Air-breathing Proton Exchange Membrane Research Articles

A novel radial air-breathing proton exchange membrane fuel cell for miniaturized applications with effective stacking potentials

Increasing volumetric power density in fuel cells can be accomplished by increasing its compactness or output power. This is very crucial for miniaturized applications due to constraints in available spaces. In this study, a three-dimensional, multiphase, and non-isothermal computational fluid dynamics (CFD) tool is used to develop a novel radial air-breathing (AB) PEM fuel cell for miniaturized applications, which has unique stack-ability feature. The noted cell can accommodate multiply higher active area in cathode electrode with respect to planar and tubular AB designs. Increasing the cathode side active area, the electrode with the highest sources of losses for the kinetics of reactions in proton exchange membrane (PEM) fuel cells, has shown to play a significant role in performance enhancement of radial AB cells. For instance, at 0.4 Acm−2 the radial AB PEM fuel cell, can deliver 27.9 % and 10 % more power than the earlier planar and tubular AB ones, respectively. The stack-ability of AB fuel cells usually face severe challenges due to non-uniform air supply to the cells, resulting in imbalance of the cells output power. As opposed to tubular and planar AB cells, one unique feature for the present radial AB stack design is its attack-ability that ensures adequate and uniform supply of air/oxygen to all cells.

Numerical Study on Effect of Flow Field Configuration on Air-Breathing Proton Exchange Membrane Fuel Stacks

Air-breathing proton exchange membrane fuel cells (PEMFCs) show enormous potential in small and portable applications because of their brief construction time without the need for gas supply, humidification and cooling devices. In the current work, a 3D multiphase model of single air-breathing PEMFCs is developed by considering the contact resistance between the gas diffusion layer and bipolar plate and the anisotropic thermal conduction and electric conductive in the through-plane and in-plane directions. The 3D model presents good grid independence and agreement with the experimental polarization curve. The single PEMFC with the best open area ratio of 55% achieves the maximum peak power density of 179.3 mW cm−2. For the fuel cell stack with 10 single fuel cells, the application of the anode window flow field is beneficial to improve the stack peak power density compared to the anode serpentine flow field. The developed model is capable of providing assistance in designing high-performance air-breathing PEMFC stacks.

Dynamics Management of Intermediate Water Storage in an Air-Breathing Single-Cell Membrane Electrode Assembly.

In air-breathing proton exchange membrane fuel cells (Air PEM FCs), a high rate of water evaporation from the cathode might influence the resistance of the membrane electrode assembly (MEA), which is highly dependent on the water content of the Nafion membrane. We propose a dead-end hydrogen anode as a means of intermediate storage of water/humidity for self-humidification of the membrane. Such an inflatable bag integrated with a single lightweight MEA FC has the potential in blimp applications for anode self-humidification. A dynamic numerical water balance model, validated by experimental measurements, is derived to predict the effect of MEA configuration, and the membrane's hydration state and water transfer rate at the anode on MEA resistance and performance. The experimental setup included humidity measurements, and polarization and electrochemical impedance spectroscopy tests to quantify the effect of membrane hydration on its resistance in a lightweight MEA (12 g) integrated with an inflatable dead-end hydrogen storage bag. Varying current densities (5, 10, and 15 mA/cm2) and cathode humidity levels (20, 50, and 80%) were examined and compared with the numerical results. The validated model predicts that the hydration state of the membrane and water transfer rate at the anode can be increased by using a thin membrane and thicker gas diffusion layer.

Biomimetic integrated gas diffusion layer inspired by alveoli for enhanced air-breathing fuel cell performance and stability

Inspired by the structure of alveoli, a biomimetic integrated GDL was carefully designed. The biomimetic integrated GDL structure enhances the performance and durability of PEMFC while also making its structure more compact.

Performance improvement of air-breathing proton exchange membrane fuel cell (PEMFC) with a condensing-tower-like curved flow field

Air-breathing proton exchange membrane fuel cells (PEMFCs) are very promising portable energy with many advantages. However, its power density is low and many additional supporting parts affect its specific power. In this paper, we aim to improve the air diffusion and fuel cell performance by employing a novel condensing-tower-like curved flow field rather than an additional fan, making the fuel cell more compact and has less internal power consumption. Polarization curve test and galvanostatic discharge test are carried out and proved that curved flow field can strengthen the air diffusion into the PEMFC and improve its performance. With appropriate curved flow field, the fuel cell peak power can be 55.2% higher than that of planar flow field in our study. A four-layer stack with curved cathode flow field is fabricated and has a peak power of 2.35 W (120 W/kg).

Investigation of a Symmetric Hydrogen-Purging Strategy for an Air-Breathing PEM Fuel Cell Stack Working in a Closed Environment

Autonomous Underwater Vehicles (AUVs) are becoming more and more used for different applications. Since AUVs are not physically connected to anything, they are well suited to execute long-range missions in unknown waters and to collect data from the surrounding environment. The most important parameters to consider when designing AUVs for such missions are endurance, flexibility, weight and volume. Very accurate sensors give high performances to today’s AUVs, but also make them energy intensive, which has a strong impact on the AUVs’ endurance. Hydrogen for conversion in fuel cells has a higher specific energy (kWh/kg) and a lower specific power (kW/kg) than secondary batteries. A promising alternative to reach both power and range demands of the AUVs is therefore to design hybrid fuel cell/battery systems. The Proton Exchange Membrane Fuel Cell (PEMFC) works at close to ambient temperatures and is the most common fuel cell on the market. In the AUV application the volume is limited, and both H2 and O2 utilization must be optimized as much as possible. Due to the space limitation, it is also complicated to add sub-components such as re-circulation pumps or condenser units to the system. In order to maximize the hydrogen utilization in the stack, the fuel cell is running in so-called dead-end mode, where the hydrogen is trapped inside the stack in order to force it to react. In such a mode, water accumulates in the membrane and transfers from the cathode to the anode, causing the cell performance to drop dramatically. A previous study on a 6-cells PEMFC stack in a closed environment [1] showed that the fuel cell should operate at high relative humidity, with a limited forced convection and deliver a relatively low current in order to increase the time between two necessary hydrogen purges and maintain the performance of the stack over time. In this configuration, the six cells composing the stack are in series both electronically and in terms of hydrogen flow. This means that the first cell receives fresh hydrogen and its outlet is the hydrogen inlet for the next cell. The purge valve is placed right after the last cell, in this so-called “single-purging” strategy.In a new developed setup presented in the attached Figure, the hydrogen flow within the stack is reversed after each hydrogen purge. In this configuration, the last cell that was receiving hydrogen, after each purge instead becomes the first cell to receive hydrogen. This purging strategy is called “symmetric purging”. Unlike for the previous study, the voltage of each cell is now monitored during the experiments.This study presents the results of the comparison between the two purging strategies. Galvanostatic experiments at relatively low current with different set times between the purges, or voltage-drop purge criteria, are performed and the behaviour of both the stack and each individual cell is studied. A minimum of 40 purges occurs for each experiment. Electrochemical impedance spectroscopy is performed in order to highlight the impact of each strategy on the cells’ degradation. Preliminary results show that both strategies lead to a stable voltage of the stack during the experiments. However, when studying the voltage of each individual cell over time, some differences appear depending on the purging strategy. With the symmetric purging strategy, the individual cells reach a steady-state faster and show less variation over time than with the single-purging strategy. Future experiments will provide more results and help to find the best purging strategy for a PEM fuel cell stack working in a closed environment, i.e. be the most suitable strategy for fuel cell-powered AUVs.[1]: Chiche, A., Lindbergh, G., Stenius, I., & Lagergren, C. (2021). Design of experiment to predict the time between hydrogen purges for an air-breathing PEM fuel cell in dead-end mode in a closed environment. International Journal of Hydrogen Energy, 46(26), 13806-13817. Figure 1

Hybrid System of Air-Breathing PEM Fuel Cells/Supercapacitors for Light Electric Vehicles: Modeling and Simulation

AbstractRecently, light electric vehicles such as pedelecs, electric bicycles, and electric scooters have shown excellent potential for short distances. It is essential to control the power require...

Natural wood derived robust carbon sheets with perpendicular channels as gas diffusion layers in air-breathing proton exchange membrane fuel cells (PEMFCs)

Herein, a novel natural wood derived macroporous carbon sheet with three-dimension inter-connected perpendicular-channels was engineered as gas diffusion layers (w-GDLs) for air-breathing proton exchange membrane fuel cells (PEMFCs). Beneficial to the unique accessible perpendicular channels and the presence of a microporous layer, the current density reached 0.139 A/cm2 (at 0.6 V) and the maximum power density elevated up to 0.102 W/cm2 (at 0.43 V), which are comparable to the best results reported for the air-breathing PEMFCs with high Pt loadings. Furthermore, it exhibited excellent durability during preliminary constant discharge operation, demonstrating the feasibility of this w-GDL for practical applications.

Design, simulation and experimental characterization of a high-power density fuel cell

This research proposes a novel design of a millimeter-sized air-breathing proton exchange membrane fuel cell (AB-PEMFC). The producing method of the air-breathing PEMFC consisted of the sequential deposition of the elements in layers: 1) endplate of a flat polymer, 2) fuel flow channel with gas diffusion layers (GDL), 3) silicone seal with embedded micro Pt (platinum) wires, 4) membrane electrode assembly (MEA) with high platinum load, 5) GDL with micro Pt wires. Performance tests were done using an AB-PEMFC and the stack of two mono cells under different conditions. The results obtained by the computational fluid dynamics (CFD) allowed analyzing the current collector (CC) position. The performance results show 110 W L−1 for the cell power density and 2200 W kg−1 for the specific power density.

Design of experiment to predict the time between hydrogen purges for an air-breathing PEM fuel cell in dead-end mode in a closed environment

Fuel cells are promising technologies for zero-emission energy conversion. They are used in several applications such as power plants, cars and even submarines. Hydrogen supply is crucial for such systems and using Proton Exchange Membrane Fuel Cell in dead-end mode is a solution to save hydrogen. Since water and impurities accumulate inside the stack, purging is necessary. However, the importance of operating parameters is not well known for fuel cells working in closed environments. A Design of Experiment approach, studying time between two purges and cell performance, was conducted on an air-breathing stack in a closed environment. The most influential parameters on the time between two purges are the relative humidity and the current load. Convection in the closed environment can decrease the stability of the fuel cell. A linear model with interactions between these last three parameters was found to accurately describe the studied responses.

Passive Regulation of the Water Content at the Anode Chamber under Dead-Ended Conditions: Innovative Design of an Air-Breathing Proton Exchange Membrane Fuel Cell

A passive regulation system for the water content has been developed and evaluated for a proton exchange membrane fuel cell. It is of particular relevance for micro-fuel cells, whose volume, weight and extra-consumption of fuel and power for subsidiary components must be kept to a minimum. This solution consists of a self-regulating humidity system implemented at the anode chamber that allows free water exchange with the environment through the surface of a gas-tight membrane. The micro-fuel cell, which is designed according to the patent WO2015025070A1, has been assembled and operated under completely passive conditions. The behavior of the anode humidity regulation system has been analyzed externally and in situ. The external part of the anode, where the humidity exchange with the environment takes place, has been isolated in a closed chamber and a hygrometer has been used to register the relative humidity in the zone near to the water exchange film. The results obtained from the operation of this innovative system are discussed in the light of the water permeation behavior of different Nafion membranes.

Effects of Various Operating Parameters on the Performance of an Air Breathing PEM Fuel Cell

The objective of the presented work is to study the operating parameters and their effects on the performance of an air breathing PEM fuel cell. In this study, we have theoretically calculated the losses associated with the fuel cells. The performance of the fuel cell can be determined by using the polarisation curve. Polarization curves from which the output voltage can be found are studied in detail. The drop in cell voltage occurs due to several irreversibility in the working environment. Reduction in resistance due to activation energy, mass transport and charge transport can help in increasing the performance of the Fuel cells. The performance of a fuel cell is also affected by the factors such as exchange current density, transfer coefficient. The operating parameters like pressure, temperature are varied and the performance of the PEM fuels cells is recorded.

Performance improvement of air-breathing proton exchange membrane fuel cell stacks by thermal management

Air-breathing is known as a way to reduce the weight, volume, and the cost of PEMFCs. In this study, the thermal management of the high-powered air-breathing PEMFC stacks by applying different cathode flow channel configurations is carried out to improve the stack performance. In order to verify the thermal management results, numerical simulation is also performed. The research results show that a combination of the 50% and 58.3% opening ratios in the air-breathing stack reduces the stack temperature and enhances the temperature distribution uniformity, leading to a better and more stable stack performance. In addition, it is found that the stack performance is significantly improved under the assisted-air-breathing condition. Moreover, the simulation results and the experimental data are basically consistent. It is suggested to adopt the average temperature over the cross-sectional flow region from simulation as fitting the simulation results and the measured data.

Effects of hydrogen relative humidity on the performance of an air-breathing PEM fuel cell

PurposeThe purpose of this paper is to investigate the effects of hydrogen humidity on the performance of air-breathing proton exchange membrane (PEM) fuel cells.Design/methodology/approachAn efficient mathematical model for air-breathing PEM fuel cells has been built in MATLAB. The sensitivity of the fuel cell performance to the heat transfer coefficient is investigated first. The effect of hydrogen humidity is also studied. In addition, under different hydrogen humidities, the most appropriate thickness of the gas diffusion layer (GDL) is investigated.FindingsThe heat transfer coefficient dictates the performance limiting mode of the air-breathing PEM fuel cell, the modelled air-breathing fuel cell is limited by the dry-out of the membrane at high current densities. The performance of the fuel cell is mainly influenced by the hydrogen humidity. Besides, an optimal cathode GDL and relatively thinner anode GDL are favoured to achieve a good performance of the fuel cell.Practical implicationsThe current study improves the understanding of the effect of the hydrogen humidity in air-breathing fuel cells and this new model can be used to investigate different component properties in real designs.Originality/valueThe hydrogen relative humidity and the GDL thickness can be controlled to improve the performance of air-breathing fuel cells.

Modelling of a Light-Weight, Flexible, Air-Breathing PEMFC

Flexible, light-weight and air breathing proton-exchange membrane fuel cells (F-PEMFC) are promising electricity generators for various future applications like drones and small portable devices [1, 2]. However, compared with “classic” fuel cells, such devices have worse performance in terms of power density on the basis of membrane area (W/cm²). Furthermore, reproducible fabrication is a challenge; promising prototypes were hand-fabricated using expensive equipment. For commercial success, F-PEMFCs must improve in terms of performance and manufacturability. However, this requires a good understanding of the respective device details down to the basic level. For this work, a COMSOL Multiphysics simulation of a F-PEMFC prototype [3] is built. The simulation will be fed with accurate catalytic and physical parameters and used for an interactive process of (A) describing the F-PEMFC’s operating characteristics in detail, (B) finding approaches for performance optimization and (C) comparing experimental with simulation results. Therefore, polarization curves are created, and reactant and current generation distributions are examined. Although collection of accurate catalytic and physical parameters is ongoing, preliminary results with comparable data [4] showed that it is likely that the F-PEMFC design is limited by oxygen mass transport. Consequently, we will present results of various changes in device configuration which might enhance cell performance, for example, in the cathode’s catalyst layer morphology geometry.

Critical importance of current collector property to the performance of flexible electrochemical power sources

Flexible electrochemical power sources are attracting increasing attentions for their unique advantages like flexibility, shape diversity, light weight and excellent mechanical properties. In this research, we discover that the current collector can dramatically affect the performance of flexible electrochemical power sources with large size. For flexible air-breathing proton exchange membrane fuel cell (PEMFC), the performance could have more than 8 times increase by only adjusting the directions of current collectors. The different performances of different current collection types are mainly attributed to the diverse lengths of the electron transfer pathways. In addition, the conductivity of current collector can dramatically affect the capability of flexible PEMFCs with large-size. The flexible PEMFCs with thicker carbon nanotube membrane as current collector (low electric resistance) show higher ability. A mathematic model is successfully built in this work to further understand the performance. Moreover, the model and simulation are also applicable to other flexible power sources, such as flexible Li-ion battery and supercapacitor.

Performance optimization of an air-breathing PEM fuel cell

In this study, Taguchi?s experimental design is used to determine the optimum component combination of a membrane electrode assembly and cathode current collector opening geometry to obtain maximum power density of an airbreathing polymer electrolyte membrane fuel cell at 0.5 V. An analysis of variance was conducted to figure out the optimum levels and significant differences of the effect of the combinations, followed by a performance measurement analysis. Experimental investigations of the effecting parameters enabled the determination of the optimum configuration of the MEA and cathode current collector opening geometry design parameters for maximum power density at a certain cell potential. Effective parameters which enable withdrawal of a maximum power output from an ABPEMFC at 0.5 V are, in order of effectiveness: the amount of platinum on the cathode, the thickness of the Nafion membrane, the cathode current collector opening geometry, and the amount of platinum on the anode. Optimum component combinations are: 0.45 mgPt cm?2 for the platinum loading on the cathode, Nafion 112 for membrane, a vertical cathode opening geometry and 1.78 mg cm?2 for the amount of platinum on the anode. For these component combinations, a 98.5 mW cm?2 power output was obtained from an ABPEMFC at 0.5 V cell voltage.

Robust control design for air breathing proton exchange membrane fuel cell system via variable gain second‐order sliding mode

AbstractThe nonlinear and time‐dependent characteristic and unknown modeling uncertainty of proton exchange membrane fuel cell (PEMFC) such as complex electro‐chemical, thermal, and fluid mechanic phenomena make its controller design quite challenging. In this paper, a controller based on a super twisting algorithm (STA) with variable gains is proposed to control the air breathing system of PEMFC. The strategy includes regulating the oxygen excess ratio () for preventing the stack oxygen starvation and maintaining optimum net power output in spite of external disturbances and model uncertainties. The proposed algorithm has the main advantages of the fixed gain STA, such as robustness against the disturbance and parametric uncertainties with the unknown boundary, chattering reduction, and finite time convergence. The Lyapunov analysis was proposed to assess the stability of the Variable Gain Super Twisting Algorithm (VGSTA). The results verified the effectiveness of the proposed controller with attaining robust regulation against uncertainties, disturbances, and noisy circumstance compared to fixed gain SOSM controllers.

Performance Analysis of Air Breathing Proton Exchange Membrane Fuel Cell Stack (PEMFCS) At Different Operating Condition

The answer for an emission free power source in future is in the form of fuel cells which combine hydrogen and oxygen producing electricity and a harmless by product-water. A proton exchange membrane (PEM) fuel cell is ideal for automotive applications. A single cell cannot supply the essential power for any application. Hence PEM fuel cell stacks are used. The effect of different operating parameters namely: type of convection, type of draught, hydrogen flow rate, hydrogen inlet pressure, ambient temperature and humidity, hydrogen humidity, cell orientation on the performance of air breathing PEM fuel cell stack was analyzed using a computerized fuel cell test station. Then, the fuel cell stack was subjected to different load conditions. It was found that the stack performs very poorly at full capacity (runs only for 30 min. but runs for 3 hours at 50% capacity). Hence, a detailed study was undertaken to maximize the duration of the stack’s performance at peak load.

Application of Open Pore Cellular Foam for air breathing PEM fuel cell

Open Pore Cellular Foam (OPCF) has received increased attention for use in Proton Exchange Membrane (PEM) fuel cells as a flow plate due to some advantages offered by the material, including better gas flow, lower pressure drop and low electrical resistance.In the present study, a novel design for an air-breathing PEM (ABPEM) fuel cell, which allows air convection from the surrounding atmosphere, using OPCF as a flow distributor has been developed. The developed fuel cell has been compared with one that uses a normal serpentine flow plate, demonstrating better performance.A comparative analysis of the performance of an ABPEM and pressurised air PEM (PAPEM) fuel cell is conducted and poor water management behaviour was observed for the ABPEM design.Thereafter, a PTFE coating has been applied to the OPCF with contact angle and electrochemical polarisation tests conducted to assess the capability of the coating to enhance the hydrophobicity and corrosion protection of metallic OPCF in the PEM fuel cell environment. The results showed that the ABPEM fuel cell with PTFE coated OPCF had a better performance than that with uncoated OPCF.Finally, OPCF was employed to build an ABPEM fuel cell stack where the performance, advantages and limitations of this stack are discussed in this paper.