scholarly journals Parameter Identification of a Quasi-3D PEM Fuel Cell Model by Numerical Optimization

Processes ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1808
Author(s):  
Maximilian Haslinger ◽  
Christoph Steindl ◽  
Thomas Lauer
Keyword(s):  
Numerical Optimization ◽  
Cell Model ◽  
Polymer Electrolyte Membrane ◽  
Catalyst Layer ◽  
Transient Behavior ◽  
Simplex Algorithm ◽  
Gas Diffusion ◽  
Material Parameters ◽  
Electrolyte Membrane

Polymer electrolyte membrane fuel cells (PEMFCs) supplied with green hydrogen from renewable sources are a promising technology for carbon dioxide-free energy conversion. Many mathematical models to describe and understand the internal processes have been developed to design more powerful and efficient PEMFCs. Parameterizing such models is challenging, but indispensable to predict the species transport and electrochemical conversion accurately. Many material parameters are unknown, or the measurement methods required to determine their values are expensive, time-consuming, and destructive. This work shows the parameterization of a quasi-3D PEMFC model using measurements from a stack test stand and numerical optimization algorithms. Differential evolution and the Nelder–Mead simplex algorithm were used to optimize eight material parameters of the membrane, cathode catalyst layer (CCL), and gas diffusion layer (GDL). Measurements with different operating temperatures and gas inlet pressures were available for optimization and validation. Due to the low operating temperature of the stack, special attention was paid to the temperature dependent terms in the governing equations. Simulations with optimized parameters predicted the steady-state and transient behavior of the stack well. Therefore, valuable data for the characterization of the membrane, the CCL and GDL was created that can be used for more detailed CFD simulations in the future.

Microscopic Observation of Ice Distribution in PEM Fuel Cell at Cold Start

2011 ◽  
Author(s):  
Yutaka Tabe ◽  
Masataka Saito ◽  
Ryosuke Ichikawa ◽  
Takemi Chikahisa
Keyword(s):  
Produced Water ◽  
Polymer Electrolyte Membrane ◽  
Catalyst Layer ◽  
Cold Start ◽  
Optical Microscope ◽  
Gas Diffusion ◽  
Ice Formation ◽  
Electrolyte Membrane ◽  
Cathode Catalyst Layer ◽  
Observation Results

In Polymer electrolyte membrane fuel cells (PEFCs), freezing of produced water induces the extreme deterioration of cell performance below zero. This phenomenon is a serious problem in cold regions and is needed to be solved to achieve the practical use of PEFCs. In this study, we investigated ice distribution at the cold start in a PEFC using an optical microscope and a CRYO-SEM to clarify the freezing mechanism. The observation results showed that the cold start at −10°C makes ice at the interface between the cathode catalyst layer (CL) and the micro porous layer of gas diffusion layer. Little ice was, however, observed in the cold start at −20°C, which indicated the ice formation inside the CL. The CRYO-SEM observation was conducted at −20°C to investigate the ice formation inside the CL, and this identified the effects of the current density and the cathode gas species on the ice distribution.

Pore Space Characterization of Compressed PEMFC GDLs Using 3D Micro-Computed Tomography

2012 ◽  
Author(s):  
Pradyumna R. Challa ◽  
A. Bazylak
Keyword(s):  
Computed Tomography ◽  
Pore Space ◽  
Polymer Electrolyte Membrane ◽  
Gas Diffusion ◽  
Ex Situ ◽  
Micro Computed Tomography ◽  
Porous Layers ◽  
Electrolyte Membrane ◽  
Diffusion Layers

In this work, micro-computed tomography was employed to characterize the effect of rib and channel compression on the through-plane porosity distributions of polymer electrolyte membrane fuel cell (PEMFC) gas diffusion layers (GDLs). Two GDLs with micro-porous layers (MPLs): a paper based GDL (GDL A), and a felt GDL (GDL B) were compressed at 1.2 MPa in an ex situ flow field apparatus with 1mm × 1mm channels. Porosity distributions of compressed GDLs were compared with those of uncompressed GDLs, and the microstructural differences caused during the manufacturing of paper, felt, and cloth GDLs are discussed. The results of this study will aid modellers in generating realistic stochastic GDL pore structures for multiphase flow simulations.

3D Modeling of Polymer Electrolyte Membrane Fuel Cells

2003 ◽  
Author(s):  
Sacheverel Eldrid ◽  
Mehrdad Shahnam ◽  
Michael T. Prinkey ◽  
Zhirui Dong
Keyword(s):  
Fuel Cell ◽  
Polymer Electrolyte Membrane ◽  
Catalyst Layer ◽  
Pem Fuel Cell ◽  
Gas Diffusion ◽  
Hydrogen Ions ◽  
Electrolyte Membrane ◽  
Diffusion Layers ◽  
Flow Channels ◽  
Porous Anode

Polymer Electrolyte Membrane (PEM) fuel cell performance can be optimized and improved by modeling the complex processes that take place in the various components of a fuel cell. Operability over a range of conditions can be assessed using a robust design methodology. Sensitivity analysis can identify critical characteristics in order to guide hardware and softgoods development. A computational model is necessary which captures the critical physical processes taking place within the cell. Such a model must be validated against experimental data before it can be used for product development. A computational model of an experimental PEM fuel cell has been developed. The model is based on the FLUENT CFD solver with the addition of user-defined functions supplied by FLUENT. These functions account for local electrochemical reactions, electrical conduction within diffusion layers and current collectors, mass and heat transfer in the diffusion layers and the flow channels along with binary gas diffusion. The results of this model are compared to experimental data. A PEM fuel cell consists of an ion conducting membrane, anode and cathode catalyst layers, anode and cathode gas diffusion layers, flow channels, and two bipolar plates. Hydrogen and oxygen are supplied to the anode and cathode respectively. As a result of hydrogen oxidation at the anode catalyst layer, hydrogen ions and electrons are produced. The hydrogen ions are conducted through the membrane to the cathode catalyst layer where they combine with oxygen and electrons to produce water and heat. Therefore, a PEM fuel cell model has to take into account: • Fluid flow, heat transfer, and mass transfer in porous anode and cathode diffusion layers; • Electrochemical reactions; • Current transport and potential field in porous anode, cathode, and solid conducting regions. FLUENT Inc. has developed such a model based on their commercially available FLUENT CFD code. This model was exercised on an experimental Plug Power fuel cell. The voltage characteristic of the model was compared to the experimentally measured values. The preliminary comparison between the predicted polarization curve and the experimental results are very favorable.

Exploring Transient Behavior at Startup of a Polymer Electrolyte Membrane Fuel Cell

2010 ◽  
Vol 7 (2) ◽  
Author(s):  
Bikash Mishra ◽  
Junxiao Wu
Keyword(s):  
Fuel Cell ◽  
Mass Transport ◽  
Current Density ◽  
Liquid Water ◽  
Initial Conditions ◽  
Polymer Electrolyte Membrane ◽  
Transient Behavior ◽  
Gas Diffusion ◽  
Electrolyte Membrane ◽  
Start Up

A two phase nonisothermal 3D unsteady model is used to study the transients at start-up of a polymer electrolyte membrane fuel cell. The model is used to simulate start-up under different starting or initial conditions. The objective is to study the transient behavior of current and the phenomena affecting it. The transient current density obtained from simulation under purged and inflow/equilibrium initial conditions are plotted. The saturation and the temperature profile evolution within the gas diffusion layer under different conditions are also studied. The effect of gas diffusion layer thickness and reaction rate on the current density evolution is analyzed. It is found that the transient current density depends on the initial condition. Mass transport is the major phenomenon influencing the current density profile, and the mass transport transients are found to be subsecond in nature. The consumption and transport time scales are seen to affect the current undershoot at high loads. The liquid water evolution and distribution behaves very differently, under different initial conditions, as well as different inflow conditions. However, the total time taken by liquid water and temperature to reach steady state for different initial conditions is very close. It is also seen that the temperature transient is less than the liquid water transient, overall.

In Situ Measurements of Through-Plane, Ionic Potential Distributions in Porous Electrodes

2010 ◽  
Author(s):  
Katherine C. Hess ◽  
William K. Epting ◽  
Shawn Litster
Keyword(s):  
Polymer Electrolyte Membrane ◽  
Porous Electrode ◽  
Catalyst Layer ◽  
In Situ Measurements ◽  
Porous Electrodes ◽  
Ionic Potential ◽  
Electrolyte Membrane ◽  
Insight Into

We present a novel apparatus for gathering in situ measurements of through-plane, ionic potential distributions in the porous electrodes of a polymer electrolyte membrane (PEM) fuel cell. Our diagnostic method uses a micro-structured electrode scaffold (MES) that is comprised of alternating layers of insulating and sensing materials into which a 100 μm diameter hole is micro-milled and then filled with catalyst ink. Using the MES, we performed a polarization curve experiment where the ionic potential was measured within a 50 μm thick catalyst layer at 8 and 24 μm from membrane. Our results show that there are significant ionic potential variations within the electrode. Such data is valuable in the electrochemical characterization of electrodes and catalysts. The MES potential measurements also provide insight into reaction distributions across the thickness of the electrode, which is valuable in the validation of porous electrode models.

Determination of the Relationship Between Capillary Pressure and Saturation in PEMFC Gas Diffusion Media

2008 ◽  
Author(s):  
Joshua D. Sole ◽  
Michael W. Ellis
Keyword(s):  
Capillary Pressure ◽  
Liquid Water ◽  
Polymer Electrolyte Membrane ◽  
Catalyst Layer ◽  
Gas Diffusion ◽  
Carbon Cloth ◽  
Electrolyte Membrane ◽  
Diffusion Media ◽  
Capillary Pressures ◽  
The Relationship

This paper describes a method of measuring the relationship between capillary pressure and porous media saturation in the gas diffusion layer (GDL) of a polymer electrolyte membrane fuel cell (PEMFC). Such a relationship is commonly used to model the liquid water flow in the GDL. The method utilized to characterize the GDL behavior mimics the actual transport of liquid water within the GDL by utilizing the actual fluids of interest in a PEMFC cathode (water and air), and by introducing all water from a single face to simulate the water production at the catalyst layer. Other porosimetry methods rely on totally non-wetting or totally wetting fluids to achieve saturation and consequently the resulting capillary pressure measurements must be scaled to the emulate the situation in the PEMFC GDL. Capillary pressure versus saturation curves for two different GDL materials (one paper, one cloth), each with four different bulk loadings of PTFE (0, 10, 20 and 30 wt%), were measured. Results show that the PTFE loading has a relatively small effect on the capillary pressure within the pressure range normally associated with PEMFC water transport. The results also show that carbon cloth based GDL materials require greater capillary pressures than paper materials to achieve significant saturation and that compression has a homogenizing effect on the pore structure and the slope of the capillary pressure – saturation Pc(S) behavior of both materials. Representative curves for the derivative of the Pc(S) function are developed for each type of diffusion media within the appropriate saturation range.

Graduated Flow Resistance Through a GDL in a Novel PEM Stack

2009 ◽  
Author(s):  
Terry B. Caston ◽  
Kanthi L. Bhamidipati ◽  
Haley Carney ◽  
Tequila A. L. Harris
Keyword(s):  
Fuel Cell ◽  
Polymer Electrolyte Membrane ◽  
Catalyst Layer ◽  
Current Density Distribution ◽  
Pem Fuel Cell ◽  
Bipolar Plate ◽  
Gas Diffusion ◽  
Carbon Paper ◽  
Carbon Cloth ◽  
Electrolyte Membrane

The goal of this study is to design a gas diffusion layer (GDL) for a polymer electrolyte membrane (PEM) fuel cell with a graduated permeability, and therefore a graduated resistance to flow throughout the GDL. It has been shown that using conventional materials the GDL exhibits a higher resistance in the through-plane direction due to the orientation of the small carbon fibers that make up the carbon paper or carbon cloth. In this study, a GDL is designed for an unconventional PEM fuel cell stack, where the reactant gases are supplied through the side of the GDL rather than through flow field channels, which are machined into a bipolar plate. The effects of changing in-plane permeability, through-plane permeability, and thickness of the GDL on the expected current density distribution at the catalyst layer are studied. Three different thicknesses are investigated, and it is found that as GDL thickness increases, more uniform reactant distribution over the face of the GDL is obtained. Results also show that it is necessary to design a GDL with a much higher in-plane resistance than through-plane resistance for the unconventional PEM stack studied.

3-D Multiphase Cold Start Model for PEMFCs

2009 ◽  
Author(s):  
Kui Jiao ◽  
Xianguo Li
Keyword(s):  
Polymer Electrolyte Membrane ◽  
Three Dimensional ◽  
Catalyst Layer ◽  
Cold Start ◽  
Gas Diffusion ◽  
Multiphase Model ◽  
Pore Region ◽  
Heating Source ◽  
Electrolyte Membrane ◽  
Subzero Temperatures

A three-dimensional multiphase model has been developed to simulate the cold start processes in a polymer electrolyte membrane fuel cell (PEMFC). This model uniquely includes the water freezing in the membrane, the non-equilibrium mass transfer between the water in the ionomer and the water (vapour, liquid and ice) in the pore region of the catalyst layer (CL), and the water freezing and melting in the CL and gas diffusion layer (GDL). Numerical simulations have been conducted for a single PEMFC starting from different subzero temperatures to investigate both the failed and successful cold start processes. Numerical results indicate that the ohmic heat is the largest heating source at low cell voltages. It is observed that water freezes first in the cathode CL under the land, and ice melts first in the CLs under the flow channel, the melted water in the anode is also removed faster than in the cathode.

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