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Evaluation of Performance and Degradation Profiles of a Metal Supported Solid Oxide Fuel Cell Under Electrolysis Operation
No full textIn the context of energy transition, the use of renewable energies through the conversion of different resources with promising technologies into storable energy carriers is of eminent importance for a sustainable energy supply. Hydrogen production from steam using solid oxide electrolysis cells (SOEC) is part of this so called
“energy mix”. Recently, promising progress appeared from the investigation of metal supports in the solid oxide cell architecture. Metal-supported solid oxide fuel cells (MS-SOFCs) show not only good mechanical strength, relatively low operating temperature (500-750°C) and improved sealing capability but also low materials cost and tolerance towards rapid thermal cycling and redox cycling (1-3). In the present study, a MS-SOFC was tested under
electrolysis conditions. The cell consisted of Ni-catalyst loaded La0.1Sr0.9TiO3-α/gadolinium-doped ceria (Ni-LST/GDC) as fuel electrode, gadolinium-doped ceria / yttrium-stabilized zirconia (GDC/YSZ) as electrolyte and La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) as O2 electrode. The cell was first tested in fuel cell mode under different gas compositions. Subsequently, a first evaluation of the
cell performance profile in electrolysis mode was performed. Thus, a series of current-voltage curves as well as impedance diagrams (under OCV and under load) was recorded. Furthermore, degradation under electrolysis operation was also investigated based on the evolution of the cell voltage against time
LaNi0.6Fe0.4O3 as Cathode Contacting Material: Effect on Anode Supported Cell Performances
Full text linkIn this work, LaNi0.6Fe0.4O3 (LNF) powders have been synthesized by sol-gel methods and used to prepare a contacting paste. A testing setup, developed to test anode-supported cells with different contacting geometries, has been used to investigate the effect of LNF contacting paste between the cathode and the current collector. The cell performances were comparable to those measured using a state-of-the-art La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) contacting paste, however, showing better stability under electric load. Cell performances have been investigated by means of current-voltage curves. Electrochemical impedance spectroscopy has been used to distinguish the loss contribution within the investigated system and to measure its evolution over time. The performances evolution was confirmed by microstructural changes and migration of elements characterized post-experiment by means of scanning electron rnicroscopy-energy dispersive X-ray and X ray diffraction techniques
Carbon-Tolerant Ni/ScCeSZ Via Aqueous Tape Casting for IT- SOFCs
Full text linkNickel-Yttria stabilized zirconia (Ni/8YSZ) and Nickel Ceria doped-Scandia stabilised zirconia (Ni/10ScCeSZ) anode supported cells were successfully fabricated using a reverse aqueous tape casting method. The performance of the full cells were tested using both hydrogen and dry biogas at the anode side and ambient air at the cathode side in the temperature range 750°C to 800°C. In hydrogen, Ni/10ScCeSZ showed better performance at 800°C compared to the Ni/8YSZ cell. Switching the fuel from hydrogen to dry biogas, the performance of the Ni/8YSZ cell reduced significantly from 0.31 W/cm2 to 0.06 W/cm2. With Ni/10ScCeSZ cells, the cell performance in biogas was 4 times higher than the corresponding Ni8YSZ cells. The maximum power density decreased only from 0.36 W/cm2 to 0.22 W/cm2 in Ni/10ScCeSZ cell tested when switched from hydrogen to biogas. The results of this work indicate the possibility of using biogas or other carbonaceous fuel in SOFCs without the addition of water (steam)
Carbon-Tolerant Ni/ScCeSZ Via Aqueous Tape Casting for IT- SOFCs
Full text linkNickel-Yttria stabilized zirconia (Ni/8YSZ) and Nickel Ceria doped-Scandia stabilised zirconia (Ni/10ScCeSZ) anode supported cells were successfully fabricated using a reverse aqueous tape casting method. The performance of the full cells were tested using both hydrogen and dry biogas at the anode side and ambient air at the cathode side in the temperature range 750°C to 800°C. In hydrogen, Ni/10ScCeSZ showed better performance at 800°C compared to the Ni/8YSZ cell. Switching the fuel from hydrogen to dry biogas, the performance of the Ni/8YSZ cell reduced significantly from 0.31 W/cm2 to 0.06 W/cm2. With Ni/10ScCeSZ cells, the cell performance in biogas was 4 times higher than the corresponding Ni8YSZ cells. The maximum power density decreased only from 0.36 W/cm2 to 0.22 W/cm2 in Ni/10ScCeSZ cell tested when switched from hydrogen to biogas. The results of this work indicate the possibility of using biogas or other carbonaceous fuel in SOFCs without the addition of water (steam)
Effect of Alloy Composition on the Oxidation Behaviour and Cr Vaporisation of High-Cr Steels for SOFC Cathode Air Preheater
Full text linkWe investigated the capability of aluminised and alumina-forming alloys to reduce the Cr vaporisation and increase the corrosion resistance by the growth and formation of alumina scale. The Cr evaporation tests have been performed for Inconel 625, AluChrom 318, SS309 and aluminised SS309 by applying a denuder technique at 850 °C with 6 L/min airflow and 3 vol% H2O to simulate the cathode atmosphere in SOFC. Chemical analysis of the oxide scales formed was subsequently studied by XRD and SEM/EDX. Inconel 625 and uncoated SS309 exhibited relatively higher Cr evaporation due to a Cr-rich oxide layer, in comparison with other materials. The chromium evaporation of uncoated SS309 was dramatically decreased by aluminising. The experiments showed that Cr retention of the aluminised surface of SS309 is comparable to that of alumina-forming steel, AluChrom 318, over 168 hours. However, spallation of PVD applied alumina scales was detected for aluminised SS309 after 1000 hours oxidation
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Effect of Alloy Composition on the Oxidation Behaviour and Cr Vaporisation of High-Cr Steels for SOFC Cathode Air Preheater
Full text linkWe investigated the capability of aluminised and alumina-forming alloys to reduce the Cr vaporisation and increase the corrosion resistance by the growth and formation of alumina scale. The Cr evaporation tests have been performed for Inconel 625, AluChrom 318, SS309 and aluminised SS309 by applying a denuder technique at 850 °C with 6 L/min airflow and 3 vol% H2O to simulate the cathode atmosphere in SOFC. Chemical analysis of the oxide scales formed was subsequently studied by XRD and SEM/EDX. Inconel 625 and uncoated SS309 exhibited relatively higher Cr evaporation due to a Cr-rich oxide layer, in comparison with other materials. The chromium evaporation of uncoated SS309 was dramatically decreased by aluminising. The experiments showed that Cr retention of the aluminised surface of SS309 is comparable to that of alumina-forming steel, AluChrom 318, over 168 hours. However, spallation of PVD applied alumina scales was detected for aluminised SS309 after 1000 hours oxidation
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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