Numerical Study on Thermoelectric Performance of Cross-Flow Planar Solid Oxide Fuel Cell

2018 ◽  
Author(s):  
Haibin Lu ◽  
Changcheng Xie ◽  
Xiuwen Hua ◽  
Taosif Iqbal ◽  
Xiongwen Zhang ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Current Density ◽  
Electromotive Force ◽  
Electrochemical Reaction ◽  
Numerical Study ◽  
Cross Flow ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Reactant Concentration

This paper investigates the thermoelectric characteristics of cross-flow planar type solid oxide fuel cell (SOFC) with natural gas as fuel by using a three-dimensional numerical model. The results reveal that temperature and reactant concentration increase gradually along the direction of fuel gas flow, and the reactant concentration increases in the first and subsequently decreases. In addition, the lower the temperature, the higher ideal electromotive force is as well as the less actual output electromotive force. The hydrogen concentration is positively correlated with the current density and the ideal electromotive force. However, increasing the mass flow continuously beyond the reasonable range can decrease the current and electrochemical reaction intensity. Variation in wall thickness was also simulated and found that increasing the thickness would result in higher intensity of electrochemical reaction and increased current density but at the cost of low efficiency in SOFC. Thus an optimal design can make a balance between fuel utilization and output power of SOFC.

Numerical Study of Thermal Stresses in a Planar Solid Oxide Fuel Cell Stack

2017 ◽  
Author(s):  
Cun Wang ◽  
Tao Zhang ◽  
Cheng Zhao ◽  
Jian Pu
Keyword(s):  
Thermal Stress ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Thermal Stresses ◽  
Coefficient Of Thermal Expansion ◽  
Numerical Study ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Compressive Loads ◽  
Cte Mismatch

A three dimensional numerical model of a practical planar solid oxide fuel cell (SOFC) stack based on the finite element method is constructed to analyze the thermal stress generated at different uniform temperatures. Effects of cell positions, different compressive loads, and coefficient of thermal expansion (CTE) mismatch of different SOFC components on the thermal stress distribution are investigated in this work. Numerical results indicate that the maximum thermal stress appears at the corner of the interface between ceramic sealants and cells. Meanwhile the maximum thermal stress at high temperature is significantly larger than that at room temperature (RT) and presents linear growth with the increase of operating temperature. Since the SOFC stack is under the combined action of mechanical and thermal loads, the distribution of thermal stress in the components such as interconnects and ceramic sealants are greatly controlled by the CTE mismatch and scarcely influenced by the compressive loads.

Dynamics of Solid Oxide Fuel Cell Operation

2004 ◽  
Author(s):  
Randall S. Gemmen ◽  
Christopher D. Johnson
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Cross Flow ◽  
Reverse Current ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Flow Geometry ◽  
Load Increase ◽  
The Moment ◽  
Fuel Cell Operation

The dynamics of solid oxide fuel cell operation (SOFC) have been considered previously, but mainly through the use of one-dimensional codes applied to co-flow fuel cell systems. In this paper a cross-flow geometry is considered. The details of the model are provided, and the model is compared with some initial experimental data. For parameters typical of SOFC operation, a variety of transient cases are investigated, including representative load increase and decrease and system shutdown. Of particular note are results showing cases having reverse current over significant portions of the cell, starting from the moment of load perturbation up to the point where equilibrated conditions again provide positive current. Consideration is given as to when such reverse current conditions might most significantly impact the reliability of the cell.

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.

Multiscale Parametric Studies on the Transport Phenomenon of a Solid Oxide Fuel Cell

2005 ◽  
Vol 2 (4) ◽  
pp. 219-225 ◽  
Author(s):  
C. H. Cheng ◽  
Y. W. Chang ◽  
C. W. Hong
Keyword(s):  
Transport Phenomenon ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Solid Electrolyte ◽  
Parametric Study ◽  
Cross Flow ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Distribution Maps ◽  
Operation Temperature

This paper conducts a multiscale parametric study of temperature and composition effects on the transport phenomenon of a solid oxide fuel cell (SOFC). The molecular dynamics technique was employed to study the transport phenomenon of the solid electrolyte, which is made of yttria-stabilized zirconia. The influences of Y2O3 concentration and various operation temperatures on the SOFC were studied. Simulation results show that there exists an optimal concentration of 8mol% of Y2O3 in the composition for oxygen transport. Also higher operation temperature promotes the oxygen ion-hopping process that increases the ionic conductivity. A macroscale parametric study was also conducted in this paper to validate the influence of the temperature uniformity in the solid electrolyte by employing the computational fluid dynamics technique. The temperature distribution maps of a single-cell planar SOFC with coflow, counterflow and cross-flow channel designs are presented. The results conclude that the coflow configuration is the best design of the three.

Cracking Reaction of Octane Fuel and Electrochemical Reaction on Ni-YSZ Cermet Anode of Internal Steam Reforming Solid Oxide Fuel Cell

2015 ◽  
Vol 68 (1) ◽  
pp. 2831-2843
Author(s):  
M. Kinoshita ◽  
K. Tomomichi ◽  
S. Yamagami ◽  
Y. Yamada ◽  
T. Terai ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Steam Reforming ◽  
Electrochemical Reaction ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Cracking Reaction

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.

Sign in / Sign up

Export Citation Format

Share Document