Performance Of Polymer Electrolyte Membrane Research Articles

Pore-scale parametric sensitivity analysis of liquid water transport in the gas diffusion layer of polymer electrolyte membrane fuel cell

Water management in the gas diffusion layer (GDL) is crucial for improving the performance of polymer electrolyte membrane fuel cells (PEMFCs). In this study, a modified stochastic method that fully took into account the fiber deflection and layered structure in the thickness direction was proposed to reconstruct the realistic porous structures of three-dimensional (3D) GDL. The liquid water transport within the GDL was then numerically studied using the 3D Lattice Boltzmann method (LBM). Subsequently, the contributions of different parameters (porosity, fiber diameter, thickness, wettability, and pressure difference) to the transport process of liquid water were elucidated by implementing a multi-parametric sensitivity analysis (MPSA). The numerical results indicate that the liquid water penetration process can be divided into initial injection, selective percolation, and diffusion stages. With the decreases in porosity or increase in contact angle, the flow is inclined to transform from gentle flow to accumulation and secondary breakthrough owing to the increased percolation resistance. Further accumulation of the liquid within GDL can be identified when the evolution time progresses from the breakthrough point to the creep point. Moreover, for GDL, the degree of influence of the structural parameters on the breakthrough velocity is ranked in the order of GDL porosity, fiber diameter, GDL thickness, pressure difference, and GDL wettability. The total liquid saturation is dominated by GDL wettability and is insensitive to GDL porosity and fiber diameter owing to the conflict between the percolation resistance of the pores and the percolation time within GDL. The current work consolidates the understanding of the influencing mechanisms of different structural parameters on liquid water transport characteristics, contributing to the optimal design of the gas diffusion layer.

Quantifying key parameters to provide better understating of microstructural changes in polymer electrolyte membrane fuel cells during degradation: A startup/shutdown case study

Despite the great progress that has been made in improving the performance of polymer electrolyte membrane fuel cells (PEMFCs), they still suffer from the degradation of catalyst components. Multiple startup/shutdowns (SUSDs) of a fuel cell electric vehicle (FCEV) is one of the situations in which the catalyst and its support degradation can cause PEMFC failure. Hence, in this study, comprehensive quantification of key microstructural parameters was implemented to correlate the microstructural changes with performance data of SUSD samples. Pt loss from the cathode and particle size distribution, as well as cathode porosity and thickness changes, were quantified and discussed with respect to the electrochemical performance. The reported values indicated severe carbon corrosion and Pt degradation during an unprotected SUSD operation at 35 °C. Moreover, the elevation of the operating temperature to 70 °C exacerbated the degradation to the point that the cathode catalyst layer collapsed after a low number of cycles. After a protective protocol was implemented, microstructural and electrochemical characterization showed a significant decrease in carbon corrosion and Pt degradation. The structure-property-performance relationship confirmed and quantified the effects of unprotected SUSD operation, but also showed how the protective protocol will preserve the microstructure of the PEMFC and hence improve its lifetime.

A study of the influence of current ramp rate on the performance of polymer electrolyte membrane fuel cell

Durability and reliability are the key factors that prevent fuel cells from successful implementation in automotive sector. Dynamic load change is a common and frequent condition that the fuel cell has to undergo in automotive applications. Fuel cells are more sensitive to changes in load conditions and degrade based on load variation representing idling, rated power, and high power operating conditions. To examine the influence of dynamic load step on the fuel cell performance, two similar cells of active 25 cm2 was tested under two different load step for the same dynamic load cycle. The main difference in dynamic load cycle 2 was the ramp rate which was fixed as 0.1, 0.3, and 0.25 A/cm2/s for 0.2, 0.6, and 1.0 A/cm2 respectively. To investigate the degradative effects, polarization curves, electrochemical impedance spectroscopy, and field emission scanning electron microscopy were used. The results indicated that the degradation rate increased in both dynamic load cycles but however the impact of load change was comparatively minimal in dynamic load cycle 2. The total degradation in performance was 20.67% and 10.72% in dynamic load cycles 1 and 2 respectively. Fuel cell performance degraded in a manner that was consistent with the electrochemical impedance spectroscopy and cross-sectional analysis of field emission scanning electron microscopy. The results prove that the degradation rate is dependent on the load step and the number of load cycles. Severe catalyst degradation and delamination were observed in fuel cells operated under dynamic load cycle 1.

Comparison of PEMFC performance with parallel serpentine and parallel serpentine-baffled flow fields under various operating and geometrical conditions; a parametric study

Optimal flow channel design of a fuel cell is crucial to further improve the performance of polymer electrolyte membrane fuel cell (PEMFC). In this work, a comprehensive parametric study was conducted to analyze the performance of a PEMFC with conventional parallel serpentine flow fields (PSFF) and parallel serpentine-baffled flow fields (PSBFF). A three-dimensional two-phase computational fluid dynamics model was used to numerically simulate the fuel cell performance. The effects of operating parameters such as pressure, temperature, and stoichiometric ratio, as well as the geometric parameters of channel height to channel width ratio and rib width to channel width ratio for both flow fields on fuel cell performance were investigated. The results show that as pressure, temperature, and stoichiometric ratio increase, cell performance increases for both flow fields, with a more substantial rate of improvement for the PSBFF design. A 16.1% improvement in cell performance at an operating pressure of 1 atm, a 19.9% improvement at a cell temperature of 70 °C, and a 16.1% improvement at a stoichiometric ratio of 2 were obtained when PSBFF was used instead of PSFF. By increasing the channel height and rib width, the cell performance for PSBFF remains almost constant due to the improved forced convection of the gas mixture and the reduction in concentration loss, while the cell performance for PSFF decreases significantly. At the largest channel height to channel width ratio of 1.5 and rib width to channel width ratio of 1.315 studied in this work, an improvement in cell performance of 53.3% and 58.5%, respectively, was achieved when PSBFF was used instead of PSFF. In addition, PSBFF was more effective in removing water from the porous zones than PSFF under all conditions.

Polymer electrolyte membrane modification in direct ethanol fuel cells: An update

AbstractDirect ethanol fuel cells (DEFCs) offer a high degree of design flexibility, ranging from a single cell to a massive multi‐cell that can be used in various applications, including portable devices, transportation, and stationary applications. Unfortunately, the most significant barrier to the commercialization of DEFCs is getting low‐cost and ethanol permeability, high conductivity performance, and extended durability of polymer electrolyte membranes, as key components that highly influence the overall performance. In this paper, the recent progress in developing the polymer electrolyte membrane for the application of DEFCs has been comprehensively reviewed. Focusing on an updated modification of polymeric materials in the last 5 years, including Nafion‐based membrane, polyvinyl alcohol‐based membrane, polybenzimidazoles‐based membrane, chitosan‐based membrane, and sodium alginate‐based membrane, as well as factors and challenges that affected the performance of polymer electrolyte membranes have been discussed, including the main characterization, catalyst selection, cell design, and work in membrane and cell performance of DEFCs. All discussion addresses the strategy to improve the performance of polymer electrolyte membranes in DEFCs in order to penetrate the commercialization stages.

Controlling the microphase morphology and performance of cross-linked highly sulfonated polyimide membranes by varying the molecular structure and volume of the hydrophobic cross-linkable diamine monomers

Morphological control is essential for tuning the performance of polymer electrolyte membranes (PEMs). Block copolymerization is an effective but complicated way to control the morphology of PEMs. It is urgent to explore a simple alternative method to achieve this target. Herein, the molecular engineering strategy that changes the molecular structure and volume of hydrophobic cross-linkable diamine and introduces a hydrophobic network structure was used to optimize the microphase morphology of sulfonated polyimides (SPIs). Three diamine monomers containing tetrafluorostyrol pendant groups have been synthesized (4-(2,3,5,6-tetrafluoro-4-vinylphenoxy)benzene-1,3-diamine (TFVPDM), 1,3-bis(2-trifluoromethyl-4-amino-phenoxy)-5-(2,3,5,6-tetrafluoro-4-vinylphenoxy)benzene (6FTFPB), 2,2-bis(3-amino-4-(2,3,5,6-tetrafluoro-4-vinylphenoxy)phenyl)hexafluoropropane (6FATFVP)). Based on these monomers, 4,4′-diaminostilbene-2,2′-disulfonic acid (DASDSA) and 1,4,5,8-naphthalenetetracarboxylicdianhydride (NTDA), three cross-linked SPIs (CSPIs: CSPI-T-10, CSPI-TP-10, CSPI-AP-10) with similar ion-exchange capacity (IEC) value of 2.29–2.46 meq. g−1 but different main-chain structures were prepared through polycondensation and thermal cross-linking process. The introduced hydrophobic cross-linked structure improves the oxidative stability and methanol resistance of CSPI membranes. The CSPI membranes prepared from cross-linkable hydrophobic diamine with larger molecular volume and containing hydrophobic structural units in the main chain exhibit more pronounced phase separation morphology and higher proton conductivity. Moreover, the methanol resistance of CSPI membranes is dependent on the combined effect of IEC, degree of crosslinking (DC), and main-chain structure. The higher DC and main-chain containing hydrophobic structure are beneficial for enhancing the methanol resistance. The CSPI-AP-10, which was prepared from the 6FATFVP with the largest molecular volume, more hydrophobic cross-linkable pendant groups and hydrophobic linkages, exhibits the best performance. The CSPI-AP-10 membranes showed high proton conductivity and excellent methanol resistance. The direct methanol fuel cells (DMFCs) assembled from CSPI-AP-10 have a high max power density (PDmax) of 106.2 mW cm−2 in 2 M methanol and 75.1 mW cm−2 in 10 M methanol. The results indicated that the CSPI-AP-10 was a promising candidate as a PEM in DMFC application.

Visualizing 4D Pore-Scale Gas Transport in Operating PEM Electrolyzers Using X-Ray Computed Tomography

Mass transport losses in polymer electrolyte membrane (PEM) electrolyzers are predominantly caused by the accumulation of oxygen gas within the pores of the porous transport layer (PTL), hindering reactant water delivery to reaction sites (1). To enhance mass transport and optimize electrolyzer performance, a comprehensive understanding of the mechanisms driving oxygen gas transport in the PTL is required. Numerous studies have utilized various imaging techniques - including optical, neutron, and X-ray radiography to elucidate the evolution and transport of oxygen gas in the multiphase flow regime during PEM electrolyzer operation (2). However, these techniques only capture two-dimensional (2D) images, resolving average gas distributions rather than a holistic pore-scale quantification. Few studies have used three-dimensional (3D) imaging to resolve the dynamic microscale distributions of oxygen gas in the PTL. Understanding the impact of key parameters affecting 3D oxygen gas transport, such as PTL morphology, will allow for tailored pore-scale material optimization for enhanced gas transport and improved performance of PEM electrolyzers.This study presents a non-destructive operando imaging approach using X-ray computed tomography (CT), enabling the visualization of transient 3D oxygen gas evolution and transport in the PTL of a PEM electrolyzer. Using state-of-the-art synchrotron X-rays, high temporal and spatial resolutions were achieved to capture the pore-scale formation and growth of oxygen gas pathways within the PTL at various operating conditions. Electrochemical performance of an in-house designed electrolyzer cell was also characterized while acquiring tomographic images to investigate the impact of observed transport mechanisms on performance. The methodology presented in this work showcases the capability of using X-ray CT to visualize the complex interfacial multiphase flow in PTLs. Findings from this study will provide valuable insight towards pore-scale material optimization of clean energy porous materials aimed at curtailing the costs of green hydrogen production.

Numerical Investigation of Compressive Stress and Wettability Effects on Fluid Transport in Polymer Electrolyte Membrane Fuel Cell Porous Layers

The performance of polymer electrolyte membrane fuel cells (PEMFCs) is greatly influenced by the residual water content generated during the cell operation. A comprehensive understanding of water management at the interfacial regions of PEMFC components is critical for elevating the efficiency of PEMFCs. Herein, the liquid transport and accumulation at the interfacial region of 2D microporous layer (MPL) and catalyst layer (CL) are investigated numerically, considering the effects of compression stress, porosity, and wettability. The numerical scheme is assembled by finite element method (for interfacial contact mechanics) and lattice Boltzmann method (for multiphase flow and permeability calculation). Different levels of compression stress derived from fuel cell assembly pressure are applied on the MPL/CL components, which consequently lead to variations in the pore size distribution and porosity change of the MPL/CL. The results highlight the importance of considering porosity change in the compression process, where increasing compression stress significantly decreases the liquid saturation in the MPL and interfacial gap region. Additionally, strong hydrophobicity can alleviate the heterogeneity of liquid accumulation at the MPL/CL interfacial region. The liquid and gas relative permeability are also investigated to assess the liquid drainage and fuel supply efficiency with different compression stress.

Optimal design of cathode gas diffusion layer with arrayed grooves for performance enhancement of a PEM fuel cell

A novel cathode gas diffusion layer (GDL) with arrayed grooves is proposed to enhance the performance of polymer electrolyte membrane (PEM) fuel cells. The influence of various geometric parameters regarding the novel GDL on internal physical quantities transport and cell performance is examined by a 3D multiphase fuel cell model. Results found that oxygen diffusion and water drainage are remarkably enhanced for the novel GDL, thereby leading to an augmented fuel cell performance. A reasonable design of structure parameters, such as the groove size and interval, the length of the GDL with arrayed grooves, and the nonuniform arrayed grooves, could further benefit current density homogeneity and performance for fuel cells. The results reveal that the novel GDL with a groove width, length and interval of 0.1 mm, 0.3 mm and 1.0 mm, respectively, a total arrayed groove length of 15 mm, and a nonuniform arrayed grooves exhibits a better cell performance than all the other designed GDLs and the traditional GDL tested in this simulation. The optimally designed GDL with arrayed grooves improves the maximum power density by approximately 5.6%, enhancing the current density within the regions of CCL near the outlet, thereby favoring the operational stability of fuel cells.

Carbon Shell‐Encapsulated Metal Alloy Catalysts with Pt‐Rich Surfaces for Selective Hydrogen Oxidation Reaction

AbstractThe performance of polymer electrolyte membrane fuel cells (PEMFCs) is deteriorated by the occurrence of reverse current flow. To suppress the reverse current flow, a hydrogen oxidation reaction (HOR)‐selective catalyst based on the molecular sieve effect should be developed. Here, considering the carbon solubility in transition metals, carbon shell‐encapsulated metal alloy nanoparticles with superior HOR selectivity were fabricated using carbon source in metal precursors. In particular, we introduced carbon solubility as the important parameter that should be considered in the catalyst design. Using Pt and Co with different carbon solubility, as a model catalyst, the effect of the metal composition of the core material on the carbon shell structure was discussed in detail. Due to the formation of high‐density carbon shell and Pt‐rich surface on the alloy nanoparticle, the HOR selectivity was remarkably enhanced. Therefore, this study provides insights into the development of carbon shell‐encapsulated nanoparticles for reaction‐selective catalysis.

Influence of Three-Dimensional Flow Field Structures Consisting of Expanded Metal Meshes on the Physicochemical Loss Processes in Pemfcs

To further increase the performance of polymer electrolyte membrane fuel cells (PEMFCs) at high current densities, a reduction of mass transport losses by an enhanced evacuation of water from the cell and an improved supply of gases to the reactive sites are necessary.The application of three-dimensional flow field structures in PEMFCs is a promising measure to promote the evacuation of excess liquid water from the cell while boosting the transport of reactants from the gas channel in the direction of the cell. Expanded metal meshes offer a three-dimensional geometry, which predestines them to be used as flow field structures in PEMFCs. In the past, their application as flow fields has primarily been investigated for direct methanol fuel cells (DMFCs) [1, 2, 3] and electrolyzers [4, 5]. To gain a profound understanding of the impact of such three-dimensional flow field structures on the electrochemical properties of PEMFCs, the physicochemical loss processes of the cell have to be analyzed in detail.In this contribution, the results of an in-depth analysis of the influence of three-dimensional flow field structures consisting of expanded metal meshes on the physicochemical loss processes in PEMFCs and their effect on the cell performance is presented. To assess the impact of expanded metal meshes in comparison to a conventional channel rib flow field design, the physicochemical loss processes were examined for both flow field designs. The operating conditions (j, RH, T, pO2) of the incremental PEM fuel cells (1 cm2 active cell area) [6] were varied systematically and the cells were analyzed by means of polarization curves and electrochemical impedance spectroscopy (EIS). The physicochemical loss processes of the cells were identified by a subsequent impedance data analysis by the distribution of relaxation times (DRT) [7, 8].This investigation aims to determine the physicochemical loss process in PEMFCs with expanded metal meshes as flow field structures and compare them to the results of a conventional flow field design. Based on the physical interpretation of the results, consequences and conclusions for the further development of the expanded metal flow field geometries are discussed.

Molecular dynamics study on the impacts of cations in sea salt aerosol on transport performance of Nafion Membranes for PEMFCs in marine application

The application of polymer electrolyte membrane fuel cells (PEMFCs) in marine industry receives a widespread attention, due to the severe emission regulations. However, cationic contaminants in sea salt aerosol have detrimental effects on the transport performance of polymer electrolyte membranes, which are the core components of PEMFCs. In this study, the effects of K+ and Mg2+ in marine atmosphere on the transport performance of Nafion 117 membranes were evaluated by molecular dynamics simulations. Moreover, the influence of temperature is considered for the first time. The mean square displacements are used to evaluate the diffusion coefficients of water molecules (H2O) and hydronium ions (H3O+). In addition, the effect mechanisms are analyzed using radial distribution functions, water clusters distribution and relative concentration distribution. Results show that the diffusion of H3O+ and H2O is significantly weakened by K+ and Mg2+. Moreover, the impact of Mg2+ is more serious. The difference in the influence of these two kinds of cations on the transport performance of Nafion membranes is discussed by hydrated radius, hydration degree of cations, and the interaction between cations and sulfonic groups. The diffusion coefficients increase significantly with the increase of temperature. The increase of the temperature can also increase the interaction between the cations and the sulfonic groups. In contrast, the interaction between the sulfonic groups and water molecules is decreased.

Study on the transport performance degradation of Nafion membrane due to the presence of Na+ and Ca2+ using molecular dynamics simulations

Foreign cations have detrimental effects on the transport performance of polymer electrolyte membranes. In this study, the effects of two typical kinds of cations (Na+ and Ca2+) on the diffusion of hydronium ions (H3O+) and water molecules (H2O) in Nafion 117 membranes are investigated using molecular dynamics simulations, at the same time the effects of temperature are considered. The mechanisms of effects are analyzed using radial distribution functions, water clusters distribution and relative concentration distribution. Results show that the diffusion coefficients of H3O+ and H2O are significantly reduced by the presence of Na+ and Ca2+. Moreover, the impact of Ca2+ is more serious. Further investigations show that cations affect intramembrane transport properties by occupying sulfonic groups and disrupting the connectivity of water clusters. The difference in the effects of these two kinds of cations is discussed by hydrated radius, hydration degree of cations, and the interaction between cations and sulfonic groups. Increasing temperature can increase not only the diffusion coefficients, but also interaction between the cations and the sulfonic groups. However, the interaction between the sulfonic groups and H2O is decreased by the increasing temperature.

Electrochemical performance and water management investigation of polymer electrolyte membrane fuel cell (PEMFC) using gas diffusion layer with polytetrafluoroethylene (PTFE) content gradients in through-plane direction

The water management capability and electrochemical performance of polymer electrolyte membrane fuel cell (PEMFC) using gas diffusion layers (GDLs) with polytetrafluoroethylene (PTFE) content variation in through-plane direction are investigated. Four PTFE content variation cases are considered by stacking GDLs with different amounts of PTFE content. Polarization curves and electrochemical impedance spectroscopy are experimentally obtained. The liquid water saturation and effective diffusion factor are numerically studied. In high humidity condition, a PEMFC containing a GDL without PTFE content variation and without PTFE treatment shows the best performance due to the highest effective diffusion factor and the lowest mass transport resistance. Despite the lowest liquid water saturation in a GDL with decreasing PTFE content toward channel, the effective diffusion factor of the GDL is not the highest because of the decreased porosity by PTFE treatment. In low humidity condition, a PEMFC containing a GDL with increasing PTFE content toward channel has the best performance because of the lowest ohmic resistance. The GDL has the largest liquid water saturation and the lowest effective diffusion factor, resulting in the better membrane hydration. In high current density, however, the performance of the PEMFC containing the GDL with increasing PTFE content toward channel drastically decreases due to large mass transport resistance.

High Performance and Self-Humidifying of Novel Cross-Linked and Nanocomposite Proton Exchange Membranes Based on Sulfonated Polysulfone.

The introduction of inorganic additive or nanoparticles into fluorine-free proton exchange membranes (PEMs) can improve proton conductivity and have considerable effects on the performance of polymer electrolyte membrane fuel cells. Based on the sol–gel method and in situ polycondensation, novel cross-linked PEM and nanocomposite PEMs based on a sulfonated polysulfone (SPSU) matrix were prepared by introducing graphene oxide (GO) polymeric brushes and incorporating Pt-TiO2 nanoparticles into an SPSU matrix, respectively. The results showed that the incorporation of Pt-TiO2 nanoparticles could obviously enhance self-humidifying and thermal stability. In addition, GO polymer brushes fixed on polymeric PEM by forming a cross-linked network structure could not only solve the leakage of inorganic additives during use and compatibility problem with organic polymers, but also significantly improve proton conductivity and reduce methanol permeability of the nanocomposite PEM. Proton conductivity, water uptake and methanol permeability of the nanocomposite PEM can be up to 6.93 mS cm−1, 46.58% and be as low as 1.4157 × 10−6 cm2 s−1, respectively, which represent increases of about 70%, about 22% and a decrease of about 40%, respectively, compared with that of primary SPSU. Therefore, the synergic action of the covalent cross-linking, GO polymer brush and nanoparticles can significantly and simultaneously improve the overall performance of the composite PEM.

Improved performance of polymer electrolyte membrane fuel cell using leaf-baffle flow field design

The hydrogen fuel cell is an environmentally friendly alternative energy converter. Its performance is quite influenced by the geometry of the flow field. This study proposes a leaf-baffle flow field design with experimental testing compared to conventional models. Experiments were carried out on a single cell Polymer Electrolyte Membrane Fuel Cell with an active area of 25 cm2, with flow field design variations of parallel, leaf, and leaf-baffle on the cathode. The performance of each design is compared with the polarisation and power density graphs, the pressure drop due to energy loss is also compared. The results showed that the leaf-baffle design produces the best performance, increased by 37.14% compared to parallels. Furthermore, to obtain better performance, the ratio of the reactants velocity to the branch length needs to be considered for designing the flow field.

Impact of catalyst support morphology on 3D electrode structure and polymer electrolyte membrane fuel cell performance

AbstractPorous carbon‐based electrodes are frequently applied in electrochemical energy technologies, for instance in fuel cells and redox flow batteries. In previous work, we observed that the final structure of a fuel cell electrode is dominated by both the morphology of the support material and its processing into a 3D porous structure. Herein, the impact of catalyst support morphology on the performance of polymer electrolyte membrane fuel cells was studied comparing carbon‐supported platinum catalysts only differing in the shape of the carbon support material with otherwise similar features. Carbon‐supported Pt catalysts were obtained by carbonization of polyaniline (PANI) in long fibrous, short fibrous, and granular shape. The chemical identity of the PANI precursors was demonstrated by FTIR spectroscopy and elemental analysis (EA). The final carbon‐supported platinum catalysts were characterized by EA, Raman spectroscopy, XRD, and TEM exhibiting similar degree of carbonization, nanoparticle size, and nanoparticle dispersion. The effect of support morphology and the resulting differences in the 3D structure of the porous electrode were investigated by focused ion beam‐scanning electron microscopy slice and view technique and correlated to their fuel cell performance.

Performance of fuel cells using biogas and its sensitivity analysis

The use of renewable fuels has been currently increased since the non-renewable sources of energy are depleting. H₂ is one of the main energy carriers which can be derived from various renewable and non-renewable fuels. Biogas has high methane content and that can be converted to H₂ using reforming reaction followed by water–gas shift reaction. The main objective of this study is to optimize H₂ yield by using autothermal reforming followed by the water–gas shift reaction and preferential oxidation and to analyze the performance of polymer electrolyte membrane fuel cell under different operating parameters. Sensitivity analysis using methane, steam and air flowrate, conversion of methane and oxygen, reactor temperature and pressure on the yield of H₂ and carbon-monoxide yield has been performed. The H₂ yield obtained from Autothermal reactor is 64.73 % which is increased to the value of 75.21 % after the preferential oxidation reactor. The H₂ yield achieved after the optimization is 68.64 % from the Autothermal reactor. The Optimum Air/Steam/Feed ratio obtained is 1:2.23:4.60. H₂ is produced at the rate of 330 kg/hr. Results showed that Polymer Electrolyte Membrane fuel cell efficiency and stack consumption is decreased with the increase in fuel flowrate. There is slight variation in polymer electrolyte membrane fuel cell efficiency and stack consumption with the increase in fuel and air supply pressure. Stack efficiency remained constant with increasing fuel and oxidant composition. Polymer Electrolyte Membrane fuel cell operates effectively at both the temperatures of 65 °C and 600 °C.

Multi-Variate Optimization of Polymer Electrolyte Membrane Fuel Cells in Consideration of Effects of GDL Compression and Intrusion

This study applies, tests, and compares comprehensive surrogate-based optimization techniques to optimize the performance of polymer electrolyte membrane fuel cells (PEMFCs). Moreover, parametric cases considering four important design variables, i.e., gas diffusion layer thickness (), channel depth (), channel width (), and land width (), are defined using the latin hypercube sampling technique under reasonable constraint conditions. Multidimensional, two-phase PEMFC model simulations are performed to generate the training and test data under these design conditions. Three famous surrogate models, i.e., response surface approximation (RSA), radial basis neural network (RBNN), and kriging (KRG), are employed to construct objective functions for the PEMFC cell voltages operating in the galvanostatic mode, and their accuracies are tested and compared using root mean square error and adjusted R-square. The surrogates are then linked to stochastic optimization algorithms, i.e., genetic algorithm and particle swarm optimization, to determine the optimal design points. A comparative study of these surrogates reveals that the KRG model outperforms the RBNN and RSA models in terms of prediction capability. Furthermore, the PEMFC model simulations at the optimal design points clearly demonstrate that performance improvements of around 56–69 mV at 2.0 A cm−2 are achieved with the optimum design values compared to typical PEMFC design conditions.

The identification of optimal operating parameters under high energy efficiency conditions for a single polymer electrolyte membrane (PEM) fuel cell

The performance of PEM fuel cells is influenced by several factors such as: the operating temperature of the cell, the reactant gas flow, work pressures, the reaction gas humidity. In the present work we aimed to identify the optimal values of these parameters for operation of a PEM cell to achieve maximum power in conditions of high efficiency; the technological possibilities of its use in a portable energy application have been evaluated. Experimental measurements regarding the integrating polymeric membrane in three different fuel cell construction designed were performed. The influence of the mechanical compression of the GDL diffusion layer on the total internal resistance of the cell was achieved by comparative analysis of the polarization curves. It was found that as the deformation level of the MEA increases, the power generated by the battery increases progressively. The resulting experimental data subsequently allowed the design and implementation of a PEM fuel cell assembly, fully functional at power level, corresponding to the number of constituent elements.