EZelleron GmbH

Dresden, Germany

EZelleron GmbH

Dresden, Germany
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Lawlor V.,Upper Austria University of Applied Sciences | Lawlor V.,Dublin City University | Hochenauer C.,Upper Austria University of Applied Sciences | Griesser S.,Upper Austria University of Applied Sciences | And 9 more authors.
Journal of Fuel Cell Science and Technology | Year: 2011

Micro-tubular solid oxide fuel cells (MT-SOFCs) are a much smaller version of larger tubular SOFCs. They are operational within seconds and allow a higher power density per volume than the larger version. Hence they are a potential technology for automotive, auxiliary and small scale power supply devices. In this study a commercially available computational fluid dynamic (CFD) software program was used to predict a MT-SOFCs performance when located inside a high temperature wind tunnel experimental apparatus. In Part I, experimentally measured temperature profiles were recorded via thermo-graphic analyses and I/V curves. These measurements were used in this study to establish the predictability and validity of the CFD code and furthermore understand the MT-SOFC attributes measured in Part I. A maximum 4 I/V curve deviation and 6 K temperature deviation between the experimentally measured and model predicted results was observed. Thus, the model predicted the MT-SOFCs performance in the experimental environment very accurately. A very critical observation was the current density and temperature profile across the MT-SOFC that was strongly dependent on the distance from the hydrogen/fuel inlet. Not only was the model validated but also a grid and quantitative solution analysis is explicitly shown and discussed. This resulted in the optimum grid density and the indication that a normally undesirable high grid aspect ratio is acceptable for similar MT-SOFC modeling. These initial simulations and grid/solution analysis are the prerequisite before performing a further study including multiple MT-SOFCs within a stack using different fuels is also envisaged. © 2011 American Society of Mechanical Engineers.


Lawlor V.,Upper Austria University of Applied Sciences | Lawlor V.,Dublin City University | Zauner G.,Upper Austria University of Applied Sciences | Hochenauer C.,Upper Austria University of Applied Sciences | And 11 more authors.
Journal of Fuel Cell Science and Technology | Year: 2010

The purpose of the first part of this study was to compare four different temperature measuring methods. The application of these tools for possible temperature monitoring or calibration of monitors of microtubular solid oxide fuel cells (MT-SOFCs) is explored. It was found that a thermographic camera is very useful to visualize the temperature gradient on the outside of a cell, while an electrochemical impedance spectroscopy method was useful for estimating the core temperature of a test cell. A standard thermocouple was also used in combination with the previous two methods. Furthermore, an inexpensive laser guided thermometer was also tested for MT-SOFC temperature measurement. This initial study has opened up a range of questions not only about the effect of the experimental apparatus on the measurement results but also about the radial temperature distribution through a MT-SOFC in a working mode. Both these topics will be further investigated in part II of this study through a computational fluid dynamics study. This should provide additional interesting information about any differences between testing single cells and those within a bundle of cells. The discussed results are expected to be mainly temperature related, which should have direct consequences on power output and optimized gas inlet temperatures. © 2010 American Society of Mechanical Engineers.


Lawlor V.,Upper Austria University of Applied Sciences | Lawlor V.,Dublin City University | Klein K.,EZelleron GmbH | Hochenauer C.,Upper Austria University of Applied Sciences | And 5 more authors.
Journal of Fuel Cell Science and Technology | Year: 2013

Standard anode supported micro tubular-solid oxide fuel cell (MT-SOFC) stacks may provide the oxidant, in relation to the fuel, in three different manifold regimes. Firstly, "co-flow" involves oxidant outside the MT-SOFC flowing co-linearly in relation to the fuel inside. Secondly, "counter flow" involves oxidant outside the MT-SOFC flowing counter-linearly in relation to the fuel inside the MT-SOFC. Finally, "cross-flow" involves the oxidant outside the MT-SOFC flowing perpendicular to the fuel flow inside the MT-SOFC. In order to examine the effect of manifold technique on MT-SOFC performance, a combination of numerical simulation and experimental measurements was performed. Furthermore, the cathode current tap location, in relation to the fuel flow, was also studied. It was found that the oxidant manifold and the location of the cathode current collection point on the MT-SOFC tested and modeled had negligible effect on the MT-SOFC's electrical and thermal performance. In this study, a single MT-SOFC was studied in order to establish the measurement technique and numerical simulation implementation as a prerequisite before further test involving a 7 cell MT-SOFC stack. Copyright © 2013 by ASME.


Paciejewska K.,EZelleron GmbH | Weber A.,EZelleron GmbH | Kuhn S.,EZelleron GmbH | Kleber M.,EZelleron GmbH
Ceramic Engineering and Science Proceedings | Year: 2016

This study addresses the preparation of chemical reaction blocking layer (CRBL) for SOFC microtubes by dip coating in GDC suspensions and subsequent sintering. Experiments with three different commercial GDC powders revealed that optimum layer properties are determined by colloidal stability and particle size distribution (PSD) of the slurry. Colloidal stability and high disintegration level of the powders is much harder to achieve for powders with a large specific surface area than powders with lower specific surface area. Milling, sonication and centrifugation were applied for diminishing of well colloidal stabilized GDC aggregates. After centrifugation as a refinement approach, the particles could be sintered together at 1400 °C and a layer with density close to 99% could be reached. In contrast, simple ultrasonic dispersion or milling diminished the distribution width insufficiently and give porous layer even at 1600°C.


Paciejewska K.,EZelleron GmbH | Kuhn S.,EZelleron GmbH | Mnich S.,EZelleron GmbH
Ceramic Engineering and Science Proceedings | Year: 2014

The objective of the experimental investigations presented here was the development of a dense chemical reaction blocking layer (CRBL) from commercially available gadolinium-doped ceria (GDC) powders deposited by dip coating onto microtubular solid oxide fuel cells (SOFC). The preparation of suspensions as well as the process of sintering was adjusted. The results indicate that the layer properties are essentially determined by the width of the particle size distribution (PSD) - apart from the colloidal stability. Two methods were applied for achieving narrow size distribution additional to dispersion: grinding and centrifugation for achieving a narrow PSD width. As a result, the particles could be sintered together even at l300°C and a layer with a density close to 99% could be reached. In contrast, simple ultrasonic dispersion of powders diminished the distribution width insufficiently and gave porous layer even at l600°C. Furthermore, experiments at the sintering process showed that particles with the narrowest original PSD can be sintered at lower temperature than others with a broader PSD. Copyright © 2015 by The American Ceramic Society.


Paciejewska K.M.,EZelleron GmbH | Yu Y.,EZelleron GmbH | Kuhn S.,EZelleron GmbH | Weber A.,EZelleron GmbH | Kleber M.,EZelleron GmbH
Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi/Journal of the Ceramic Society of Japan | Year: 2015

The development of a dense chemical reaction blocking layer (CRBL) for micro-tubular solid oxide fuel cells (SOFC) was the aim of this study. The electrochemical performance and stability of SOFCs were also investigated since they strongly depend on fabrication conditions for the electrolyte and CRBL layers. Slurries of two commercial Ce0.8Gd0.2O1.90 powders were prepared and deposited by dip coating onto micro-tubular SOFCs. The results indicate that the layer density and homogeneity are essentially determined by the width of particle size distribution (PSD) apart from the colloidal stability. Two methods were applied for achieving a narrow PSD additional to dispersion: grinding and centrifugation. Particles with a very narrow PSD obtained through centrifugation process could be sintered together even at 1300°C and a layer with a density close to 99% could be reached. In contrast, simple ultrasonic dispersion of powders diminished the distribution width insufficiently and gave porous layer. Impedance measurements showed clear relationship between GDC layer density and ohmic resistance of the cells which directly correlates to their performance with a power density 0.75W/cm2 at 0.7 volt and OCV∼1.06V obtained at 850°C for the cells with the densest GDC layer. © 2015 The Ceramic Society of Japan.


Stoeck A.,EZelleron GmbH | Mnich S.,EZelleron GmbH | Kuhn S.,EZelleron GmbH
ECS Transactions | Year: 2013

A major issue for the use of ceramic cathodes in solid oxide fuel cells (SOFCs) is their limited conductivity and fragility. Therefore silver based current collectors were used to obtain highly conductive cathodes. Incorporation of oxide particles prevents densification and led to porous films with enhanced stability and excellent electrochemical properties. © The Electrochemical Society.


Patent
EZelleron GmbH | Date: 2010-07-16

The present invention relates to a fuel cell system, in particular solid oxide fuel cell system (SOFC-System), with several tubular fuel cells, whereby several of these fuel cells respectively have at least one inner electrode, an electrolyte surrounding this/these inner electrode(s) at least in sections and at least one outer electrode surrounding the electrolyte at least in sections, so that the electrolyte spatially separates the inner and the outer electrode(s) from each other, at least two of these fuel cells are located or fixated in or on an electrically conducting carrier and/or contact, which connectselectrically conductingthe inner electrode(s) and/or one/several electrical contact(s) of one/several inner electrode(s) of a first tubular fuel cell or a part of such with the outer electrode(s) and/or one/several electrical contact(s) of one/several outer electrode(s) of a second tubular fuel cell or a part of such, whereby the second tubular fuel cell is preferably located directly adjacent to the first tubular fuel cell or to the part of this fuel cell.

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