Characterization of Multilayer Anodes for SOFC

2002 ◽  
Vol 756 ◽  
Author(s):  
Axel C. Müller ◽  
Albert Krügel ◽  
André Weber ◽  
Ellen Ivers-Tiffée
Keyword(s):  
Single Cells ◽  
Oxidation Stability ◽  
Anode Layer ◽  
Gas Distribution ◽  
Functional Layer ◽  
Fuel Gas ◽  
Term Operation ◽  
Operation Conditions ◽  
Electrochemically Active ◽  
Screen Printed

ABSTRACTSOFC anodes have to combine various tasks. In anode supported single cells a thick anode substrate is used for current collecting and gas distribution whereas a thin functional layer adjacent to the electrolyte is the electrochemically active part of the anode. This functional anode layer is cofired together with the thin film electrolyte to obtain an enhanced interface with low polarisation losses. This multilayer structure was transferred to an electrolyte supported single cell. The electrochemical active Ni/8YSZ anode layer was screen printed onto a 8YSZ electrolyte green tape and subsequently cofired at 1350 °. Mechanical stresses during cofiring due to shrinkage mismatch of anode and electrolyte were avoided by changing the geometry of the anode layer from a continuous layer to a large number of small sized individual areas. Simulations by finite element modeling indicated that a hexagonal pattern similar to honeycombs is preferable. The second layer which adjoins to the fuel gas channels and which is responsible for current collecting and gas distribution was later on screen printed on top and sintered together with the cathode. Single cells with a multilayer anode and different functional layers were electrochemically characterised under realistic operation conditions. The performance and reduction/oxidation stability of this type of anode was investigated. The electrochemically active layer showed only small degradation during redox cycling and long term operation at high fuel utilisation. In contradiction to single layer anodes Nickel agglomeration was not observed in the functional layer.

The Electrochemical Performance of Anode-Supported SOFCs with LSM-Type Cathodes Produced by Alternative Processing Routes

2005 ◽  
Vol 3 (2) ◽  
pp. 125-130 ◽  
Author(s):  
J. Mertens ◽  
V. A. C. Haanappel ◽  
C. Tropartz ◽  
W. Herzhof ◽  
H. P. Buchkremer
Keyword(s):  
Electrochemical Performance ◽  
Single Cells ◽  
Tape Casting ◽  
Current Collector ◽  
Functional Layer ◽  
Fuel Gas ◽  
Production Route ◽  
Alternative Processing ◽  
Cathode Current ◽  
Alternative Processing Routes

The electrochemical performance of La0.65Sr0.3MnO3-type (LSM) anode-supported single cells, produced by alternative production processes, has been investigated at intermediate temperatures. In particular, three different variations of the production route were investigated in more detail: (1) the use of nonground LSM powder for the cathode current collector layer, (2) the use of noncalcined and nonground YSZ powder for the cathode functional layer, and (3) the use of tape casting versus warm pressing as the production process for anode substrates. Results from electrochemical measurements performed between 700 and 900°C with H2 (3vol%H2O) as fuel gas and air as the oxidant showed that performance increased with increasing grain size of the outer cathode current collector layer: the highest performance was achieved with nonground LSM powder. Furthermore, performance was not adversely influenced by the use of noncalcined and nonground YSZ for the cathode functional layer. Also the use of anode substrates with a thickness of about 0.7mm and produced by tape casting, instead of those with a thickness of about 1.5mm and applied by warm pressing, did not detrimentally affect the electrochemical performance of this type of SOFC.

Properties of TiC-Ni Based Coatings Deposited by Different HVOF Spraying

2000 ◽  
Author(s):  
P. Vuoristo ◽  
M. Väisänen ◽  
T. Mäntylä ◽  
L.-M. Berger
Keyword(s):  
Wear Resistance ◽  
Flame Temperature ◽  
Oxygen Flow ◽  
Spray Parameters ◽  
Coating Properties ◽  
Hvof Spraying ◽  
Fuel Gas ◽  
Wear Rates ◽  
Operation Conditions ◽  
Satisfactory Coating

Abstract Hardmetal-like coatings of the TiC-Ni system are potential for use as wear, corrosion and heat resistant coatings in various operation conditions. Our previous works [1-12] have shown that these materials are well sprayable using different thermal spray processes such as plasma, D-Gun and HVOF spraying. Since HVOF spraying is today the most important process used to apply carbide based coatings, this study was carried out in order to evaluate more systematically the sprayability of these novel spray powders and the influence of HVOF spray parameters on some coating properties. Coating samples were prepared by using DJ Hybrid gun with propane as a fuel gas, and a CDS gun with hydrogen fuel gas. Oxygen flow rate was varied in both cases for changing the flame temperature. Microstructure, phase composition, hardness, and abrasion wear resistance of the coated samples were investigated. The results showed that both HVOF processes used give satisfactory coating properties and that the use of high oxygen flow rates is beneficial for improving the wear resistance of the coatings. Powders with fine particle size are beneficial in the DJ Hybrid process; the use of coarse powders results in coatings with somewhat higher wear rates. The optimum spray condition for the TiC-Ni system powders differs from that typically used for conventional WC-Co and Cr3C2-NiCr powders by a higher flame temperature.

FULL SCALE EXPERIMENT AND NUMERICAL ANALYSIS FOR THE PERFORMANCE OF HEAT EXCHANGER IN MOLTEN CARBONATE FUEL CELLS

2016 ◽  
Vol 40 (5) ◽  
pp. 799-810
Author(s):  
Seon-Hwa Kim ◽  
Byeong-Keun Choi ◽  
Young-Su An
Keyword(s):  
Heat Exchanger ◽  
Fuel Cell ◽  
Flow Characteristics ◽  
Cell System ◽  
Molten Carbonate Fuel Cell ◽  
Molten Carbonate ◽  
Fuel Gas ◽  
Operation Conditions ◽  
Scale Down ◽  
Scale Experiment

This study presents a numerical simulation of heat transfer and flow characteristics of the heat exchanger in molten carbonate fuel cell system. In this study, the actual size of the heat exchanger was simulated in order to avoid errors that can occur from the scale-down test, also the simulation gas (air) was verified with the heat duty of 800,000 kcal/hr. It is analyzed by using a commercial heat exchanger calculation code based upon the test condition. It is found that a reasonable agreement is obtained from comparison between the predicted results and the measured data. Furthermore, the verified similarity was presented in this analysis. In particular, the simulation gas used for the shell side service for the heat exchanger is obtained through the combustion calculation, i.e. by using a flow rate of the fuel gas. In addition, the performance of the heat exchanger is predicted under various conditions in the fuel cell operation conditions by the numerical model.

Performance Improvement of (La,Sr)MnO3 and (La,Sr)(Co,Fe)O3-Type Anode-Supported SOFCs

2006 ◽  
Vol 3 (3) ◽  
pp. 263-270 ◽  
Author(s):  
Vincent A. C. Haanappel ◽  
Josef Mertens ◽  
Andreas Mai
Keyword(s):  
Electrochemical Performance ◽  
Performance Improvement ◽  
Sintering Temperature ◽  
High Reliability ◽  
Single Cells ◽  
Tape Casting ◽  
Slip Casting ◽  
Production Costs ◽  
Processing Route ◽  
Functional Layer

Targets in the development of anode-supported or planar solid oxide fuel cells (SOFCs) are low operation temperatures, high durability, high reliability, high power density, and low production costs. During the past ten years steps have already been taken at Forschungszentrum Jülich to lower the operating temperatures while maintaining the power output. This was achieved by optimizing processing and microstructural parameters of the electrodes. This paper presents the latest results concerning performance improvement through variations of the processing route and the microstructure of La0.65Sr0.3MnO3 (LSM) and La0.58Sr0.4Co0.2Fe0.8O3−δ (LSCF)-type SOFCs. In the case of the LSM-type single cells, the following aspects relating to the electrochemical performance were investigated in more detail: (1) production of the anode substrate by tape casting versus warm pressing; (2) deposition of the anode functional layer (AFL) and electrolyte by screen printing versus vacuum slip casting; (3) use of noncalcined and non-ground YSZ for applying the cathode functional layer (CFL); and (4) sintering temperature of the CFL and cathode current collector layer (CCCL). In the case of LSCF-type cells, a systematic approach was initiated for optimizing the Ce0.8Gd0.2O2−δ (CGO) diffusion barrier layer: (1) deposition techniques of the CGO layer and (2) sintering temperature of the screen-printed CGO layer. Results have shown that certain modifications of the processing route led to a slightly lower electrochemical performance, whereas others did not affect the performance at all. Regarding LSCF-type SOFCs, a slight improvement of the performance was achieved by optimizing the sintering temperature of the CGO layer.

Flame Transfer Function Characteristics of Swirl Flames for Gas Turbine Applications

2003 ◽  
Author(s):  
Martin Lohrmann ◽  
Horst Bu¨chner ◽  
Nikolaos Zarzalis ◽  
Werner Krebs
Keyword(s):  
Gas Turbine ◽  
Uv Radiation ◽  
Radiation Intensity ◽  
Transfer Functions ◽  
Full Scale ◽  
Oh Radicals ◽  
Mixture Formation ◽  
Fuel Gas ◽  
Operation Conditions ◽  
Flame Response

For the suppression or reduction of self-sustained combustion instabilities, modifications of the burner outlet conditions, that strongly influence the dynamic flame response, seem to be the most promising way. Therefore, to derive a detailed physical understanding of the feedback mechanisms the dynamic flame response characteristics, quantified by flame transfer functions, are required in dependence of flame type and operation conditions of the combustor. In the present paper measurements of flame transfer functions of an industrial, full-scale prototype gas turbine burner are discussed. For the detection of periodically-unsteady OH radical radiation (response of the flame) two different UV detection systems were compared. Because the concentration of electronically-excited OH radicals in the reaction zone and therefore, of the measured UV radiation intensity, is strongly depending on volumetric reaction density and local flame temperatures, the UV radiation intensity commonly used for the quantification of the heat release can be misinterpreted. Hence, two different concepts of fuel gas/air mixture formation have been realized in the experiments to separate and to physically interpret the influence of the mixture formation and its quality on the UV radiation intensity of the determined flame transfer functions. The derived understanding of the complex interactions of mixture mass flow oscillations, fluctuations of the mixture composition and the periodic combustion of ring vortices at a full-scale burner is an essential requirement for the interpretation of flame dynamics based on measurements of the UV radiation intensity.

scholarly journals Performance test on a 5kW SOFC system under high fuel utility with practical syngas feeding

2020 ◽  
Author(s):  
ming xu ◽  
Hanlin Wang ◽  
Mingxian Liu ◽  
Jianning Zhao ◽  
Yuqiong Zhang ◽  
...  
Keyword(s):  
Power Generation ◽  
Fuel Cell ◽  
Large Scale ◽  
Performance Test ◽  
High Efficiency ◽  
Green Energy ◽  
Commercial Application ◽  
Fuel Gas ◽  
Term Operation

Abstract With increasing demand of green energy supply with high efficiency and low CO2 emission, Solid oxide fuel cell (SOFC) has been intensively developed in recent years. And the integration of gasification with fuel cell (IGFC) shows potential in large scale power generation to further increase the system efficiency. Reliable design of multi-stacks for large system and long term stability of stacks with practical fuel gas from industrial equipment are the key for commercial application of IGFC. In this work, a test rig of 5kW SOFC system was fabricated using practical syngas from industrial gasifiers as fuel and long term test under high fuel utility was conducted to investigate the system performance. The results show that the maximum steady output power of system is 5700W for hydrogen case and 5660W for syngas case, and the maximum steady electrical efficiency is 61.24% while the fuel utility efficiency is 89.25%. The test lasted for more than 500h as the fuel utility efficiency was larger than 83%. The performances of each stack tower are almost identical at both initial stage and after long term operation. After 500h operation, the performances of stack towers just slight decrease under lower current and almost not change under higher current. Therefore, the results illustrate that the reliability of multi-stacks design and the prospect of SOFC power generation system for further enlarging its application in a MWth demonstration.

Synthesis and Characterization of Nanocrystalline La0.65Sr0.3 MnO3 and La0.8Sr0.2MnO3 Cathode Powders by Auto-ignition Technique for Solid Oxide Fuel Cells (SOFC)

2016 ◽  
Vol 19 (2) ◽  
pp. 065-076
Author(s):  
G. N. Almutairi ◽  
M. Ghouse ◽  
Y. M. Alyousef ◽  
F. S. Alenazey
Keyword(s):  
Fuel Cells ◽  
Solid Oxide Fuel Cells ◽  
High Efficiency ◽  
Single Cells ◽  
Average Crystallite Size ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Functional Layer ◽  
Auto Combustion

Solid Oxide fuel Cells (SOFCs) are considered to be one of the most promising energy conversion devices that have several advantages such as high efficiency, system compactness and low environmental pollution. In the present investigation La0.65Sr0.3MnO3 (LSM-1) and La0.8Sr0.2MnO3 (LSM-2) nanoceramic powders were prepared by citrate-nitrate route of auto-combustion with citrate to nitrate (c/n) ratio 0.50 to see the effect of these cathode powders on the performance of SOFC cells. The as prepared powder were calcined at 900oC for 4hrs using the Thermolyne 47900 furnace to remove carboneous residues and characterized them using SEM / EDS, XRD, TGA techniques and their results are presented . From calculations using Debye Scherrer’s equation, the average crystallite size of the powders were found to be around 16nm. The SEM indicates the particle sizes are within the range of around 200nm.The surface area of the calcined LSM-2 powder was found to be ~21m2/g. The TGA studies indicate the completion of combustion since there was no further weight loss after reaching temperature of ~ 650oC. Also, Electrochemical characterization of LSM cathode powders were carried out by coating these powders (as cathode functional layer CFL-Bottom and current collector layer CL- Top) using Screen printing on the SOFC half cells (NiO-YSZ+YSZ) procured from CGCRI, Kolkata, India with a cell size of 16mm dia x1.6mm and tested these cells with H2-O2 at 750-800oC with the flow rates of 100-200 sccm. The results of the performances of single cells are presented in this paper. The Current density and powder density values obtained are 0.80A/cm2 (at 0.7V) and 0.55 W/cm2 at 800oC with 200 sccm of hydrogen and oxygen respectively. The area surface resistance (ASR) values obtained were ~0.50 Ωcm2 at 0.7V at 800oC.

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