Oscillation Phenomenon of the Cell Performance for an Anode-Supported Solid Oxide Fuel Cell with a Low-Porosity/High-Thickness Anode Structure

2015 ◽  
Vol 656-657 ◽  
pp. 124-128 ◽  
Author(s):  
Wei Xin Kao ◽  
Tai Nan Lin ◽  
Yang Chuang Chang ◽  
Maw Chwain Lee
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Current Density ◽  
Concentration Polarization ◽  
Cell Voltage ◽  
Solid Oxide ◽  
Constant Current ◽  
Oxide Fuel ◽  
Oscillation Phenomenon ◽  
Low Porosity

The anode-supported solid oxide fuel cell (SOFC) with low-porosity anode structure is fabricated and the electrochemical characteristics are investigated. The electrochemical characterization of the cell shows a periodic oscillation phenomenon of the cell voltage under the constant current density operation. The low-porosity anode structure results in the decrease in the effective diffusion coefficient and the accumulation of water vapor. The cell voltage oscillation is mainly caused by the concentration polarization as well as the boundary migration of the reaction zone. The profound influence on the concentration polarization can be observed when the cell test is executed with operation condition of higher current density, lower hydrogen concentration, and lower hydrogen flow rate in the anode side.

Application of an Anode Model to Investigate Physical Parameters in an Internal Reforming Solid-Oxide Fuel Cell

2005 ◽  
Vol 2 (2) ◽  
pp. 136-140 ◽  
Author(s):  
Eric S. Greene ◽  
Maria G. Medeiros ◽  
Wilson K. S. Chiu
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Structural Parameters ◽  
Porous Electrode ◽  
Cell Voltage ◽  
Solid Oxide ◽  
Physical Parameters ◽  
Oxide Fuel ◽  
Internal Reforming ◽  
Porous Anode

A one-dimensional model of chemical and mass transport phenomena in the porous anode of a solid-oxide fuel cell, in which there is internal reforming of methane, is presented. Macroscopically averaged porous electrode theory is used to model the mass transfer that occurs in the anode. Linear kinetics at a constant temperature are used to model the reforming and shift reactions. Correlations based on the Damkohler number are created to relate anode structural parameters and thickness to a nondimensional electrochemical conversion rate and cell voltage. It is shown how these can be applied in order to assist the design of an anode.

Investigation on the Performance and Durability Behavior for the Anode-Supported Solid Oxide Fuel Cell with Composite Cathodes

2019 ◽  
Vol 962 ◽  
pp. 101-111
Author(s):  
Tai Nan Lin ◽  
Yang Chuang Chang ◽  
Maw Chwain Lee ◽  
Wei Xin Kao
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Solid Oxide ◽  
Cell Performance ◽  
Constant Current ◽  
External Loading ◽  
Testing Time ◽  
Oxide Fuel ◽  
Transfer Resistance ◽  
Composite Cathodes

The anode-supported solid oxide fuel cell (SOFC) comprises of NiO-8YSZ | 8YSZ | LSM-GDC | LSCF and the performance durability is executed for over 1000 hours. It shows low degradation phenomena under constant current operation during the complete testing period. The cell performance decreases with the decreasing of the temperature, and the maximum power densities are 408, 265, and 163 mW cm-2at 800, 750, and 700 °C, respectively. According to the EIS analysis with the equivalent circuit model of five serial components, all resistances decrease with the testing time except the non-charge transfer resistance of the cathode. However all resistances increase with the decreasing of the temperature on the contrary. The ohmic resistance of the cell (RO) dominates the cell performance under the whole durability test period as well as the operation temperature. In this study, the ROis determined by the interfacial contact resistances, which occurred between the cell and the connecting components. The LSM-GDC | LSCF interfaces formed the discontinuous gap due to the weak attachment and external loading. The result of the activation energy analysis shows that the rate-determination step of the cell is existed in the anode side between 700 and 800 °C. However, the cell performance is controlled from the domination of the ROat 800 °C shift to the joint contributions of the RO, anodic polarization (RAP), and cathodic polarization (RCP) at 700 °C.

Performance Metrics for Solid Oxide Fuel Cell Cross-Section Design

2009 ◽  
Author(s):  
George J. Nelson ◽  
Comas Haynes ◽  
William Wepfer
Keyword(s):  
Fuel Cell ◽  
Partial Pressure ◽  
Solid Oxide Fuel Cell ◽  
Correction Factor ◽  
Current Density ◽  
Performance Metrics ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Pressure Distributions ◽  
Button Cell

Analytical models have been developed to describe the partial pressure distributions of reactants within solid oxide fuel cell (SOFC) electrodes and introduce the concept of a reactant depletion current density. These existing analytical expressions for two-dimensional reactant partial pressure distributions and the reactant depletion current density are presented in non-dimensional form. Performance metrics for SOFC electrodes are developed including a correction factor that can be applied to button-cell predictions of pressure distribution and two forms of dimensionless reactant depletion current density. Performance predictions based on these metrics are compared to numerical predictions of partial pressure and depletion current density based on a finite element solution of the dusty-gas model (DGM) within SOFC electrodes. It is shown that the pressure correction factor developed provides a reasonable prediction of interconnect geometry effects. Thus, it is presented as a modeling tool that can be applied to translate component level fidelity to cell and stack level models. The depletion current density metrics developed are used to present basic design maps for SOFC unit cell cross-sections. These dimensionless forms of the depletion current density quantify the influence of sheet resistance effects on reactant depletion and can predict the deviation from the limiting current behavior predicted using a button-cell model.

Modeling, parametric analysis and optimization of an anode-supported planar solid oxide fuel cell

2015 ◽  
Vol 229 (17) ◽  
pp. 3125-3140 ◽  
Author(s):  
Mehdi Borji ◽  
Kazem Atashkari ◽  
Nader Nariman-zadeh ◽  
Mehdi Masoumpour
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Temperature Difference ◽  
Current Density ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Multi Objective Optimization ◽  
Average Current Density ◽  
Multi Objective ◽  
Average Current

Solid oxide fuel cell is a promising tool for distributed power generation systems. This type of power system will experience different conditions during its operating life. The present study aims to simulate mathematically a direct internal reforming planar type anode supported solid oxide fuel cell considering mass and energy conservation equations along with a complete electrochemical model. Two main reactions, namely water–gas shift reaction and methane steam reforming reaction, are considered as two dominant reactions occurring in a fuel cell. Such a model may be employed to examine the effect of different operating conditions on main solid oxide fuel cell parameters, such as temperature gradients, power, and efficiency. Furthermore, using such mathematical model, a multi-objective optimization procedure can be applied to determine maximum cell efficiency and output power under constraints such as the allowable temperature difference and limited operating potential. The selected design variables are air ratio, fuel utilization, average current density, steam to carbon ratio, and pre-reforming rate of methane. It has been revealed that any increase in pre-reforming rate of methane and steam to carbon ratio of the entering fuel will lead to efficiency penalty and more uniform temperature distribution along the cell. In addition, the more average current density increases, the less electric efficiency is achieved, and on the other hand, the more temperature difference along the cell is seen. Besides, it is shown that some interesting and important relationships as useful optimal design principles involved in the performance of solid oxide fuel cells can be discovered by Pareto based multi-objective optimization of the mathematically obtained model representing their electric performance. Such important optimal principles would not have been obtained without the use of both mathematical modeling and the Pareto optimization approach.

Optimization of the Anode Current Collector Layer Thickness for the Cathode-Supported Solid Oxide Fuel Cell

2013 ◽  
Vol 712-715 ◽  
pp. 1325-1329 ◽  
Author(s):  
Wei Kong ◽  
Shi Chuan Su ◽  
Xiang Gao ◽  
Dong Hui Zhang ◽  
Zi Dong Yu
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Layer Thickness ◽  
Current Density ◽  
High Performance ◽  
Current Collector ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Anode Current ◽  
Output Current

The influence of anode current collector layer (ACCL) thickness is studied for different ACCL porosity and different pitch width. The results shows conclusively that the output current density depends strongly on the ACCL thickness and a suitable choice of the ACCL thickness is very important for the high performance of a SOFC stack. Furthermore, the optimal ACCL thickness is found to be dependent linearly on the pitch width and the parameters for the linearity are given.

scholarly journals Modelling the leakage current in a solid oxide fuel cell with bi-layer electrolyte

2020 ◽  
Author(s):  
Balaji Krishnamurthy ◽  
Hariharan Ramasubramanian
Keyword(s):  
Experimental Data ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Leakage Current ◽  
Operating Temperature ◽  
Cell Voltage ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Operating Cell ◽  
Interfacial Oxygen

<p class="PaperAbstract">A mathematical model is developed to study the leakage current in a solid oxide fuel cell (SOFC) with a bi-layer electrolyte. The model predicts the variation of leakage current and power density with various design and operating factors of SOFC, namely thickness of the bi-layer electrolyte, operating temperature and operating cell voltage. The interfacial oxygen pressure in SOFC is also studied as a function of the thickness of YSZ layer. Modelling results are compared with experimental data and found to compare well.</p>

Effects of Electrode Microstructure on Intermediate Temperature Solid Oxide Fuel Cell Performance

2010 ◽  
Vol 7 (5) ◽  
Author(s):  
Edward J. Naimaster ◽  
A. K. Sleiti
Keyword(s):  
Grain Size ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Phase Boundary ◽  
Pore Size ◽  
Current Density ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Triple Phase Boundary ◽  
Microstructure Parameters

In this study, the effects of electrode microstructure and electrolyte parameters on intermediate temperature solid oxide fuel cell (ITSOFC) performance were investigated using a one-dimensional solid oxide fuel cell model from the Pacific Northwest National Laboratory (PNNL). The activation overpotential was investigated through the exchange current density term, which is dependent on the cathode activation energy, the cathode porosity, and the pore size and grain size at the cathode triple phase boundary. The cathode pore size, grain size, and porosity were not integrated in the PNNL model, therefore, an analytical solution for exchange current density from Deng and Petric (2005, “Geometric Modeling of the Triple-Phase Boundary in Solid Oxide Fuel Cells,” J. Power Sources, 140, pp. 297–303) was utilized to optimize their effects on performance. Through parametric evaluation and optimization of the electrode microstructure parameters, the activation overpotential was decreased by 29% and the overall ITSOFC maximum power density was increased by almost 400% from the benchmark PNNL case. The effects and importance of electrode microstructure parameters on ITSOFC performance were defined. Optimization of such parameters will be the key in creating viable ITSOFC systems. Although this was deemed successful for this project, future research should be focused on numerically quantifying and modeling the electrode microstructure in two- and three-dimensions for more accurate results, as the electrode microstructure may be highly multidimensional in nature.

Electrochemical Characterization and Mechanisms of Solid Oxide Fuel Cells by Electrochemical Impedance Spectroscopy Under Different Applied Voltages

2010 ◽  
Author(s):  
Li Sun ◽  
Gianfranco DiGiuseppe
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Fuel Cell ◽  
Impedance Spectroscopy ◽  
Solid Oxide Fuel Cell ◽  
Current Density ◽  
Electrochemical Impedance ◽  
Density Measurement ◽  
Electrical Circuit ◽  
Solid Oxide ◽  
Oxide Fuel

In this paper, the behavior of an anode-supported solid oxide fuel cell is studied by using voltage-current density measurement and electrochemical impedance spectroscopy. The cell total polarization obtained from electrochemical impedance spectroscopy results is shown to be consistent with the area-specific resistance calculated from the voltage-current density curve. An electrolyte-supported solid oxide fuel cell is then used to build an equivalent electrical circuit model using reference electrodes and electrochemical impedance spectroscopy. A four-constant phase element model is proposed to analyze the anode-supported solid oxide fuel cell. The model is used to evaluate an anode-supported solid oxide fuel cell under different cell voltages. The individual resistances are also studied as a function of applied voltage, and their physical meaning is explained in terms of reaction mechanisms occurring at the cathode and anode. It is shown that some of the obtained resistances are independent of diffusion while others have both a charge transfer and diffusion component.

Sign in / Sign up

Export Citation Format

Share Document