PEMFC Performance Research Articles

Catalytic layer-membrane electrode assembly methods for optimum triple phase boundaries and fuel cell performances

A critical overview of MEA fabrication techniques is given focusing on the formation of triple phase boundaries, known for increasing PEMFC performances. Print-light-synthesis is a new emerging technology to achieve nanostructred MEA.

Fabrication of VN/TaC Composites with Dual Functions of VN as a Catalyst Support and a Cocatalyst for Improved PEMFC Performance

Tantalum carbide (TaC) was prepared by a salt flux method, and vanadium nitride (VN) and VN/TaC composites (with 2.5, 5.0, and 10.0 wt % VN) were prepared by a sol–gel method. Pt nanoparticles were...

Configuring the Porosity and Microstructure of Carbon Paper Electrode Using Pore Formers and Its Influence on the Performance of PEMFC

Carbon papers (CPs) are used as an electrode backing in PEMFC. It assists the diffusion of both the reactant gases and products toward and from the reaction site and aids the flow of electrons. CP ...

Single Stack Performance using Chromium Carbide (Cr‒C) and Niobium Carbide (Nb‒C) Coated on 316 L Bipolar Plates

Metallic bipolar plates tendency to have high contact resistance and corrosion after several times of usage affected performance of a cell in PEMFC stack. This study focused on the interfacial contact resistance (ICR) and corrosion resistance of SUS 316 L bipolar plates using Cr‒C and Nb‒C as coating layer, single stack performance in PEMFC were observed by experimental. The Cr‒C and Nb‒C coating layer acted as protective layer between SUS 316 L bipolar plates. Therefore, coating is a method in preventing the bipolar plates surface material from damage in the acidic environment of PEMFC. To develop corrosion-resistant and high conductivity bipolar plates for PEMFC, the coatings bipolar plates were applied to cell fabrication in comparison with bare SUS 316 L bipolar plates. The SUS 316 L bipolar plates size and electrode area were 50 mm2 and 25 mm2, respectively. The experiment was carried out on a prepared assembled single cell bipolar plates with the commercial membranes, conductive carbon papers and gasket. Initial performance of the single cells using Cr‒C and Nb‒C coatings over SUS 316 L bipolar plates were recorded at a cell voltage between 0.4 to 0.5 V, respectively. In comparison, Nb‒C gives good performance of corrosion resistance and the ICR value as low as 10‒12 A/cm2 and 1.22 mΩ cm−2. Additionally, it gives maximum power density of 137 mW/cm2 at the cell voltage 0.51 V. The lifetime durability of the single cell significantly improved from the uncoated current density of 390 mA/cm2 to 450 mA/cm2 with Nb‒C coating layer.

Incorporation of Graphene and Graphene-Based Materials into Membranes As an Alternative Electrolyte Configuration for Low and High Temperature Polymeric Electrolyte Membranes Fuel Cells.

The electrolyte plays an important role in the Membrane Electrode Assembly (MEA) of Polymeric Electrolyte Membranes Fuel Cells, (PEMFCs), having three main functions, to act as ion conductor, electronic insulator and a separator for the reactant gases [1]. The electrolyte is a Proton Exchange Membrane and Nafion is the most widely used polymeric membrane in this technology. However, because its particular structure it requires a good hydration to lead a high proton conductivity, which limit the operating temperature to lower than 100 oC. Poly[2,2′-m-(phenylene)-5,5′-benzimidazole (PBI) membrane doped with Phosphoric Acid, has been presented as an alternative to Nafion membranes allowing higher operating temperatures, 200oC, which enhance the kinetics of the reactions. However, during the operation of High Temperature Fuel Cells (HT-PEMFCs) these membranes suffer Phosphoric Acid leaching leading to a low proton conductivity and degradation of the fuel cell [2].The 2D honeycomb lattice of Graphene provides this material particular properties such as high surface area, exceptionally high electrical conductivity, good chemical and thermal stability and excellent barrier properties, which make it a potential material for a large number of applications. In addition to this [1], Hu. et al. [3] have demonstrated that Single Layer Graphene present a high proton conductivity being at the same time a barrier for other elements, which makes this material a potential electrolyte for PEMFC. However, SLG has some drawbacks notably due to the complex process to produce it and its high cost. These limitations leave an open window to Graphene based materials such as Graphene Oxide, which shows very attractive properties to act as filler in Nafion and PBI membranes due to its chemical functionalization and its non-porous structure, which provides additional resistance for mass transport and increases the tortuosity of the permeation pathways leading to higher selectivity [1].Here we will describe the work carried out at University of Manchester incorporating SLG and GO composite membranes into the MEA of both PEM Fuel Cells, Low Temperature (LT-PEMFC) and HT-PEMFC. The addition of the SLG produced by CVD into the MEA of LT-PEMFC has demonstrated no change in the proton conductivity, supporting the hypothesis that SLG is a good proton conductor. In addition, for a particular LT-PEMFC, Direct Methanol Fuel Cells (DMFC), a decreasing of the methanol crossover has found leading a significant enhancement of the power density [4]. SLG has been also incorporated into the MEA of HT-PEMFC, which use PBI membrane instead of Nafion, to evaluate its proton conductivity and barrier properties, this time to stop the Phosphoric Acid leaching.Although positive results have been reported by adding SLG into the MEAs, a different approach has been conducted by the development of GO-composite membranes also for both type of PEMFC. Exfoliated Graphene Oxide has been synthesized by electrochemical exfoliation of graphite and has been incorporated as a filler into two different of matrix polymer, Nafion and PBI, to evaluate their performance in both PEMFC, high and low temperature.

Structured Electrodes for PEM Fuel Cells

Slow reaction rates for oxygen reduction reaction (ORR) is one of the major barriers for improving PEMFC performance. Optimizing electrode structures for enhanced transport properties can improve high current density performance of PEMFCs. Conventional porous electrodes are fabricated by coating or spraying techniques with minimal control of its micro-structure, rendering random and tortuous transport pathways (Fig. 1a left). As a result, proton transport through the ionomer and oxygen diffusion in primary and secondary pores are sub-optimal and often become a performance limiting factor depending on the cell’s operation conditions. Therefore, a carefully designed electrode micro-structure should significantly improve proton and oxygen transport. In this work we developed structured electrodes (Fig. 1a right) for Platinum based PEMFCs where different components of the electrode serve a dedicated function (i.e., transport of proton or oxygen). These electrodes are highly ordered to reduce transport losses associated with tortuosity and non-percolation. In addition, the structural attributes are controlled on multiple length scales to minimize transport resistance and improve the PEMFC performance. For design optimization and to improve the fundamental understanding of the transport mechanism in the electrode, we developed a state-of-the-art multi-physics electrode model to perform parametric study. The model accurately accounts for ORR kinetics, agglomerate structure, proton transport in bulk membrane and thin film ionomer, oxygen diffusion in the pores, heat transfer, as well as vapor and liquid phase water transport in the electrode. By varying geometric and cell operating conditions, we conducted more than 12,000 simulations using COMSOL Multiphysics to identify critical electrode design parameters that enable fast reaction and improved transport phenomena. Results from our continuum scale simulation show significant performance improvement for structured electrodes compared to conventional electrodes (Fig. 1b). The performance improvement is due to the reduced proton and oxygen transport resistances. Altogether, our findings unveil structured electrodes as a new resource for efficient charge and mass transport, and as a promising material design platform towards obtaining reliable PEMFCs with enhanced energy conversion performance. Figure 1

Salt‐recrystallization preparation of metal organic framework derived porous carbon support for highly‐efficient proton exchange membrane fuel cell

We report a novel porous and high-specific surface area carbon support material (C-framework) for PEMFC by the salt-recrystallization-fixing HKUST-1 template. We believe this will be a universal method to convert high-temperature unstable MOF materials, such as HKUST-1. NaCl crystals serve as completely closed nanoreactors, which facilitate graphitization and structure inheritance. Electrochemical evaluation showed that the C-framework loaded with Pt nanoparticles exhibits high ORR activity and excellent electrochemical performance in acidic electrolytes. The PEMFC performance reached a maximum power density of 780 mW/cm2 under the H2/air testing condition in ultra-low Pt loading (cathode 0.1 mg/cm2).

Optimizing the Composition of the PEMFC Catalyst Layer

PEMFC performance is very sensitive to the design of the catalyst layers of the membrane electrode assembly, in particular the cathode catalyst layer. The overall performance of the cell is affected by the catalyst density, porosity, electrolyte distribution, agglomerate size, agglomerate volume fraction, etc. The ideal values of these parameters vary throughout the catalyst layer, requiring a non-uniform 3-dimensional distribution. Therefore, it is useful to be able to determine this 3-dimensional catalyst layer composition at the time of design, based on anticipated operating conditions, cell physical geometry, and other design constraints.Previously we developed a gradient-based technique to optimize the catalyst distribution within the PEMFC catalyst layer. Our technique requires the computation of a sensitivity function for the platinum distribution using an adjoint space method originally developed by the applied mathematics community to solve 1-D optimization problems in fluid dynamics, climate, and heat transfer problems. The sensitivity functions are then applied using an iterative method to find the optimum platinum distribution throughout the catalyst layer. The computational cost required for computing the sensitivity functions using the adjoint space method is relatively small since this method requires solving only one sparse system of linear equations instead of performing multiple fuel cell simulations.Now we have extended this technique to allow for the simultaneous optimization of multiple catalyst layer design parameters, including electrolyte volume fraction, carbon volume fraction, and porosity, in addition to platinum. Our technique allows for constrained optimization (where the overall quantity of material being optimized is constant) and unconstrained optimization (where the overall quantity of material being optimized is allowed to vary). Constrained optimization is applied to platinum optimization, as the cost of the material limits how much can be used in practical applications. Unconstrained optimization is applied to optimization of electrolyte and carbon, as the material cost of these components in the catalyst layer is negligible.Using this technique, we are able to estimate the optimum 3-D distribution of platinum, carbon agglomerate, electrolyte, and void fraction within the catalyst layer to maximize the power density of the cell at different operating current densities. The optimum distributions depend on the positions of the landings and openings and the geometry and dimensions of the cell.The figure below shows optimization of electrolyte fraction, only, for a PEMFC. More details about the technique, the numerical implementation, and a number of fully optimized structures will be presented at the meeting.

Ultrathin Electrolyte Membranes with PFSA-Vinylon Intermediate Layers for PEM Fuel Cells.

We prepared ultrathin PFSA/PFSA-vinylon/PFSA laminated electrolyte membranes (thickness = 10 μm) for fuel cells without using a reinforcing material. Nafion and Aquivion solutions were used as PFSA polymers. Vinylon was synthesized by formalizing polyvinyl alcohol. From the current-voltage measurements using ultrathin PFSA/PFSA-vinylon/PFSA membranes; the cell resistances are significantly lower than that using a 50 μm Nafion membrane. A high current density was obtained under both low- and high-humidity conditions. Ultrathin PFSA/PFSA-vinylon/PFSA laminated membranes will help to further improve the performance of PEMFCs.

Sealing performance and mechanical behavior of PEMFCs sealing system based on thermodynamic coupling

The reliability of sealing system is closely related to the work performance of PEMFCs. The model of steel-strip PEMFCs is established in this paper, the stress-strain distribution of sealing system in single-cell and multi-cells structures under three different working temperature were investigated. Effects of compression ratio, fluid pressure, dislocation and dimension of gasket on the sealing performance and mechanical behavior of PEMFCs were studied. The results show that the sealing performances of single-cell and multi-cells structures are similar under different working temperatures. Temperature has a great influence on the von-Mises stress of sealing system and the deformation of MEA frame. The research results of single-cell can be extended to the multi-cells, but the influence of temperature can't be ignored. With the increasing of compression ratio, fluid pressure and dimension, the sealing performance also be improved. Excessive dislocation may aggravate the deformation of MEA frame. The high stress area appears inside cross section which is prone to cause seal failure and full cells collapse.

Ecological Performance of an Irreversible Proton Exchange Membrane Fuel Cell

In this paper a novel PEMFC voltage model considering the leakage current is established. Numerical simulation results based on the newly established PEMFC model is compared with the experimental results and indicates that they have a good match with the experimental results. Based on the proposed voltage model and previous studies, the PEMFC ecological criterion was proposed and derived. As well, other finite time thermodynamics objective functions including entropy yield, ecological objective function and ecological performance coefficient formula are derived for PEMFCs. Detailed numerical simulations are performed considering different design parameters and operating parameters. Ecological performance of an irreversible PEMFC is gained and such results can be further used for ecological optimization to yield maximum performance of the PEMFC.

The influence of temperature on the impedance characteristics of PEMFC

Electrochemical impedance spectroscopy (EIS) is one of the main characterization methods of PEMFC, which has important reference value for evaluating the performance of PEMFC. In this paper, the impedance curves of PEMFC at different temperatures are measured by experiments, and the equivalent circuit is used to analyze the influence of battery temperature and humidification temperature on the impedance. The study found that when the battery temperature is higher than the humidification temperature, both the ohmic impedance and the Faraday impedance increase significantly; the double layer in the PEMFC mainly embodies the capacitive reactance characteristics, and the more the humidification temperature is higher than the cell temperature, the more obvious the degree of the double layer embodies the capacitive reactance characteristics. The results of this study have a certain reference value for understanding the working principle of PEMFC and improving its performance.

Synthesis and characterization of poly 2‐ N ‐acrylamido‐2‐methyl−1‐propane sulfonic acid functionalized graphene oxide embedded electrolyte membrane using DOE for PEMFC

A novel proton exchange membrane consisting of 2-N-acrylamido-2-methyl−1-propane sulfonic acid modified graphene oxide nanocomposite (PAMPS-mGO), carboxylated poly(vinyl chloride) (CPVC), and poly 2-N-acrylamido-2-methyl−1-propane sulfonic acid (PAMPS) has been successfully prepared by simple and scalable polymer blending methodology. Different compositions of PEM in terms of its constituting precursors such as PAMPS-mGO, CPVC, and PAMPS were optimized by Placket Burman Design and their ion exchange capacity (IEC), oxidative stability, water uptake percentage, mechanical stability, and proton conductivity were evaluated. The amounts of significant precursors were further optimized by Central Composite Design. The membrane with excellent performance in PEMFC was obtained when appropriate proportions of CPVC (10%), PAMPS (20%), and PAMPS-mGO (20%) were blended. Among all membrane with mentioned composition exhibited IEC 1.3 mmol/g, oxidative stability 97.2%, WU 40.8%, proton conductivity 151 S/cm, water content 17.43, current density 1537 mA/cm2 at 120°C, power density 566.5 mW/cm2 at 120°C, Young modulus 797 MPa, tensile strength 16.8 MPa, and elongation at break % of 2.7 MPa. These results are in good comparison with PEM based on Nafion. Thus, the CPVC, PAMPS, and PAMPS-mGO-based composite PEM is a good candidate for PEMFC at elevated temperature under anhydrous conditions.

Performance Prediction of Proton Exchange Membrane Fuel Cells (PEMFC) Using Adaptive Neuro Inference System (ANFIS)

This investigation explored the performance of PEMFC for varying ambient conditions with the aid of an adaptive neuro-fuzzy inference system. The experimental data obtained from the laboratory were initially trained using both the input and output parameters. The model that was trained was then evaluated using an independent variable. The training and testing of the model were then utilized in the prediction of the cell-characteristic performance. The model exhibited a perfect correlation between the predicted and experimental data, and this stipulates that ANFIS can predict characteristic behavior of fuel cell performance with very high accuracy.

Roughness effects of gas diffusion layers on droplet dynamics in PEMFC flow channels

Water management remains one of the major challenges in optimising the performance of PEMFCs, in which liquid accumulation and removal in gas diffusion layers (GDLs) and flow channels should be addressed. Here, effects of GDL surface roughness on the water droplet removal inside a PEMFC flow channel have been investigated using the Volume of Fluid method. Rough surfaces are generated according to realistic GDL properties by incorporating RMS roughness and roughness wavelength as the main characteristic parameters. Droplet dynamics including emergence, growth, detachment, and removal in flow channels with various airflow rates are simulated on rough substrates. The influences of airflow rate on droplet dynamics are also discussed by comparing the detachment time and droplet morphology. The liquid removal efficiency subject to different surface roughness parameters is evaluated by droplet detachment time and elongation, and regimes of detachment modes are identified based on the droplet breakup location and detachment ratio. The results suggest that rough surfaces with higher RMS roughness can facilitate the removal of liquid inside flow channel. Whilst surface roughness wavelength is found less significant to the liquid removal efficiency. The results here provide qualitative assessments on identifying the key surface characteristics controlling droplet motion in PEMFC channels.

Incorporation of Graphene and Graphene-Based Materials into Membranes As an Alternative Electrolyte Configuration for Low and High Temperature Polymeric Electrolyte Membranes Fuel Cells

The electrolyte plays an important role in the Membrane Electrode Assembly (MEA) of Polymeric Electrolyte Membranes Fuel Cells, (PEMFCs), having three main functions, to act as ion conductor, electronic insulator and a separator for the reactant gases [1]. The electrolyte is a Proton Exchange Membrane and Nafion is the most widely used polymeric membrane in this technology. However, because its particular structure it requires a good hydration to lead a high proton conductivity, which limit the operating temperature to lower than 100 oC. Poly[2,2′-m-(phenylene)-5,5′-benzimidazole (PBI) membrane doped with Phosphoric Acid, has been presented as an alternative to Nafion membranes allowing higher operating temperatures, 200oC, which enhance the kinetics of the reactions. However, during the operation of High Temperature Fuel Cells (HT-PEMFCs) these membranes suffer Phosphoric Acid leaching leading to a low proton conductivity and degradation of the fuel cell [2].The 2D honeycomb lattice of Graphene provides this material particular properties such as high surface area, exceptionally high electrical conductivity, good chemical and thermal stability and excellent barrier properties, which make it a potential material for a large number of applications. In addition to this [1], Hu. et al. [3] have demonstrated that Single Layer Graphene present a high proton conductivity being at the same time a barrier for other elements, which makes this material a potential electrolyte for PEMFC. However, SLG has some drawbacks notably due to the complex process to produce it and its high cost. These limitations leave an open window to Graphene based materials such as Graphene Oxide, which shows very attractive properties to act as filler in Nafion and PBI membranes due to its chemical functionalization and its non-porous structure, which provides additional resistance for mass transport and increases the tortuosity of the permeation pathways leading to higher selectivity [1].Here we will describe the work carried out at University of Mancheschester incorporating SLG and GO composite membranes into the MEA of both PEM Fuel Cells, Low Temperature (LT-PEMFC) and HT-PEMFC. The addition of the SLG produced by CVD into the MEA of LT-PEMFC has demonstrated no change in the proton conductivity, supporting the hypothesis that SLG is a good proton conductor. In addition, for a particular LT-PEMFC, Direct Methanol Fuel Cells (DMFC), a decreasing of the methanol crossover has found leading a significant enhancement of the power density [4]. SLG has been also incorporated into the MEA of HT-PEMFC, which use PBI membrane instead of Nafion, to evaluate its proton conductivity and barrier properties, this time to stop the Phosphoric Acid leaching.Although positive results have been reported by adding SLG into the MEAs, a different approach has been conducted by the development of GO-composite membranes also for both type of PEMFC. Exfoliated Graphene Oxide has been synthesized by electrochemical exfoliation of graphite and has been incorporated as a filler into two different of matrix polymer, Nafion and PBI, to evaluate their performance in both PEMFC, high and low temperature.

Designing the Ideal Catalyst Layer in PEMFCs

Many design parameters affect the performance of PEMFCs, including catalyst density, porosity, nafion distribution, agglomerate size, etc. The ideal values of these parameters vary not only from layer to layer (for instance from catalyst layer to gas diffusion layer or from anode catalyst layer to cathode catalyst layer) but also from location to location inside the same layer, resulting in non-uniform 3-dimensional spatial distributions of the platinum, nafion, and pore and agglomerate sizes. Furthermore, the optimal values of these parameters also depends on the operating conditions, such as electrical current density, pressure, and temperature, which increases the complexity of the problem even more. To design the ideal catalyst layer, the designer must determine the optimum distributions of the above parameters within each layer. In this work, we focus on estimating the ideal structure of the catalyst layer in PEMFCs, in particular on determining the optimum spatial distributions of the platinum, porosity, nafion, and agglomerate size.To solve the above problem, we apply the adjoint method to compute the optimum parameters for the microstructure of the catalyst layer. We start by computing the sensitivity functions (which are related to the Gâteaux derivatives) of the cell voltage or current in the direction of the design parameter variation. The sensitivity functions are then applied to adjust the parameters of the entire catalyst layer in a point-by-point fashion. The process is repeated until convergence is obtained.Numerical results will be presented showing the non-optimized and optimized distributions at different values of the operating current density, temperature, and pressure for a 25 μm membrane PEMFC, as well as the polarization curves for non-optimized and optimized configurations.

Degradation Mechanism of an IrO2 Anode Co-Catalyst for Cell Voltage Reversal Mitigation Under Transient Operation Conditions of a PEM Fuel Cell

The cell voltage reversal which can occur during the transient operation of PEM (proton exchange membrane) fuel cells on account of a short under-supply of hydrogen to one or several cells in a fuel cell stack can lead to the substantial degradation of anode catalysts and anode electrodes. This damage can be substantial even if the cell reversal only occurs over time scales of tens of milliseconds, which puts a high requirement on the fuel cell controls system. During cell reversal, the anode potential rises to far above 1 V vs. the reversible hydrogen electrode potential (RHE), causing platinum dissolution and oxidation of the carbon support; the latter leads to a collapse of the anode catalyst layer and to cell failure. One strategy to mitigate the damages of H2-starvation is the addition of a co-catalyst to the anode electrode which catalyzes the oxygen evolution reaction (OER), so that the non-damaging OER rather than the damaging carbon oxidation reaction (COR) will take place. A commonly used anode co-catalyst to facilitate the OER over the COR during cell reversal events is iridium oxide (IrO2).1 Many studies have investigated the effect of IrO2 co-catalyst on mitigating cell reversal damages in PEMFC anodes.2 However, there is no comprehensive study on the effect of the strongly reducing hydrogen atmosphere in a PEMFC anode on the chemical stability of IrO2, which could ultimately affect the stability of an IrO2 anode co-catalyst particularly during the repetitive transitions between normal operating conditions where the anode potential is at ≈0 V vs. RHE and the high anode potentials (≥1 V vs. RHE) during cell voltage reversal and start-up/shut-down (SUSD) transients. That these voltage cycles might be damaging is indicated in a recent publication from our group, where we had shown that H2 permeating through the membrane from the hydrogen electrode to the oxygen electrode of a PEM water electrolyzer during open circuit conditions voltage (OCV) leads to a reduction of the surface of IrO2 OER catalyst to metallic Ir, which in turn gets oxidized to an amorphous IrOx during the subsequent normal operation period of the electrolyzer at the high oxygen evolution potentials. The repetitive cycling between reducing conditions during OCV periods and oxidizing conditions during operation were shown to cause the enhanced dissolution of Ir, which could result in a loss of active material.3 In this contribution, we will discuss the consequences of using an IrO2 based anode co-catalyst to mitigate cell voltage reversal degradation in PEMFCs. Thermal gravimetric analysis (TGA) in reductive atmosphere (5 volume% H2/Ar) is a powerful tool to simulate the chemical environment of PEMFC anode during normal operation. By utilizing this tool, it is shown that the near-surface region of IrO2 can be completely reduced to metallic Ir under the operating condition of PEMFC anode. The formation of metallic Ir has been proven by post characterization of the reduced powders after the TGA experiments using X-ray photoelectron spectroscopy (XPS) and by cyclic voltammetry, where the development of hydrogen under potential deposition (HUPD) features of metallic Ir reveals the time-dependent reduction of IrO2 upon extended exposure to PEMFC anode conditions. Finally, it will be shown that anode potential transients caused, e.g., by SUSD events, leads to the dissolution of iridium from the IrO2 based anode co-catalyst. The consequences of this on the long-term PEMFC performance will be discussed.

A numerical study of proton exchange membrane fuel cell performances affected by various porosities of gas difussion layer materials

One of the factors that can increase the surface transfer property for gas diffusivity apart from the membrane material in PEMFC is the porosity of the gas diffusion layer material affecting species mass distribution at the electrodes. The present study simulates the performance of PEMFC by investigating the effect of GDL porosities in some commercial ELAT-TEK-1200W (e=0.31), and SIGRACET 25BA (e=0.63), also an organic material coconut coir (e=0.88) numerically. It was carried out using COMSOL Multiphysics 5.3a in the form of species mass concentrations plotted in the surface contour and cut points at the electrodes in the elapsed time transiently. Afterward, the results were used to determine the PEMFC performance by calculating some losses; activation, ohmic, and mass concentration polarization. The results showed that the PEMFC performance was only influenced by the mass polarization. It means that the power density is strongly influenced by the concentration of species in the anode and the cathode. The mass concentration is strongly influenced by the distribution of species; H2, O2, and H2O formed during the reaction. The highest H2 concentration at the anode occurs in the GDL using ELAT-TEK-1200W having the smallest porosity producing the highest power density compared to other GDL materials. It makes an easier diffusion process between H2 and O2 species to work properly. However, coconut coir as an organic material can be a promising GDL in the future because of its performance compared to the others.

A novel experimental based statistical study for water management in proton exchange membrane fuel cells

Water management is a key issue in low-temperature PEMFCs. For proper water management, processes leading to dehydration or flooding of cells should be clearly understood, hence prevented. Here, the effects of Anode Stoichiometry (AST), Cathode Stoichiometry (CST) and inlet gas temperature (T*) on the cell performance and water management in PEMFC are experimentally studied. Two methods, namely (i) direct- and (ii) indirect-method are employed to monitor water accumulation in cathode flow channels of a multi-path-parallel-serpentine PEMFC. Flow visualization served as direct method (item (i)), in which recorded videos of transparent channels were analyzed via an image-processing algorithm to monitor water coverage ratio (WCR). Simultaneously an inlet-to-exit pressure drop coefficient (Φ) was defined for indirect-method (item (ii)). AST, CST and T* were taken as input to provide three experimental based correlations for generated electrical power, WCR and Φ as a response. According to the results, an increase in AST reduces water-content in cathode channels; decreases performance also raises the sensitivity of generated power to variations in other operating-parameters. However, an increase in CST and T* reduces water contents in cathode channels also increases the cell power and lowers sensitivity of the power to the variation of other operating-parameters. It is observed that strong connectivity exists between WCR and Φ. This is verified by obtaining a high Pearson correlation coefficient of 0.887 between WCR and Φ. It is demonstrated that dehydration and flooding could be prevented when 3 ≤ WCR ≤ 4, from which appropriate operating-parameters AST, CST and T* could be retrieved.