Modeling and Numerical Simulation of PEM Fuel Cell Transient

2010 ◽  
Author(s):  
Yun Wang ◽  
Pengtao Sun
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Pem Fuel Cells ◽  
Polymer Electrolyte Fuel Cells ◽  
Operating Conditions ◽  
Dynamic Responses ◽  
Density Distributions ◽  
Power Load ◽  
Electrochemical Double Layer ◽  
Detailed Picture

This paper develops a 3D dynamic model for polymer electrolyte fuel cells (PEFCs also called PEM fuel cells) and investigates the internal physicochemical processes that occur during PEFC transients as well as fuel cell dynamic responses. This model couples various dynamic mechanisms in the key components of PEFC, such as electrochemical double-layer discharging/charging, species transport, heat transfer, and membrane water uptake. The model is further discretized for 3D numerical simulations with focus on transient operation upon the step change in power density. The numerical results show that over/undershoot dynamic responses may take place during transient. A detailed picture of internal operating conditions, such as water and current density distributions, is presented to develop a comprehensive understanding of fuel cell transient during power/load variation.

Transients of Polymer Electrolyte Fuel Cell and Hydrogen Tank

2009 ◽  
Author(s):  
Yun Wang ◽  
Xiaoguang Yang
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Polymer Electrolyte ◽  
Dynamic Models ◽  
Cell Voltage ◽  
Polymer Electrolyte Fuel Cells ◽  
Dynamic Responses ◽  
Polymer Electrolyte Fuel Cell ◽  
Electrochemical Double Layer ◽  
The One

This paper seeks to develop 3D dynamic models for polymer electrolyte fuel cells (PEFCs) and hydrogen tanks, respectively. The dynamic model of PEFCs consists of multiple layers of a single PEFC and couples the various dynamic mechanisms in fuel cells, such as electrochemical double-layer discharging/charging, species transport, heat transfer, and membrane water uptake. The one of hydrogen tanks includes a 3D description of the hydride kinetics coupled with mass/heat transport in the hydrogen tank. Transient of fuel cell during step change in current is simulated. Dynamic responses of the cell voltage and heat generation rate are discussed. Hydrogen absorption process in the tank is considered. Temperature, reaction rate and heat rejection in the fuel tank are presented. Efforts are also made to discuss the coupling of these two systems in practice and associated issues.

Characterizing Performance of a PEM Fuel Cell for a CMET Balloon

2011 ◽  
Author(s):  
Denise A. McKahn ◽  
Whitney McMackin
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Mass Density ◽  
Pem Fuel Cell ◽  
Pem Fuel Cells ◽  
Cell Polarization ◽  
Operating Conditions ◽  
Design Parameters ◽  
Design System ◽  
Power Densities

We present the design of a multi-cell, low temperature PEM fuel cell for controlled meteorological balloons. Critical system design parameters that distinguish this application are the lack of reactant humidification and cooling due to the low power production, high required power mass-density and relatively short flight durations. The cell is supplied with a pressure regulated and dead ended anode, and flow controlled cathode at variable air stoichiometry. The cell is not heated and allowed to operate with unregulated temperature. Our prototype cell was capable of achieving power densities of 43 mW/cm2/cell or 5.4 mW/g. The cell polarization performance of large format PEM fuel cell stacks is an order of magnitude greater than for miniature PEM fuel cells. These performance discrepancies are a result of cell design, system architecture, and reactant and thermal management, indicating that there are significant gains to be made in these domains. We then present design modifications intended to enable the miniature PEM fuel cell to achieve power densities of 13 mW/g, indicating that additional performance gains must be made with improvements in operating conditions targeting achievable power densities of standard PEM fuel cells.

Thermodynamic Analysis of the Performance of an Irreversible PEMFC

2018 ◽  
Vol 388 ◽  
pp. 350-360 ◽  
Author(s):  
Chang Jie Li ◽  
Ye Liu ◽  
Zhe Shu Ma
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Pem Fuel Cells ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Operating Pressure ◽  
Controllable Factors ◽  
Temperature Operating ◽  
Exchange Membrane

An irreversible model of proton exchange membrane fuel cells working at steady-state is established, in which the irreversibility resulting from overpotentials, internal currents and leakage currents are taken into account．In this paper, the irreversibility of fuel cell is expounded mainly from electrochemistry. The general performance characteristic curves are generated including output voltage, output power and output efficiency. In addition, the irreversibility of a class of PEMFC is studied by changing the operating conditions (controllable factors) of the fuel cell, including effect of operating temperature, operating pressure and leakage current. The results provide a theoretical basis for both the operation and optimal design of real PEM fuel cells．

Analysis of Water Morphology in the Active Area and Channel-to-Manifold Transitions of a PEM Fuel Cell

2014 ◽  
Author(s):  
Daniel J. Fenton ◽  
Jeffrey J. Gagliardo ◽  
Thomas A. Trabold
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Flow Field ◽  
Current Density ◽  
Liquid Water ◽  
Pem Fuel Cells ◽  
Operating Conditions ◽  
Active Area ◽  
Water Volume ◽  
Crossover Point

To achieve optimal performance of proton exchange membrane (PEM) fuel cells, effective water management is crucial. Cells need to be fabricated to operate over wide ranges of current density and cell temperature. To investigate these design and operational conditions, the present experiment utilized neutron radiography for measurement of in-situ water volumes of operating PEM fuel cells under varying operating conditions. Fuel cell performance was found to be generally inversely correlated to liquid water volume in the active area. High water concentrations restrict narrow flow field channels, limiting the reactant flow, and causing the development of performance-reducing liquid water blockages (slugs). The analysis was performed both quantitatively and qualitatively to compare the overall liquid water volume within the cell to the flow field geometry. The neutron image analysis results revealed interesting trends related to water volume as a function of time. At temperatures greater than 25°C, the total liquid water volume at start-up in the active area was the lowest at 1.5 A/cm2. At 25°C, 0.1 A/cm2 performed with the least amount of liquid water accumulation. However, as the reaction progressed at temperatures above 25°C, there was a crossover point where 0.1 A/cm2 accumulated less water than 1.5 A/cm2. The higher the temperature, the longer the time required to reach this crossover point. Results from the current density analysis showed a minimization of water slugs at 1.5 A/cm2, while the temperature analysis showed unexpectedly that, independent of current density, the condition with lowest water volume was always 35°C.

scholarly journals Mass Spectrometry of Polymer Electrolyte Membrane Fuel Cells

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Viktor Johánek ◽  
Anna Ostroverkh ◽  
Roman Fiala ◽  
Andrii Rednyk ◽  
Vladimír Matolín
Keyword(s):  
Mass Spectrometry ◽  
Fuel Cells ◽  
Fuel Cell ◽  
Polymer Electrolyte ◽  
Polymer Electrolyte Membrane ◽  
Operating Conditions ◽  
Cell Potential ◽  
Electrolyte Membrane ◽  
Power Load ◽  
Wide Range

The chemical analysis of processes inside fuel cells under operating conditions in either direct or inverted (electrolysis) mode and their correlation with potentiostatic measurements is a crucial part of understanding fuel cell electrochemistry. We present a relatively simple yet powerful experimental setup for online monitoring of the fuel cell exhaust (of either cathode or anode side) downstream by mass spectrometry. The influence of a variety of parameters (composition of the catalyst, fuel type or its concentration, cell temperature, level of humidification, mass flow rate, power load, cell potential, etc.) on the fuel cell operation can be easily investigated separately or in a combined fashion. We demonstrate the application of this technique on a few examples of low-temperature (70°C herein) polymer electrolyte membrane fuel cells (both alcohol- and hydrogen-fed) subjected to a wide range of conditions.

scholarly journals Optimal Estimation of Proton Exchange Membrane Fuel Cells Parameter Based on Coyote Optimization Algorithm

2021 ◽  
Vol 11 (5) ◽  
pp. 2052
Author(s):  
Amlak Abaza ◽  
Ragab A. El-Sehiemy ◽  
Karar Mahmoud ◽  
Matti Lehtonen ◽  
Mohamed M. F. Darwish
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Optimization Algorithm ◽  
Distribution Systems ◽  
Proton Exchange Membrane ◽  
Pem Fuel Cell ◽  
Pem Fuel Cells ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Exchange Membrane

In recent years, the penetration of fuel cells in distribution systems is significantly increased worldwide. The fuel cell is considered an electrochemical energy conversion component. It has the ability to convert chemical to electrical energies as well as heat. The proton exchange membrane (PEM) fuel cell uses hydrogen and oxygen as fuel. It is a low-temperature type that uses a noble metal catalyst, such as platinum, at reaction sites. The optimal modeling of PEM fuel cells improves the cell performance in different applications of the smart microgrid. Extracting the optimal parameters of the model can be achieved using an efficient optimization technique. In this line, this paper proposes a novel swarm-based algorithm called coyote optimization algorithm (COA) for finding the optimal parameter of PEM fuel cell as well as PEM stack. The sum of square deviation between measured voltages and the optimal estimated voltages obtained from the COA algorithm is minimized. Two practical PEM fuel cells including 250 W stack and Ned Stack PS6 are modeled to validate the capability of the proposed algorithm under different operating conditions. The effectiveness of the proposed COA is demonstrated through the comparison with four optimizers considering the same conditions. The final estimated results and statistical analysis show a significant accuracy of the proposed method. These results emphasize the ability of COA to estimate the parameters of the PEM fuel cell model more precisely.

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.

Numerical Approach to the Optimization of Operating Conditions for Hydrogen Polymer Electrolyte Fuel Cells

2005 ◽  
Author(s):  
Junxiao Wu ◽  
Qingyun Liu ◽  
Hongbing Fang
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Polymer Electrolyte ◽  
Polymer Electrolyte Fuel Cells ◽  
Operating Conditions ◽  
Simulation Tool ◽  
Control Parameters ◽  
Optimal Solutions ◽  
Cell Simulation ◽  
Current Loading

An efficient and systematic approach for finding the optimal operating conditions of hydrogen polymer electrolyte fuel cells has been developed by combining an efficient optimization method and a validated multi-resolution fuel cell simulation tool. Four control parameters including cell temperature, cathode stoichiometry, cathode pressure and cathode relative humidity are used to build the optimization objective, which is defined as the maximum overall efficiency of the fuel cell system under ideal or realistic system assumptions. Through the design of experiment method, a set of sample simulations are first carried out using the fuel cell simulation tool. An analytic metamodel is then constructed using the radial basis function approach based on the simulation results. A feasible sequential quadratic programming scheme is then employed to optimize the metamodel to achieve the global optimal solutions. The study shows that different optimal solutions exist for different system assumptions, as well as different current loading levels, classified into small, medium and large current densities. The approach adopted in this study is generic and can be readily applied to more control parameters and further to the fuel cell design optimizations.

Effect of Membrane Properties on Dynamic Behavior of Polymer Electrolyte Membrane Fuel Cells

2013 ◽  
Author(s):  
Atul Verma ◽  
Ranga Pitchumani
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Dynamic Behavior ◽  
Water Transport ◽  
Pem Fuel Cells ◽  
Complex Interaction ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Membrane Properties ◽  
Voltage Response

Understanding the performance of proton exchange membrane (PEM) fuel cells is critical to the water management in the fuel cell system. Low-humidity operating conditions present a complex interaction between dynamic behavior and water transport owing to different time scales of water transport mechanisms in the transient process. Toward understanding the effects of membrane properties on the dynamic behavior, this paper presents numerical simulations for a single channel PEM fuel cell undergoing changes in load, by subjecting the unit cell to step change in current. The objective is to elucidate the complex interaction between cell voltage response and water transport dynamics for various membrane properties, where the performance is critically related water content of the membrane. Detailed computational fluid dynamics (CFD) simulations are carried out to show that step increase in current density leads to anode dryout due to electro-osmotic drag, and investigate its dependence on variations in membrane properties.

Viscoelastic Stress Model and Mechanical Characterization of Perfluorosulfonic Acid (PFSA) Polymer Electrolyte Membranes

2005 ◽  
Author(s):  
Yeh-Hung Lai ◽  
Cortney K. Mittelsteadt ◽  
Craig S. Gittleman ◽  
David A. Dillard
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Mechanical Stress ◽  
Polymer Electrolyte ◽  
Elastic Moduli ◽  
Creep Compliance ◽  
Pem Fuel Cells ◽  
Operating Conditions ◽  
Stress Model ◽  
Membrane Stress

Many of the premature failures in the PEM fuel cells are attributed to crossover of the reactant gas from pinholes or through-the-thickness flaws in the membranes. The formation of these pinholes is not fully understood, although mechanical stress is often considered one of the major factors in their initiation and/or propagation. This paper reports evidence of pinhole failure from mechanical stress by cycling between wet and dry conditions in a normally built single 50cm2 fuel cell. In an effort to understand the source of the mechanical stress, to quantify the magnitude, and to correlate its role in membrane failure, a membrane stress model based on linear viscoelastic theory was developed. The effects of temperature, water content, and time are accounted for in the membrane stress model. To satisfy the inputs for the membrane model and to characterize the mechanical behavior of the polymer electrolyte membrane, a series of experiments was performed. Using commercially available Nafion® NR111 membrane as a model material, swelling of 15% and shrinkage of 4% were found from a hydration and de-hydration cycle. Data on elastic moduli versus relative humidity showed discontinuity at the vapor and liquid water transition. We also found that creep compliance master curves can be obtained by double-shifting the compliance curves according to the time-temperature-moisture superposition principle, which significantly simplifies the modeling effort. Combining data on hygro-expansion, elastic moduli, and creep compliance data through the membrane stress model, it was found that the de-hydration process induces significant stress in the membrane. Due to fluctuations in fuel cell operating conditions, the membrane and the associated components are subject to mechanical fatigue which may mechanically degrade the membrane of PEM fuel cells and eventually lead to pinhole formation.

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