scholarly journals Analysis of Fuel Cell Stack Performance Attenuation and Individual Cell Voltage Uniformity Based on the Durability Cycle Condition

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1199
Author(s):  
Chunjuan Shen ◽  
Sichuan Xu ◽  
Yuan Gao
Keyword(s):  
Fuel Cell ◽  
Current Density ◽  
Individual Cell ◽  
Cell Voltage ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Variation Coefficient ◽  
Fuel Cell Stack ◽  
Cycle Condition ◽  
Attenuation Rate

Based on the dynamic cycle condition test of a 4.5 kW fuel cell stack, the performance attenuation and individual cell voltage uniformity of the proton exchange membrane fuel cell (PEMFC) stack was evaluated synthetically. The performance decay period of the fuel cell stack was 180–600 h, the decrease of voltage and power was evaluated by rate and amplitude. The results show that the performance of the fuel cell stack decreased with the increase of test time and current density. When the test was carried out to 600 h, under rated operating conditions, the voltage attenuation rate was 130 μV/h, and the voltage reduced by 71 mV, with a decrease of 10.41%. The power attenuation rate was 0.8 W/h, with a decrease of 10.42%. The statistical parameter variation coefficient was used to characterize the voltage consistency of individual cells. It was found that the voltage uniformity is worse at the high current density point and with a long-running process. The variation coefficient was 3.1% in the worst performance.

Parameterization of Fuel Cell Stack Voltage: Issues on Sensitivity, Cell-to Cell Variation, and Transient Response

2006 ◽  
Author(s):  
Arlette L. Schilter ◽  
Denise A. McKay ◽  
Anna G. Stefanopoulou
Keyword(s):  
Fuel Cell ◽  
Cell Voltage ◽  
Cell System ◽  
Cell Polarization ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Water Dynamics ◽  
Lumped Parameter Model ◽  
Experimental Methodology ◽  
Fuel Cell Stack

We present here a calibrated and experimentally validated lumped parameter model of fuel cell polarization for a hydrogen fed multi-cell, low-pressure, proton exchange membrane (PEM) fuel cell stack. The experimental methodology devised for calibrating the model was completed on a 24 cell, 300 cm2 stack with GORE™ PRIMERA® Series 5620 membranes. The predicted cell voltage is a static function of current density, stack temperature, reactant partial pressures, and membrane water content. The maximum prediction error associated with the sensor resolutions used for the calibration is determined along with a discussion of the model sensitivity to physical variables. The expected standard deviation due to the cell-to-cell voltage variation is also modelled. In contrast to other voltage models that match the observed dynamic voltage behavior by adding unreasonably large double layer capacitor effects or by artificially adding dynamics to the voltage equation, we show that a static model can be used when combined with dynamically resolved variables. The developed static voltage model is then connected with a dynamic fuel cell system model that includes gas filling dynamics, diffusion and water dynamics and we demonstrate the ability of the static voltage equation to predict important transients such as reactant depletion and electrode flooding. It is shown that the model can qualitatively predict the observed stack voltage under various operating conditions including step changes in current, temperature variations, and anode purging.

An Efficient Approximation Method for an Individual Fuel Cell Impedance Characterization

2010 ◽  
Author(s):  
Taehee Han ◽  
Tessa A. Haagenson ◽  
Hossein Salehfar ◽  
Samir Dahal ◽  
Mike D. Mann
Keyword(s):  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Individual Cell ◽  
Cell Voltage ◽  
Pem Fuel Cell ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Experimental Result ◽  
Pure Hydrogen ◽  
Cell Impedance

In this study, an efficient method of approximating individual fuel cell impedances in a stack is proposed and experimentally verified. Two different proton exchange membrane (PEM) fuel cell stacks (600 W with 24 cells and 1.2 kW with 47 cells) were used to develop and verify the method. Both PEM fuel cell stacks were operated using room air and pure hydrogen (99.999%). Impedance and current - voltage (I-V) data were collected for stack and individual cell levels under various operating conditions. The experimental result shows that the individual cell impedance is directly proportional to the corresponding cell voltage. Therefore individual cell impedance can be accurately estimated by performing only stack impedance and individual cell voltage measurements.

The Effects of Feeding Configurations to Water Flooding and General Performance of a Proton Exchange Membrane Fuel Cell

2005 ◽  
Author(s):  
A. B. Mahmud Hasan ◽  
S. M. Guo ◽  
S. V. Ekkad
Keyword(s):  
Fuel Cell ◽  
Power Density ◽  
Current Density ◽  
Proton Exchange Membrane ◽  
Cell Voltage ◽  
Bipolar Plate ◽  
Proton Exchange ◽  
Water Flooding ◽  
Cathode Side ◽  
Exchange Membrane

The performance of a Proton Exchange Membrane Fuel Cell (PEMFC) using different feeding configurations has been studied. Three bipolar plates, namely serpentine, straight channel and interdigitated designs, were arranged in different combinations for the PEMFC anode and cathode sides. Nine combinations in total were tested under different flow rates, working temperatures and loadings. The cell voltage versus current density and the cell power density versus current density curves were obtained. After operating the PEMFC under high current densities, the cell was split and the water flooding in the feeding channels was visually inspected. Experimental results showed that for different feeding configurations, interdigitated bipolar plate in anode side and serpentine bipolar plate in cathode side had the best performance in terms of cell voltage-current density curve, power density output rate, percentage of flooded area in the feeding channels, the pattern of flooding and the fuel utilization rate.

scholarly journals Effect of compressive force on the performance of a proton exchange membrane fuel cell

2007 ◽  
Vol 221 (9) ◽  
pp. 1067-1074 ◽  
Author(s):  
T Ous ◽  
C Arcoumanis
Keyword(s):  
Fuel Cell ◽  
Mass Transport ◽  
Current Density ◽  
Proton Exchange Membrane ◽  
Compressive Force ◽  
Cell Voltage ◽  
Proton Exchange ◽  
Excessive Pressure ◽  
Transport Region ◽  
Exchange Membrane

The effect of the compressive force on the performance of a proton exchange membrane fuel cell has been examined experimentally. The performance has been evaluated on two polarization regions of the cell: ohmic and mass transport. Cell voltage and current density as a function of pressure were measured under constant load and various inlet air humidity conditions. The pressure distribution on the surface of the gas diffusion layer was measured using a pressure detection film and the results show that increasing the pressure improves the performance of the cell. The improvement of the cell voltage in the ohmic region was found to be greater than that in the mass transport region, whereas for the cell current density, the mass transport region exhibited higher change. The increase in the cell specific power in the ohmic and mass transport regions, as pressure increases from 0 to 2MNm-2, is estimated to be 9 and 18mWcm−2, respectively. However, the fuel cell performance in these two regions declined dramatically when excessive pressure (≥5 MNm−2) was applied. The mass transport region proved to be more susceptible to this sharp decline under excessive pressure than the ohmic region.

An Analytical Solution to Predict the Inception of Two-Phase Flow in a Proton Exchange Membrane Fuel Cell

2010 ◽  
Vol 7 (6) ◽  
Author(s):  
A. S. Bansode ◽  
T. Sundararajan ◽  
Sarit K. Das
Keyword(s):  
Fuel Cell ◽  
Analytical Model ◽  
Current Density ◽  
Proton Exchange Membrane ◽  
Two Phase Flow ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Phase Flow ◽  
Two Phase ◽  
Exchange Membrane

The presence of liquid water at the cathode of proton exchange membrane fuel cell hinders the reactant supply to the electrode and is known as electrode flooding. The flooding at the cathode due to the presence of two-phase flow of water is one of the major performance limiting conditions. A pseudo-two-dimensional analytical model is developed to predict the inception of two-phase flow along the length of the cathode channel. The diffusion of the water is considered to take place only across the gas diffusion layer (GDL). The current density corresponding to the inception of two-phase flow, called the threshold current density, is found to be a function of the channel length and height, GDL thickness, velocity, and relative humidity of the air at the inlet and cell temperature. Thus, for given design and operating conditions, the analytical model is capable of predicting the inception of two-phase flow, and therefore a flooding condition can be avoided in the first place.

scholarly journals High Temperature Water Electrolysis Using Metal Supported Solid Oxide Electrolyser Cells (SOEC)

2010 ◽  
Vol 72 ◽  
pp. 135-143 ◽  
Author(s):  
Günter Schiller ◽  
Asif Ansar ◽  
Olaf Patz
Keyword(s):  
High Temperature ◽  
Fuel Cell ◽  
Current Density ◽  
Degradation Rate ◽  
Cell Voltage ◽  
Operating Conditions ◽  
Solid Oxide ◽  
Metallic Interconnect ◽  
A Current

Metal supported cells as developed at DLR for use as solid oxide fuel cells by applying plasma deposition technologies were investigated in operation of high temperature steam electrolysis. The cells consisted of a porous ferritic steel support, a diffusion barrier layer, a Ni/YSZ fuel electrode, a YSZ electrolyte and a LSCF oxygen electrode. During fuel cell and electrolysis operation the cells were electrochemically characterised by means of i-V characteristics and electrochemical impedance spectroscopy measurements including a long-term test over 2000 hours. The results of electrochemical performance and long-term durability tests of both single cells and single repeating units (cell including metallic interconnect) are reported. During electrolysis operation at an operating temperature of 850 °C a cell voltage of 1.28 V was achieved at a current density of -1.0 A cm-2; at 800 °C the cell voltage was 1.40 V at the same operating conditions. The impedance spectra revealed a significantly enhanced polarisation resistance during electrolysis operation compared to fuel cell operation which was mainly attributed to the hydrogen electrode. During a long-term test run of a single cell over 2000 hours a degradation rate of 3.2% per 1000 hours was observed for operation with steam content of 43% at 800 °C and a current density of -0.3 Acm-2. Testing of a single repeating unit proved that a good contacting of cell and metallic interconnect is of major importance to achieve good performance. A test run over nearly 1000 hours showed a remarkably low degradation rate.

scholarly journals Measurement of polarization curve and development of a unique semi empirical model for description of PEMFC and DMFC performances

2011 ◽  
Vol 17 (2) ◽  
pp. 207-214 ◽  
Author(s):  
T. Selyari ◽  
A.A. Ghoreyshi ◽  
M. Shakeri ◽  
G.D. Najafpour ◽  
T. Jafary
Keyword(s):  
Experimental Data ◽  
Fuel Cells ◽  
Fuel Cell ◽  
Current Density ◽  
Power Output ◽  
Cell Voltage ◽  
Operating Conditions ◽  
Cell Performance ◽  
Oxygen Stoichiometry ◽  
Semi Empirical

In this study, a single polymer electrolyte membrane fuel cell (PEMFC) in H2/O2 form with an effective dimension of 5?5 cm as well as a single direct methanol fuel cell (DMFC) with a dimension of 10?10 cm were fabricated. In an existing test station, the voltage-current density performances of the fabricated PEMFC and DMFC were examined under various operating conditions. As was expected DMFC showed a lower electrical performance which can be attributed to the slower methanol oxidation rate in comparison to the hydrogen oxidation. The results obtained from the cell operation indicated that the temperature has a great effect on the cell performance. At 60?C, the best power output was obtained for PEMFC. There was a drop in the cell voltage beyond 60?C which can be attributed to the reduction of water content inside the membrane. For DMFC, maximum power output was resulted at 64oC. Increasing oxygen stoichiometry and total cell pressure had a marginal effect on the cell performance. The results also revealed that the cell performance improved by increasing pressure differences between anode and cathode. A unified semi-empirical thermodynamic based model was developed to describe the cell voltage as a function of current density for both kinds of fuel cells. The model equation parameters were obtained through a nonlinear fit to the experimental data. There was a good agreement between the experimental data and the model predicted cell performance for both types of fuel cells.

scholarly journals Investigation on the Operating Conditions of Proton Exchange Membrane Fuel Cell Based on Constant Voltage Cold Start Mode

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 660
Author(s):  
Yanbo Yang ◽  
Tiancai Ma ◽  
Boyu Du ◽  
Weikang Lin ◽  
Naiyuan Yao
Keyword(s):  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Great Influence ◽  
Cell Voltage ◽  
Cold Start ◽  
High Heat ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Constant Voltage ◽  
Start Up

The cold start property is one of the main factors restricting the fuel cell application in the automotive field. The constant voltage cold start method of the fuel cell works under low start voltage and produces high heat, which can shorten the start-up time of the fuel cell at low temperature and has the opportunity to be applied to fuel cell vehicles. Meanwhile, in the constant voltage cold start mode, the fuel cell needs to operate under a large current, and more water is generated during the start-up process. Thus, the optimization of operating conditions for the constant voltage cold start is particularly important. However, there are relatively few studies on the optimization of operating conditions for the constant voltage cold start with a single-cell voltage less than 0.3 V. In this work, the cold start experiment of the fuel cell with constant voltage is carried out. According to the cold start experiment, the different cold start voltage, back-pressure, and the inlet flow rate are examined. Based on the experiment data, the operating conditions have a great influence on the cold start property of the fuel cell and the optimized operating conditions of the constant voltage cold start are obtained.

Simplified Model to Predict Incipient Flooding/Dehydration in Proton Exchange Membrane Fuel Cells

2006 ◽  
Vol 4 (3) ◽  
pp. 357-364 ◽  
Author(s):  
S. Maharudrayya ◽  
S. Jayanti ◽  
A. P. Deshpande
Keyword(s):  
Fuel Cell ◽  
Current Density ◽  
Proton Exchange Membrane ◽  
Multicomponent Diffusion ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Balance Model ◽  
Closed Form Expression ◽  
Flow Channels ◽  
Exchange Membrane

Proper water management is critical for near-ambient temperature operation of a fuel cell. A simplified water balance model has been developed to predict when incipient flooding/dehydration may take place. The present model is based on multicomponent diffusion in the electrodes and molar balance in the flow channels. The overall model is in the form of a closed-form expression for the critical or threshold or balance current density at which the water production rate and the water vapor evacuation rate are exactly balanced. The model incorporates the influence of the operating conditions, properties of electrodes, and flow and geometric parameters in the gas channels on the balance current density. Predictions from the model of the state—incipient flooding or dehydration—of operation of the fuel cell agree well with the available experimental data. Using the model, a parametric study has been conducted over a range of parameters.

Modeling and Experimental Analyses of a Two-Cell Polymer Electrolyte Membrane Fuel Cell Stack Emphasizing Individual Cell Characteristics

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Sang-Kyun Park ◽  
Song-Yul Choe
Keyword(s):  
Fuel Cell ◽  
Polymer Electrolyte ◽  
Individual Cell ◽  
Polymer Electrolyte Membrane ◽  
Pem Fuel Cell ◽  
Operating Conditions ◽  
Experimental Results ◽  
Fuel Cell Stack ◽  
Electrolyte Membrane ◽  
The Individual

Performance of individual cells in an operating polymer electrolyte membrane (PEM) fuel cell stack is different from each other because of inherent manufacturing tolerances of the cell components and unequal operating conditions for the individual cells. In this paper, first, effects of different operating conditions on performance of the individual cells in a two-cell PEM fuel cell stack have been experimentally investigated. The results of the experiments showed the presence of a voltage difference between the two cells that cannot be manipulated by operating conditions. The temperature of the supplying air among others predominantly influences the individual cell voltages. In addition, those effects are explored by using a dynamic model of a stack that has been developed. The model uses electrochemical voltage equations, dynamic water balance in the membrane, energy balance, and diffusion in the gas diffusion layer, reflecting a two-phase phenomenon of water. Major design parameters and an operating condition by conveying simulations have been changed to analyze sensitivity of the parameters on the performance, which is then compared with experimental results. It turns out that proton conductivity of the membrane in cells among others is the most influential parameter on the performance, which is fairly in line with the reading from the experimental results.

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