Modification of Results From Computational-Fluid-Dynamics Simulations of Single-Cell Solid-Oxide Fuel Cells to Estimate Multicell Stack Performance

Author(s):  
William J. Sembler ◽  
Sunil Kumar

A typical single-cell fuel cell is capable of producing less than 1 V of direct current. Therefore, to produce the voltages required in most industrial applications, many individual fuel cells must typically be stacked together and connected electrically in series. Computational fluid dynamics (CFD) can be helpful to predict fuel-cell performance before a cell is actually built and tested. However, to perform a CFD simulation using a three-dimensional model of an entire fuel-cell stack can require a considerable amount of time and multiprocessor computing capability that may not be available to the designer. To eliminate the need to model an entire multicell assembly, a study was conducted to determine the incremental effect on fuel-cell performance of adding individual solid-oxide fuel cells (SOFCs) to a CFD model of a multicell stack. As part of this process, a series of simulations was conducted to establish a CFD-nodal density that would not only produce reasonably accurate results but could also be used to create and analyze the relatively large models of the multicell stacks. Full three-dimensional CFD models were then created of a single-cell SOFC and of SOFC stacks containing two, three, four, five, and six cells. Values of the voltages produced when operating with various current densities, together with temperature distributions, were generated for each of these CFD models. By comparing the results from each of the simulations, adjustment factors were developed to permit single-cell CFD results to be modified to estimate the performance of stacks containing multiple fuel cells. The use of these factors could enable fuel-cell designers to predict multicell stack performance using a CFD model of only a single cell.

Author(s):  
William J. Sembler ◽  
Sunil Kumar

A typical single-cell fuel cell is capable of producing less than one volt of direct current. Therefore, to produce the voltages required in most industrial applications, many individual fuel cells must typically be stacked together and connected electrically in series. Computational fluid dynamics (CFD) can be helpful to predict fuel-cell performance before a cell is actually built and tested. However, to perform a CFD simulation using a 3-dimensional model of an entire fuel-cell stack would require a considerable amount of time and multiprocessor computing capability that may not be available to the designer. To eliminate the need to model an entire multi-cell assembly, a study was conducted to determine the incremental effect on fuel-cell performance of adding individual solid-oxide fuel cells (SOFC) to a multi-fuel-cell stack. As part of this process, a series of simulations was conducted to establish a CFD-nodal density that would produce reasonably accurate results but that could also be used to create and analyze the relatively large models of the multi-cell stacks. Full 3-dimensional CFD models were then created of a single-cell SOFC and of SOFC stacks containing two, three, four, five and six cells. Values of the voltage produced when operating with various current densities, together with temperature distributions, were generated for each of these CFD models. By comparing the results from each of the simulations, adjustment factors were developed to permit single-cell CFD results to be modified to estimate the performance of stacks containing multiple fuel cells. The use of these factors could enable fuel-cell designers to predict multi-cell stack performance using a CFD model of only a single cell.


Author(s):  
Zongping Shao ◽  
Jennifer Mederos ◽  
Chan Kwak ◽  
Sossina M. Haile

The compound Bi2V0.9Cu0.1O5.35, a typical Aurivillius-type fast oxygen ion conductor, was evaluated as a possible cathode material for single-chamber solid-oxide fuel cells operated under mixed propane and oxygen. The material was found to be structurally stable under various C3H8+O2 environments over a wide temperature range and furthermore displayed low catalytic activity for propane oxidation. However, at temperatures above 650°C, detrimental reactions between the cathode and the ceria electrolyte occurred, producing low conductivity interfacial phases. At these high temperatures the cathode additionally underwent extensive sintering and loss of porosity and, thus, stable fuel cell operation was limited to furnace temperatures of <600°C. Even under such conditions, however, the partial oxidation occurring at the anode (a ceria nickel cermet) resulted in cell temperatures as much as 70–110°C higher than the gas-phase temperature. This explains the sharp decrease in fuel cell performance with time during operation at a furnace temperature of 586°C. Under optimized conditions, a peak power density of ∼60 mW/cm2 was obtained, which does not compete with recent values obtained from higher activity cathodes. Thus, the poor electrochemical activity of Bi2V0.9Cu0.1O5.35, combined with its chemical instability at higher temperatures, discourages further consideration of this material as a cathode in single-chamber fuel cells.


Author(s):  
Kang Wang ◽  
Pingying Zeng ◽  
Jeongmin Ahn

This work presents the performance of YSZ-SDC multilayered anode-supported solid oxide fuel cell (AS-SOFC). The anode-supported SOFC showed an extraordinary fuel cell performance of ∼1.57 W/cm2 by wet spraying a SDC layer onto YSZ layer. It was found that the fuel cell performance varied with the sintering temperature of fuel cell. At the high sintering temperatures, the reactions between YSZ and SDC have a significant effect on the fuel cell performance.


2019 ◽  
Vol 7 (36) ◽  
pp. 20624-20632 ◽  
Author(s):  
Xi Xu ◽  
Huiqiang Wang ◽  
Marco Fronzi ◽  
Xianfen Wang ◽  
Lei Bi ◽  
...  

Tailoring cathode materials with cations enables an improved hydration ability and proton migration, leading to a high fuel cell performance.


Author(s):  
Francesca L. Moloney ◽  
Nor Farida Harun ◽  
David Tucker

This study explored the potential for TES in solid oxide fuel cells (SOFCs) by investigating the steady state fuel cell performance with a one-dimensional numerical model. The effect of including TES was simulated by increasing and decreasing the mass of the interconnect, stainless steel 441, as the storage medium. Using a model previously developed and tested in MATLAB Simulink®, the interconnect mass was varied from 42% to 99% of the total SOFC mass under the same initial and inlet conditions. The SOFC fuel studied was syngas derived from coal. As the size of the TES increased for constant cathode air mass flow, the heat capacity increased, resistance to heat conduction decreased and the temperature profile through the fuel cell became more uniform. As temperature gradients decreased, thermal stresses and the chance of cell failure reduced. Larger interconnect masses resulted in higher cell voltage and thus yielded higher efficiencies. The cathode air mass flow was also adjusted to control two different temperature conditions: constant average temperature and constant solid temperature difference across the cell. Instead of minimizing the size of the interconnect to reduce the cost of the SOFC, the interconnect material can be increased to add sensible heat storage directly to the fuel cell, increase heat and electrical conduction, and improve the efficiency of the fuel cell for hybrid systems as well as stand-alone fuel cells.


2007 ◽  
Vol 539-543 ◽  
pp. 1385-1390 ◽  
Author(s):  
Olivera Kesler

Plasma spray processing is a low-cost, rapid manufacturing technique that is widely used industrially for fabrication of thermal barrier and wear- and corrosion-resistant coatings. Because the technique can be used to rapidly deposit coatings of high melting temperature materials with good substrate adhesion, it has also been applied to the production of individual component layers in tubular solid oxide fuel cells (SOFCs), and more recently, in planar SOFCs. The use of plasma spray processing for the fabrication of fuel cell components presents unique challenges, due to the high porosities required for the electrode layers and fully dense coatings required for electrolytes. Application of plasma spray processing for the manufacture of solid oxide fuel cells is discussed, with consideration of potential advantages of the technique compared to standard SOFC wet ceramic processing routes. Major challenges faced in the adaptation of the processing method to solid oxide fuel cell manufacture are discussed, along with current research approaches being used to overcome these challenges. Recent developments in the use of the technique for the rapid onestep manufacturing of direct oxidation SOFC anodes are discussed, for composite material combinations that cannot be co-sintered due to widely divergent melting points. The impacts of plasma sprayed coating properties on solid oxide fuel cell performance are considered, and implications of the use of the technique on overall stack and system manufacturing costs are discussed.


RSC Advances ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 7-14
Author(s):  
Cheng Cheng Wang ◽  
Mortaza Gholizadeh ◽  
Bingxue Hou ◽  
Xincan Fan

Strontium segregation in a La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) electrode reacts with Cr and S in a solid oxide fuel cell (SOFC), which can cause cell performance deterioration.


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