Letteratura scientifica selezionata sul tema "Triple phase boundary (TPB)"
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Articoli di riviste sul tema "Triple phase boundary (TPB)":
1
Wakamatsu, Katsuhiro, Takaaki Yasuda, Yuji Okada e Teppei Ogura. "First-Principles Studies for Optimal Model of the Ni/YSZ Triple Phase Boundary in Solid Oxide Cells". ECS Transactions 111, n. 6 (19 maggio 2023): 1333–46. http://dx.doi.org/10.1149/11106.1333ecst.
Abstract (sommario):
To resolve the existing issues of solid oxide cells such as degradation and efficiency improvement, it is essential to understand reaction mechanisms on the surface/interface such as triple phase boundary (TPB) as a highly active site that consists of catalysts, electrolytes, and gas phases. However, the reliable TPB model has not been still uniquely defined to discuss the property. In this study, we have focused on the TPB model comprising Ni catalysts, yttria-stabilized zirconia (YSZ) electrolytes, and gas phases and aimed to theoretically identify a reliable TPB model. In concrete, we identified firstly the stable structure of YSZ surface models by using density functional theory calculations considering different oxygen vacancy positions, yttrium atom arrangements, yttria concentration, and YSZ surfaces. Thereafter, we discussed a reliable Ni/YSZ interface model based on our proposed YSZ model by evaluating different Ni structure types, Ni interfaces in contact with the YSZ surface, and interface positions.
2
Zhang, Shidong, Kai Wang, Shangzhe Yu, Nicolas Kruse, Roland Peters, Felix Kunz e Rudiger-A. Eichel. "Multiscale and Multiphysical Numerical Simulations of Solid Oxide Cell (SOC)". ECS Transactions 111, n. 6 (19 maggio 2023): 937–54. http://dx.doi.org/10.1149/11106.0937ecst.
Abstract (sommario):
This study presents a novel model for investigating the microstructural evolution of nickel (Ni), yttria-stabilized zirconia (YSZ), and gas phases in a solid oxide cell (SOC), and its effects on cell performance. The triple-phase-boundary (TPB), which is the interface between the three phases, plays a crucial role in the electrochemical reaction of the SOC. However, during operation, nickel particles coarsen or migrate, leading to the redistribution of the TPB. To study this phenomenon, a phase field method was utilized to simulate the fuel electrode's detailed structure, and an approach was developed to track the TPB lines (TPBl) and voxels (TPBv). The study then employed the open-source computational fluid dynamics library, OpenFOAM, to simulate the half-cell performance. The results provide a detailed understanding of the dynamics of the TPB and its impact on multiphysical transport phenomena.
3
Putri, Rihan Amila, Dani Gustaman Syarif e Atiek Rostika Noviyanti. "Correlation Microstructure of Triple Phase Boundary and Crystallinity in SOFC Cells NiO/LSGM/LCM". Research Journal of Chemistry and Environment 26, n. 8 (25 luglio 2022): 44–50. http://dx.doi.org/10.25303/2608rjce044050.
Abstract (sommario):
The electrochemical process in the TPB microstructure depends on the conductivity of the SOFC cell constituent materials. Electrolyte and electrode materials must have good conductivity. The crystallinity of an electrolyte can affect its conductivity. In this study, the electrolyte La0.8Sr0.2Ga0.8Mg0.2O3–δ (LSGM) was used and is known to have good conductivity at intermediate temperatures. The single cell of LSGM electrolyte with La0.7Ca0.3MnO3 (LCM) cathode which has high electronic conductivity and NiO anode which has low area-specific resistance (ASR) is expected to produce compatible cells. The production of NiO/LSGM/LCM cells was carried out through the solid-solid phase synthesis method. Microstructural analysis of TPB was performed using SEM-EDS; meanwhile, crystallinity was obtained through XRD analysis. The crystallinity values of NiO, LSGM and LCM cell components above 80% allow the cells to produce high conductivity with a three-phase boundary microstructure from porous electrodes and relatively dense electrolytes which can increase the possibility of gas, ion and electron encounters in the TPB. In SOFC NiO/LSGM/LCM cells, Ni=11.08%; Ca=6.84%; Mn=9.28% and no precipitate is formed at the electrolyte-electrode boundary, so that the electrochemical process on the TPB microstructure could run well.
4
Rix, Jillian G., Boshan Mo, Alexey Y. Nikiforov, Uday B. Pal, Srikanth Gopalan e Soumendra N. Basu. "Quantifying Percolated Triple Phase Boundary Density and Its Effects on Anodic Polarization in Ni-Infiltrated Ni/YSZ SOFC Anodes". Journal of The Electrochemical Society 168, n. 11 (1 novembre 2021): 114507. http://dx.doi.org/10.1149/1945-7111/ac3599.
Abstract (sommario):
Increasing the density of percolated triple phase boundaries (TPBs) by infiltrating nanoscale electrocatalysts can improve the performance of solid oxide fuel cell (SOFC) anodes. However, the complex microstructure of these infiltrated nanocatalysts creates challenges in quantifying their role in anode performance improvements. In this research, scanning electron microscopy of fractured cross-sections of a Ni-nanocatalyst infiltrated anodic symmetric cell along with three-dimensional (3-D) reconstruction of the same anode have been used to quantify the changes in percolated TPB densities due to infiltration. This change in percolated TPB density has been compared to the improvement in anode activation polarization resistance measured by electrochemical impedance spectroscopy (EIS). It was found that increased TPB densities only partially accounted for the measured performance improvement. Distribution of relaxation times (DRT) analyses showed that a reduction in the time constants of the catalytic processes in the anode also play a role, suggesting that the added nanoscale percolated TPB boundaries are more electrochemically active as compared to the cermet TPB boundaries.
5
Wilson, James R., Marcio Gameiro, Konstantin Mischaikow, William Kalies, Peter W. Voorhees e Scott A. Barnett. "Three-Dimensional Analysis of Solid Oxide Fuel Cell Ni-YSZ Anode Interconnectivity". Microscopy and Microanalysis 15, n. 1 (15 gennaio 2009): 71–77. http://dx.doi.org/10.1017/s1431927609090096.
Abstract (sommario):
AbstractA method is described for quantitatively analyzing the level of interconnectivity of solid-oxide fuel cell electrode phases. The method was applied to the three-dimensional microstructure of a Ni–Y2O3-stabilized ZrO2 (Ni-YSZ) anode active layer measured by focused ion beam scanning electron microscopy. Each individual contiguous network of Ni, YSZ, and porosity was identified and labeled according to whether it was contiguous with the rest of the electrode. It was determined that the YSZ phase was 100% connected, whereas at least 86% of the Ni and 96% of the pores were connected. Triple-phase boundary (TPB) segments were identified and evaluated with respect to the contiguity of each of the three phases at their locations. It was found that 11.6% of the TPB length was on one or more isolated phases and hence was not electrochemically active.
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Kong, Wei, Mengtong Zhang, Zhen Han e Qiang Zhang. "A Theoretical Model for the Triple Phase Boundary of Solid Oxide Fuel Cell Electrospun Electrodes". Applied Sciences 9, n. 3 (31 gennaio 2019): 493. http://dx.doi.org/10.3390/app9030493.
Abstract (sommario):
Electrospinning is a new state-of-the-art technology for the preparation of electrodes for solid oxide fuel cells (SOFC). Electrodes fabricated by this method have been proven to have an experimentally superior performance compared with traditional electrodes. However, the lack of a theoretic model for electrospun electrodes limits the understanding of their benefits and the optimization of their design. Based on the microstructure of electrospun electrodes and the percolation threshold, a theoretical model of electrospun electrodes is proposed in this study. Electrospun electrodes are compared to fibers with surfaces that were coated with impregnated particles. This model captures the key geometric parameters and their interrelationship, which are required to derive explicit expressions of the key electrode parameters. Furthermore, the length of the triple phase boundary (TPB) of the electrospun electrode is calculated based on this model. Finally, the effects of particle radius, fiber radius, and impregnation loading are studied. The theory model of the electrospun electrode TPB proposed in this study contributes to the optimization design of SOFC electrospun electrode.
7
Wakamatsu, Katsuhiro, Takaaki Yasuda, Yuji Okada e Teppei Ogura. "First-Principles Studies for Optimal Model of the Ni/YSZ Triple Phase Boundary in Solid Oxide Cells". ECS Meeting Abstracts MA2023-01, n. 54 (28 agosto 2023): 207. http://dx.doi.org/10.1149/ma2023-0154207mtgabs.
Abstract (sommario):
Non-Faradaic electrochemical modification of catalytic activity (NEMCA) with electric field applications in solid oxide cells (SOCs) is thought to be induced by spillover effects of lattice oxygen from the bulk, although the detailed mechanism has not still been clear. In SOCs, important phenomena such as fuel decomposition, charge transfer, etc. occur at the triple phase boundary (TPB) as a highly active site that consists of catalyst, electrolyte, and gas phases. NEMCA is expected to be also induced strongly by the surface mechanism on TPB, and understanding surface reactions on TPB is essential for improving catalyst and cell performances. However, the reliable TPB model has not been still uniquely defined to discuss the property of TPB although various studies have been reported. Therefore, in this study, we have focused on the TPB model comprising Ni catalyst cluster; YSZ electrolyte; and gas phase, and aimed to identify a reliable TPB model for theoretical studies by using first-principles calculations as an initial step. In concrete, we identified firstly the stable structures of YSZ surface models by using DFT calculations taking into account oxygen vacancy positions, yttrium atom arrangements, yttria concentration, and other factors. Thereafter, we discussed a reliable Ni/YSZ interface model based on the most stable YSZ model proposed above results by evaluating the Ni structure, interface stability, and so on. In this study, DFT calculations with a plane-wave basis set were implemented using CASTEP, and GGA-PBE exchange-correlation functional was used. The plane-wave cutoff energy was set as 489.8 eV, the OTFG-ultrasoft was used as the pseudopotentials, and the spin-polarization is considered because YSZ is a ferromagnetic substance. In YSZ surface models, yttria concentrations are set to 4.35 mol% and 9.1 mol% which shows the maximum ion conductivity of ZrO2. The three-layer YSZ (111) slabs with 15 Å vacuum layer with 2×2 and 2×4 unit cells were used for repeated slab models. The DFT+U method is used to obtain the correct electric structure of metal oxides with partially filled d or f-orbital shells, and k-points were set to 4×2×1. In Ni/YSZ interface models, we considered Ni cluster and Ni belt type models based on the most stable 2×4 YSZ surface model (9.1 mol%) proposed in this study. We also considered both cases of (111) and (100) facets for the contact interface. In the case of Ni/YSZ interface models, the DFT+U method was not considered to improve the calculation convergence and k-points were set to 4×2×1. A schematic diagram of the Ni/YSZ interface model is shown in the attached Figure. In the case of the 2×2 YSZ model with the yttria concentration of 9.1 mol%, the YSZ model is stabilized when oxygen vacancy is on the second O atom layer and the second neighbor to Y atoms, indicating that improvement in the geometry instability of ZrO2 for 8-coordination is more important than keeping local electron neutrality. We have also found that oxygen vacancy positions are more sensitive to the YSZ surface stability than Y atom arrangements. In the case of the 2×4 YSZ model with the yttria concentration of 4.35 mol%, the YSZ model where there are Y atoms on the first layer is stabilized. The crystal structure achieves a more stable structure by varying bond lengths when Y3+ with the larger ionic radius is replaced with Zr4+. Therefore, the structure is easier to stabilize when the Y atom exists on the surface than in the bulk due to the higher degree of freedom of the Y atom. The most stable structure of the 2×4 YSZ model with the yttria concentration of 9.1 mol% given based on the above results is 0.18 eV more stable than the previously reported structure [1]. This is because the number of Y atoms on the first layer with the second neighbor from oxygen vacancy is larger than the previously reported structure. We evaluated then the structural stability of the Ni/YSZ interface model based on the above YSZ model. As a result, we have found that adhesion energy between Ni and YSZ is independent of the relative position of Ni atoms. In addition, the larger the number of Ni atoms is, the more stable the structure is. This is because the electronic property of Ni atoms approaches the metal as increasing the number of Ni atoms. Other results and a detailed discussion will be reported in our meeting publications (ECS Transactions) and the presentation. [1] M. Shishkin and T. Ziegler, Phys. Chem. Chem. Phys., 16, 1798-1808 (2014). Figure 1
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Gao, Min, Cheng Xin Li, Ming De Wang, Hua Lei Wang e Chang Jiu Li. "Influence of the Surface Roughness of Plasma-Sprayed YSZ on LSM Cathode Polarization in Solid Oxide Fuel Cells". Key Engineering Materials 373-374 (marzo 2008): 641–44. http://dx.doi.org/10.4028/www.scientific.net/kem.373-374.641.
Abstract (sommario):
Under SOFCs operating condition, the cathode reaction rate is determined by triple phase boundary (TPB) areas which are associated with the geometry of the interface between the cathode and the electrolyte. In this paper, YSZ electrolyte was deposited by atmospheric plasma spraying (APS). A nano-scaled lanthanum strontium manganate (LSM) cathode was prepared by sol-gel process on APS YSZ with different surface roughness to aim at increasing the TPB. The polarization curves of LSM cathode were characterized by potentiostat. The influence of the roughness of APS YSZ on the polarization of LSM cathode was investigated. It was found that the overpotential of the LSM cathode is significantly reduced with the increase of YSZ surface roughness.
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Shaikh Abdul, Muhammed Ali, Ahmad Zubair Yahaya, Mustafa Anwar, Mun Teng Soo, Andanastuti Muchtar e Vadim M. Kovrugin. "Effect of Synthesis Method of Nickel–Samarium-Doped Ceria Anode on Distribution of Triple-Phase Boundary and Electrochemical Performance". Crystals 11, n. 5 (6 maggio 2021): 513. http://dx.doi.org/10.3390/cryst11050513.
Abstract (sommario):
Two-dimensional (2D) electron back scattered diffraction (EBSD) is a powerful tool for microstructural characterization of crystalline materials. EBSD enables visualization and quantification of the effect of synthesis methods on the microstructure of individual grains, thus correlating the microstructure to mechanical and electrical efficiency. Therefore, this work was designed to investigate the microstructural changes that take place in the Ni-SDC cermet anode under different synthesis methods, such as the glycine–nitrate process (GNP) and ball-milling. EBSD results revealed that different grain size and distribution of Ni and SDC phases considerably influenced the performance of the Ni–SDC cermet anodes. The performance of the Ni–SDC cermet anode from GNP was considerably higher than that of Ni-SDC from ball-milling, which is attributed to the triple-phase boundary (TPB) density and phase connectivity. Due to the poor connectivity between the Ni and SDC phases and the development of large Ni and SDC clusters, the Ni-SDC cermet anode formed by ball milling had a lower mechanical and electrical conductivity. Moreover, the Ni–SDC cermet anode sample obtained via GNP possessed sufficient porosity and did not require a pore former. The length and distribution of the active TPB associated with phase connectivity are crucial factors in optimizing the performance of Ni-SDC cermet anode materials. The single cell based on the Ni–SDC composite anode prepared through GNP exhibited a maximum power density of 227 mW/cm2 and 121 mW/cm2 at 800 °C in H2 and CH4, respectively.
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Jeong, Davin, Yonghyun Lim, Hyeontaek Kim, Yongchan Park e Soonwook Hong. "Silver and Samaria-Doped Ceria (Ag-SDC) Cermet Cathode for Low-Temperature Solid Oxide Fuel Cells". Nanomaterials 13, n. 5 (27 febbraio 2023): 886. http://dx.doi.org/10.3390/nano13050886.
Abstract (sommario):
This study demonstrated a silver (Ag) and samarium-doped ceria (SDC) mixed ceramic and metal composite (i.e., cermet) as a cathode for low-temperature solid oxide fuel cells (LT-SOFCs). Introducing the Ag-SDC cermet cathode for LT-SOFCs revealed that the ratio between Ag and SDC, which is a crucial factor for catalytic reactions, can be tuned by the co-sputtering process, resulting in enhanced triple phase boundary (TPB) density in the nanostructure. Ag-SDC cermet not only successfully performed as a cathode to increase the performance of LT-SOFCs by decreasing polarization resistance but also exceeded the catalytic activity of platinum (Pt) due to the improved oxygen reduction reaction (ORR). It was also found that less than half of Ag content was effective to increase TPB density, preventing oxidation of the Ag surface as well.
Tesi sul tema "Triple phase boundary (TPB)":
1
Soltanzadeh, Marjan. "Modeling Triple Phase Boundary (TPB) in Solid Oxide Fuel Cell (SOFC) Anode". Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28843.
Abstract (sommario):
The idea of having the triple phase boundary (TPB) is extensively used in the fuel cell literature, especially with respect to solid oxide fuel cells (SOFC). The TPB concept indicates that the hydrogen oxidation reaction and the oxygen reduction reaction, which produce electric current, can actually occur at special sites, called "triple phase boundaries" where the gaseous fuel phase, ion conducting phase: electrolyte, and electron conducting phase, come into contact. Recent study shows that despite the common assumption about TPB, it is not just a point, but a zone that consists of two lines. The kinetic reaction often introduces a significant limitation to fuel cell performance. Therefore, understanding, characterizing, and optimizing the TPB content in fuel cells provides excellent opportunities for performance improvement.
Studying the kinetics of the reaction that takes place at the triple phase boundary is one aspect of this paper. It includes the study of all kinds of chemical and electrochemical reactions as well as their reaction rates, the surface species, and the electrochemical parameters, such as reaction rate constants and conductivity. A mathematical model is developed to describe a simplified anodic solid oxide fuel cell (SOFC) system, Ni/ H2--H 2O/YSZ, and its reaction occurring in the vicinity of the triple phase boundary (TPB).
The model incorporates coupled diffusion, migration and reaction phenomena of the chemical components in the gas phase, Ni particle and zirconia solid state. The kinetic constants necessary for the simulations are estimated on the basis of literature data.
2
Watkins, John D. "Enhancing triple phase boundary electrosynthesis". Thesis, University of Bath, 2011. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.547876.
Abstract (sommario):
The first part of this thesis is concerned with the synthesis, characterisation and applications of surface functionalised carbon nanoparticles. Synthetic techniques are used to modify the existing surface architecture of carbon nanoparticles towards high surface area modified electrodes and pH sensing applications. Electrochemical and synthetic techniques have been used to study triple phase boundaries and enhance their properties towards a bulk synthetic technique, in which an electrolyte phase and redox probe phase are held separate. A salt matrix, ultrasound, high shear force and a carbon fibre membrane have all been used to form unique triple phase boundary environments in which electron and ion transfer processes can be studied and enhanced towards analytical and electrosynthetic applications. A number of electro-reduction reactions have been shown to be feasible using the triple phase boundary methodology. Alkenes, aldehydes and imines have all been successfully electro-reduced, analysed and optimised to elucidate the synthetic triple phase boundary mechanism.
3
Turtayeva, Zarina. "Genesis of AEMFC (anion exchange membrane fuel cell) at the lab scale : from PEMFC’s inks composition toward fuel cell bench tests in alkaline media". Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0285.
Abstract (sommario):
Les piles à combustible à membrane échangeuse d'anions (AEMFC) ont récemment attiré l'attention en tant que piles à combustible alternatives à faible coût aux piles à combustible à membrane échangeuse de protons traditionnelles en raison de l'utilisation possible d'électrocatalyseurs non-nobles. Bien que l'AEMFC ressemble à la PEMFC, les problèmes de gestion de l'eau sont plus prégnants dans une AEMFC car l'ORR en milieu alcalin nécessite de l'eau, tandis qu'en même temps, de l'eau est produite en grande quantité du côté de l'anode. Pour mieux comprendre la gestion de l'eau dans ce type de pile à combustible, il faut d'abord développer et acquérir de l'expérience avec ce type de pile à combustible à l'échelle du laboratoire. Puisque les matériaux prêts à l'emploi n'existaient pas au commencement de la thèse, nous avons dû fabriquer nos propres assemblages électrode-membranes (AMEs) à partir des matériaux disponibles dans le commerce. Etant donné que la thématique de fabrication des AMEs est nouvelle pour les chercheurs du LEMTA, cette thèse est articulée en deux parties, une dédiée à la formulation, la préparation et l'optimisation des AMEs pour PEMFC ; et une autre dédiée au développement d'AEMFC. Les résultats ont indiqué que la composition et préparation de l'encre, ainsi que la manière de déposer l'encre modifient systématiquement la structure de l'électrode, de même que ses performances en piles à combustible. En outre, l'étude fournit des informations sur les procédures et les méthodes pour les tests en AEMFC. Ici, nous souhaiterions partager notre savoir-faire avec les nouveaux venus dans le domaine de la préparation des AMEs pour piles à combustibles à membranes échangeuses d'ionsAnion exchange membrane fuel cells (AEMFCs) have recently attracted significant attention as low-cost alternative fuel cells to traditional proton exchange membrane fuel cells as a result of the possible use of platinum-group metal-free electrocatalysts. Although AEMFC is a mimic of PEMFC but working in an alkaline medium, water management issues are more severe in AEMFC because ORR in alkaline media requires water, while at the same time water is produced at the anode side. To better understand water management in this type of fuel cell, it is necessary first to develop and gain experience with this kind of fuel cell on the laboratory scale. Since no ready-to-use materials are available at the beginning of the project, the necessity of fabricating homemade MEAs from commercially available materials becomes a reality that we must face. As MEA fabrication is a new topic to LEMTA's researchers, this is why this thesis was divided into two parts: one part dedicated to the formulation, preparation, and optimization of MEAs for PEMFC through physico-chemical and electrochemical characterizations; another part dedicated to the development of AEMFC. The results indicated that ink deposition, composition, and preparation systematically change the electrode structure and thus affect fuel cells performance. Furthermore, the study provides information on the AEMFC procedures and methods. Here, we would like to share our know-how with newcomers in the field of preparation of MEA in ion exchange membrane fuel cells
4
Collins, Andrew. "Photo-electrochemical processes at the triple phase boundary". Thesis, University of Bath, 2012. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.557818.
Abstract (sommario):
The main aim and ultimate final goal of the work carried out in this thesis is a drive towards a feasible system for light harvesting, which is in short, using the Sun’s energy to create electricity or a fuel for our energy requirements here on Earth. This work will see an approach using the triple phase boundary afforded by a microdroplet array. Although light harvesting is an ambition which has seen decades of work and uncountable man-hours, approaching it from the angle of utilizing the triple phase boundary between two immiscible liquids and a solid electrode is a new, and novel concept. Before any attempts towards a light harvesting technique can be made, we will need to have characterized and fully understood the mechanisms and nuances, both for dark and light processes, that are observed at the triple phase boundary. This initial process will start by selection of a suitable redox molecule, and exploring its reactivity in microdroplets under dark conditions. Once this has been achieved, an attempt can be made to use this knowledge, and implement it towards light harvesting. This will eventually include an attempt to couple photo-excited states with other molecules, this will be an important step if energy is ever able to be stored from such a system. This early phase will also see the need to employ many other techniques other than electrochemistry in an effort to aid in the understanding and characterization of the triple phase boundary at microdroplets. This will include travelling to other laboratories in search of specialized scientific skills and apparatus, such as electron paramagnetic resonance, or photocurrent spectroscopy. It will also see the need to build new equipment needed to conduct tests such as surface tension visualization, or new electrochemical cells for photocurrent measurement. In summary, this report will see initial characterization of the processes, both light and dark, that occur within the triple phase boundary of a microdroplet for a given redox molecule dissolved within. Early attempts at coupling excited states with other molecules are also explored. Serendipity has always played a part in scientific discovery and the work outlined in this report was no different. The choice of oil used for the organic phase microdroplet deposits yielded some interesting and unexpected results, and has been implicated as one of the key aspects of the photoreactions that have been explored.
5
Wang, Chingfu. "Triple phase boundary engineering of electrodes for solid oxide fuel cells by inkjet printing". Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708301.
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Ye, Haihui. "Microstructure and chemistry of grain-boundary films and triple-junction phases in liquid-phase sintered SiC ceramics". [S.l. : s.n.], 2002. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB9831555.
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Ye, Haihui [Verfasser]. "Microstructure and chemistry of grain boundary films and triple junction phases in liquid phase sintered SiC ceramics / Institut für Nichtmetallische Anorganische Materialien der Universität Stuttgart ... Vorgelegt von Haihui Ye". Stuttgart : Max-Planck-Inst. für Metallforschung, 2002. http://d-nb.info/964301148/34.
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Parikh, Harshil R. "Microstructure Changes In Solid Oxide Fuel Cell Anodes After Operation, Observed Using Three-Dimensional Reconstruction And Microchemical Analysis". Case Western Reserve University School of Graduate Studies / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=case1417765534.
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Noël, Emeline. "Simulation numérique directe d’écoulements à l’aide d’une méthode de frontière immergée". Thesis, Rouen, INSA, 2012. http://www.theses.fr/2012ISAM0020/document.
Abstract (sommario):
Les travaux menés, depuis plusieurs années, au CORIA ont abouti à la construction d’un outil numérique (ARCHER) permettant la simulation numérique directe d’écoulements diphasiques et notamment l’atomisation d’un jet liquide à haute vitesse. Ce type de simulation permet de capturer les phénomènes d’atomisation au voisinage de l’injecteur difficilement caractérisables par les outils expérimentaux actuels. Ces simulations requièrent des conditions d’injection délicates à évaluer a priori car elles dépendent des caractéristiques de l’écoulement au sein de l’injecteur. Or, certains jets présentent une grande sensibilité à ces conditions d’injection. Dès lors, il est nécessaire de simuler l’écoulement au sein de l’injecteur afin d’appréhender la nature de cette sensibilité. L’utilisation d’un maillage cartésien par le code ARCHER conjuguée à la volonté de simuler le système d’atomisation dans son ensemble ont orienté ces travaux vers l’utilisation d’une méthode de frontière immergée. Ces travaux ont ainsi permis de reproduire des écoulements au sein d’injecteurs de forme quelconque tout en conservant le maillage cartésien d’origine, précieux tant pour l’efficacité du solveur que pour sa précision. Dans un premier temps, l’implantation dans le code ARCHER d’une méthode de frontière immergée a été réalisée et testée sur des configurations de canal et de conduite et de l’écoulement autour d’un cylindre. L’application de cette méthode a porté sur la simulation de l’écoulement au sein d’un injecteur triple disque mono-trou et a notamment permis de caractériser l’origine de l’écoulement secondaire formé dans l’orifice de décharge. Afin d’évoluer vers la construction d’un outil numérique capable de simuler le système d’atomisation dans son ensemble, un couplage entre la méthode de frontière immergée et la méthode Ghost fluid a été nécessaire. La version bi-dimensionnelle développée a été testée sur la relaxation d’une goutte posée sur une paroi. Cette version a permis de simuler des écoulements au sein de canaux à différents rapports de longueur sur diamètre et l’écoulement au sein d’une buse convergente. La simulation simultanée de l’écoulement interne et externe a permis de lier les fluctuations de vitesses des écoulements internes à la création de surface engendrée sur les écoulements externesSince several years, the research conducted at the CORIA laboratory led to the development of a numerical tool (ARCHER) alllowing direct numerical simulations of two phase flows. In particular, the simulations of high speed liquid jet primary break-up have been strongly investigated. These simulations are able to capture primary break-up phenomena near the nozzle exit where experimental characterisations are difficult to conduct. These simulations need injection conditions tricky to gauge a priori, since they depend on the flow characteristics inside the nozzle. Moreover, some jets are highly sensitive to these injection conditions. Therefore, it becomes necessary to simulate the flow inside the nozzle to better understand this sensitive nature. The objective to simulate the whole atomization system guided the present work dedicated to the use of an immersed boundary method (IBM). Such an approach allows reproducing flows inside nozzles of arbitrary shape while keeping the original cartesian mesh valuable for numerical efficiency and accuracy. As a first step, the implementation of an IBM in ARCHER was carried out and tested on channels, pipes and uniform flows past a circular cylinder. An industrial application focused on the flow inside a triple disk compound injector. This work led to a refined description of the secondary flow origin in the discharge hole. In order to move towards the design of a numerical tool able to simulate the whole injection system, a coupling between IBM and the Ghost Fluid Method (GFM) has been found necessary. This allows accounting for two phase flows inside the nozzle where the dynamics of the triple line has to be considered. The bidimensional developments have been tested on drops released on walls. This version enabled to simulate flows inside channels with different ratios of length over diameter and the flow inside a convergent nozzle. The simultaneous computation of flows inside and outside nozzle has enabled to link the velocity fluctuations of internals flows to the surface setting-up gene-rated on external flows
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Ramasamy, Devaraj. "Extension of electrochemically active sites in SOFCs and SOECs". Doctoral thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/14813.
Abstract (sommario):
Doutoramento em Nanociências e NanotecnologiaSolid oxide fuel (SOFCs) and electrolyzer (SOECs) cells have been promoted as promising technologies for the stabilization of fuel supply and usage in future green energy systems. SOFCs are devices that produce electricity by the oxidation of hydrogen or hydrocarbon fuels with high efficiency. Conversely, SOECs can offer the reverse reaction, where synthetic fuels can be generated by the input of renewable electricity. Due to this similar but inverse nature of SOFCs and SOECs, these devices have traditionally been constructed from comparable materials. Nonetheless, several limitations have hindered the entry of SOFCs and SOECs into the marketplace. One of the most debilitating is associated with chemical interreactions between cell components that can lead to poor longevities at high working temperatures and/or depleted electrochemcial performance. Normally such interreactions are countered by the introduction of thin, purely ionic conducting, buffer layers between the electrode and electrolyte interface. The objective of this thesis is to assess if possible improvements in electrode kinetics can also be obtained by modifying the transport properties of these buffer layers by the introduction of multivalent cations. The introduction of minor electronic conductivity in the surface of the electrolyte material has previously been shown to radically enhance the electrochemically active area for oxygen exchange, reducing polarization resistance losses. Hence, the current thesis aims to extend this knowledge to tailor a bi-functional buffer layer that can prevent chemical interreaction while also enhancing electrode kinetics.The thesis selects a typical scenario of an yttria stabilized zirconia electrolyte combined with a lanthanide containing oxygen electrode. Gadolinium, terbium and praseodymium doped cerium oxide materials have been investigated as potential buffer layers. The mixed ionic electronic conducting (MIEC) properties of the doped-cerium materials have been analyzed and collated. A detailed analysis is further presented of the impact of the buffer layers on the kinetics of the oxygen electrode in SOFC and SOEC devices. Special focus is made to assess for potential links between the transport properties of the buffer layer and subsequent electrode performance. The work also evaluates the electrochemical performance of different K2NiF4 structure cathodes deposited onto a peak performing Pr doped-cerium buffer layer, the influence of buffer layer thickness and the Pr content of the ceria buffer layer. It is shown that dramatic increases in electrode performance can be obtained by the introduction of MIEC buffer layers, where the best performances are shown to be offered by buffer layers of highest ambipolar conductivity. These buffer layers are also shown to continue to offer the bifunctional role to protect from unwanted chemical interactions at the electrode/electrolyte interface.
As pilhas de combustível e eletrolisadores de óxido sólido (PCOSs e EOSs) têm sido promovidas a tecnologias promissoras para estabelecer o abastecimento de combustível e sua utilização futura em sistemas de energia limpa. As PCOSs são dispositivos que produzem energia elétrica pela oxidação de combustíveis como o hidrogénio ou de hidrocarbonetos de elevada eficiência. Alternativamente, as EOSs funcionam de maneira inversa, na qual podem ser gerados combustíveis sintéticos ao fornecer energia eléctrica renovável ao sistema. É, pois, devido a esta natureza semelhante e ainda que inversa, que estes dispositivos têm sido tradicionalmente construídos a partir de materiais compatíveis. No entanto, a entrada no mercado destas tecnologias encontra-se ainda condicionada por diversos factores. Um dos mais limitantes, está associado a problemas de estabilidade química entre os constituintes da célula, que podem reduzir a longevidade a elevadas temperaturas de operação e/ou a um desempenho eletroquímico insuficiente. Normalmente, tais problemas de compatibilidade são minimizados pela introdução de uma camada de proteção muito fina constituída por um material condutor puramente iónico, na interface elétrodo/eletrólito. Deste modo, o objetivo deste trabalho é avaliar se modificando as propriedades de transporte destas camadas de proteção se pode conduzir ao aumento das propriedades de cinética do elétrodo, através da introdução de catiões polivalentes. A introdução de condutividade eletrónica menor na superfície do electrólito foi anteriormente relatada apresentando uma melhoria muito considerável das zonas eletroquimicamente activas para a permuta de oxigénio, reduzindo, desta forma, as perdas de resistência de polarização.Assim, esta dissertação tem por objetivo desenvolver este conhecimento para adaptar uma camada de proteção bifuncional que consiga evitar os problemas de interação química e ao mesmo tempo aumentar a cinética dos elétrodos. Esta dissertação apresenta um cenário típico de um eletrólito à base de zircónia estabilizada com ítrio combinado com um elétrodo de oxigénio contendo lantanídeos. Foram investigados como materiais de proteção, os sistemas de céria dopada com gadolínio, térbio e praseodímio. As propriedades inerentes à condução eletrónica e iónica mista (MIEC) dos materiais dopados foram analisadas e agrupadas. Posteriormente, foi realizada uma análise detalhada sobre o impacto das camadas de proteção na cinética do elétrodo de oxigénio em dispositivos PCOS e EOS. Foi dada especial atenção às potenciais relações entre as propriedades de transporte da camada proteção e subsequente desempenho do elétrodo. O trabalho também avalia o desempenho eletroquímico de cátodos de K2NiF4 com diferentes estruturas, depositadas sobre a camada de proteção que apresentou melhor desempenho, isto é, a céria dopada com praseodímio, assim como a influência da espessura da camada e da fração de Pr presente na céria. Demonstrou-se que a introdução de camadas de proteção à base de MIECs levou a um aumento drástico no desempenho do elétrodo, nomeadamente pelos MIECs de maior condutividade ambipolar. Estas camadas de proteção utlizadas provaram ser também eficazes em manter o papel de inibidores de interactividade química na interface elétrodo/eletrólito.
Capitoli di libri sul tema "Triple phase boundary (TPB)":
1
Munakata, Hirokazu, Masashi Otani, Yuki Katsuki e Kiyoshi Kanamura. "Creation of Triple-Phase-Boundary in a Solid Oxide Fuel Cell Using a Three-Dimensionally Ordered Structure". In Ceramic Transactions Series, 243–48. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2010. http://dx.doi.org/10.1002/9780470917145.ch35.
2
Lock, G. S. H. "The Evaporative, Tubular Thermosyphon". In The Tubular Thermosyphon, 103–76. Oxford University PressOxford, 1992. http://dx.doi.org/10.1093/oso/9780198562474.003.0003.
Abstract (sommario):
Abstract Above the critical pressure, the tubular thermosyphon behaves as a singlephase system. The same is often true below the critical pressure provided that the fluid specific volume is very much different from the critical value. As Fig. 3.1 indicates, v≪vcr corresponds to a liquid-filled device while v≫vcr corresponds to a gas-filled device unless the pressure is very low, that is P≪Pcr Under such single-phase conditions, the descriptions presented in the previous chapter continue to apply. If the critical point is approached in these circumstances, the behaviour of the system changes but not in any fundamental way. The thermal expansion coefficient increases and the circulation becomes more vigorous, but it is still driven by thermal buoyancy forces, directly or indirectly. In the vicinity of the critical point, however, a discontinuity appears in the fluid density if the pressure falls beneath the critical value; a less-ordered vapour phase then coexists with a more-ordered liquid phase at the same pressure and temperature. This molecular-based alteration of fluid properties produces a different type of thermosyphon behaviour, the upper boundary of which is therefore marked by the critical point; the lower boundary is found at the triple point.
3
Ryan, Paul D., e John F. Dewey. "The Ordovician South Mayo Trough, a basin that recorded the passage of a triple junction along the Laurentian margin". In Laurentia: Turning Points in the Evolution of a Continent. Geological Society of America, 2022. http://dx.doi.org/10.1130/2022.1220(29).
Abstract (sommario):
ABSTRACT Tectonic models for arc-continent collision can be overly complex where, for example, diachronous sedimentation and deformation along a single plate boundary are attributed to separate tectonic events. Furthermore, continuous sedimentation in a single basin recording a diachronous collision along a plate margin makes it difficult to use classical unconformable relationships to date an orogenic phase. In this chapter, we describe the Ordovician South Mayo Trough of western Ireland, a remarkable example of such a basin. It originated in the late Cambrian–Early Ordovician as a Laurentia-facing oceanic forearc basin to the Lough Nafooey arc. This arc was split by a spreading ridge to form a trench-trench-ridge triple junction at the trench. The basin remained below sea level during Grampian/Taconic arc-continent collision and, following subduction flip, received sediment from an active continental margin. Sedimentation ended during Late Ordovician Mayoian “Andean”-style shortening, broadly coeval with a marked fall in global sea level. These major tectonic events are traced through the nature of the detritus and volcanism in this basin, which is preserved in a mega-syncline. The Grampian orogen is not recorded as a regional unconformity, but as a sudden influx of juvenile metamorphic detritus in a conformable sequence.
Atti di convegni sul tema "Triple phase boundary (TPB)":
1
Grew, Kyle N., Abhijit S. Joshi, Aldo A. Peracchio e Wilson K. S. Chiu. "Detailed Electrochemistry and Gas Transport in a SOFC Anode Using the Lattice Boltzmann Method". In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-13621.
Abstract (sommario):
A coupled electrochemical reaction and diffusion model has been developed and verified for investigation of mass transport processes in Solid Oxide Fuel Cell (SOFC) anode triple-phase boundary (TPB) regions. The coupled model utilizes a two-dimensional (2D), multi-species Lattice Boltzmann Method (LBM) to model the diffusion process. The electrochemical model is coupled through localized flux boundary conditions and is a function of applied activation overpotential and the localized hydrogen and water mole fractions. This model is designed so that the effects of the anode microstructure within TPB regions can be examined in detail. Results are provided for the independent validation of the electrochemical and diffusion sub-models, as well as for the coupled model. An analysis on a single closed pore is completed and validated with a Fick's law solution. A competition between the electrochemical reaction rate and the rate of mass transfer is observed to be dependent on inlet hydrogen mole fraction. The developed model is presented such that future studies on SOFC anode microstructures can be completed.
2
Khan, Munir, Yexiang Xiao, Bengt Sunde´n e Jinliang Yuan. "Analysis of Multiphase Transport Phenomena in PEMFCS by Incorporating Microscopic Model for Catalyst Layer Structures". In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-65142.
Abstract (sommario):
The catalyst layer (CL) in polymer electrolyte membrane (PEM) fuel cells is one of the key components regulating the overall performance of the cell. In PEM fuel cells, there are two CLs having identical composition for hydrogen oxidation (HO) and oxygen reduction (OR) reactions. There are four phases inside the CL, namely: carbon, Pt particles, ionomer and voids. In this work, a micro-model of the cathode CL has been developed mathematically using finite volume (FV) technique to investigate the transport phenomena of reactants and product species, ions and electrons by incorporating the above stated phases at the cathode side only, due to the fact that the OR reactions are the rate limiting as compared to HO reaction. The 3D CL has been reconstructed based on a regularly distributed sphere’s method with dimensions 4.1 × 4.1 × 4.1 μm3. Platinum particles combined with carbon spheres (C/Pt) are regularly placed in the domain, an ionomer layer of a given thickness is extruded from the sphere surfaces. The C/Pt, ionomer and void distribution, as well as the triple phase boundary (TPB) are analysed and discussed. A microscopic model has been developed for water generation and species transport via Knudsen diffusion through the voids and the proton transport in the ionomer has been included here to aim for the rigorousness of the work. In addition, the electrochemical reactions have been simulated on the surface of Pt particles fulfilling the TBP conditions.
3
Zhang, Xiaohang, Frank Marken e Christopher A. Paddon. "Screening Anti-Oxidant Activity at Oil Microdroplet Triple Phase Boundary Electrodes". In 9th International Conference on Engines and Vehicles. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2009. http://dx.doi.org/10.4271/2009-24-0103.
4
Chen, Qiuyang, Jian Zhang, Qiuwang Wang e Min Zeng. "Effect of Bi-Layer Interconnector Design on the Current Density of Solid Oxide Fuel Cells". In ASME 2009 7th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2009. http://dx.doi.org/10.1115/fuelcell2009-85024.
Abstract (sommario):
The concentration gradient of fuel and oxidant gas is great in the plane normal to the solid oxide fuel cells (SOFC) three-phase-boundary (TPB) layer, especially in the porous electrode. We present a novel interconnector design, termed bilayer interconnector, for SOFC. It can distribute the fuel and air gas in the plane normal to the SOFC TPB layer. In this paper, we develop a 3D model to study the current density of the SOFC with conventional and novel bi-layer interconnectors. The numerical results show that the novel SOFC design Rib1 can slightly enhance the mass transfer in the porous anode and current density. The novel SOFC design Rib2 can improve the current density significantly under low electrical conductivity of interconnector.
5
Garcke, Harald, Kazuo Ito e Yoshihito Kohsaka. "Stability analysis of phase boundary motion by surface diffusion with triple junction". In Nonlocal and Abstract Parabolic Equations and their Applications. Warsaw: Institute of Mathematics Polish Academy of Sciences, 2009. http://dx.doi.org/10.4064/bc86-0-5.
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Deutsch, Todd, Yingying Chen, Ashlee Vise, Walter Klein, Guido Bender e KC Neyerlin. "Electrocatalytic Reduction of Carbon Dioxide at a Triple Phase Boundary in Flow Reactors". In nanoGe Fall Meeting 2019. València: Fundació Scito, 2019. http://dx.doi.org/10.29363/nanoge.ngfm.2019.163.
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Deutsch, Todd, Yingying Chen, Ashlee Vise, Walter Klein, Guido Bender e KC Neyerlin. "Electrocatalytic Reduction of Carbon Dioxide at a Triple Phase Boundary in Flow Reactors". In nanoGe Fall Meeting 2019. València: Fundació Scito, 2019. http://dx.doi.org/10.29363/nanoge.nfm.2019.163.
8
Liu, Lin, Gap-Yong Kim e Abhijit Chandra. "Deposition of Porous Anode Electrode of a Solid Oxide Fuel Cell by Ultrasonic Spray Pyrolysis". In ASME 2010 8th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2010. http://dx.doi.org/10.1115/fuelcell2010-33216.
Abstract (sommario):
A modified spray pyrolysis approach has been utilized to fabricate anode electrode of a Solid Oxide Fuel Cell (SOFC). It was designed to control the anode microstructure to achieve large triple phase boundaries (TPBs) and high gas diffusion capability, which are critical in enhancing the performance of a SOFC. Deposition of porous anode film of Nickel and Ce0.9Gd0.1O1.95 on dense 8 mol.% yttria stabilized zirconia (YSZ) substrate was carried out using the modified spray pyrolysis. Effects of precursor solution feed rates, precursor solution concentrations and deposition temperatures on the TPB formation and porosity were investigated. The composition of the deposited anode film was evaluated by energy dispersive X-ray spectroscopy (EDS). Scanning electron microscope (SEM) examinations revealed that the deposition temperature and precursor solution concentration were the most critical parameters that influenced the morphology, porosity and the particle size of the anode film.
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Puranen, J., J. Laakso, L. Hyvärinen, M. Kylmälahti e P. Vuoristo. "Influence of Spray Parameters and Characteristics of Solutions on Microstructure and Phase Composition of Solution Precursor Atmospheric Plasma Sprayed (SPPS) Mn-Co Spinel Coating". In ITSC 2012, a cura di R. S. Lima, A. Agarwal, M. M. Hyland, Y. C. Lau, C. J. Li, A. McDonald e F. L. Toma. ASM International, 2012. http://dx.doi.org/10.31399/asm.cp.itsc2012p0810.
Abstract (sommario):
Abstract Manufacturing of MnCo2O4 spinel coatings by solution precursor plasma spraying (SPPS) was studied in order to produce thin ceramic coating on a ferritic stainless steel interconnect for SOFC’s. The main purpose to use MnCo2O4 coating in SOFC devices is to prevent the migration of harmful CrO3 and Cr2(OH)2 compounds to the triple phase barriers (TPB) of the cathode. In this study Mn(NO3)2•4H2O and Co(NO3)2•6H2O were diluted to deionized water and mixture of deionized water and ethanol at 3 M mixture rate. The solutions were sprayed on 0.5 mm thick Crofer 22 APU substrate by Sulzer Metco F4-MB plasma gun with a modified solution feeder. Microstructural characterizations for the as-sprayed coatings were done by using a field-emission scanning electron microscopy (FESEM) with SE-mode. Elemental analyses were done with energy dispersive spectroscopy (EDS) and an X-ray diffraction (XRD) was used for crystallographic studies. The coating with full equivalence of the crystallographic structure of MnCo2O4 spinel was sprayed using argon-helium plasma and water based solution. Plasma gas with hydrogen as a secondary or ternary gas and ethanol based solutions caused the formation of the mixed phases of CoO and MnCo2O4. Although the microstructures of sprayed coatings were still quite porous, the influence of relevant gun and solution parameters were found in order to improve coating denseness in further studies.
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Harsha, Shreyas, Rakesh Sharma, Martin Dierner, Chris Baeumer, Guido Mul, Igor Makhotkin, Paolo Ghigna, Erdmann Spiecker, Johannes Will e Marco Altomare. "Dewetted Pt nanoparticles for electrochemical hydrogen evolution: Role of Pt structure and Pt-substrate-electrolyte triple-phase boundary". In Catalyst Design Strategies for Photo- and Electrochemical Fuel Synthesis. València: FUNDACIO DE LA COMUNITAT VALENCIANA SCITO, 2023. http://dx.doi.org/10.29363/nanoge.ecat.2023.009.