PEMFC Performance Research Articles

Metal-organic framework-decorated PTFE reinforced membranes with immobilized caffeic acid radical scavenger towards improved performance and durability of PEMFC

During the continuous operation of fuel cell, the generated free radicals have an irreversible effect on the proton exchange membrane (PEM), and the introduction of free radical scavengers is an effective strategy for improving its durability. In this study, we proposed to prepare thin and highly durable reinforced membranes by immobilizing organic radical scavenger caffeic acid on the fibrous PTFE supporting layer decorated with amino-functionalized metal-organic framework. The electrostatic force between the amino and sulphonic acid groups can induce an orderly aggregation of hydrophilic cationic groups within the Nafion, endowing the reinforced composite PEMs with superior proton conductivity. The mechanical properties and dimensional stability of the reinforced membranes were effectively enhanced by the reinforcement of the PTFE layer decorated with the MOF network, and the hydrogen crossover was mitigated. The thickness of Nafion reinforced membranes was reduced to 25 µm with the PTFE reinforcement. After assembling in a single cell, the Nafion composite membrane (PPUC-Nafion-3) with a 3 wt% doping of caffeic acid achieved a maximum power density (PDmax) of 812.64 mW cm−2 and the open circuit voltage (OCV) decay rate of only 1.11 mV h−1 over 100 h. For comparison under the same conditions, recast Nafion possessed a much lower PDmax of only 486.30 mW cm−2 and a higher OCV decay rate of 1.91 mV h−1. This study demonstrates an effective approach to developing highly durable and thin PEMs for the realization of PEMFC with improved output performance and durability simultaneously.

Simulation of PEMFC performance

Throughout literature, there are two approaches to estimate fuel cells (FC) performance, by the evaluation of polarization curve. One includes, physical modelling of heat and mass transfer with electrochemical phenomena; the second is based on semiempirical equation used in order to analysis the effect of different physical perturbation on the polarization curve and consider FC as a black box. The aim of this study is to present a simple but enhanced and accurate expression of PEMFC output voltage. The model includes operative conditions, current density and geometric parameter of the FC.

Effect of obstacle arrangement and depth in parallel flow fields on the performance of PEMFC

Effect of obstacle arrangement and depth in parallel flow fields on the performance of PEMFC

Predicting PEMFC performance from a volumetric image of catalyst layer structure using pore network modeling

A pore-scale model of a PEMFC cathode catalyst layer was developed using the pore network approach and used to predict polarization behavior. A volumetric image of a PEMFC catalyst layer was obtained using FIB-SEM with 4 nm resolution in all 3 directions. The original image only differentiated between solid and void, so a simple but effective algorithm was developed to insert tightly packed, but non-overlapping carbon spheres into the solid phase, which were then decorated with catalyst sites. The resultant image was a 4-phase image containing void, ionomer, carbon, and catalyst, each in proportion to the known Pt loading, carbon-to-ionomer ratio, and porosity. A multiphase pore network model was extracted from this image, and multiphysics simulations were conducted to predict the polarization behavior of an operating cell. It was shown that not only can beginning of life polarization performance be predicted with minimal fitting parameters, but degraded performance 30 k cycles was also well captured with no additional fitting. This latter result was accomplished by deleting catalyst sites from the network in proportion to the experimentally observed distribution of electrochemical surface area loss, obtained from TEM image of catalyst loading. The model included partitioning of oxygen into the ionomer phase, explicitly incorporating the oxygen transport resistance which dominates cell performance at higher current density. Although Knudsen diffusion is present at the scales present (<100nm), it represented a negligible fraction of the total transport resistance, which was dominated by the low solubility and slow diffusivity in the ionomer phase. This work showed that the performance of a typical PEMFC is highly dependent on the structural details of the catalyst layer, to the extent that polarization curves can be well predicted by direct inspection of an image of the catalyst layer. This work paves the way for a deeper understanding of the structure-performance relationship in these complex materials and the search for optimized catalyst layer designs.

Challenges and optimization of PEMFC system in vehicles

Switching from fossil fuel energy to clean and renewable energy to minimize car emissions is becoming more and more vital and crucial in the current condition of severe environmental pollution and serious fossil fuel shortage. However, there are still several issues with current fuel cell systems that prevent their widespread use. Due to Proton Exchange Membrane Fuel Cells’ (PEMFCs) poor performance and the expensive operating costs of their catalysts, fuel cells are presently not widely accessible on the market. Fuel cells are seen as a potential method to reach the goal of zero emissions since they offer excellent benefits in terms of zero emissions and high efficiency. They do this by converting chemical energy into electrical energy using hydrogen. In this study, the three main parameters that affect the performance of PMFCs and the way in which the fuel cell converts chemical energy into electrical energy are investigated. Carbon corrosion damages PEMFCs performance because of high cathode potential during startup and shutdown. The breakdown of platinum particles employed as catalysts reduces the lifetime of PEMFCs and raises costs. The improvement of fuel cell systems is reviewed, along with methods for gas purification and catalysts produced from various cutting-edge materials including graphitized carbon. In order to address any potential environmental issues with fuel cells and seek to lower greenhouse gas emissions, this paper intends to explore better alternatives and give better remedies for PEMFC performance improvement and cost reduction.

CFD investigation of the effect of flow field channel design based on constriction and enlargement configurations on PEMFC performance

In this study, a three-dimensional CFD, non-isothermal model was developed to identify an optimal layout for key geometrical parameters of PEMFC flow field designs with constriction and enlargement cross-sections located at the middle of the channel. For this purpose, the effect of channel configurations with both constriction and enlargement cross-sections was explored and compared with a conventional constant channel segment, under varying hydraulic diameter and lengths. As results, the constriction configuration channel with a hydraulic diameter reduction of 50% has shown the best performance among the enlargement and straight channels for all considered lengths. The constriction configuration enhances fluid velocity, resulting in improved flow distribution and relatively increased pressure drop across the flow channels. Moreover, a better temperature distribution, higher oxygen consumption, improved membrane humidification, and water removal were observed. This leads to an increased net power output of the PEMFC. However, considering different hydraulic diameters of the constriction geometry, the best performance of the cell was achieved at a hydraulic diameter reduction of 60%, combined with a length of 4/7 of the total channel length. This optimal balance between pressure drops and reactants’ flow has enhanced the net power of the proposed geometry by 26.30 %, compared to the straight channel. The novel proposed single-channel configuration based on a simple constriction, is a low-cost design that has significantly improved cell performance compared to the straight one. Since operating conditions are crucial for cell performance, the effects of operating temperature and relative humidity were investigated, and the optimum conditions were determined.

Numerical simulation of using DBD plasma air blower for a proton exchange membrane fuel cell

In this study, a novel air blower by applying the DBD plasma actuator for a PEM fuel cell is proposed for reducing power consumption and air flow saving. For this purpose, the DBD plasma actuators are installed on the bottom surface of the cathode channel of a PEMFC. The impact of the application of DBD plasma and the number of DBDs on the air mass flow rate and performance of PEMFC were numerically investigated. Results show that in comparison to the conventional air blower model, using the DBD plasma air blower at the cathode channel of a PEMFC results in a reduction of velocity magnitude and uniform velocity distribution of airflow within the cathode channel. Also, results indicate that the DBD plasma air blower model with less air flow consumption provides almost the same current density and performance as the conventional model. Results illustrate that the DBD plasma air blower with 3 DBDs can be a suitable candidate to obtain the best design for the DBD plasma air blower. The robust advantages of using the DBD plasma air blower become more underscored when the findings present the 90.31% reduction in the average power consumption.

Modeling and Simulation of a High Temperature Proton Exchange Membrane Fuel Cell

High temperature (HT) (around 120-200°C) PEM FCs are predicted to be the next generation of PEMFCs particularly for hydrogen-powered automobiles and combined heat and power (CHP) systems because the water management can be simplified at such temperatures as only a single phase of water vapor needs to be considered. Additionally, the cooling system can be streamlined due to an increase in temperature gradient between the coolant and the FC stack. This will also allow easy recovery of waste heat that can be used as a practical heat source. Furthermore, the CO tolerance improves dramatically at high temperatures thereby allowing HT PEMFCs to utilize reformed and impure hydrogen.A single phase three-dimensional, steady-state, isothermal model for a single 5 HT PEM fuel cell with serpentine flow channels is implemented in COMSOL to investigate the effect of various operating conditions like temperature, back pressure and cathode flow rate and design parameters like catalyst layer loading, cathode GDL porosity, and flow field channels including parallel and interdigitated channels. Different performance indicators in terms of polarization curve, loss mechanisms, oxygen molar concentration, and anode and cathode pressure are represented for a complete overall analysis. In fact, the breakdown of different overpotential loss mechanism for HT PEMFC presented here is unique that not only quantifies these losses but also provides an accurate comparison with corresponding low temperature counterpart. The result from the computational model follows the experimental result very closely, thus, validating our model. The simulations stipulates that the performance of a HT PEMFC improves with increasing temperature, back pressure, and air flow rate. Increasing catalyst layer loading improves the performance up to a point after which it starts to drop at low voltages because of hindered gas diffusion. Similarly, a comparative study among different flow field channel is also presented indicating improved performance when going from parallel to interdigitated and serpentine channels. Furthermore, this study provides guidelines to optimize HT PEMFC performance through comprehensive parametric study.

Design of a New Single-Cell Flow Field Based on the Multi-Physical Coupling Simulation for PEMFC Durability

The fuel cell with a ten-channel serpentine flow field has a low operating pressure drop, which is conducive to extended test operations and stable use. According to numerical results of the ten-channel serpentine flow field fuel cell, the multi-channel flow field usually has poor mass transmission under the ribs, and the lower pressure drop is not favorable for drainage from the outlet. In this paper, an optimized flow field is developed to address these two disadvantages of the ten-channel fuel cell. As per numerical simulation, the optimized flow field improves the gas distribution in the reaction area, increases the gas flow between the adjacent ribs, improves the performance of PEMFC, and enhances the drainage effect. The optimized flow field can enhance water pipe performance, increase fuel cell durability, and decelerate aging rates. According to further experimental tests, the performance of the optimized flow field fuel cell was better than that of the ten-channel serpentine flow field at high current density, and the reflux design requires sufficient gas flow to ensure the full play of the superior performance.

Effect of Baffle Pattern Applied to Cathode Parallel Channel on PEMFC Performance

Effect of Baffle Pattern Applied to Cathode Parallel Channel on PEMFC Performance

Optimization of Cooling Channel Structure of Bipolar Plate for Proton Exchange Membrane Fuel Cells Based on CFD Analysis

The working temperature affects the performance of PEMFC, so a reasonable and efficient cooling channel is necessary to control the working temperature in an efficient area. In this study, the channel structure of the bipolar plate for PEMFC is analyzed using the FLUENT simulation calculation method. The influence of cell size and cooling water flow direction on cell temperature distribution is analyzed, including an examination of the channel ridge width, depth, and aspect ratio of the bipolar plate. After comparing and analyzing three ridge width sizes (0.5 mm, 1.5 mm and 2 mm) in the paper, it was found that a ridge width of 2 mm had the best heat transfer performance. And it was found that a groove depth of 0.5 mm had the best heat transfer performance when comparing three groove depth dimensions (0.5 mm, 1 mm and 1.5 mm). The aspect ratio size parameters had almost no effect on the maximum and average temperatures of the electric stacks, while the relative flow direction of cooling water had a great influence on the temperature distribution of the bipolar plate.

Two-stage confinement derived small-sized highly ordered L10-PtCoZn for effective oxygen reduction catalysis in PEM fuel cells

Intermetallic ordered PtCo is effective for high oxygen reduction reaction (ORR) activity and stability. However, preparing small-sized, highly ordered PtM alloys is still challenging. Herein, we report a controlled two-stage confinement strategy, in which highly ordered PtCoZn/NC nanoparticles of 5.3 nm size were prepared in a scalable process. The contradiction between the high ordering degree with the small particle size as well as the atomic migration with the space confinement was well resolved. An outstanding PEMFC performance was achieved for L10-PtCoZn/NC with a high mass activity (MA) of 1.21 A/mgPt at 0.9 ViR-free, 80.1 % MA retention after 30 k cycles in H2-O2 operation, and a high mass-specific power density of 8.24 W mg-1Pt in H2-Air operation with a slight loss of cell voltage@0.8 A cm−2 of 28 mV after 30 k cycles. The high performance can be ascribed to the high Pt area exposure, the enhanced Pt-Co coupling, and the prevented agglomeration in the mesoporous carbon wall. Overall, this strategy may contribute to the commercialization of fuel cells.

Innovative Approaches to Enhance the Performance and Durability of Proton Exchange Membrane Fuel Cells

PEMFCs, or proton exchange membrane fuel cells, have enormous potential for clean energy and environmentally friendly transportation. PEMFCs’ cost, performance, and durability, however, continue to be major obstacles to their mainstream deployment. This study examines recent developments in PEMFC technology with an emphasis on novel oxygen reduction reaction catalysts, creative flow field designs, methods for reducing degradation processes, and system-level optimization and integration. The results show that innovative studies in these fields have significantly increased the performance and longevity of PEMFCs while lowering expenses. For PEMFC technology to evolve further, be successfully implemented in a variety of applications, and contribute to a more sustainable future, more research and development must be put forward.

Investigation on the effect of transverse distribution obstacles on PEMFC performance

Investigation on the effect of transverse distribution obstacles on PEMFC performance

A System-Level Modeling of PEMFC Considering Degradation Aspect towards a Diagnosis Process

This paper proposes a modular modeling towards a health system integration of fuel cells by considering not only the dynamics of the gases but also fault models that affect the PEMFC performances. The main goal is to simulate the faulty state in order to overcome data scarcity, since running a fuel cell to generate a database under faulty conditions is a costly process in time and resources. The degradation processes detailed in this paper allow to introduce a classification of faults that can occur, giving a better understanding of the performance losses necessary to simulate them. The faults that are detailed and modeled are the flooding, drying and aging processes. This modeling is based on a system approach, so it runs faster than real-time degradation tests, allowing the training and validation of online supervisors, such as the energy management strategy (EMS) method or diagnosis. The faults are reproduced according to the study requirements to be a very effective support tool to help design engineers to include faulty conditions in early design stages toward a diagnosis process and health-conscious energy management strategies.

Numerical Simulation of a Novel Flow Channel with Aligned Concave-Convex Cavities to Enhance the Performance of PEMFC

The bipolar plates are important components of fuel cells and its characteristics and cross-section shape have a significant influence on the performance of PEMFCs. A new-type flow channel with aligned fan-shape concave-convex cavities is presented. A 3D, single-phase model for PEMFC with the new-type flow channel is developed. The polarization curve, current density distribution as well as the oxygen concentration distribution of straight channel and the new-type flow channel are compared through CFD simulation. The performance of PEMFC with the new-type flow channel has been more improved than that with straight flow channels. The simulation results also show that the new-type flow channel with aligned fan-shaped concave-convex cavities improves the current density and the net power is increased by 2.6%. Moreover, the proposed novel flow channel is also very simple and inexpensive for manufacturing.

The Effect of Flow Field Design Parameters on the Performance of PEMFC: A Review

Proton exchange membrane fuel cell is essentially utilized to generate energy with zero emission. There are many drawbacks in PEMFC, such as the mal-distribution of reactants, water management between the catalyst layer and the GDL, and the mass transport issue of reactants. Flow field design parameters can overcome these problems to improve cell performance. Where the flow field is an essential element of the fuel cell, and it is designed to provide the required amount of both hydrogen and oxygen with the lowest possible pressure drop on the anode and cathode sides, respectively. In this paper, the cell performance with different flow field design parameters, such as conventional flow field configuration, nature-inspired flow field configuration, and geometric parameters, as well as their modifications, is reviewed in detail. It has been demonstrated through the current review paper that the flow field design parameters can significantly affect the overall behavior of PEMFC, and each design parameter has advantages and disadvantages that make the flow fields suitable for specific applications.

Reactive Transport Processes in Proton Exchange Membrane Fuel Cells

Proton exchange membrane fuel cells are devices that directly convert chemical energy to electricity. A hydrogen oxidation reaction takes place on the anode side, generating protons and electrons. In the cathode, oxygen reduction reaction involving oxygen, proton and electron occurs, producing water and heat. The water content in PEMFCs should be maintained at a reasonable amount to avoid water flooding or membrane dehydration. The thermal management and water management of PEMFCs are important for an efficient and stable operation of PEMFCs. Inside the multiscale spaces of PEMFCs, multiphase flow with a phase change, heat and mass transfer, proton and electron conduction, and electrochemical reaction simultaneously take place, which play important roles in the performance, lifetime and cost of PEMFCs. These processes should be well understood for better designing PEMFCs and improving the thermal management and water management.

Numerical Simulation of the Effect of Heat Conductivity on Proton Exchange Membrane Fuel Cell Performance in Different Axis Directions

In this paper, the effect of changes in the thermal conductivity of porous electrodes in three coordinate directions on the capability of proton exchange membrane fuel cells is investigated on the basis of current density versus voltammetry curves, and the temperature distribution and water-carrying capacity distribution of the membrane. The results show that when the cell discharge voltage of the PEMFC is 0.3 V, the thermal conductivity in the Z-direction of the porous electrode has a greater effect on the performance of the PEMFC than in the other directions, with the thermal conductivity in the X- and Y-directions of the porous electrode having less than a 5% effect on the performance of the PEMFC, which can therefore be neglected. When the thermal conductivity of the porous electrode in the Z-direction of the PEMFC is 500 W/(m·K) and 1000 W/(m·K), the performance of the PEMFC is improved by 5.78% and 5.87%, respectively, and when the thermal conductivity of the porous electrode in the X-direction of the PEMFC is 500 W/(m·K) and 1000 W/(m·K), the performance of the PEMFC is improved by 2.09% and 2.89%, and the PEMFC performance is improved by 1.51% and 2.00% when the Y-direction thermal conductivity of the porous electrode of the PEMFC is 500 W/(m·K) and 1000 W/(m·K), respectively. The improvement in performance decreases with increasing thermal conductivity, because the thickness of the porous electrode is too thin. Since the side of the model is set to adiabatic heat exchange conditions, while the top and bottom surfaces are set to natural convection heat exchange conditions, the Z-direction thermal conductivity of the porous electrode plays the most important role in the temperature distribution of the PEMFC. The Z-direction thermal conductivity of the porous electrode causes the temperature distribution of the PEMFC assembly to be more uniform, and the Z-direction thermal conductivity of the porous electrode also causes the area of the high-water-content region on the proton exchange membrane to significantly increase.

Multi-objective optimization of PEMFC performance based on grey correlation analysis and response surface method

This paper aims to combine grey correlation analysis and response surface method to propose a fast and effective performance optimization method for PEMFC. First, based on orthogonal test data, grey correlation analysis method is used to select four variables that have significant influence on PEMFC’s comprehensive performance from eight common parameters. Secondly, based on grey correlation analysis, the multi-objective optimization problem is transformed into a single objective optimization problem about correlation degree, and applying the response surface method to build the key parameters and the correlation between the second order prediction model. Therefore, the current density, system efficiency and oxygen distribution uniformity on cathode catalyst layer of PEMFC were optimized as a whole. Finally, the optimal parameter combination was obtained by optimizing the prediction model. The simulation results show that the optimized operating conditions are significantly improved in the three performance indexes compared with the basic model, which confirms the feasibility of this method in solving the multi-objective optimization problem, and can provide some reference for the optimal design of hydrogen fuel cells.