Cycling of three solid oxide fuel cell types

Bujalski, W.; Dikwal, Chinnan M.; Kendall, Kevin

doi:10.1016/j.jpowsour.2007.01.029

Cited by 139 publications

(76 citation statements)

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“…Such start-stop operation results in thermal cycling, and is often associated with an interruption in fuel supply. Although it is well known that thermal and redox cycling under startstop operation deteriorates SOFC electrochemical performance, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] there are only a limited number of studies that systematically focus on this technologically relevant issue.Continuous SOFC stack operation with constant power output generally results in a gradual degradation in performance during long-term operation (SOFCs should run for up to a decade). However, SOFCs can suffer to a greater degree from changes in operation conditions.…”

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confidence: 99%

SOFC Durability against Standby and Shutdown Cycling

Hanasaki

Uryu

Daio

et al. 2014

J. Electrochem. Soc.

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To simulate realistic operating conditions in SOFC systems, we investigate the influence of thermal cycling on the performance of electrolyte-supported planar SOFCs. Thermal cycling is often associated with interruption of fuel supply, with three main modes; hot standby, cold standby, and shutdown. Cell performance degradation is most significant during shutdown cycles. Nickel oxidation and agglomeration are more pronounced when SOFCs are subjected to lower temperatures for longer periods of time, leading to significant performance degradation. Ostwald ripening at the anode leads to degradation as Ni grains increase in size with cycling. Ni particle precipitation on the anode zirconia grains and along electrolyte grain boundaries is found for the first time in shutdown cycling tests. When H 2 S is mixed with the fuel, the internal reforming reactions and electrode reactions are inhibited by sulfur poisoning of the Ni anodes, accelerating degradation. The SOFC cycling degradation mechanisms are discussed in detail. Solid oxide fuel cells (SOFCs) have several advantages including high efficiency, fuel flexibility, and utilization of non-noble metal, Pt-free catalysts, due to their relatively high operation temperature. Commercialization of SOFC systems for residential electric power applications began in Japan in 2011. Such systems are frequently stopped and restarted in normal operation, e.g. when power is not required, or in an emergency. Such start-stop operation results in thermal cycling, and is often associated with an interruption in fuel supply. Although it is well known that thermal and redox cycling under startstop operation deteriorates SOFC electrochemical performance, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] there are only a limited number of studies that systematically focus on this technologically relevant issue.Continuous SOFC stack operation with constant power output generally results in a gradual degradation in performance during long-term operation (SOFCs should run for up to a decade). However, SOFCs can suffer to a greater degree from changes in operation conditions. Due to thermal expansion mismatch between the different components, the cells can suffer from mechanical degradation mechanisms, such as delamination and crack formation with simple thermal cycling. Changes in atmosphere can result in more serious degradation. The influences of thermal cycling and current density cycling on cell degradation have been previously investigated.1-4 The change in volume causes Ni agglomeration. [5][6][7] Redox cycles are typically associated with oxidation of Ni particles at the anode. [8][9][10][11][12] Furthermore, redox cycling results in the formation of Ni hydroxides at a certain vapor pressure in oxidizing atmosphere, with a high water vapor concentration. 13,14 In real residential SOFC power units, cells and stacks are not subjected to these different conditions independently; the changes occur much more dynamically. Therefore, cycle durability studies should be performed using reali...

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mentioning

confidence: 99%

SOFC Durability against Standby and Shutdown Cycling

Hanasaki

Uryu

Daio

et al. 2014

J. Electrochem. Soc.

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“…As a result, an exclusive characteristic of mT-SOFCs is the rapid start-up time (Kendall and Sales, 1994). In fact, Bujalski et al (2007) demonstrated that individual YSZsupported mT-SOFCs could be switched on in <1 min, stacks will need much longer start-up times. In a recent paper, Kendall and Meadowcroft (2013) discussed the benefits of reducing tube diameter, both in fast cell thermal response and in the increase of cell mechanical strength.…”

Section: Introductionmentioning

confidence: 99%

Fabrication Methods and Performance in Fuel Cell and Steam Electrolysis Operation Modes of Small Tubular Solid Oxide Fuel Cells: A Review

2014

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Higher energetic density, better resistance to thermal stresses, and smaller starting times as compared with conventional planar stacks, make the so-called microtubular SOFC (mT-SOFCs with diameters in the millimeter size region) devices suitable for portable applications in the sub kilowatt energy range. However, fabrication of mT-SOFCs is a challenging process, where a number of ceramic layers with different compositions and characteristics have to be placed together in the cylindrical device. Several co-sintering processes have to be performed at different temperatures and using distinct atmospheres to complete cell fabrication. In this review, we summarize recent activity in the field of fabrication and characterization of mT-SOFCs, including the use of mT-SOFCs for steam electrolysis.

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“…The Micro Tubular Solid Oxide Fuel Cell (MT-SOFC) is a much smaller version of the standard planar and tubular SOFC systems. It is an evolution of the standard SOFC that has added resilience against thermal shocks, which allows a fast start-up and a high power per volume [8]. Also, with regard to manufacture, the smaller MT-SOFC is desirable as for example, Appelby [9] suggested that ceramic parts have thermo-mechanical problems and special *Address correspondence to this author at the Department of Eco-Energy, Upper Austrian University of Applied Science, A-4600 Wels, Austria; Tel: +43-7242-72811-5507; E-mails: vlawlor@gmail.com, Vincent.lawlor@fh-wels.at reliability aspects, which influence their manufacture rejection rate.…”

Section: Introductionmentioning

confidence: 99%

“…Most groups publishing work in the sector usually use anode supported MT-SOFCs, where the electrolyte and cathode layers are dip coated or deposited onto a substrate [8,[21][22][23][24][25][26][27][28][29]. A few groups have published work on cathode supported MT-SOFCs [26,30].…”

Section: Introductionmentioning

confidence: 99%

“…Smaller MT-SOFCs have been shown to be more desirable with regard to hydrogen concentration and temperature [34], thermal shock resistance [8] and power density [19,35] than larger cells. A goal of this paper was to use a commercially available CFD modelling package with electrochemical models in order to explore the attributes of the various manifolding techniques, discussed above, for a MTSOFCs with a diameter under 3 mm.…”

Section: Introductionmentioning

confidence: 99%

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Scrutiny of MT-SOFC Stack Manifolding Design Using CFD

Lawlor¹,

Hochenauer

Mariani³

et al. 2012

TOFCJ

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Abstract:In this work we investigated the use of Computational Fluid Dynamics (CFD) in order to describe the behaviour of a single Micro Tubular Solid Oxide Fuel Cell (MT-SOFC) and a bundle thereof. It is the first step before building a rather necessarily complicated experimental apparatus in order to compare the predictions with experimental measurement. The first goal of this study was to test the suitability of commercially available CFD & SOFC modelling software, with some modified features. The second goal was to predict the effects of various fuel and oxidant manifolding techniques regarding temperature, species and current density distributions. A result of this paper showed that CFD is a very useful tool, when a SOFC module is incorporated for MT-SOFC stack modelling. A second result showed that the oxidant flow regime was much more important than the fuel regime in order to manipulate a single MT-SOFC's temperature profile. The cases investigated had a radiation model included and the differences in temperature profiles, when radiation was included and neglected, especially for MT-SOFCs with view factors to the reactor housing, was shown to be important. The CFD predictions clearly showed the benefits and advantages associated with the different forms of fuel and oxidant manifoldings. A future experimental analysis is currently being designed.

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Cycling of three solid oxide fuel cell types

Cited by 139 publications

References 3 publications

SOFC Durability against Standby and Shutdown Cycling

SOFC Durability against Standby and Shutdown Cycling

Fabrication Methods and Performance in Fuel Cell and Steam Electrolysis Operation Modes of Small Tubular Solid Oxide Fuel Cells: A Review

Scrutiny of MT-SOFC Stack Manifolding Design Using CFD

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