Degradation of Solid Oxide Fuel Cell Cathodes Accelerated at a High Water Vapor Concentration

2010 ◽  
Vol 7 (2) ◽  
Author(s):  
S. H. Kim ◽  
K. B. Shim ◽  
C. S. Kim ◽  
J. T. Chou ◽  
T. Oshima ◽  
...  
Keyword(s):  
Water Vapor ◽  
Voltage Drop ◽  
Cell Voltage ◽  
High Water ◽  
Solid Oxide ◽  
Constant Current ◽  
Vapor Concentration ◽  
Water Vapor Concentration ◽  
Oxide Fuel ◽  
Constant Current Density

The influence of water vapor in air on power generation characteristic of solid oxide fuel cells was analyzed by measuring cell voltage at a constant current density, as a function of water vapor concentration at 800°C and 1000°C. Cell voltage change was negligible at 1000°C, while considerable voltage drop was observed at 800°C accelerated at high water vapor concentrations of 20 wt % and 40 wt %. It is considered that La2O3 formed on the (La0.8Sr0.2)0.98MnO3 surface, which is assumed to be the reason for a large voltage drop.

Effect of Water Vapor and SOx in Air on the Cathodes of Solid Oxide Fuel Cells

2007 ◽  
Vol 1041 ◽  
Author(s):  
Seon Hye Kim ◽  
Toshihiro Ohshima ◽  
Yusuke Shiratori ◽  
Kohei Itoh ◽  
Kazunari Sasaki
Keyword(s):  
Water Vapor ◽  
Solid Oxide Fuel Cells ◽  
Degradation Mechanism ◽  
Chemical Species ◽  
Cell Voltage ◽  
Ambient Air ◽  
Open Circuit ◽  
Constant Current ◽  
Constant Current Density

AbstractAmbient air is used as an oxygen source in SOFCs to be commercialized. Various chemical species which can lead to poisoning of SOFC cathodes are included as minor constitutions in air, such as water vapor, SOx, NOx and NaCl etc. However, their effects on the cathode performance have not yet well known, even though they are expected to cause a degradation of the electrode performance and to reduce the long-term durability of SOFCs. Therefore, in this study, we focused on the poisoning caused by water vapor and SOx in the oxygen source to clarify their effects on SOFCs performances and to reveal the degradation mechanism of cathodes. SOFCs with typical electrolyte-supported structure were used in this work, which were composed with ScSZ (10 mol% Sc2O3, 1mol% CeO2, 89 mol% ZrO2) plate with the thickness of 200 µm as electrolyte, NiO-ScSZ (mixture of 56 wt% NiO and 44 wt% ScSZ) porous layer as anode, and two cathode layers of LSM ((La0.8Sr0.2)0.98MnO3) and LSM-ScSZ (mixture of 50 wt% LSM and 50 wt% ScSZ). Power generation characteristics of the cells had been analyzed by measuring cell voltage at a constant current density (200 mA/cm2) and by comparing changes in cell impedance, upon supplying the artificially-contaminated air with water vapor or SOx, to the SOFC cathodes at various operational temperatures. High-resolution FESEM (S-5200, Hitachi) was used to analyze microstructural changes caused by the impurities. Mg Kα radiation from a monochromatized X-ray source was used for XPS measurements (ESCA-3400, KRATOS). AC impedance was measured at various temperatures under the open circuit voltage condition by an impedance analyzer (Solatron 1255B/SI 1287, Solatron), in a frequency range from 0.1 to 105 Hz with an amplitude of 10 mV.

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.

Dependence of hydrogen oxidation reaction on water vapor in anode-supported solid oxide fuel cells

2021 ◽  
Vol 362 ◽  
pp. 115565
Author(s):  
R.A. Budiman ◽  
T. Ishiyama ◽  
K.D. Bagarinao ◽  
H. Kishimoto ◽  
K. Yamaji ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Water Vapor ◽  
Solid Oxide Fuel Cells ◽  
Oxidation Reaction ◽  
Hydrogen Oxidation ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Hydrogen Oxidation Reaction

scholarly journals Numerical Simulation of the Water Vapor Separation of a Moisture-Selective Hollow-Fiber Membrane for the Application in Wood Drying Processes

Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 593
Author(s):  
Nasim Alikhani ◽  
Douglas W. Bousfield ◽  
Jinwu Wang ◽  
Ling Li ◽  
Mehdi Tajvidi
Keyword(s):  
Water Vapor ◽  
Constant Temperature ◽  
Hollow Fiber ◽  
Hollow Fiber Membrane ◽  
Vacuum Pressure ◽  
Vapor Concentration ◽  
Water Vapor Concentration ◽  
Fiber Membrane ◽  
Wood Drying ◽  
Air Velocity

In this study, a simplified two-dimensional axisymmetric finite element analysis (FEA) model was developed, using COMSOL Multiphysics® software, to simulate the water vapor separation in a moisture-selective hollow-fiber membrane for the application of air dehumidification in wood drying processes. The membrane material was dense polydimethylsiloxane (PDMS). A single hollow fiber membrane was modelled. The mass and momentum transfer equations were simultaneously solved to compute the water vapor concentration profile in the single hollow fiber membrane. A water vapor removal experiment was conducted by using a lab-scale PDMS hollow fiber membrane module operated at constant temperature of 35 °C. Three operation parameters of air flow rate, vacuum pressure, and initial relative humidity (RH) were set at different levels. The final RH of dehydrated air was collected and converted to water vapor concentration to validate simulated results. The simulated results were fairly consistent with the experimental data. Both experimental and simulated results revealed that the water vapor removal efficiency of the membrane system was affected by air velocity and vacuum pressure. A high water vapor removal performance was achieved at a slow air velocity and high vacuum pressure. Subsequently, the correlation of Sherwood (Sh)–Reynolds (Re)–Schmidt (Sc) numbers of the PDMS membrane was established using the validated model, which is applicable at a constant temperature of 35 °C and vacuum pressure of 77.9 kPa. This study delivers an insight into the mass transport in the moisture-selective dense PDMS hollow fiber membrane-based air dehumidification process, with the aims of providing a useful reference to the scale-up design, process optimization and module development using hollow fiber membrane materials.

scholarly journals A Coated Spherical Microresonator for Measurement of Water Vapor Concentration at PPM Levels in Very Low Humidity Environments

2018 ◽  
Vol 36 (13) ◽  
pp. 2667-2674 ◽  
Author(s):  
Arun Kumar Mallik ◽  
Gerald Farrell ◽  
Dejun Liu ◽  
Vishnu Kavungal ◽  
Qiang Wu ◽  
...  
Keyword(s):  
Water Vapor ◽  
Vapor Concentration ◽  
Water Vapor Concentration ◽  
Low Humidity

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.

Simultaneous water vapor concentration and temperature measurements in unsteady hydrogen flames

2009 ◽  
Vol 32 (2) ◽  
pp. 2527-2534 ◽  
Author(s):  
David Blunck ◽  
Sumit Basu ◽  
Yuan Zheng ◽  
Viswanath Katta ◽  
Jay Gore
Keyword(s):  
Water Vapor ◽  
Temperature Measurements ◽  
Vapor Concentration ◽  
Water Vapor Concentration
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