Effect of Operating Parameters on the DMFC Performance

2004 ◽  
Vol 2 (2) ◽  
pp. 81-85 ◽  
Author(s):  
Guo-Bin Jung ◽  
Ay Su ◽  
Cheng-Hsin Tu ◽  
Fang-Bor Weng
Keyword(s):  
Concentration Polarization ◽  
Solution Concentration ◽  
Open Circuit ◽  
Methanol Solution ◽  
Operating Conditions ◽  
Cell Performance ◽  
Membrane Electrode ◽  
Membrane Thickness ◽  
Methanol Crossover ◽  
Cell Temperature

Methanol crossover largely affects the efficiency of power generation in the direct methanol fuel cell. As the methanol crosses over through the membrane, the methanol oxidizes at the cathode, resulting in low fuel utilization and in a serious overpotential loss. In this study, the commercial membrane electrode assemblies (MEAs) are investigated with different operating conditions such as membrane thickness, cell temperature, and methanol solution concentration. The effects of these parameters on methanol crossover and power density are studied. With the same membrane, increasing the cell temperature promotes the cell performance as expected, and the lower methanol concentration causes the concentration polarization effects, thus resulting in lower cell performance. Although higher methanol solution concentration can overcome the concentration polarization, a serious methanol crossover decreases the cell performance at high cell temperature. In this study, the open circuit voltage (OCV) is inversely proportional to methanol solution concentration, and is proportional to membrane thickness and cell temperature. Although increasing membrane thickness lowers the degree of methanol crossover, on the other hand, the ohmic resistance increases simultaneously. Therefore, the cell performance using Nafion 117 as membrane is lower than that of Nafion 112. In addition, the performance of the MEA made in our laboratory is higher than the commercial product, indicating the capability of manufacturing MEA is acceptable.

Nafion/PBI Nanofiber Composite Membranes for Fuel Cells Applications

2010 ◽  
Author(s):  
Tzyy-Lung Leon Yu ◽  
Shih-Hao Liu ◽  
Hsiu-Li Lin ◽  
Po-Hao Su
Keyword(s):  
Thin Film ◽  
Fuel Cell ◽  
Composite Membrane ◽  
Fiber Composite ◽  
Composite Membranes ◽  
Cell Performance ◽  
Membrane Electrode ◽  
Membrane Thickness ◽  
Fuel Cell Performance ◽  
Nano Fiber

The PBI (poly(benzimidazole)) nano-fiber thin film with thickness of 18–30 μm is prepared by electro-spinning from a 20 wt% PBI/DMAc (N, N′-dimethyl acetamide) solution. The PBI nano-fiber thin film is then treated with a glutaraldehyde liquid for 24h at room temperature to proceed chemical crosslink reaction. The crosslink PBI nano-fiber thin film is then immersed in Nafion solutions to prepare Nafion/PBI nano-fiber composite membranes (thickness 22–34 μm). The morphology of the composite membranes is observed using a scanning electron microscope (SEM). The mechanical properties, conductivity, and unit fuel cell performance of membrane electrode assembly (MEA) of the composite membrane are investigated and compared with those of Nafion-212 membrane (thickness ∼50 μm) and Nafion/porous PTFE (poly(tetrafluoro ethylene)) composite membrane (thickness ∼22 μm). We show the present composite membrane has a similar fuel cell performance to Nafion/PTFE and a better fuel cell performance than Du Pont Nafion-212.

scholarly journals The Effect of Cell Compression and Cathode Pressure on Hydrogen Crossover in PEM Water Electrolysis

2021 ◽  
Author(s):  
Agate Martin ◽  
Patrick Trinke ◽  
Markus Stähler ◽  
Andrea Stähler ◽  
Fabian Scheepers ◽  
...  
Keyword(s):  
Mass Transport ◽  
Cell Voltage ◽  
Water Electrolysis ◽  
Material Design ◽  
Operating Conditions ◽  
Cell Performance ◽  
Membrane Electrode ◽  
Current Densities ◽  
Hydrogen Crossover ◽  
The Impact

Abstract Hydrogen crossover poses a crucial issue for polymer electrolyte membrane (PEM) water electrolysers in terms of safe operation and efficiency losses, especially at increased hydrogen pressures. Besides the impact of external operating conditions, the structural properties of the materials also influence the mass transport within the cell. In this study, we provide an analysis of the effect of elevated cathode pressures (up to 15 bar) in addition to increased compression of the membrane electrode assembly on hydrogen crossover and the cell performance, using thin Nafion 212 membranes and current densities up to 3.6 A cm-2. It is shown that a higher compression leads to increased mass transport overpotentials, although the overall cell performance is improved due to the decreased ohmic losses. The mass transport limitations also become visible in enhanced anodic hydrogen contents with increasing compression at high current densities. Moreover, increases in cathode pressure are amplifying the compression effect on hydrogen crossover and mass transport losses. The results indicate that the cell voltage should not be the only criterion for optimizing the system design, but that the material design has to be considered for the reduction of hydrogen crossover in PEM water electrolysis.

scholarly journals An experimental investigation of solid oxide fuel cell performance at variable operating conditions

2016 ◽  
Vol 20 (5) ◽  
pp. 1421-1433 ◽  
Author(s):  
Ismet Tikiz ◽  
Imdat Taymaz
Keyword(s):  
Fuel Cell ◽  
Flow Rate ◽  
Operating Conditions ◽  
Solid Oxide ◽  
Cell Performance ◽  
Oxide Fuel ◽  
Nitrogen Flow ◽  
Cell Temperature ◽  
Hydrogen Flow ◽  
Fuel Cell Performance

Cell temperature and selection of the reactant gases are crucial parameters for the design and optimization of fuel cell performance. In this study, effect of operating conditions on the performance of Solid Oxide Fuel (SOFC) has been investigated. Application of Response Surface Methodology (RSM) was applied to optimize operations conditions in SOFC. For this purpose, an experimental set up for testing of SOFC has been established to investigate the effect of Hydrogen, Oxygen, Nitrogen flow rates and cell temperature parameters on cell performance. Hydrogen flow rate, oxygen flow rate, nitrogen flow rate and cell temperature were the main parameters considered and they were varied between 0.25 and 1 L/min, 0.5 and 1 L/min, 0 and 1 L/min and 700-800 oC in the analyses respectively. The maximum power density was found as 0.572 W/cm2 in the experiments.

scholarly journals Optimization of Membrane Electrode Assembly of PEM Fuel Cell by Response Surface Method

Molecules ◽  
2019 ◽  
Vol 24 (17) ◽  
pp. 3097 ◽  
Author(s):  
Vuppala ◽  
Chedir ◽  
Jiang ◽  
Chen ◽  
Aziz ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Response Surface ◽  
Response Surface Method ◽  
Current Density ◽  
Membrane Electrode Assembly ◽  
Proton Exchange ◽  
Cell Performance ◽  
Membrane Electrode ◽  
Membrane Thickness ◽  
Surface Method

The membrane electrode assembly (MEA) plays an important role in the proton exchange membrane fuel cell (PEMFC) performance. Typically, the structure comprises of a polymer electrolyte membrane sandwiched by agglomerate catalyst layers at the anode and cathode. Optimization of various parameters in the design of MEA is, thus, essential for reducing cost and material usage, while improving cell performance. In this paper, optimization of MEA is performed using a validated two-phase PEMFC numerical model. Key MEA parameters affecting the performance of a single PEMFC are determined from sensitivity analysis and are optimized using the response surface method (RSM). The optimization is carried out at two different operating voltages. The results show that membrane thickness and membrane protonic conductivity coefficient are the most significant parameters influencing cell performance. Notably, at higher voltage (0.8 V per cell), the current density can be improved by up to 40% while, at a lower voltage (0.6 V per cell), the current density may be doubled. The results presented can be of importance for fuel cell engineers to improve the stack performance and expedite the commercialization.

Effects of Operating Parameters and Loading Modes on the Dynamic Cell Performance of PEM Fuel Cells

2012 ◽  
Vol 532-533 ◽  
pp. 135-139
Author(s):  
Han Chieh Chiu ◽  
Jer Huan Jang ◽  
Wei Mon Yan ◽  
Chun I Lee ◽  
Chang Chung Yang
Keyword(s):  
Fuel Cell ◽  
Pem Fuel Cell ◽  
Pem Fuel Cells ◽  
Operating Conditions ◽  
Cell Performance ◽  
Optimal Conditions ◽  
Cell Temperature ◽  
Dynamic Loadings ◽  
Dynamic Cell ◽  
Loading Modes

This paper experimentally investigates the dynamic response of a single fuel cell under various dynamic loadings with different operating conditions. Three kinds of loadings are applied to the PEM fuel cell and they are simulated NEDC mode, simulated 10/15 mode, and modified mode. The operating conditions are set at different cell temperatures, humidification temperatures, and stoichiometric rates during each test to study the effects of these parameters on the cell performance of a PEM fuel cell. The cell performance is found increased with increasing cell temperature in the range of 45-65°C. On the other hand, there exist optimal conditions for the humidification temperature and the stoichiometric rate at 70°C/60°C and 1.5/2.0 on the anode and cathode sides, respectively.

scholarly journals Experimental Study on the Effect of Hydrogen Sulfide on High-Temperature Proton Exchange Membrane Fuel Cells by Using Electrochemical Impedance Spectroscopy

Catalysts ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 441 ◽  
Author(s):  
Ren-Jun Kang ◽  
Yong-Song Chen
Keyword(s):  
Hydrogen Sulfide ◽  
High Temperature ◽  
Proton Exchange Membrane ◽  
Electrochemical Impedance ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Cell Performance ◽  
Membrane Electrode ◽  
Pure Hydrogen ◽  
Exchange Membrane

When the fuel supplied to a high-temperature proton exchange membrane fuel cell (HT-PEMFC) is produced by hydrocarbon formation, hydrogen sulfide (H2S) may appear, resulting in decreased cell performance and durability. To study the effects of H2S on the performance and durability of the HT-PEMFC, a series of experiments was conducted. In the first step, the effects of polyvinylidene fluoride (PVDF) and platinum loading on cell performance were investigated and discussed under pure hydrogen operation conditions. Optimal PVDF and platinum compositions in the catalyst layer are suggested. Then, the effect of H2S on membrane electrode assembly (MEA) performance with various platinum loadings was investigated by supplying hydrogen containing 5.2 ppm of H2S to the anode of the MEA. An electrochemical impedance spectroscope was employed to measure the impedance of the MEAs under various operating conditions. Finally, degradation of the MEA when supplied with hydrogen containing 5.2 ppm of H2S was analyzed and discussed. The results suggest that the performance of an MEA with 0.7 mg Pt cm−2 and 10% PVDF can be recovered by supplying pure hydrogen. The rate of voltage decrease is around 300 μV h−1 in the presence of H2S.

Supported Nafion Membrane for Direct Methanol Fuel Cell

2006 ◽  
Vol 4 (3) ◽  
pp. 248-254 ◽  
Author(s):  
Guo-Bin Jung ◽  
Ay Su ◽  
Cheng-Hsin Tu ◽  
Fang-Bor Weng ◽  
Shih-Hung Chan ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Direct Methanol Fuel Cells ◽  
Open Circuit ◽  
Nafion Membrane ◽  
Membrane Thickness ◽  
Methanol Crossover ◽  
Negative Effects ◽  
Mechanical Reinforcement ◽  
Direct Methanol ◽  
Methanol Fuel Cells

The performances of direct methanol fuel cells are largely dependent on the methanol crossover, while the amount of methanol crossover is reported to strongly rely on membrane materials and thickness. In this research, two new membranes (Nafion 211 and Nx-424), along with well-known Nafion 117 and 112 were studied as electrolytes in the direct methanol fuel cells (DMFC). The Nafion 211 is the thinnest and latest membrane of Nafion series products and Nx-424 is a Nafion membrane with polytetrafluoroethylene (PTFE) fibers as mechanical reinforcement. Nx-424 is used primarily for chloro-alkali production and the electrolytic processes. Although open circuit voltage provides a quick way to evaluate the effect of methanol crossover, the amount of methanol crossover through the membranes was studied in detail via the electrochemical oxidation technique. Both methods show the same trend of methanol crossover of different membranes in this study. Nafion 211 was found to present the highest degree of methanol crossover, however, its’ best performance implied the fact that the influence of the cell resistance (membrane thickness) is dominated in the traditional Nafion system. Although Nafion membrane with thicker thickness and PTFE fiber within Nx-424 provided higher resistance for methanol to cross through, the negative effects of its’ hydrophobic properties also prevent the transport of H2O accompanied by the proton. Therefore, the cell performance of Nx-424 is lower both due to poor proton conductivity and thickest membrane. In other words, the cell performances of traditional Nafion series membranes (Nafion 211, 112, 117) were fully controlled by the thickness while Nx-424 was controlled both by its’ blend properties (hydrophilic-Nafion and hydrophobic-PTFE ) and thickness.

scholarly journals Methanol Electrolysis for Hydrogen Production Using Polymer Electrolyte Membrane: A Mini-Review

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5879
Author(s):  
Sethu Sundar Pethaiah ◽  
Kishor Kumar Sadasivuni ◽  
Arunkumar Jayakumar ◽  
Deepalekshmi Ponnamma ◽  
Chandra Sekhar Tiwary ◽  
...  
Keyword(s):  
Polymer Electrolyte ◽  
Polymer Electrolyte Membrane ◽  
Pem Fuel Cells ◽  
H2 Production ◽  
Operating Conditions ◽  
Catalyst Loading ◽  
Membrane Electrode ◽  
Membrane Thickness ◽  
Electrolyte Membrane ◽  
The Impact

Hydrogen (H2) has attained significant benefits as an energy carrier due to its gross calorific value (GCV) and inherently clean operation. Thus, hydrogen as a fuel can lead to global sustainability. Conventional H2 production is predominantly through fossil fuels, and electrolysis is now identified to be most promising for H2 generation. This review describes the recent state of the art and challenges on ultra-pure H2 production through methanol electrolysis that incorporate polymer electrolyte membrane (PEM). It also discusses about the methanol electrochemical reforming catalysts as well as the impact of this process via PEM. The efficiency of H2 production depends on the different components of the PEM fuel cells, which are bipolar plates, current collector, and membrane electrode assembly. The efficiency also changes with the nature and type of the fuel, fuel/oxygen ratio, pressure, temperature, humidity, cell potential, and interfacial electronic level interaction between the redox levels of electrolyte and band gap edges of the semiconductor membranes. Diverse operating conditions such as concentration of methanol, cell temperature, catalyst loading, membrane thickness, and cell voltage that affect the performance are critically addressed. Comparison of various methanol electrolyzer systems are performed to validate the significance of methanol economy to match the future sustainable energy demands.

scholarly journals Effects of Cell Temperature and Reactant Humidification on Anion Exchange Membrane Fuel Cells

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2048
Author(s):  
Van Men Truong ◽  
Ngoc Bich Duong ◽  
Chih-Liang Wang ◽  
Hsiharng Yang
Keyword(s):  
Anion Exchange ◽  
High Performance ◽  
Water Concentration ◽  
Gas Diffusion ◽  
Anion Exchange Membrane ◽  
Operating Conditions ◽  
Cell Performance ◽  
Cell Temperature ◽  
Exchange Membrane ◽  
Gas Humidification

The performance of an anion exchange membrane fuel cell (AEMFC) under various operating conditions, including cell temperature and humidification of inlet gases, was systematically investigated in this study. The experimental results indicate that the power density of an AEMFC is susceptible to the cell temperature and inlet gas humidification. A high performance AEMFC can be achieved by elevating the cell operating temperature along with the optimization of the gas feed dew points at the anode and cathode. As excess inlet gas humidification at the anode is supplied, the flooding is less severe at a higher cell temperature because the water transport in the gas diffusion substrate by evaporation is more effective upon operation at a higher cell temperature. The cell performance is slightly affected when the humidification at the anode is inadequate, owing to dehydration of the membrane, especially at a higher cell temperature. Furthermore, the cell performance in conditions of under-humidification or over-humidification at the cathode is greatly reduced at the different cell temperatures tested due to the dehydration of the anion exchange membrane and the water shortage or oxygen mass transport limitations, respectively, for the oxygen reduction reaction. In addition, back diffusion could partly support the water demand at the cathode once a water concentration gradient between the anode and cathode is formed. These results, in which sophisticated water management was achieved, can provide useful information regarding the development of high-performance AEMFC systems.

How do Buffer Layers Affect Solar Cell Performance and Solar Cell Stability?

2001 ◽  
Vol 668 ◽  
Author(s):  
Bolko von Roedern
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Carrier Transport ◽  
Open Circuit ◽  
Operating Conditions ◽  
Cell Performance ◽  
Buffer Layers ◽  
Limiting Current ◽  
Solar Cell Performance ◽  
A Cell

ABSTRACTBuffer layers are commonly used in the optimization of thin-film solar cells. For CuInSe2-and CdTe-based solar cells, multilayer transparent conductors (TCOs, e.g., ZnO or SnO2) are generally used in conjunction with a CdS heterojunction layer. Optimum cell performance is usually found when the TCO layer in contact with the CdS is very resistive or almost insulating. In addition to affecting the open-circuit voltage of a cell, it is commonly reported that buffer layers affect stress-induced degradation and transient phenomena in CdTe- and CuInSe2-based solar cells. In amorphous silicon solar cells, light-induced degradation has a recoverable and a nonrecoverable component too, and the details of the mechanism may depend on the p-type contact layer. Because of the similarity of transients and degradation in dissimilar material systems, it is suggested that degradation and recovery are driven by carriers rather than by diffusing atomic species. The question that must be addressed is why, not how, species diffuse and atomic configurations relax differently in the presence of excess carriers. In this paper, I suggest that the operating conditions of a cell can change the carrier transport properties. Often, excess carriers may enhance the conductance in localized regions (“filaments”) and buffer layers; limiting current flow into such filaments may therefore control the rate and amount of degradation (or recovery).

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