A Feasibility Study of Ribbon Architecture for PEM Fuel Cells

2010 ◽  
Vol 7 (5) ◽  
Author(s):  
Daniel F. Walczyk ◽  
Jaskaran S. Sangra
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
High Volume ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Open Circuit ◽  
Membrane Electrode ◽  
Fixture Design ◽  
Design Development ◽  
Test Fixture

The feasibility of an alternative fuel cell architecture, called a ribbon membrane electrode assembly (MEA), is demonstrated for low-temperature polymer electrolyte membrane (PEM) fuel cells used in portable power applications by comparing it to a traditional bipolar “stack” architecture. A ribbon MEA consists of adjacent PEM cells sharing a common gas diffusion layer to allow for lateral electrical current flow and an integral gas-tight, conductive interconnect/seal, where adjacent cells meet to prevent reactant gas leakage. The resulting lateral arrangement of MEAs can be used to supply all MEAs simultaneously instead of individual bipolar plates with flow fields for a stack. A pair of two-cell ribbon MEAs, with and without an interconnect/seal, were designed, prototyped, and sealed by thermal pressing. The MEAs were clamped in a two-piece box fixture to provide reactant gases on the anode and cathode sides, hooked to a fuel cell (FC) test stand and yielded an open circuit voltage (OCV) of 1.43 V with an interconnect/seal and 0.6 V without. A two-cell bipolar stack PEMFC with identical MEA specifications had an OCV of 1.86 V. Polarization curves for the ribbon MEA with interconnect/seal showed the sensitivity of performance to clamping pressure and positioning of the copper current collectors. The ribbon MEA polarization curve was also shifted downward by 0.42 V as compared with that of the traditional stack, and suspected causes (e.g., gas leaking) are attributable to the nonoptimal test fixture design. Hence, the ribbon MEA architecture is shown to be feasible. Future work suggested includes improvements to the test fixture design, development of automated manufacturing capabilities for high volume production, and demonstration of a multicell (>2) ribbon MEA PEMFC design.

Effect of Vibration on the Liquid Water Transport of PEM Fuel Cells

2009 ◽  
Author(s):  
Luis Breziner ◽  
Peter Strahs ◽  
Parsaoran Hutapea
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Water Transport ◽  
Liquid Water ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Cell Performance ◽  
Sinusoidal Vibration ◽  
Fuel Cell Performance ◽  
Liquid Water Transport

The objective of this research is to analyze the effects of vibration on the performance of hydrogen PEM fuel cells. It has been reported that if the liquid water transport across the gas diffusion layer (GDL) changes, so does the overall cell performance. Since many fuel cells operate under a vibrating environment –as in the case of automotive applications, this may influence the liquid water concentration across the GDL at different current densities, affecting the overall fuel cell performance. The problem was developed in two main steps. First, the basis for an analytical model was established using current models for water transport in porous media. Then, a series of experiments were carried, monitoring the performance of the fuel cell for different parameters of oscillation. For sinusoidal vibration at 10, 20 and 50Hz (2 g of magnitude), a decrease in the fuel cell performance by 2.2%, 1.1% and 1.3% was recorded when compared to operation at no vibration respectively. For 5 g of magnitude, the fuel cell reported a drop of 5.8% at 50 Hz, whereas at 20 Hz the performance increased by 1.3%. Although more extensive experimentation is needed to identify a relationship between magnitude and frequency of vibration affecting the performance of the fuel cell as well as a throughout examination of the liquid water formation in the cathode, this study shows that sinusoidal vibration, overall, affects the performance of PEM fuel cells.

Fluorescence Microscopy for the Measurement of the Surface Properties of the Gas Diffusion Layers of Fuel

2010 ◽  
Author(s):  
Brooks Friess ◽  
Mina Hoorfar
Keyword(s):  
Water Management ◽  
Fuel Cells ◽  
Fuel Cell ◽  
Fluorescence Microscopy ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Experimental Methodology ◽  
Test Fluid ◽  
Average Height ◽  
Wetted Area

One of the major problems of current proton exchange membrane (PEM) fuel cells is water management. The gas diffusion layer (GDL) of the fuel cell plays an important role in water management since humidification and water removal are both achieved through the GDL. Various numerical models developed to illustrate the multiphase flow and transport in the fuel cell require the accurate measurement of the GDL properties (wettability and surface energy). In a recent study, the capillary penetration technique has been used to measure indirectly the wettability of the GDL based on the experimental height penetration of the sample liquid into the porous sample. In essence, a high resolution microscope/camera was used to detect the rate of penetrated height into the sample GDL. The shortcoming of this type of visualization is that it can only be used for thin hydrophilic GDL samples with zero Teflon loadings. For the thick and high Teflon loading GDLs, there is not enough contrast to detect the height of the penetrated liquid. In the real fuel cells, the GDLs are made of the micro-porous and macro-porous layers with an optimum Teflon loading. Therefore, it is required to develop a new experimental methodology capable of detecting the rate of penetration and as a result the wettability of GDLs samples used in fuel cells. In this paper, the fluorescence microscopy technique is integrated into the experimental setup of the capillary penetration method to improve the contrast between the wetted and non-wetted area. The fluorescence setup uses a powder die, dissolved in the test fluid, which is excited by a concentrated ultraviolet light illuminated in the vertical manner. To acquire the profile images of the penetrated liquid, an optical mirror was used. This new setup has the added advantage of providing a visual representation of the different regimes of penetration (e.g., the fingering effect reported for the pathways of the liquid penetrated into the GDLs) that are defined by the capillary number and mobility ratio of each fluid. Since the GDL samples used in this study are relatively hydrophobic (e.g., with 40% Teflon loadings), the pattern of liquid penetration is not uniform. Thus, an image analysis program was developed to determine the average height of penetration based on the area under the entire wetted area. The general Washburn equation was then used to fit the extracted height data and provide the average internal contact angle for each test liquid.

GOLD-PLATED TITANIUM VS CARBON-IMPLANTED TITANIUM AS MATERIAL FOR BIPOLAR PLATES IN PEM FUEL CELLS

2019 ◽  
Vol 26 (08) ◽  
pp. 1950038
Author(s):  
M. S. VLASKIN ◽  
A. V. GRIGORENKO ◽  
E. I. SHKOLNIKOV ◽  
A. S. ILYUKHIN
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Performance Enhancement ◽  
Precious Metals ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Electrical Performance ◽  
Carbon Ions ◽  
Bipolar Plates ◽  
Gold Plating

Three different types of current-collecting plates for air-hydrogen PEM fuel cell were manufactured and tested: unmodified titanium plates; gold-plated titanium plates and titanium plates treated by carbon ions implantation. It was shown that the applied surface modifications reduce contact resistance between titanium plate and carbon gas diffusion layer. Total ohmic resistance of fuel cell is reduced by 1.8 and 1.4 times in case of gold-plated titanium and carbon-implanted titanium, respectively, in comparison with uncoated titanium. Although gold plating turned out to be more profitable than carbon ion implantation in terms of electrical characteristics, in the last case, the performance enhancement was reached without using precious metals, which at mass production must play more important role. This technology promises to reduce the cost of bipolar plates manufacturing, while maintaining high electrical performance of PEM fuel cells.

scholarly journals Effective Technique for Improving Electrical Performance and Reliability of Fuel Cells

2017 ◽  
Vol 8 (4) ◽  
pp. 1868
Author(s):  
A. Albarbar ◽  
M. Alrweq
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Water Content ◽  
Proton Exchange Membrane ◽  
Pem Fuel Cell ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Electrical Performance ◽  
And Performance

To optimise the electrical performance of proton exchange membrane (PEM) fuel cells, a number of factors have to be precisely monitored and controlled. Water content is one of those factors that has great impact on reliability, durability and performance of PEM fuel cells. The difficulty in controlling water content lies in the inability to determine correct level of water accumulated inside the fuel cell. In this paper, a model-based technique, implemented in COMSOL, is presented for monitoring water content in PEM fuel cells. The model predicts, in real time, water content taking account of other processes occurring in gas channels, across gas diffusion layers (GDL), electrodes, and catalyst layer (CL) and within the membrane to minimize voltage losses and performance degradation. The level of water generated is calculated as function of cell’s voltage and current. Model’s performance and accuracy are verified using a transparent 500 mW PEM fuel cell. Results show model predicted current and voltage curves are in good agreement with the experimental measurements. The unique feature of this model is that, no special requirements are needed as only current, and voltage of the PEM fuel cell were measured thus, is expected to pave the path for developing non-intrusive control and monitoring systems for fuel cells.

scholarly journals Use of Electrochemical Impedance Spectroscopy for the Evaluation of Performance of PEM Fuel Cells Based on Carbon Cloth Gas Diffusion Electrodes

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Saverio Latorrata ◽  
Renato Pelosato ◽  
Paola Gallo Stampino ◽  
Cinzia Cristiani ◽  
Giovanni Dotelli
Keyword(s):  
Fuel Cells ◽  
Electrochemical Impedance Spectroscopy ◽  
Fuel Cell ◽  
Impedance Spectroscopy ◽  
Current Density ◽  
Electrochemical Impedance ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Carbon Cloth ◽  
Gas Diffusion Electrodes

Polymer electrolyte membrane fuel cells (PEMFCs) have attracted great attention in the last two decades as valuable alternative energy generators because of their high efficiencies and low or null pollutant emissions. In the present work, two gas diffusion electrodes (GDEs) for PEMFCs were prepared by using an ink containing carbon-supported platinum in the catalytic phase which was sprayed onto a carbon cloth substrate. Two aerograph nozzles, with different sizes, were used. The prepared GDEs were assembled into a fuel cell lab prototype with commercial electrolyte and bipolar plates and tested alternately as anode and cathode. Polarization measurements and electrochemical impedance spectroscopy (EIS) were performed on the running hydrogen-fed PEMFC from open circuit voltage to high current density. Experimental impedance spectra were fitted with an equivalent circuit model by using ZView software which allowed to get crucial parameters for the evaluation of fuel cell performance, such as ohmic resistance, charge transfer, and mass transfer resistance, whose trends have been studied as a function of the applied current density.

Electrical Performance of PEM Fuel Cells With Different Gas Diffusion Layers

2011 ◽  
Vol 8 (4) ◽  
Author(s):  
P. Gallo Stampino ◽  
L. Omati ◽  
G. Dotelli
Keyword(s):  
Water Management ◽  
Fuel Cells ◽  
High Current Density ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Open Circuit ◽  
Electrical Performance ◽  
Carbon Paper ◽  
Carbon Cloth ◽  
Current Densities

The microporous layer (MPL) is a key component of polymer electrolyte membrane fuel cells (PEM-FCs), and it is in charge of the gas and water management at the electrode-gas diffusion layer (GDL) interfaces. A MPL was prepared and coated onto two different commercial GDLs: a carbon paper (woven-non-woven (WNW)) and a carbon cloth (CC). Electrical performances of the so-obtained gas diffusion media (GDM), i.e., GDL coated with the MPL, were investigated in single cell testing (steady-state polarization curves) using a Nafion® catalyst coated membrane with a platinum loading of 0.5 mg/cm2 both for the anode and the cathode. Moreover, in order to better understand the polarization phenomena during the running of the FC, impedance spectroscopy was carried out in galvanostatic mode at different current densities. In particular, the effect of the air relative humidity (RH 100%, 80%, and 60%) was investigated, while the hydrogen was fed always fully humidified (100%). The WNW substrate has demonstrated to be superior to CC in a vast range of current densities (from open circuit voltage to 0.8 A/cm2). However, at high current density, the WNW GDM has some problems in water management.

Effects of Freezing and Thawing on the Structures of Porous Gas Diffusion Media

2007 ◽  
Author(s):  
Joaquin A. Pelaez ◽  
Satish G. Kandlikar
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Active Surface ◽  
Membrane Electrode Assembly ◽  
Gas Diffusion ◽  
Membrane Electrode ◽  
Active Surface Area ◽  
Freezing And Thawing ◽  
Diffusion Media ◽  
Cell Components

Fuel cells are a very promising technology for transportation applications in the future. Many companies are performing research in order to make the implementation of fuel cell-powered vehicles more feasible. One issue that needs to be addressed is the fact that fuel cell vehicles will be used in sub-freezing climates. Vehicles undergo frequent shut down and startup events, and as such, freezing and thawing effects on fuel cell components become important when the vehicle is stored overnight in cold climates. When shut off, fuel cells will maintain water in the membrane electrode assembly (MEA) and gas diffusion media unless certain purging protocols are adhered to. When the cell is subjected to sub-freezing temperatures, the water remaining in these media will freeze. This freezing could have a detrimental impact on the pore structure, fiber integrity, and binder effectiveness in the GDL, thereby decreasing the electrochemical active surface area of the electrolytes and hurting the overall performance of the cell. This paper details the prior research in the area of freezing and thawing effects in these media and also details current research on the degradation of the GDL specifically.

Effect of Sub-Freezing Temperature on a PEM Fuel Cell

2006 ◽  
Author(s):  
Q. G. Yan ◽  
H. Toghiani
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Cold Start ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Operating Conditions ◽  
Normal Operation ◽  
Subzero Temperatures ◽  
Wide Range ◽  
Backing Layer

The cold-start behavior and the effect of subzero temperatures on fuel cell performance were studied using a 25-cm2 PEMFC. The fuel cell system was housed in an environmental chamber that allowed the system to be subjected to temperatures ranging from sub-freezing to those encountered during normal operation. Fuel cell cold-start was investigated under a wide range of operating conditions. The cold-start measurements showed that the cell was capable of starting operation at −5 °C without irreversible performance loss when the cell was initially dry. The fuel cell was also able to operate at low environmental temperatures, down to −15 °C. However, irreversible performance losses were found if the cell cathode temperature fell below −5 °C during operation. Freezing of the water generated by fuel cell operation damaged fuel cell internal components. Several low temperature failure cases were investigated in PEM fuel cells that underwent sub-zero start and operation from −20 °C. Cell components were removed from the fuel cells and analyzed with scanning electron microscopy (SEM). Significant damage to the MEA and backing layer was observed in these components after operation below −5 °C. Catalyst layer delamination from both the membrane and the gas diffusion layer (GDL) was observed, as were cracks in the membrane, leading to hydrogen crossover. The membrane surface became rough and cracked and pinhole formation was observed in the membrane after operation at subzero temperatures. Some minor damage was observed to the backing layer coating Teflon and binder structure due to ice formation during operation.

Modeling Water Content Distribution in the Polymer Electrolyte Membrane of PEM Fuel Cell

2011 ◽  
Author(s):  
Bahareh Alsadat Tavakoli ◽  
Ramin Roshandel
Keyword(s):  
Fuel Cell ◽  
Water Content ◽  
Current Density ◽  
Pem Fuel Cell ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Cell Polarization ◽  
Proton Exchange ◽  
Membrane Electrode ◽  
Isothermal Model

Models play an important role in fuel cell design and development. One of the critical problems to overcome in the proton exchange membrane (PEM) fuel cells is the water management. In this work a steady state, two dimensional, isothermal model in a single PEM fuel cell using individual computational fluid dynamics code was presented. Special attention was devoted to the water transport through the membrane which is assumed to be combined effect of diffusion, electro osmotic drag and convection. The effect of current density variation distribution on the Water content (λ) in membrane/electrode assembly (MEA) was determined. After that detailed distribution of oxygen concentration, water content in membrane, net water flux and different overpotentials were calculated. Simulation results show that the reduction of reactant concentration in flow channels has a significant effect on electrochemical reaction in the gas diffusion and catalyst layer. Different fluxes are compared to investigate the effect of operating condition on the water fluxes in membrane. The amount of different fluxes is a strong function of current density which is related to external load. The model prediction of water content curves are compared with one dimensional model predictions data reported in the validated open literature and good compatibility were observed. In addition, the model predicted fuel cell polarization curves compared well with experimental and numerical data.

Stack Compression of PEM Fuel Cells

2004 ◽  
Author(s):  
Yeh-Hung Lai ◽  
Daniel P. Miller ◽  
Chunxin Ji ◽  
Thomas A. Trabold
Keyword(s):  
Fuel Cell ◽  
Membrane Electrode Assembly ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Membrane Electrode ◽  
Gas Diffusion Layers ◽  
Dimensional Changes ◽  
Diffusion Layers ◽  
Wide Range ◽  
Electrolyte Membranes

The effect of dimensional changes of fuel cell components from temperature and hydration cycles on the stack compression is investigated in this paper. Using a simple spring model including the membrane electrode assembly (MEA), gas diffusion layers (GDL), bipolar plates, seal gaskets, current collectors, insulation plates, end plates, and side plates, we find significant compression changes from 30% over-compression to 23% compression loss from both temperature and humidity changes. The wide range of variation in stack compression is attributed to the swelling behavior of polymer electrolyte membranes, the compression behavior of gas diffusion layers, and the design of stack assembly. This paper also reports the use of finite element method to investigate the compression of MEA and GDL over the channel area where MEA buckling from membrane swelling can result in separation of MEA and GDL. It is suggested that the compression over channels can be improved with higher transverse shear modulus in the GDL in addition to the use of narrower channels. In this paper, we will also discuss the challenges facing the fuel cell manufacturers and component suppliers on the needs for new materials with improved mechanical properties and better testing/modeling techniques to help achieving stable compression and better fuel cell stack designs.

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