scholarly journals Tortuosity in anode-supported proton conductive solid oxide fuel cell found from current flow rates and dusty-gas model

2011 ◽  
Vol 196 (2) ◽  
pp. 692-699 ◽  
Author(s):  
Chih-Long Tsai ◽  
V. Hugo Schmidt
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Current Flow ◽  
Solid Oxide ◽  
Dusty Gas ◽  
Oxide Fuel ◽  
Flow Rates ◽  
Dusty Gas Model

Analysis of Long-Term and Thermal Cycling Tests for a Commercial Solid Oxide Fuel Cell

2017 ◽  
Vol 14 (4) ◽  
Author(s):  
Dustin Lee ◽  
Jing-Kai Lin ◽  
Chun-Huang Tsai ◽  
Szu-Han Wu ◽  
Yung-Neng Cheng ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Thermal Cycling ◽  
Solid Oxide Fuel Cell ◽  
Coefficient Of Thermal Expansion ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Flow Rates ◽  
Degradation Rates ◽  
Two Stages

The effects of isothermally long-term and thermal cycling tests on the performance of an ASC type commercial solid oxide fuel cell (SOFC) have been investigated. For the long-term test, the cells were tested over 5000 h in two stages, the first 3000 h and the followed 2000 h, under the different flow rates of hydrogen and air. Regarding the thermal cycling test, 60 cycles in total were also divided into two sections, the temperature ranges of 700 °C to 250 °C and 700 °C to 50 °C were applied for the every single cycle of first 30 cycles and the later 30 cycles, respectively. The results of long-term test show that the average degradation rates for the cell in the first 3000 h and the followed 2000 h under different flow rates of fuel and air are 1.16 and 2.64%/kh, respectively. However, there is only a degradation of 6.6% in voltage for the cell after 60 thermal cycling tests. In addition, it is found that many pores formed in the anode of the cell which caused by the agglomeration of Ni after long-term test. In contrast, the vertical cracks penetrating through the cathode of the cell and the in-plane cracks between the cathode and barrier layer of the cell formed due to the coefficient of thermal expansion (CTE) mismatch after 60 thermal cycling tests.

Performance of an Integrated Microtubular Fuel Reformer and Solid Oxide Fuel Cell System

2010 ◽  
Vol 7 (3) ◽  
Author(s):  
John R. Izzo ◽  
Aldo A. Peracchio ◽  
Wilson K. S. Chiu
Keyword(s):  
Heat Transfer ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Solid Oxide ◽  
Packed Bed Reactor ◽  
Limiting Current ◽  
Design Parameters ◽  
Heat Of Reaction ◽  
Oxide Fuel ◽  
Flow Rates

A numerical model is developed to study the performance of an integrated tubular fuel reformer and solid oxide fuel cell (SOFC) system. The model is used to study how the physical dimensions of the reformer, gas composition and the species flow rates of a methane feed stream undergoing autothermal reforming (ATR) affect the performance of an SOFC. The temperature in the reformer changes significantly due to the heat of reaction, and the reaction rates are very sensitive to the temperature and species concentrations. Therefore, it is necessary to couple the heat and mass transfer to accurately model the species conversion of the reformate stream. The reactions in the SOFC contribute much less to the temperature distribution than in the reformer and therefore the heat transfer in the SOFC is not necessary to model. A packed bed reactor is used to describe the reformer, where the chemical mechanism and kinetics are taken from the literature for nickel catalyst on a gamma alumina support. Heat transfer in the reformer’s gas and solid catalyst phases are coupled while the gas phase in the SOFC is at a uniform temperature. The SOFC gas species are modeled using a plug flow reactor. The models are in good agreement with experimental data. It is observed that the reformer temperature decreases with an increase in the reformer inlet water-to-fuel ratio and there is a slight decrease in the voltage of the SOFC from higher water content but an increase in limiting current density from a higher hydrogen production. The numerical results show that the flow rates and reformer length are critical design parameters because if not properly designed they can lead to incomplete conversion of the methane fuel to hydrogen in the reformer, which has the greatest impact on the SOFC performance in the integrated ATR reformer and SOFC system.

Analytical Expression for Concentration Overpotential of Anode-Supported Solid Oxide Fuel Cell Based on the Dusty Gas Model

2020 ◽  
Vol 17 (3) ◽  
Author(s):  
Sandipan Kumar Das
Keyword(s):  
Fuel Cell ◽  
Concentration Polarization ◽  
Porous Electrode ◽  
Analytical Framework ◽  
Gas Diffusion ◽  
Solid Oxide ◽  
Dusty Gas ◽  
Oxide Fuel ◽  
Viscous Effects ◽  
Dusty Gas Model

Abstract The Dusty Gas model (DGM), despite being arguably the most accurate representation of gas diffusion in electrodes, is not readily adopted in the literature as it entails relatively expensive numerical integration of differential equations for concentration polarization calculations. To address this issue, this article demonstrates an analytical procedure to solve the DGM equations in a fuel cell electrode setting. In the process, it highlights the differences with previous attempts in the literature and improves upon the shortcomings. This paper specifically provides explicit expressions of concentration overpotentials of anode-supported solid oxide fuel cells (SOFCs) for binary and ternary gas systems via the analytical solution of DGM equations in one dimension without considering the viscous effects. The model predictions match very well with the experimental data available in the open literature. This paper also provides a semi-analytical framework for higher-order multicomponent systems. Finally, the effect of the pore-size distribution in the porous electrode on the concentration polarization is thoroughly explored.

The effect of fuel gas mixtures and air flow rates on electrical properties of solid oxide fuel cell

2021 ◽  
Vol 2021 (3) ◽  
pp. 119-126
Author(s):  
N. O. Lysunenko ◽  
◽  
Y. M. Brodnikovskyi ◽  
V. I. Chedryk ◽  
D. M. Brodnikovskyi ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Electrical Properties ◽  
Solid Oxide Fuel Cell ◽  
Gas Flow ◽  
Optimal Operation ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Flow Rates ◽  
Model Fuel

Fuel Cells are one of the most efficient and environmentally friendly devices for electricity generation, which are developing rapidly and are already in the early stages of commercialization. Solid Oxide Fuel Cells (SOFC) areone of the most promising their types due to the highest efficiency, fuel flexibility (H2, CnHm, CO etc.) and no needs in platinum group catalysts. The performance of SOFC is affected by various polarization losses, which aredependant on selected materials, their structure and SOFC operation parameters. Over the last decade, much attention is given to the study of SOFC’s electrochemical properties at different operating regimes: temperatures, fuels, fuel and oxidantflow rates etc. The work is devoted to studying the influence of the model fuel (5% H2—Ar) and air (oxidant) flow rates on electrical properties of Solid Oxide Fuel Cellat 800 °C to determine the best combination of gas flow rates, which provide the maximum values of specific electric power. The fuel (0,35 l/min) and oxidant (1 l/min)flow rates was found as the optimal operation regime of fuel and air supply for the SOFC tested. The highest electrical densityto be ensured by the model fuel was determined as 34 mW/cm2. The amount / flow rate of oxidant and fuel gases supplied to the fuel cell does not correspond to the ratio of the reagents of the chemical reaction of oxidation of the fuel. This difference is explained by the fact that the SOFC effectiveness of fuel and oxidant utilization depends not only from to the properties structure and materials of each components: anode, cathode, electrolyte, but also from concentration of fuel and oxidant in model fuel or air, which also creates a barrier for oxidant and fuel molecules to reach the reaction zone. Keywords: Solid Oxide Fuel Cell, electrical properties, fuelgasmixtures, hydrogen, oxidant.

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