Reaction Rate Distribution Research Articles

Effect of rhenium on the activity of ZrO2-supported copper catalysts for hydrodeoxygenation of m-cresol

This work studies the effect of adding different loadings of Re on the performance of ZrO2-supported Cu catalysts for hydrodeoxygenation (HDO) of m-cresol. H2-TPR and XPS show a synergistic effect between Cu and Re, decreasing the reduction temperature of both metals and promoting the reduction of Re oxide. Moreover, the addition of Re changes Cu dispersion and acid properties of all catalysts. High Re contents results in a coverage of Cu surface. Catalytic tests reveal that HDO reaction rate and product distribution vary considerably depending on the Re loading. Cu catalyst was inactive for HDO reaction, forming only hydrogenation products. In contrast, Re catalyst stood out for its high capacity to promote HDO reaction, with significant production of toluene. For the bimetallic catalysts, the addition of Re increases HDO reaction rate from 0 to 0.39 mmol gmetal−1 min−1 and the selectivity towards toluene (0–82.6 %), whereas the formation of hydrogenation and dehydration products decreases.

Thermal explosion and distribution of hydromagnetic Eyring–Prandtl double exothermic diffusion-reaction fluid in a porous channel

Harmful waste discharge poses a global threat to environmental degradation, as incomplete combustion of hydrocarbons can lead to unusual diseases and natural disasters, as well as toxic discharge. Therefore, this research aims to investigate the thermal explosion and distribution of hydromagnetic Eyring–Prandtl fluid during double exothermic combustion in a porous channel. The working Eyring–Prandtl fluid is assumed to be fully viscoelastic to inspire the combustion process in the absence of material deformation. A partial differential model of an electromagnetic pressure-driven flow is developed to govern the combustion reaction process in the presence of chemical kinetics, non-isothermal fixed wall constraints, and without fluid material reactant consumption. The model is transformed into an invariant form by introducing similarity variables; the resultant dynamical equations are solved via a finite difference semi-implicit scheme. The graphs and tables demonstrate that the rising parameter values for the double reaction step propelled heat transfer to help improve combustion processes. Also, the material dilatant parameter enhanced the fluid viscosity for increased chemical industrial usage which implies that, excessive heat generation due to exothermic combustion must be supervised to circumvent reactant species blowup. In addition, the magnetic field created complex dynamics in the fluid by introducing electromagnetic Lorentz forces, which changed the reaction rate and heat distribution inside the channel. Furthermore, there is a strong positive correlation between the results obtained in the current study and the existing published data.

Influence of operating conditions on heat and mass transfer in PEMFCs with platinum loading random distributions

The catalyst loading random distribution has a divergent effect on heat transfer and electrical property inside fuel cells than the catalyst loading homogeneous distribution, but the effects of different stoichiometric ratios and average platinum loadings on electrical property, heat as well as species transfer in the fuel cell considering catalyst content random setting are still unclear. Hence, the impacts of stoichiometric ratios and average platinum loadings on the electrical property of fuel cell considering catalyst content random distribution are explored in this paper by using a steady state, two-dimensional, two-phase, non-isothermal fuel cell model coupled the catalyst layer agglomerate model considering the multi-scale problem of catalyst layer. Results indicate that stoichiometric ratio and average platinum loading do not influence the effect direction of catalyst content distributed randomly on the output power. However, with the stoichiometric ratio rising, the impact degree of catalyst content distributed randomly on the output power first enhances and then diminishes. When the stoichiometric ratio is 1.3, the power density of uniform random distribution changes the most, decreasing by 3.91 %. As the average platinum loading rises, the impact degree of catalyst content distributed randomly on the output power gradually decreases. The power density of uniform random distribution decreases by 4.93 % when the catalyst content is 0.2 mg/cm2. Furthermore, the variation trends of temperature distribution, product and reactant content with stoichiometric ratio and average platinum loading under the platinum loading random distribution condition are consistent with that under the platinum loading homogeneous distribution condition. However, as the stoichiometric ratio rises, the reaction rate distribution becomes more uniform for normal random and homogeneous distributions, but the reaction rate distribution becomes uneven under uniform random distribution.

Verification of direct coupling code system using FRENDY version 2 and GENESIS for light water reactor lattices

ABSTRACT This study newly established a direct coupling code system consisting of the nuclear data processing code FRENDY version 2, and the three-dimensional heterogeneous transport code GENESIS (FRENDY-V2/GENESIS) for easy implementation of the random-sampling-based uncertainty quantification considering the implicit effect due to nuclear cross-section (XS) perturbations. The multi-group macroscopic XSs prepared for GENESIS were generated by FRENDY version 2, where the Dancoff factor was calculated by the neutron current method. Then the background XSs were evaluated based on the Carlvik two-term rational approximation. The infinite multiplication factor (k-infinity) and the fission reaction rate distribution in UO2 and MOX lattice geometries were compared with MVP3 to verify the calculation accuracy of FRENDY-V2/GENESIS. The sensitivity analyses on the discretization conditions such as the ray tracing of the method of characteristics were also carried out. Through several comparisons between FRENDY-V2/GENESIS and MVP3, FRENDY-V2/GENESIS with the SHEM 361-group structure calculates the k-infinity within approximately 50 pcm and the fission reaction rate distribution within approximately 0.1% by the root mean square, respectively. Consequently, the applicability of FRENDY-V2/GENESIS was verified, and FRENDY-V2/GENESIS can be used to discuss the implicit effect due to multi-group XS perturbations.

Integrated modeling of anisotropic neutron yields of classical and spherical tokamaks

Estimations of counting rates of neutron spectrometers in experiments on controlled fusion with magnetic confinement, as well as calculations of energy resolved flux densities of fusion neutrons from plasma to the walls of a reactor require spatial integration of the local, usually anisotropic function of the neutron source. The integrated modeling consists of three main stages. First, sources of fast particles in beam- or wave-heated plasma are calculated. The next stage deals with spatial, energetic, and angular velocity distributions of plasma ions. Finally, double differential rate coefficients of nuclear fusion reactions are computed. This article describes calculations of spatial distributions of nuclear fusion reaction rates in classical and spherical tokamaks and the anisotropy of the neutron yield and spectra. The results are based on analytical formulas for energetic and angular distributions of the local source of fusion products in plasma. Examples of energetic spectral densities of neutron fluxes on first walls are presented, as well as energy resolved counting rates of collimated neutron spectrometers for perpendicular and tangential lines of sight.

Segmented distribution of gas diffusion layer porosity and catalyst layer ionomer content in a polymer electrolyte membrane fuel cell

Gas diffusion layer porosity and ionomer content inside catalyst layer both can affect cell performance. Electrochemical reaction rate is non-uniform inside the cell. Non-uniform design of components or structures can improve the electrochemical reaction rate distribution and thus promote cell performance. Thus, the investigations on the optimal distribution are done using the optimization solver within COMSOL Multiphysics 5.3a to seek the optimal segmented distribution of porosity or ionomer content to obtain higher current density. The distributions in cathode side along three directions are all investigated. The optimized results show that the porosity increases along main gas flow direction and the ionomer content reduces. With voltage decreasing, the value of porosity around outlet region reduces and the value around outlet region increases, ionomer content shows opposite trend. The porosity under gas channel is higher than that under land. Ionomer content increases under land and reduces under gas channel with voltage decreasing. The porosity is high near catalyst layer and ionomer content near proton exchange membrane is higher at low voltages. The ionomer content distribution along thickness direction can improve current density by 5.596 % at 0.2 V. For better overall cell performance, the porosity changing along x-axis can be selected, the values from under land to under gas channel are 0.384, 0.499, 0.618. These results can provide theoretical guidance for cell components design to obtain higher cell output performance.

Effect of catalyst distribution in the combustion catalytic layer on heat and mass transport characteristics of the microchannel reactor

PurposeThe purpose of this study is to investigate the effect of catalyst distribution in the combustion catalytic layer on heat and mass transport characteristics of the auto-thermal methanol steam reforming microchannel reactor.Design/methodology/approachComputational fluid dynamics (CFD) method is used to study four different gradient designs. The corresponding distributions of temperature, species and chemical reaction rate are provided and compared.FindingsThe distributions of species, temperature and chemical reaction rate are significantly affected by the catalyst distribution in the combustion catalytic layer. A more uniform temperature distribution can be observed when the gradient design is used. Meanwhile, the methanol conversion rate is also improved.Practical implicationsThis work reveals the effect of catalyst distribution in the combustion catalytic layer on heat and mass transport characteristics of the auto-thermal methanol steam reforming microchannel reactor and provides guidance for the design of reactors.Originality/valueThe temperature uniformity and hydrogen production performance can be improved by the gradient design in the combustion catalytic layer.

Experimental and numerical investigation of chemical-loop steam methane reforming on monolithic BaCoO3/CeO2 oxygen

Chemical looping steam methane reforming (CL-SMR) is a promising approach to co-production of syngas and hydrogen. As the CL-SMR process relies on the redox reaction of the oxygen carriers, the reactivity of oxygen carriers is crucial in the performance of CL-SMR. In this study, a monolithic BaCoO3/CeO2 oxygen carrier was synthesized, and the reaction performance was evaluated in CL-SMR. The kinetic parameters were determined based on Sestak-Berggren model, an unsteady-state CFD model was established to predict the dynamic reaction processes in three reaction stages of CL-SMR. The result suggests that the flow rate of inlet gas in reaction stages could affect the mass transfer during gas-solid reactions, and then change the evolution and distribution of reaction rate in monolithic oxygen carrier. Increasing the flow rate could improve the uniformity of reaction rate distribution and decrease the time consumption for cyclic process, but decreased the concentration of gas productions and increased the burden of gas product separation at the same time. Among three reaction stages, the conversion of oxygen carrier was accelerated with the increase of temperature, and the varied half-life time of conversions suggested that the reactivity in RS stage is intense and the reactivity in AC stage is mild.

Influence of raw material properties on microscopic and mechanical characteristics of alkali-activated materials

Alkali-activated fly ash and slag pastes are considered a new low-carbon cementitious material with good mechanical characteristics and durability. However, the mechanical characteristics of the alkali-activated materials are uncertain due to the multiplicity of the raw material properties. Few studies clarify how the raw material properties affect the mechanical characteristics of hardened pastes. The correlation between the raw material properties and the reaction rate, product composition, gel content, and pore size distribution is discussed in this study. The increase in the CaO content of the precursor will accelerate the degree of alkali activation. In this case, the reaction production becomes relatively more, and the pore size distribution becomes relatively denser, improving the compressive strength of the pastes. Moreover, the effects of the activator modulus and alkali content on the compressive strength of the pastes are not monotonically increasing. The excessive alkali will cause the surface of raw material particles to form a gel layer quickly, which could prevent the further alkali activation of the particles. This case is not conducive to gel formation and will cause the pore structure of the hardening pastes to be relatively loose. Furthermore, the influence of activator modulus on the compressive strength of pastes is lower than that of alkali content. Excess activator modulus is also unfavourable for pore structure densification.

Combustor shape optimization and NO emission characteristics for premixed NH3-CH4 turbulent swirling flame towards sustainable combustion

Ammonia is considered an attractive carbon-free fuel for energy generation in aerospace gas turbine engines. However, ammonia is often used with methane fuel blend due to its low combustion limits. The formation of nitrogen oxides (NOx) during the combustion of ammonia-methane fuel blend is a fundamental problem of interest in the scientific community. To date, there have been several studies of ammonia-methane fuel blend, but none of them have considered the effect of combustor shape on NO emission. In this work, large eddy simulations (LES) are carried out at stoichiometric condition to analyze the flame structure and NO emission characteristics of the ammonia-methane premixed turbulent swirling flame in box and cylindrical shaped combustors. The fuel blend used in this study is 70% ammonia and 30% methane by volume. The LES solver employs a dynamic thickened flame (DTF) combustion model along with Okafor's reduced mechanism, which consists of 43 species and 130 elementary reactions. The flame shape and stabilization are discussed for both combustors, along with the effects of flowfield on the flame. The characteristics of the swirl stabilized flame are illustrated using several time-averaged and instantaneous contours of parameters, including heat release rate, local equivalence ratio, axial velocity, and NO emission. The effect of mixing and reaction rate distribution in the premixed configuration is studied quantitatively, subsequently identifying several flame regions. It is identified from the LES results that the NO emission is 1.6 times higher in the cylindrical combustor compared to the box combustor. While a typical V-shape flame is observed for both combustors, a flame tail also co-exits for the cylindrical combustor. The heat release rate in the flame tail is about 33% higher than the main flame which reignites the unburnt gases for a secondary combustion and generates NO. Thus, a box combustion chamber design is beneficial to minimize the NO emission. The residence time is also analyzed in both combustor to understand the oxidation process and identify the key reaction pathways for NH3/CH4 premixed flames.

Advancing 2D reaction rate measurements in BNCT: Validation of the indirect neutron radiography method

The precise characterization of neutron beams is a cornerstone of Boron Neutron Capture Therapy (BNCT). While Instrumental Neutron Activation Analysis (INAA) is the standard technique for neutron flux measurement, it is limited in its ability to capture two-dimensional (2D) reaction rate distributions. This study aims to validate the Indirect Neutron Radiography (INR) method for 2D reaction rate quantification, addressing critical variables such as temperature sensitivity and signal fading. We designed and constructed an optimized INR platform comprising an Imaging Plate (IP), readout device, activation detectors (copper foils), and real-time temperature monitoring. Comprehensive experiments were conducted to investigate the impact of ambient temperature and fading time on IP signal reliability. A robust calibration curve was formulated, linking IP signals to dose deposition metrics, thereby enabling precise reaction rate assessments. The study found that IP signals are minimally sensitive to temperature variations (less than 0.1% change per 1 °C), but are subjected to linear fading over time, necessitating stringent temperature control and time-dependent signal corrections. A mathematical relationship between IP signals and dose deposition was established, represented by Y = 20,500 × x0.01803-21103. Application of the INR method revealed that the depth-dependent reaction rates in copper strips closely aligned with those acquired through INAA, exhibiting a relative deviation of less than 5% within a 4cm depth range inside the phantom. Our findings demonstrate that the INR method offers a robust alternative to traditional INAA for capturing 2D reaction rates, effectively addressing complexities like temperature sensitivity and signal fading. While challenges persist, particularly in the realm of measurement errors, this study lays the groundwork for further methodological refinements and broadens the scope for future research in BNCT neutron beam characterization.

Evaluation of Reaction Rate Distribution for Shielding Region in the Prototype Fast Reactor Monju

The reliability and usefulness of the reaction rate distribution data measured in the prototype fast breeder reactor Monju were examined through a comparison with a calculation using JENDL-4.0, mainly focusing on shielding regions around the reactor core. The reaction rates of 238U (n,f) and 58Ni (n,p) sensitive to high-energy neutrons were all judged reliable. The calculation-to-experiment values were slightly worse in the shielding regions; however, those for the 58Ni (n,p) reaction rates were improved by employing JEFF-3.3 instead of JENDL-4.0. A different tendency was observed between the two reactions, probably due to the 238U (n,f) cross section in the energy range of around 700 eV. The reaction rates of 235U (n,f), 239Pu (n,f), 238U (n,γ), and 197Au (n,γ) sensitive to the lower-energy neutrons were mostly judged reliable. The data in the lower axial shielding region are less reliable but may be acceptable for the shielding calculation.

Evaluation of Reaction Rate Distribution Measurement in the Prototype Fast Reactor Monju

In the prototype fast breeder reactor Monju, reaction rate distributions of the fission reaction rates of 239Pu, 235U, and 238U and the capture reaction rate of 238U were measured using activation foils during its system startup test. The measurements in the core and radial blanket regions were evaluated in detail, and their reliability and usefulness as the validation data for fast reactor neutronics design methodologies were examined through a comparison with calculations. The reaction rate data measured in Monju were confirmed all reliable and useful as the validation data. The fission reactions of 239Pu, 235U, and 238U can be validated with an accuracy of a few percent in the core and blanket regions. The capture reaction of 238U in the core region also can be validated with a similar accuracy, whereas a precise calculation of the foil cross section is necessary to consider the resonance shielding effects of the surrounding fuel pins and a foil.

Randomness effect of platinum loading distribution in a proton exchange membrane fuel cell: A numerical simulation

The platinum loading is randomly distributed within catalyst layers because of the fabrication way, whereas the platinum loading is considered to follow the homogeneous distribution in the traditional catalyst layer model. The cell performance and heat and species transport laws of the fuel cell with platinum loading random distribution within catalyst layers are not yet clear. Therefore, in this work, a two-dimensional, non-isothermal proton exchange membrane fuel cell model considering the two-phase flow and agglomerate structure of catalyst layers is established to simulate the fuel cell having the catalyst layer where platinum loading is random distribution in a way that is closer to the actual structure. The effect of random distribution of platinum loading on the electrical property, species transfer and temperature distribution is analyzed. Results suggest that the randomness influence needs to be considered when the local distributions of parameters are studied and the research accuracy of parameters is relatively high. In contrast with the homogeneous distribution of platinum loading, the cell performance for the normal random distribution and uniform random distribution cases is reduced. The effects of catalyst loading random patterns on cell performance, species and temperature distributions are different, and the decrease of cell performance for the uniform random distribution case is more obvious. Furthermore, the influence degree of randomness on each parameter is different. The distributions of electrochemical reaction rate, oxygen concentration and temperature display random characteristics, while the liquid water saturation distribution is less influenced by randomness and does not show an obvious random change. These findings can provide a reference for the randomness verification in random simulations and deepen the understanding of species and heat transfer laws in the catalyst layer which is closer to the reality to improve the accuracy of fuel cell simulations.

A new generation pathway of singlet oxygen in heterogeneous single–atom Mn catalyst/peroxymonosulfate system

The function of heterogeneous catalyst in singlet oxygen (1O2) generation under acidic and neutral conditions and the effect of sulfate radical on the generation of 1O2 is still unclear. This study provided a novel generation pathway of 1O2 in the heterogeneous Mn single − atom catalyst (Mn SAC)/peroxymonosulfate (PMS) system. The MnN4 site with the ideal binding strength promoted the activation of PMS to generate sulfate radical (SO4•–), which would be adsorbed on the carbon/nitrogen sites forming SO4•–(s), reacting spontaneously to produce 1O2. The presence of MnN4 and carbon/nitrogen structure sites could shift the oxidation process from a bulk–phase oxidation to a surface oxidation. This shift has important implications in terms of reaction rate and product distribution, as the dual reaction sites decrease the required migration distance for the active species to form 1O2, avoiding the pointless consumption of active substances.

Laser Perforated Dual-Scale Porous Electrodes Considering the Interdigitated Flow Field for Vanadium Redox Flow Battery

The conflict between the specific surface area and hydraulic permeability of carbon-based porous electrodes limits the further improvement of redox flow battery (RFB) system performance. Dual-scale electrode design is a feasible approach to overcome this contradiction. In this study, we prepared dual-scale electrodes by perforating graphite felts using an infrared laser. Based on the symmetry of the interdigitated flow field structure, we proposed three dual-scale structure designs with different combinations of large and small pores and tested their performance on a vanadium redox flow battery (VRFB) single cell. The results showed that the design with perforations under the center of the rib could increase the maximum power density by approximately 2.4 times compared to the original electrode. Furthermore, to investigate the effect of the large pores formed by laser perforation on the local electrolyte velocity, active species concentration, and reaction rate distribution, we proposed a pore-network model and investigated the influence of different combinations of large and small pores and different operating conditions on overall performance through numerical simulation. The results showed that the optimal combination of large and small pores is related to the flow rate and other operating conditions, and that setting large pores under the rib near the outlet channel is expected to provide more performance gains in VRFBs equipped with interdigitated flow fields under typical operating flow rates.

An innovative neutronic deterministic scheme for moderator high-void effect calculation in PWR partially loaded with MOX assemblies

In some countries, as France, plutonium is used in industrial Pressurized Water Reactors (PWRs), using Mixed Oxides (MOX) fuels. To avoid a reactivity increase during a loss of coolant accident, the plutonium content in a PWR is limited at 12 wt%. This limit, that have been determined in the early 1990 s using a very conservative approach, is a strong constraint on the possibility to stabilize the plutonium inventory. Thus, further studies are now conducted to refine the plutonium limit content in the fuel. One interesting case is the local moderator voiding, which could for instance occurs at the beginning of a core depressurization accident. To study this phenomenon, a 2-steps neutronic deterministic scheme is proposed in this paper, using the APOLLO3® code. It is shown that the choice of the selfshielding method to use at the lattice step has a strong influence on the precision of the calculation. It is shown that, as expected, the subgroup formalism is the more precise to cope with both nominal and voided configurations. However, methods relying on this formalism are numerically costly. The use of a method relying on the finestructure formalism allow to conserve a satisfying estimation of the void effect on the reactivity or the spatial distribution of energy-integrated reaction rates. Unfortunately, we show that those good results are due to compensation of large energetic biases in the nominal case. A combination of Tone’s and finestructure selfshielding methods is presented. This method permit to strongly improve per-energetic-groups precision in the voided configuration compared to the method solely relying on the finestructure formalism, while drastically decreasing the numerical cost and duration compared to the subgroup method. The necessity to perform environed lattice calculation is demonstrated in the case of the voiding of a single assembly. A Local Flux Volume normalization of SPH coefficients is proposed to run equivalence calculation on this heterogeneous geometry. A method of characteristic solver is used for the flux calculation at the lattice step, while a S8 transport calculation is performed at the core level, using pin-by-pin discretization and a 26-groups energy mesh. Finally, the precision of the calculation scheme is assessed by comparison to Monte Carlo calculation ran with TRIPOLI–4® on a two-dimensional clusters of assemblies.

A 3D PtCo degradation model for long-term performance prediction of a scaled-up PEMFC under constant voltage operation

The non-uniform distribution of reactants, pressure, temperature and reaction rate in a scaled-up proton exchange membrane fuel cell (PEMFC) can lead to different catalyst degradation rate, impacting the long-term performance of PEMFCs. However, the local catalyst degradation behaviors in a PEMFC stack have not yet been fully understood due to the lack of experimental approaches and catalyst degradation model. In the present study, a numerical model is established for a 200 cm2 commercial-sized PEMFC stack with realistic anode and cathode flow fields. PtCo is employed as the cathode catalyst, and a 3D PtCo catalyst degradation model is developed to analyze the non-uniform evolution of the electrochemical active surface area (ECSA), current density, and Co2+ in the catalyst layers under the constant voltage conditions. The modeling results demonstrated that catalyst degradation is more severe downstream as well as under land of the cathode flow field, and the cathode catalyst layer (CCL) is the area most contaminated by the Co2+. The non-uniform catalyst degradation as well as Co2+ contamination increased the activation losses and local oxygen transport resistance. The catalyst degradation leads to a total power loss of 43.3 % after 80,000 h operation. The aging model provides a better understanding for large scale PEMFC stacks regarding its non-uniform PtCo degradation and can assist the future design of commercial PEMFCs with better lifetime.

About the in-plane distribution of the reaction rate in lithium-ion batteries

Reaction rate distribution and current density distribution of Li-ion batteries largely determine the local aging and heat generation. Homogenous distribution contributes to better durability and safety of Li-ion batteries. This paper focuses on modeling the in-plane distribution of electrochemical reaction current, and the general equation relating space derivatives of the overvoltage to the electrochemical and electronic current densities is derived. Furthermore, this work investigates the impact of various battery parameters on the distribution by considering the cylindrical battery, one of the most used battery types. An explicit closed-form solution for a short time after the current supplied is obtained. It is found that the dimensions of cylindrical batteries, tabbing design, parameters of current collectors, and electrode materials are all indicated to affect the current density distribution. The electronic current density distribution is also demonstrated. This model and related analyses are incredibly beneficial for further optimizing Li-ion batteries’ electronic and electrode properties and as interesting cases for testing battery modeling tools.

Investigation of the Distribution of the Mass Transport and Reaction Rates in a Fuel Cell By the Integrated Fuel Cell System Simulator Including the Dynamics of Air, H2, and Cooling Systems

A 1+1D model to estimate the distribution of the mass transport and reaction rates in the through-plane and along-channel directions in a fuel cell (FC) was developed. The developed model was integrated to the FC system model and controllers which reproduce the dynamics of the 2nd-generation MIRAI, state-of-the-art fuel cell electric vehicle (FCEV). The dynamic behavior of the distribution of mass transport and reaction rates are investigated in low to high load and temperature conditions with the integrated simulator. It was shown that the H2O recirculation from the cathode outlet to inlet region inside the cell through the anode channel played an important role to the determination of the distribution. It was unique feature with the FC system without a humidifier in the air system and the counter-flow configuration of a fuel cell. The impacts of the specification of the controller in the H2 and air system on the overall system performance and the dynamic behavior of the distribution in a fuel cell. The increase of the anode inlet flowrate and cathode inlet pressure enhanced the H2O recirculation in the cell and improved the intensively nonuniform distribution of the humidity, which can cause the acceleration of mechanical degradation of the MEA. The tradeoff of the change of the controller specifications were assessed. It was demonstrated that the relationships among the specification of the controller, the overall system performance, and the dynamic behavior of the distribution in a fuel cell can be evaluated quantitatively.