Polymer Electrolyte Membrane Fuel Cell Power Research Articles

A comprehensive modeling, analysis, and optimization of two phase, non–isobaric, and non–isothermal PEM fuel cell

This study models a non-isobaric, non-isothermal two-phase flow in a Polymer Electrolyte Membrane Fuel Cell (PEM-FC), focusing on conservation equations for mass, energy, and momentum across its components. Verification involves comparing PEM-FC performance and temperature distribution with experimental and literature data, showing consistent agreements. Results indicate that increasing cathode channel pressure enhances membrane moisture and reduces power loss. Higher oxygen partial pressure improves PEM-FC performance, whereas increased anode channel pressure heightens ohmic losses and lowers output voltage. Temperature distribution reveals highest temperatures near the cathode catalyst layer due to electrochemical reactions. Adjusting pressures in cathode and anode channels affects these temperatures accordingly. PEM-FC power density is optimized using various algorithms, with simulated annealing proving most effective. Optimal values for gas diffusion layer thickness, electrode porosity, and inlet humidity are determined. Under constant current density, power density increases by 6 % compared to baseline conditions, demonstrating effective parameter optimization for enhancing PEM-FC performance.

A study into Proton Exchange Membrane Fuel Cell power and voltage prediction using Artificial Neural Network

Polymer Electrolyte Membrane fuel cell (PEMFC) uses hydrogen as fuel to generate electricity and by-product water at relatively low operating temperatures, which is environmentally friendly. Since PEMFC performance characteristics are inherently nonlinear and related, predicting the best performance for the different operating conditions is essential to improve the system’s efficiency. Thus, modeling using artificial neural networks (ANN) to predict its performance can significantly improve the capabilities of handling multi-variable nonlinear performance of the PEMFC. This paper predicts the electrical performance of a PEMFC stack under various operating conditions. The four input terms for the 5 W PEMFC include anode and cathode pressures and flow rates. The model performances are based on ANN using two different learning algorithms to estimate the stack voltage and power. The models have shown consistently to be comparable to the experimental data. All models with at least five hidden neurons have coefficients of determination of 0.95 or higher. Meanwhile, the PEMFC voltage and power models have mean squared errors of less than 1 × 10−3 V and 1 × 10−3 W, respectively. Therefore, the model results demonstrate the potential use of ANN into the implementation of such models to predict the steady state behavior of the PEMFC system (not limited to polarization curves) for different operating conditions and help in the optimization process for achieving the best performance of the system.

(Digital Presentation) Corrosion Behavior of Aluminum-Carbon Composite Bipolar Plates in Polymer Electrolyte Membrane Fuel Cells

ABSTRACT Bipolar plate (BP) is an important multifunctional component in polymer electrolyte membrane fuel cells (PEMFCs) system (1,2) which should possess some specifications such as superior electrical and thermal conductivity, high corrosion resistance, good mechanical performance, and low cost (3). BP candidate materials are roughly classified into carbon-based and metal-based materials. Carbon-based materials are lightweight and have excellent corrosion resistance, but are inferior to metal-based materials in terms of gas shielding properties and mechanical strength. Metallic materials have the opposite characteristics, and corrosion resistance is a particular and important issue. Aluminum (Al) is considered as a promising BP material because of having some important characteristics such as low density and low cost (4). Earlier, it was proposed that the PEMFC BP can be divided into two parts: gas isolation plate and flow path forming material (5). Normally, metallic BPs are corroded exclusively at the rib part where BP contacts with the gas diffusion layer (GDL), while there is not much corrosion at the bottom of the flow path. Therefore, the corrosion resistance required for the reaction gas isolation plate would not be as high as required for the flow path forming material (5). In this study, a composite BP using Al as the reaction gas isolation plate and a carbon-based material as the flow path forming material was fabricated to investigate the corrosion behavior of Al through power generation test.A single cell was assembled using a BP consisting of a 1 mm thick glassy carbon flow path forming material and an Al reaction gas isolation plate, and the power generation tests were performed for 500-1000 h to investigate the corrosion of Al. Separately, Al plates were subjected to exposure tests in the expected environment during the cell operation. After the exposure and power generation tests, the Al bipolar plates were analyzed by SEM and TEM. Furthermore, in order to improve the contact resistance, a power generation test using a bipolar plate coated with TiN-SBR on both sides of Al isolation plate (6) was also conducted.When Al plate was immersed in water at 80 °C, a thick oxide layer of about 1.3 µm was formed with whitish appearance. On the contrary, Al maintained its gloss after exposer in the saturated steam. After 1000 h power generation test using the Al-carbon BP, the surface of Al diaphragm plate maintained its gloss at cathode side. On the other hand, a thick oxide layer of about 1 µm was formed from center part to outlet part along with the flow field on the anodic plate. It suggests that the water drops were generated on the anodic flow field although the corrosion products were slight enough for safe use of Al as BPs with the channel former made of carbon.Thus, the following findings were obtained as a result of conducting the PEMFC power generation test using a composite BP with Al as the reaction gas isolation plate and glassy carbon as the flow path forming material. No significant corrosion was observed on the Al isolation plate on the cathode side after the 1000 h power generation test, but the anode side turned into white from the center of the flow path to the gas outlet side, and about 1 µm of a thick oxide film was formed.When a power generation test was conducted using Al BP coated with TiN-SBR, the cell voltage was increased significantly which was approached as similar as the performance of graphite. It indicates that Al can be used as bipolar plates without any problem by performing surface treatment in combination with a carbon channel forming material. Acknowledgements The authors thankfully acknowledge the financial support obtained from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. References Y. C. Park, S. H. Lee, S. K. Kim, S. Lim, D. H. Jung, S. Y. Choi, Int. J. Hydrogen Energy, 38, 10567–10576 (2013).S. F. Husby H, O. E. Kongstein, A. Oedegaard, Int. J. Hydrogen Energy, 2, 951–957 (2014).S. H. Lee, V. E. Pukha, V. E. Vinogradov, N. Kakati, S. H. Jee, S. B. Cho, Int. J. Hydrogen Energy, 38, 14284–14294 (2013).C.-H. Lee, Y.-B. Lee, K.-M. Kim, M.-G. Jeong, and D.-S. Lim, Renewable Energy, 54, 46–50 (2013).H. Yashiro, T. Ichikawa, S. -T, Myung, M. Kumagai and S. Kozutsumi, Zairyo-to-Kankyo, 60, 432–434, (2011).S.-T. Myung, M. Kumagai, R. Asaishi, Y.-K. Sun, H. Yashiro, Electrochem. Comm., 10, 480–484 (2008).

Backstepping sliding-mode techniques in current control of polymer electrolyte membrane fuel cell

The polymer electrolyte membrane fuel cell (PEMFC) power conditioning is particularly crucial for a fuel cell vehicle to meet various load demands effectively. This paper focuses on the PEMFC current control addressing varied tracking references or disturbance injections. With control-oriented models of the PEMFC-fed DC–DC systems, two control methods integrated with sliding-mode control (SMC) are proposed to regulate the fuel cell current: a backstepping method dealing with high nonlinearity and coupled characteristics of the PEMFC power supply, and an adaptive approach counteracting parametric uncertainties or load disturbances. Simulations and experiments indicate that the proposed backstepping SMC could alleviate chattering of the conventional SMC effectively and maintain good robustness; in addition, the adaptive backstepping SMC could further reduce the fuel cells ′ settling time by 25 % during transient response experiment with the boost converter and make system parameters vary more smoothly with the buck converter.

A twin-nozzle ejector for hydrogen recirculation in wide power operation of polymer electrolyte membrane fuel cell system

The ejector-driven hydrogen recirculation in the polymer electrolyte membrane fuel cell (PEMFC) system is a promising alternative to the pump-driven approach due to its advantages of small volume, low cost, parasitic power free, and low noise. However, the fixed structure of the ejector limits its application to the dynamic operation of the PEMFC system. To overcome this drawback, a twin-nozzle ejector with two nozzles placed symmetrically in the suction chamber is proposed for hydrogen recirculation under different PEMFC power outputs. A three-dimensional Computational Fluid Dynamics model for the proposed twin-nozzle ejector is developed and verified with experiment results. The hydrogen recirculation performance of single-nozzle and two-nozzle working modes is analyzed by a simulation study. The simulation results indicate that the single-nozzle mode can provide acceptable recirculation performance under low power outputs of the PEMFC system, and the two-nozzle mode is more suitable for the high-power outputs with lower supply hydrogen pressure. Compared with conventional ejector, the proposed twin-nozzle ejector can be used in a wider power output range from 17.00 to 85.00 kW with supply hydrogen pressure from 250 to 700 kPa by switching the two working modes. The proposed ejector provides an effective way to extend the application of ejector in hydrogen recirculation of PEMFC system.

An Efficient and Robust Current Control for Polymer Electrolyte Membrane Fuel Cell Power System

Taking into account the restricted ability of polymer electrolyte membrane fuel cell (PEMFC) to generate energy, it is compulsory to present techniques, in which an efficient operating power can be achieved. In many applications, the PEMFC is usually coupled with a high step-up DC-DC power converter which not only provides efficient power conversion, but also offers highly regulated output voltage. Due to the no-linearity of the PEMFC power systems, the application of conventional linear controllers such as proportional-integral (PI) did not succeed to drive the system to operate precisely in an adequate power point. Therefore, this paper proposes a robust non-linear integral fast terminal sliding mode control (IFTSMC) aiming to improve the power quality generated by the PEMFC; besides, a digital filter is designed and implemented to smooth the signals from the chattering effect of the IFTSMC. The stability proof of the IFTSMC is demonstrated via Lyapunov analysis. The proposed control scheme is designed for an experimental closed-loop system which consisted of a Heliocentric hy-Expert™ FC-50W, MicroLabBox dSPACE DS1202, step-up DC-DC power converter and programmable DC power supplies. Comparative results with the PI controller indicate that a reduction of 96% in the response time could be achieved using the suggested algorithm; where, up to more than 91% of the chattering phenomenon could be eliminated via the application of the digital filter.

Composite Proton Electrolyte Membranes C Poly Ether-Ether Ketone (SPEEK) at Various Amount of Mesoporous Phosphotungstic Acid (mPTA) for Hydrogen Fuel Cell Application

Polymer electrolyte membrane fuel cells (PEMFC), also known as proton exchange membrane fuel cells utilise polymer electrolyte membranes (PEMs) to conduct protons for ion-exchange purposes. Nafion is a common polymeric material to be used as PEM for fuel cells. However, Nafion has major weaknesses such as low proton conductivity under anhydrous conditions at elevated temperatures due to water evaporation and continuous need for water management, low tolerance for fuel impurities and high cost. This study fabricates a newly composite PEM by blending SPEEK and mesoporous phosphotungstic acid (mPTA) at various loading in order to obtain the most favourable PEMFC power output. SP/2.0mPTA membrane has shown outstanding properties in terms of dense structure, 35.75% of water uptake and expected an elemental mapping of 76.20% Tungsten and 23.80% Phosphorus. Even with a lower proton conductivity of 3.502 mScm-1, this membrane has a higher power density of 154.4 mW/cm2 compared to the other four membranes. Owing to the unique characteristics of the as-synthesized mPTA such as high surface area, porous structure, good thermal and chemical resistance, SPEEK-mPTA membrane is one of the promising materials for PEMFC applications.

Real-Time Implementation of a New MPPT Control Method for a DC-DC Boost Converter Used in a PEM Fuel Cell Power System

Polymer electrolyte membrane (PEM) fuel cells demonstrate potential as a comprehensive and general alternative to fossil fuel. They are also considered to be the energy source of the twenty-first century. However, fuel cell systems have non-linear output characteristics because of their input variations, which causes a significant loss in the overall system output. Thus, aiming to optimize their outputs, fuel cells are usually coupled with a controlled electronic actuator (DC-DC boost converter) that offers highly regulated output voltage. High-order sliding mode (HOSM) control has been effectively used for power electronic converters due to its high tracking accuracy, design simplicity, and robustness. Therefore, this paper proposes a novel maximum power point tracking (MPPT) method based on a combination of reference current estimator (RCE) and high-order prescribed convergence law (HO-PCL) for a PEM fuel cell power system. The proposed MPPT method is implemented practically on a hardware 360W FC-42/HLC evaluation kit. The obtained experimental results demonstrate the success of the proposed method in extracting the maximum power from the fuel cell with high tracking performance.

Robust high order sliding mode control for performance improvement of PEM fuel cell power systems

In this paper, an efficient algorithm is applied to high step-up power converter for performance improvement of Polymer Electrolyte Membrane (PEM) Fuel Cells. The action is done on forcing the fuel cell to operate at an adequate power point by tuning the power converter duty cycle. Due to inherent nonlinearities in the fuel cell dynamics and variations of the system parameters, a nonlinear sliding mode control (SMC) is suggested. However, the SMC causes severe changes in the PEM fuel cell output power, which lead to serious life-shortening and acute cell degradation. To overcome these shortcomings, a robust high order SMC based on “Twisting Algorithm” (HOSM-TA) is designed to improve the power quality and to keep the fuel cell operating at an adequate power point. The stability of both SMC and HOSM-TA is demonstrated via Lyapunov analysis. To demonstrate the effectiveness of the proposed HOSM-TA control scheme, a hardware setup is carried out on a real PEMFC stack. The implementation of the control system and the data acquisition are done on a dSPACE real-time digital control platform. It is deduced that the proposed HOSM-TA with high robustness, fast convergence (1s), and chattering reduction of 82.7% can be used to achieve great improvements in fuel cell power system.

Improving During and Postfault Response of Fuel Cells in Symmetrical and Asymmetrical Grid Fault Cases

High-gain PID controllers with fast response are the most common schemes that are used to control polymer electrolyte membrane fuel cells (PEMFCs). However, during grid voltage sags, due to their fast response, these controllers may get saturated. Consequently, the PID controller loses the ability to control PEMFC during grid's voltage restoration period, which is not desirable for the grid. In this paper, a control strategy using proxy-based sliding mode control (PBSMC) is proposed to enhance the postdisturbance recovery of PEMFCs. The proposed control scheme operates similar to high-gain, fast response PID controllers during normal operation and small disturbances. However, during large disturbances that cause the conventional controller to reach its limit, PBSMC shows a slow and overdamped response. This leads to fast and smooth resume to the predisturbance trajectory. Additionally, in this paper, a systematic approach is developed to reduce the voltage oscillations of the capacitor of a dc/dc converter during asymmetrical faults. By employing this method, the performance of PEMFC power plant under asymmetrical faults is enhanced. Simulation results show that the proposed controller and voltage oscillation compensation method improve the response of PEMFCs to different types of faults.

Dynamic modeling and control analysis of a methanol autothermal reforming and PEM fuel cell power system

In the present study, a rigorous dynamic and control-oriented model is developed towards accurately describing the autonomous operation of a methanol reforming-fuel cell power system (up to 5kWel). The system consists of an autothermal steam reformer that provides hydrogen to a polymer electrolyte membrane (PEM) fuel cell. A purification stage (preferential oxidation reactor) intercedes between the steam reformer and the fuel cell and maintains CO levels below 10–50ppm, while a heat-exchanging network (comprising of two coolers and a burner) is employed towards managing a well-balanced autothermal operation. The proposed dynamic model is developed on the basis of describing accurately the evolving chemical and electrochemical interactions between the subsystems and utilizes a group of partial/ordinary differential equation (reactors and heat exchangers) along with a set of non-linear equations (reaction kinetics and current-voltage dependence). Based on the system main operating features, a control structure through the implementation of PI controllers is proposed for the control of (a) the reformer feed and exit temperature through methanol burning and steam reformer feed flowrate manipulation respectively, (b) CO concentration through O2/CO feed ratio manipulation, (c) power production (specified by the fuel cell operation current) through methanol reformer feed and (d) subsystem exit temperatures through coolant flowrate manipulation. An overall simulation case study reveals the proper selection of system manipulated and controlled variables towards achieving the applied operating set-points, where it is shown that the system sustains a flexible operation, along with fast start-up and dynamic transients.

The design of long-life, high-efficiency PEM fuel cell power supplies for low power sensor networks

Field sensor networks have important applications in environmental monitoring, wildlife preservation, in disaster monitoring and in border security. The reduced cost of electronics, sensors and actuators make it possible to deploy hundreds if not thousands of these sensor modules. However, power technology has not kept pace. Current power supply technologies such as batteries limit many applications due to their low specific energy. Photovoltaics typically requires large bulky panels and is dependent on varying solar insolation and therefore requires backup power sources. Polymer Electrolyte Membrane (PEM) fuel cells are a promising alternative, because they are clean, quiet and operate at high efficiencies. However, challenges remain in achieving long lives due to factors such as degradation and hydrogen storage. In this work, we devise a framework for designing fuel cells power supplies for field sensor networks. This design framework utilize lithium hydride hydrogen storage technology that offers high energy density of up to 5000 Wh/kg. Using this design framework, we identify operating conditions to maximize the life of the power supply, meet the required power output and minimize fuel consumption. We devise a series of controllers to achieve this capability and demonstrate it using a bench-top experiment that operated for 5000 h. The laboratory experiments point towards a pathway to demonstrate these fuel cell power supplies in the field. Our studies show that the proposed PEM fuel cell hybrid system fueled using lithium hydride offers at least a 3 fold reduction in mass compared to state-of-the-art batteries and 3-5 fold reduction in mass compared to current fuel cell technologies.

Optimization of catalyst distribution along PEMFC channel through a numerical two-phase model and genetic algorithm

In this paper, a new approach is presented to find the optimum catalyst loading distribution along the flow field. The optimization is performed by integrating a computational fluid dynamic (CFD) model and genetic algorithm optimization method. The CFD model is two-dimensional, steady state and two-phase. Multiphase mixture model (M2) is used to model two-phase transport in porous media of a Polymer Electrolyte Membrane Fuel Cell (PEMFC). Numerical domain includes channel, gas diffusion layer (GDL) and catalyst layer (CL) in the cathode side. In the next step, current density is assumed to be proportional with catalyst loading. Catalyst loading is considered as polynomial functions with unknown coefficients. Genetic algorithm optimization method is applied to find the unknown coefficients and as a result the optimum catalyst loading function along the flow field. The results indicate that catalyst loading distribution has a significant effect on the fuel cell performance and it is seen that in the optimum case, maximum PEMFC power density is increased by about 14%.

Power density optimization of PEMFC cathode with non-uniform catalyst layer by Simplex method and numerical simulation

One of the factors that has hindered the commercialization of Polymer Electrolyte Membrane Fuel Cells (PEMFCs) has been the high cost per kW from the high cost of platinum catalyst. Hence it is important to optimize the use of the platinum catalyst. In many previous PEMFC models, the catalyst distribution in Cathode Catalyst Layer (CCL) was assumed to be uniform, and there are very few models in which the variation of catalyst loading across the CCL is taken into account. This paper aims to enhance PEMFC power density by optimally distributing the catalyst used in CCL employing a computational fluid dynamic (CFD) simulation in conjunction with agglomerate model of the CCL. First, a numerical approach is presented to evaluate the effect of variant catalyst loading in the CCL of a PEMFC. A two-dimensional, steady state, isothermal implicit model for PEMFC has been developed. A spherical flooded agglomerate model is considered for CCL in which transport of both chemical species and charges are also taken into account. The numerical domain includes channel, land, Gas Diffusion Layer (GDL), and CCL. The developed model is used to determine the optimum catalyst loading distribution along CCL using a novel algorithm based on combining the numerical model and Nelder-Mead Simplex optimization method. In this novel algorithm, the optimum catalyst distribution function is assumed as different order polynomial functions with unknown coefficients. Unknown coefficients are calculated by considering the numerical model as a set of constraints for the optimization method. Nelder-Mead optimization method which is an unconstraint minimization heuristic method is employed to find the unknown coefficients. It is seen that in the optimum case, the maximum PEMFC density is increased about 7 percent. This improvement is a huge leap toward the commercialization of PEMFC.

Evaluation of Acid Accelerators for an Off-Grid PEM Fuel Cell Power Station Utilizing Solid Sodium Borohydride for Hydrogen Storage

Sodium borohydride was once looked at as a promising way to store hydrogen for use in polymer electrolyte membrane (PEM) fuel cells. Concerns regarding hydrogen storage capacity and sustainability of the reactants resulted in its disqualification as a viable hydrogen source in transportation vehicles. Sodium borohydride is still a promising hydrogen storage medium to meet power demands for applications such as remote sensor networks and off-grid communications. In this paper, we discuss the use of acid accelerators to enhance the borohydride hydrolysis reaction when combined with solid borohydride and liquid water. Specifically, we report results for hydrochloric acid, sulfuric acid, citric acid, and acetic acid. As a first approximation, yield of the reaction is above 90% for all these acids and a zero-order dependence on pH was observed.

Incorporation of Platinum and Gold Partially Reduced Graphene Oxide into Polymer Electrolyte Membrane Fuel Cells for Increased Output Power and Carbon Monoxide Tolerance

The Polymer Electrolyte Membrane Fuel Cells (PEMFCs) platinum catalyst’s susceptibility to poisoning by carbon monoxide (CO) reduces its output power. In an effort to diminish poisoning, gold and platinum nanoparticles were incorporated onto partially reduced graphene oxide (Au/Pt-prGO) sheets to reduce both nanoparticle aggregation and the amount of precious metal needed. Applying this material onto the electrodes and Nafion membrane of a PEMFC was hypothesized to increase CO tolerance as well as power output. Aliquots of graphene oxide (GO) were functionalized with platinum and/or gold nanoparticles using a simple desktop synthesis at room temperature. Partial reduction with NaBH4 maintained hydrophilic solubility. Test solutions applied to electrodes and to electrodes + Nafion membrane were first tested in a PEM fuel cell with a pure H2 gas feed and then repeated with a H2 gas feed containing 1000 ppm of CO. Test arrangements averaged doubling the output power of the poisoned control, with the most effective yielding an output power ∼250% that of the poisoned control. Additionally, each system’s poisoned output power (PP) was compared to its highest possible output power (PM), with the most effective setup showing no reduction in output power, even with a H2 gas feed containing 1000 ppm of CO. Thus, this offers promise of a simple, cost-effective method of both improving PEMFC power output while reducing or even eliminating CO poisoning at room temperature.

Hardware-In-the-Loop Simulation을 이용한 고분자 전해질 연료전지 냉각시스템 최적 제어기법 연구

Abstract - Polymer electrolyte membrane fuel cell(PEMFC) requires cooling system to maintain the proper operating temperature(about 65℃∼75℃) because the efficiency and power are affected by operating temperature. In order to retain the operating temperature of PEMFC, cooling system and coolant control logic are needed. Hardware-in-the-loop simulation(HILS) is one of effective methods to study and evaluate control algorithm. In this paper, the HILS system was designed to study the coolant control algorithm. The models of HILS system consisted of PEMFC, heat exchanger, and external environment associated with temperature. The hardwares in HILS system are 3-way valves, pumps, and a heat exchanger. The priority control and the control target temperature were investigated to improve the control performance using HILS. The 3-way valve in 1 st cooling circuit was selected as priority control target. The under limit value of 2 nd 3-way valve set as a function of PEMFC power and 2 nd circuit coolant temperature to correct temperature control performance. As a result, the temperature of PEMFC is stably controlled.

Simulation of a stand-alone residential PEMFC power system with sodium borohydride as hydrogen source

Catalytic hydrolysis of sodium borohydride (NaBH4) has been investigated as a method to generate hydrogen for fuel cell applications. The high purity of the generated hydrogen makes this process a potential source of hydrogen for polymer electrolyte membrane fuel cells (PEMFCs). In this paper, a PEMFC power system employing a NaBH4 hydrogen generator is designed to supply continuous power to residential power applications as stand-alone loads and simulated using Matlab/Simulink software package. The overall system is sized to meet a real end-use load, representative of standard European domestic medium electric energy consumption, over a 1-week period. Supervisory control strategies are proposed to manage the hydrogen generation and storage, and the power flow. Simulation results show that the proposed supervisory control strategies are effective and the NaBH4–PEMFC power system is a technologically feasible solution for stand-alone residential applications.

Exergy, Economic, and Environmental Analysis of a PEM Fuel Cell Power System to Meet Electrical and Thermal Energy Needs of Residential Buildings

Abstract In this paper, a Polymer Electrolyte Membrane (PEM) fuel cell power system including burner, steam reformer, heat exchanger, and water heater has been considered. A PEM fuel cell system is designed to meet the electrical, domestic hot water, heating, and cooling loads of a residential building located in Tehran. Operating conditions of the system with consideration of the electricity cost has been studied. The cost includes social cost of the environmental pollutants (e.g. CO2, CO and NO). The results show that the maximum energy needs of the building can be met by 12 fuel cell stacks with nominal capacity of 8.5 kW. Annual average electricity cost of thissystem is equal to 0.39 US$/kWh and entropy generation of this system through a year is equal to 1004.54 GJ/K1. It is also concluded that increase in ambient temperature from 1 °C to 40 °C increases the entropy generation by 5.73%, carbon monoxide by 14.56%, and nitrogen monoxide by 8.9%, but decreases carbon dioxide by 0.47%.

Assessment of PEFC performance by applying harmonized testing procedure

The performance of a polymer electrolyte membrane fuel cell (PEFC) power stack is assessed in terms of polarization measurements under laboratory conditions by applying a harmonized testing procedure. Harmonization at the level of testing procedures allows for an objective and trustworthy comparison of performance data. The harmonization of the procedure took place among the 55 partners of the Fuel Cell Testing and Standardization Network (FCTESTNET). Selected testing procedures are currently validated through experimental campaigns in the successor project (Fuel Cell Testing, Safety and Quality Assurance, FCTESQA) involving research laboratories from Europe, US, China, and Korea. This study reports the results of a test of the campaign for the performance assessment of a PEFC power stack carried out at JRC by applying the harmonized procedure for validation. Following the procedure, the test inputs and outputs are subjected to stability checks a priori and during the actual polarization measurement steps of the test. The assessment of the stack performance is based on a statistical approach of the test outputs, which includes the calculation of averages, measurement range, (relative) standard deviation and standard error as well as of a stability parameter. The study demonstrates the necessity of harmonized testing procedures and of a harmonized methodology of presenting the test results in a commonly agreed format to provide a comprehensive performance assessment for PEFC stacks. Copyright © 2011 John Wiley & Sons, Ltd.