyte membrane fuel cell (PEMFC) were measured. The MPL were made with different compositions of carbon and polytetrafluoroethylene (PTFE). A one-dimensional thermal PEMFC model was used to estimate the impact that the MPL has on the temperature profiles though the PEMFC. The thermal conductivity was found to vary from as low as 0.05 up to as high as 0.12 W K−1 m−1 while the compaction pressure was varied from 4 bar and up to around 16 bar resulting in a decrease in thickness of approximately 40%. The PTFE content, which varied between 10 and 25%, did not result in any significant change in the compression or thermal conductivity. Both the thickness and the thermal conductivity changed irreversibly with compaction pressure. Considering a MPL thermal conductivity of 0.1 W K−1 m−1, a MPL thickness of 45 μm, a current density of 10 kA m−2 (1.0 A cm−2), liquid water (production and sorption), and a 30 μm membrane it was found that the MPL is responsible for a temperature increase of up to 2 °C. This contribution can be lowered by integrating the MPL into the porous transport layer.

WOS: 000320092100023, We report that the Seebeck coefficient of a Nafion membrane cell with hydrogen electrodes saturated with water vapour, at 1 bar hydrogen pressure and 340 K, is equal to 670 +/- 50 mu V/K, meaning that the entropy change of the anode reaction at reversible conditions (67 J/(K mol)) corresponds to a reversible heat release of 22 kJ/mol. The transported entropy of protons across the membrane at Soret equilibrium was estimated from this value to 1 +/- 5J/(K mol). The results were supported by the expected variation in the Seebeck coefficient with the hydrogen pressure. We report also the temperature difference of the electrodes, when passing electric current through the cell, and find that the anode is heated (a Peltier heat effect), giving qualitative support to the result for the Seebeck coefficient. The Seebeck and Peltier effects are related by non-equilibrium thermodynamics theory, and the Peltier heat of the cathode in the fuel cell is calculated for steady state conditions to 6 +/- 2 kJ/mol at 340 K. The division of the reversible heat release between the anode and the cathode, can be expected to vary with the current density, as the magnitude of the current density can have a big impact on water transport and water concentration profile, Norwegian Research Council under the RENERGI programme [164466/S30], The authors acknowledge the Norwegian Research Council for financial support under the RENERGI programme, grant no 164466/S30.

Microporous layer (MPL) applied on one side of the porous transport layer (PTL), aka GDL, has been employed for water balance in a polymer electrolyte fuel cell (PEFC). The underlying mechanism by which MPL helps water transport is not fully understood. Proposed theories include facilitated back diffusion of water from the cathode to the anode providing humidification of the membrane [1, 2], mitigation of PTL flooding by forcing water from PTL on cathode side to channels of flow field plates [3], formation of water clusters in porous transport layer leaving open pathways for air [4], providing a barrier for diffusion of liquid water from PTL to catalyst layer (CL) preventing CL flooding [5]. Proposed mechanisms imply that the profiles for water distribution in PEFCs during operation would vary between cells with MPL and those without MPL. Accordingly, differences in the water distribution profiles can be expected for cells with and without MPL during cell dry-out.

The potential for the fabrication of patterned electrodes using a piezo-electric printer was examined. Challenges in generating sharp features were identified. The polarization behavior and electrochemically active surface area of patterned catalyst layers were found to be influenced by the geometry of the patterns.

We present calculations of the coupling effects that take place when heat and water are transported across a membrane relevant to fuel cells, using the theory of non-equilibrium thermodynamics. Numerical results are given for the Nafion membrane bounded by surfaces of molecular thickness in contact with water vapor of varying relative humidity. Analytical expressions for thermal effects of water transport are given. We show how reversible heat transport (Dufour effects) can be understood in terms of coupling coefficients (heats of transfers). The sign of the enthalpy of adsorption of water in the membrane determines the sign of the coupling coefficient, the Dufour and Soret effect as well as thermal osmosis effects meaning that the effect can be large at interfaces. We show how data presented in the literature can be understood in terms of the presented theory. Using common estimates for transport properties in the membrane and its surface, we find that the more detailed equations predict a 10–30% variation in the heat and mass fluxes as the membrane thickness drops below 1 μ m . Analysis of experiments on thermal osmosis suggests that more accurate measurements on the water content as a function of activity are required.

The through-plane thermal conductivity of artificially aged SGL Porous Transport Layers, PTLs, are measured and reported. NMR measurements of PTFE content and water/PTL contact angles are also reported. The PTLs were artificially aged in air rich water at 80 °C for 0, 200, 400, 600, 800, and 1000 h. For the dry samples, it was found that the through-plane thermal conductivity did not change significantly in response to the ageing treatment. For the samples containing water, the through-plane thermal conductivity increased by a factor of two to three and the more aged samples had the highest thermal conductivities. The through-plane thermal conductivity of dry PTLs is known to decrease with increasing PTFE content, which was also seen in this study. The chosen ageing procedure is known to wash PTFE from the PTL, and this verified using NMR. Water-PTL contact angle measurements also demonstrate that the PTL becomes less hydrophobic with ageing. This coincides with the increase in the through-plane thermal conductivity. Because the dry PTL retains its thermal conductivity while the PTFE content decreases we suggest that the PTFE remains in the fibre to fibre contact region and is removed predominantly elsewhere.

This study investigates the effects of sintering in random composite packings of spherical particles, with focus on structures with relatively low densification where the sintering is used to obtain desired catalytic and transport properties. The effects of the degree of sintering (particle–particle contact angle) and of additional porosity created by pore-former particles on coordination numbers and percolation probabilities are addressed by using both the extended percolation theory and the drop-and-roll numerical reconstruction method. The comparison of the two methods allows the assessment of two key assumptions on which percolation theory relies when applied to sintered structures: i) particles retain their position during the sintering, ii) coordination numbers in the sintered structure are evaluated as the particles were rigid spheres. The former assumption is assessed by calculating, using the drop-and-roll method, the fraction of collapsing particles, which belong to clusters completely surrounded by pore-formers. Numerical simulations show that the fraction of collapsing particles is less than 1% for porosities as high as 60%. Within the range of validity of the first assumption, the theoretical and numerical methods predict that pore-formers decrease the number of contacts and so the percolation probability. The latter assumption is assessed by comparing simulated and theoretical results for different contact angles. The comparison shows that for contact angles smaller than 15° particles behave as they were rigid. For contact angles larger than 23°, sintering effects are no longer negligible, leading to a relative error between the two methods larger than 10% in contact number estimations. This study also shows that percolation theory and numerical simulations provide very similar results over a wide range of conditions, suggesting that the two methods can be used interchangeably for describing sintered random packings.

article i nfo Reverse Electro-Dialysis, RED, is an electrochemical technique to extract work by mixing aqueous solutions of different salinities. Electro-Dialysis, ED, is an electrochemical technique to extract potable water from seawa- ter. Both RED and ED typically employs noble metal oxide catalysts in the conversion between electronic current and ionic current. By testing several different electrode materials and red-ox salts, this paper demon- strates that these electrochemical reactions are controlled by mass transfer in the electrolyte rather than by the electrocatalytic properties of the electrode material. By comparing two different carbon materials and standard noble metal oxides, we show, for two red-ox salts, that the electrochemical performances of the in- expensive and expensive materials are similar. Relatively inexpensive graphite along with environmentally benign FeCl2 and FeCl3 in moderate concentrations was demonstrated to lower the electrode concentration overpotential.

Impedance measurements of H2/N2 cell for the determination of PEMFC catalyst layer (CL) resistance can exhibit significant deviation from those predicted assuming homogeneous CL structure with uniform resistance and capacitance. Predictions from model with homogeneous structure but distributed resistance and/or capacitance shows deviation from the ideal mid-frequency response (45o line) but expected low-frequency response (vertical line). A distributed model considering agglomerate-type structure shows deviation from ideal mid-frequency response ((45o line) as well as from ideal vertical-line like response at experimentally employed frequencies although a vertical-line response is predicted at frequencies significantly lower than typically accessible in experiments.

A detailed micro-model framework is used for calculating effective microstructural properties for the porous anode and cathode electrodes in solid oxide fuel cells (SOFCs). The resulting micro-structural approach are then applied to a macro-scale SOFC cell model. The performance of the SOFC cell model is determined by the geometric and effective transport microstructural properties which properly accounting for representative porous SOFC electrode structures., 219th ECS Meeting, Solid Oxide Fuel Cells 12 (SOFC-XII), May 1-6, 2011, Montreal, Quebec, Canada

A numerical simulation of the Jülich F-design Solid Oxide Fuel Cells stack is conducted by means of an original mathematical model. The model is implemented in the open source toolbox, OpenFOAM. This cell/stack level model is a key component of a programme to develop a fully integrated multi-scale fuel cell modelling capability, from nano-scale through to system level. It is intended to share the resulting software with other parties openly. Substantial experimental data is available for the Jülich F-design; Stack configuration, flow conditions, interconnector geometries and porous electrode properties prescribed in the numerical model are based on field experiments. The numerical model generates distributions of fluid flow, species concentrations, current density and temperature. The results of the simulations are compared against experimental data obtained from short stacks., Solid Oxide Fuel Cells 12 (SOFC-XII), 1-6 May 2011, Montreal, Quebec, Canada, Montreal, Canada

A calorimeter was used to measure the heat production in polymer electrolyte membrane (PEM) fuel cells operated on hydrogen and oxygen at 50 °C and 1 bar. Two cells were examined, one using a 35 μm thick Nafion membrane and a catalyst loading of 0.6/0.4 mg Pt cm−2, for the cathode and anode layer, respectively, the other using a 180 μm thick Nafion membrane and loading of 0.4/0.4 mg Pt cm−2. The cells investigated thus had different membranes and catalyst layers, but identical porous transport layers and micro-porous layers. The calorimeter is unique in that it provides the heat fluxes out of the cell, separately for the anode and the cathode sides. The corresponding cell potential differences, ohmic cell resistance and current densities are also reported. The heat fluxes through the current collector plates were decomposed by a thermal model to give the contributions from the ohmic and the Tafel heats to the total heat fluxes. Thus, the contributions from the reversible heat (the Peltier heats) to the current collectors were determined. The analysis suggests that the Peltier heat of the anode of these fuel cell materials is small, and that it is the cathode reaction which generates the main fraction of the total heat in a PEM fuel cell. The entropy change of the anode reaction appears to be close to zero, while the corresponding value for the cathode is near −80 J K−1 mol−1.

A design procedure is presented that improves the energy efficiency and saves catalyst material of a polymer electrolyte membrane fuel cell (PEMFC). The method is demonstrated for a single cell in a stack and uses the theorem of equipartition of entropy production to maximize energy efficiency. The gas supply and water outlet systems, designed to produce entropy uniformly, have a fractal structure inspired by the human lung. The tree-like gas distributor engraved in the bipolar plates may eliminate the need for porous transport layers. Mathematical solutions are given for the optimal height, macroporosity, and nanoporous column width of the electro-catalytic layer beneath the gas supply system. It is shown that the optimal macroporosity of the catalytic layer is equal to 1/2 for the model chosen and that the optimal height of the catalytic layer depends upon the coefficient for first-order reaction kinetics at the cathode, the diffusion constant for oxygen in the gas phase, and the oxygen concentration of...

This paper presents 2D thermal model of a fuel cell to elucidate some of the issues and important parameters with respect to temperature distributions in PEM fuel cells. A short review on various properties affecting the temperature profile and the heat production in the polymer electrolyte fuel cell is included. At an average current density of 1 A cm−2, it is found that the maximum temperature of the MEA is elevated by between 4.5 and 15 K compared to the polarisation plate temperature. The smallest deviation corresponds to one dimensional transport, while the largest corresponds to the two dimensional transport considering anisotropic thermal conductivity. The two dimensional thermal model further predicts increased lost work. While most of the heat generation is allocated in the cathode, it is shown that the heat effect may be balanced by the water phase change in the anode. The most significant factor in determining the temperature distribution is the gas channel geometry (width and channel type), followed by the thermal conductivity of the porous transport layer and state of the water in the cell.

Renewable energy sources are often intermittent or unavailable for the end user, making energy storage vital. One way to store the energy is in hydrogen, and our aim is to produce hydrogen through reverse electrodialysis (RED) [1, 2, 3]. RED is a technology that uses concentration differences to create electrical energy. This is achieved through the use of ion-conducting membranes, where the membranes separate two solutions while producing an electric potential. Moreover, RED can be used to produce hydrogen in addition to electric energy. An illustration of the RED-cell is given in Figure 1. Any salt can be used for this purpose, as the potential is dependent on concentration differences only, not the specific solution used. This project utilises waste heat of low quality to build up and maintain the concentration differences (see Figure 2). The whole process is carried out in a closed system, where heat will be the only external input (in addition to electricity used for pumps). The closed energy storage system can easily be installed in connection with industrial processes where waste heat is available. As ions are transported from the concentrated to the diluted solution, the potential will decrease. Two separation techniques are evaluated for increasing the concetration difference, namely evaporation at high temperature or precipitation at low temperature. The respective process sketches are shown in Figure 2. This research investigates the suggested system with either NaCl or KNO3 as active solutions and temperature levels. Parts of the experiments include an end goal of creating sufficient potentials for hydrogen evolution, hence creating a technology where low-grade waste heat is converted to hydrogen. [1] O. S. Burheim, J. G. Pharoah, D. Vermaas, B. B. Sales, K. Nijmeijer, and H. V. Hamelers, "Reverse electrodialysis," Encyclopedia of Membrane Science and Technology, 2013. [2] M. F. M. Bijmans, O. S. Burheim, M. Bryjak, A. Delgado, P. Hack, F. Mantegazza, S. Tenisson, and H. V. M. Hamelers, "CAPMIX - Deploying capacitors for salt gradient power extraction," Energy Procedia, vol. 20, pp. 108-115, 2012. [3] O. S. Burheim, Engineering Energy Storage. Academic Press 2018, 2017. Figure 1

In this paper thermal properties for materials typically used in the proton exchange membrane fuel cell (PEMFC) are reported. Thermal conductivities of Nafion membranes were measured ex situ at 20 ◦ Ct o be 0.177 ± 0.008 and 0.254 ± 0.016 W K−1 m−1 for dry and maximally wetted membranes respectively. This paper also presents a methodology to determine the thermal conductivity of compressible materials as a function of applied load. This technique was used to measure the thermal conductivity of an uncoated SolviCore porous transport layer (PTL) at various compaction pressures. For the dry PTL at 4.6, 9.3 and 13.9 bar compaction pressures, the thermal conductivity was found to be 0.27, 0.36 and 0.40 W K −1 m −1 respectively and the thermal contact resistivity to the apparatus was determined to be

A calorimeter has been constructed and used to measure the total heat production of a single polymer electrolyte fuel cell that is operated on hydrogen and oxygen at 50 °C and 1 bar. The cell had a SolviCore Catalyst Coated Backing and Nafion membranes 112, 115 and 117. We report that the total heat production plus the power production corresponds to the enthalpy of formation of water for cell potentials above 0.55 V. For cell potentials less than 0.55 V, we measured a linear decrease in the reaction enthalpy with decreasing cell potential. This effect was obtained independently of membrane thickness and current density. We propose therefore that the main power loss at low cell potentials and the inflection point in the polarisation curve is due to hydrogen peroxide formation at the cathode. The total heat production was decomposed into reversible and irreversible effects (non-ohmic and ohmic). The non-ohmic part was evaluated using Tafel plots. We show that it is possible to determine the overpotential of an electrode also from its thermal signature.

A numerical framework to compute the effective transport coefficients for porous electrode microstructures is presented. The anode and cathode electrodes of solid oxide fuel cells are discretized as porous microstructures that are formed by randomly distributed and overlapping spheres with particle size distributions that match those of actual ceramic powders. The technique involves the construction of the composite electrode microstructure based on measureable starting parameters and the subsequent numerical evaluation of the effective transport coefficients. We use both the finite volume method and the Monte-Carlo simulation to enumerate effective transport coefficients. The results of the calculations are compared with experimental data for electron conductivities for a range of solid-matrix compositions. Comparisons are also made with theoretical correlations for effective coefficients. The effect of Knudsen diffusion on effective gas diffusivity is also addressed in this paper. Numerical results are compared with a harmonic average approximation based on Bosanquet’s formula., 216th ECS Meeting. Solid Oxide Fuel Cells, Eleventh International Symposium (SOFC-XI), October 4-9, 2009, Vienna, Austria

A numerical technique for generating the solid oxide fuel cell composite electrode structure based on measurable starting parameters has been developed. This method can be used to calculate all relevant electrode microstructural parameters. The structures are formed of randomly distributed overlapping spheres with particle size distributions that match the particle sizes of actual ceramic powders. In this work, the triple phase boundary length, internal surface area, pore size and the percolation of all relevant phases within the porous composite electrode were computed. It was found that the triple phase boundary length computed for particles with real particle size distributions was as much as 40% lower compared to mono-sized particles with the same mean particle sizes. Percolation thresholds were in the range of 30–40 vol% for solid phases and over 99% of pores were found to belong to a percolating network at porosities as low as 25%. In addition, the average pore size was found to be 0.19 μ m for typical electrode compositions, smaller than what is commonly assumed and in certain circumstances, the distribution of pore sizes may place gas transport in the free molecular flow regime.

This paper compares three different approaches for describing the cathode catalyst layer of a PEMFC, using a three-dimensional CFD model. The three catalyst treatments include: a thin-film model, a discrete-catalyst volume model and an agglomerate model. It is shown that, within a single-phase approach using physically meaningful parameters, the commonly employed thin-film or discrete-volume descriptions of the catalyst layer do not show the significant mass transport limitations which occur at higher current densities; while this region is observed using a catalyst agglomerate approach. Further, an in-depth analysis of the current density distributions indicates that for a given electrode overpotential the thin-film model significantly over-predicts the current density, compared to the discrete and agglomerate approaches. The thin-film model also greatly exaggerates the variation in current density both along and across the channel. Finally, the agglomerate model predicts noticeable mass transport losses even at very low current densities despite the use of high stoichiometric ratios and thin-electrolyte films.

The solid oxide fuel cell is an electro-chemical device which converts chemical energy into electricity and heat. To compete in today's market, design improvements, in terms of performance and life cycle, are required. Numerical prototypes can accelerate design and development progress. In this programme of research, a three- dimensional solid oxide fuel cell prototype, openFuelCell, based on open-source computational fluid dynamics software was developed and applied to a single cell. Transport phenomena, combined with the solution to the local Nernst equation for the open-circuit potential, as well as the Kirchhoff-Ohm relationship for the local current density, allow local electro-chemistry, fluid flow, multi-component species transport, and multi-region thermal analysis to be considered. The underlying physicochemical hydrodynamics, including porous- electrode and electro-chemical effects are described in detail. The openFuelCell program is developed in an object-oriented open- source C++ library. The code is available at http://openfuelcell.sourceforge.net/. The paper also describes domain decomposition techniques considered in the context of highly efficient parallel programming