Application-Oriented Design and Field Trial of the Eneramic® Power Generator

Reuber, Sebastian; Jürgens, Christian; Pfeifer, Thomas; Bednarz, Marc; Wunderlich, Christian; Michaelis, Alexander

doi:10.1149/06801.0131ecst

Cited by 6 publications

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References 4 publications

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“…The results of the oxide thickness measurements in the model samples of Crofer®22APU and CFY from the oxidation in FG1 were also compared with data from interconnects operated in different SOFC stacks. The 40 cell stack from an eneramic® SOFC system ( 18) , (19) , in which Crofer®22APU was used as interconnector, was operated in a hotbox at the following conditions: gas composition N 2 /H 2 /H 2 O = 48/48/4 vol. %, fuel utilization = 70 %, current = 5 A, voltage = 27.5 V, power = 137.8 W. The 10 cell stack with CFY as MIC material ( 20), (21) was operated in an oven at a constant reference temperature of 835°C (measured at the air outlet) with a inlet gas composition of N 2 /H 2 = 60/40 vol.…”

Section: Comparison Of the Outer Oxidation Zone With Data From Sofc S...mentioning

confidence: 99%

Interconnect Corrosion in Steam Containing Fuel Gas

et al. 2017

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Iron or chromium based alloys are currently the most preferred materials for SOFC interconnects. The poisoning of the cathode of the membrane electrode assembly (MEA) due to evaporation of chromium species from the metallic interconnect (MIC) and the oxidation of the interconnect surface during stack operation at elevated (800-900 °C) temperatures are regarded to be the major mechanisms affecting the degradation behaviour of the SOFC stack. The oxidation at the cathode side of the interconnect can cause up to one third of the total stack degradation. Despite intensive investigations on corrosion stability of MIC for SOFC application over the past decades, the main attention was focused mainly on the material properties in the cathode side gas conditions (ambient air). The growth behavior and the composition of oxides grown in the SOFC anode gas environment as well as the influence of the oxides on the contact resistance between MIC and anode contacting are still not investigated comprehensively. The MIC materials have to be stable over more than 40,000 hours to satisfy a demand for a continuous increase of operation times of the SOFC stacks. Real time tests over such long time scales are cost intensive. A modification of standard material test procedures, with the aim to accelerate material degradation, is therefore necessary. In order to realize this, three ferritic steels (Crofer 22 APU, Crofer 22 H, AISI 441) and a chromium-based alloy were tested in SOFC anode gas environment in a temperature range between 725 – 875°C. The experiments were carried out under variation of the water vapor content in the gas mixture for different exposure times in order to create the accelerated degradation testing conditions for MIC and to investigate the behavior of these materials caused by the formation of growing chromium oxide based scales. Both gravimetric measurements and FESEM/EDX data, as well as polished microimage sections were analyzed to characterize the oxidation kinetics and the microstructure of the oxide scales and interconnect materials. A clear correlation between increasing temperatures and increasing oxide growth rate constants kp,w can be demonstrated in all materials. This interrelation results in thicker surface oxide scales. A comparison of surface oxide thicknesses after 1000 h oxidation in reducing atmosphere show an increase between 725°C and 875°C with a maximum factor of about 3.8 in ferritic steels and 2.4 for CFY. The comparison of kp,w values at temperatures between 725 and 875°C show acceleration factors of 8,2-11.9 in ferritic steels and 2.3 for CFY. No significant dependence of the oxide growth rate in ferritic steels and CFY by variation of the water content in fuel gas for concentrations within H2/H2O=87/13 vol.% and H2/H2O= 50/50 vol.% was found. The structures of the oxide layers are specific for each material and consist mainly of Cr2O3 (CFY) and Cr2O3/(Cr,Mn)3O4 in ferritic steels with different element distributions and thickness ratios. Beside this, the zone of an inner oxidation of MI...

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Section: Comparison Of the Outer Oxidation Zone With Data From Sofc S...mentioning

confidence: 99%

Interconnect Corrosion in Steam Containing Fuel Gas

et al. 2017

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“…Recent test results have proven the maturity of developed solutions in terms of long-term stability and cyclization capability. eneramic ® stacks have been successfully operated for more than 16.000 hours and 110 start/stop-cycles with a power degradation rate below 0,6 % per 1.000 hours and 2 % per ten cycles, respectively 9,10 . The eneramic ® technology is currently commercialized by a corporate spin-off, aiming at SOFC-based products for off-grid power generation and stationary micro-CHP.…”

Section: Sofc Stack Technologymentioning

confidence: 99%

SOFC System Development and Held Trials for Commercial Applications

Pfeifer

Reuber

Hartmann

et al. 2016

Ceramic Transactions Series

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At Fraunhofer IKTS, appropriate processes and methods for the development of customized, application-specific SOFC concepts and prototype systems have been established during various projects in the past, funded by public bodies and industrial customers. As an outcome of the cell and stack developments during the past years, two proprietary SOFC technology platforms for system integration are readily available at IKTS. The eneramic ® technology can be utilized for SOFC devices in the power range between 50 and 300 W. CFY stacks are available in standard sizes between 10 and 40 cells with a power output between 300 W and 1.2 kW. Higher power levels can be achieved by integration of multiple stacks in joint HotBox modules. For the development of SOFC systems, a detailed plant specification and process design is prepared initially. Here, all application-specific requirements are considered and a system concept with special consideration of the proposed operating modes and fuel processing technology is derived. The proposed concept is validated afterwards by means of laboratory tests on component, HotBox and system level. Further design iterations and model-based analyses are used for the creation of optimized solutions to be implemented in prototype and demonstration systems. Two exemplary SOFC development projects are described in order to illustrate the development status and system engineering approach. INTRODUCTIONIn addition to their use in residential buildings and micro CHP applications, SOFC systems are especially suited for various industrial tasks and off-grid power supplies. In this context, the usability of different conventional fuels in SOFC systems, such as Natural Gas, LPG, biogas, ethanol, diesel and kerosene, provides crucial technological advantages for the development of application-specific and marketable power generators 1 -4 .At Fraunhofer IKTS, appropriate processes and methods for the development of customized, application-specific SOFC concepts and prototype systems have been established during various projects in the past, funded by public bodies and industrial customers. During the implementation of these projects, professionals from different working groups of IKTS are working together in interdisciplinary project teams.For the development of SOFC systems, a detailed plant specification and process design is prepared initially. Here, all application-specific requirements are considered and a system concept with special consideration of the proposed operating modes and fuel processing technology is derived. The proposed concept is validated afterwards by means of laboratory tests on component, HotBox and system level. Further design iterations and model-based analyses are used for the creation of optimized solutions to be implemented in prototype and demonstration systems. During the complete system engineering process the project partners, customers or users are directly involved. The transfer of knowledge and technology for a subsequent product development and commercialization might be...

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“…However, due to carbon deposition during direct butane supply, the Ni‐GDC anode deteriorated at temperatures higher than 660 °C . The Fraunhofer‐Institut für Keramische Technologien und Systeme (IKTS) is developing an LPG‐fueled portable SOFC system with an external partial oxidation reformer .

true \begin{matrix} center {normalC}_{4} {normalH}_{10} + 2 {normalO}_{2} \to 4 normalCO + 5 {normalH}_{2} & center Δ H_{25^{\circ} normalC} = 316 normalkJ normalmo {normall}^{- 1} \end{matrix}

…”

Section: Introductionmentioning

confidence: 99%

Internal Partial Oxidation Reforming of Butane and Steam Reforming of Ethanol for Anode‐supported Microtubular Solid Oxide Fuel Cells

et al. 2017

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Internal partial oxidation reforming of butane and steam reforming of ethanol were investigated using microtubular solid oxide fuel cells (SOFCs) supported on nickel‐gadolinia doped ceria (Ni‐GDC) anodes for portable power sources in emergency situations and for mobilities, such as vehicles, robots and drones. At an oxygen/carbon (O/C) ratio of 1.0, which is a coking condition in the equilibrium, the Ni‐GDC anode deteriorated for 28 h by internal partial oxidation of butane at 650 °C. However, power generation was also impossible after 8 h and 79 h at steam/carbon (S/C) = 1.0 and 1.5, respectively, by internal steam reforming of ethanol despite of no carbon deposition condition in the equilibrium at 650 °C. Power can be generated for more than 100 h at O/C = 1.5 in butane and at S/C = 2.0 in ethanol. For internal partial oxidation reforming of methane and steam reforming of ethanol in SOFCs, the O/C and S/C ratios are significantly important to prevent carbon deposition on the Ni‐GDC anode.

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Application-Oriented Design and Field Trial of the Eneramic® Power Generator

Cited by 6 publications

References 4 publications

Interconnect Corrosion in Steam Containing Fuel Gas

Interconnect Corrosion in Steam Containing Fuel Gas

SOFC System Development and Held Trials for Commercial Applications

Internal Partial Oxidation Reforming of Butane and Steam Reforming of Ethanol for Anode‐supported Microtubular Solid Oxide Fuel Cells

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