Academic literature on the topic 'Redox Flow Cell'
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Journal articles on the topic "Redox Flow Cell"
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Skyllas‐Kazacos, M., and F. Grossmith. "Efficient Vanadium Redox Flow Cell." Journal of The Electrochemical Society 134, no. 12 (December 1, 1987): 2950–53. http://dx.doi.org/10.1149/1.2100321.
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Skyllas‐Kazacos, M., M. Rychcik, R. G. Robins, A. G. Fane, and M. A. Green. "New All‐Vanadium Redox Flow Cell." Journal of The Electrochemical Society 133, no. 5 (May 1, 1986): 1057–58. http://dx.doi.org/10.1149/1.2108706.
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Whitley, Shaun, and Dowon Bae. "Perspective—Insights into Solar-Rechargeable Redox Flow Cell Design: A Practical Perspective for Lab-Scale Experiments." Journal of The Electrochemical Society 168, no. 12 (December 1, 2021): 120517. http://dx.doi.org/10.1149/1945-7111/ac3ab3.
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Solar-rechargeable redox flow batteries (SRFBs) offer feasible solar energy storage with high flexibility in redox couples and storage capacity. Unlike traditional redox flow batteries, homemade flow cell reactors are commonly used in most solar-rechargeable redox flow batteries integrated with photoelectrochemical devices as it provides high system flexibility. This perspective article discusses current trends of the architectural and material characteristics of state-of-the-art photoelectrochemical flow cells for SRFB applications. Key design aspects and guidelines to build a photoelectrochemical flow cell, considering practical operating conditions, are proposed in this perspective.
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Delgado, Nuno M., Carlos M. Almeida, Ricardo Monteiro, and Adélio Mendes. "Flow-Through Design for Enhanced Redox Flow Battery Performance." Journal of The Electrochemical Society 169, no. 2 (February 1, 2022): 020532. http://dx.doi.org/10.1149/1945-7111/ac4f70.
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The high capital cost, driven by the poor performance, still hinders the widespread application of vanadium redox flow batteries. This work compares two different cell designs to demonstrate that the electrolyte flow velocity and pattern is of critical importance to increase the overall battery performance. The Oriented-Distribution-Path (ODP) cell design includes inlet and outlet distribution channels, while the Multi-Distribution-Path (MDP) design does not. The introduction of the distribution channels in the ODP caused the electrolyte flow pattern through the electrode to be less uniform. However, the latter reduced the concentration polarization under high current density and low flow rate conditions. In a charge-discharge cycle comparison, the MDP displayed the highest cell energy efficiency at 80 mA cm−2 and at a flow rate of 300 cm3 min−1. However, the best overall performance was obtained using the ODP at 80 mA cm−2 and a flow rate of 10 cm3 min−1. This work demonstrates that the highest system energy efficiency is achieved when using low flow rates together with a cell design that promotes a high pressure drop. The insights of this study apply to other chemistries making it useful to define guidelines for designing energy-efficient redox flow batteries.
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Liu, Tianbiao. "Half-Cell Flow Batteries: A Powerful Approach to Evaluating Cycling Stability of a Redox Active Electrolyte." ECS Meeting Abstracts MA2022-01, no. 3 (July 7, 2022): 485. http://dx.doi.org/10.1149/ma2022-013485mtgabs.
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Aqueous redox flow batteries (ARFBs) represent one promising energy storage technology for integration of renewable energy and balancing the electricity grids because of their technical merits of decoupled energy and power, sustainable and tunable redox active materials, and non-flammable and low cost aqueous supporting electrolytes. Despite numerous new flow battery chemistries reported in the last decade, the cycling life of ARFBs is still primarily limited by the chemical stability of redox active electrolytes. This presentation discusses the proper use and data interpretation of a half-cell flow battery to evaluate the cycling stability of a single redox active electrolyte. Specifically, the half-cell flow battery studies of K4[Fe(CN)6]/K3[Fe(CN)6] at alkaline conditions using balanced and unbalanced cell configurations will be discussed and compared. Our results reveal that the capacity loss of the K4[Fe(CN)6]/K3[Fe(CN)6] half-cell is attributed to cyanide ligand dissociation and then subsequent redox degradation. The reported half-cell flow battery methodology can be widely applied to develop new redox active electrolyte materials.
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Singh, Siddhant, Wei Lu, Jeff Sakamoto, and David G. Kwabi. "Electrochemical Desalination Using a Hybrid Redox Flow Cell." ECS Meeting Abstracts MA2022-01, no. 55 (July 7, 2022): 2285. http://dx.doi.org/10.1149/ma2022-01552285mtgabs.
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Electrochemical desalination is an attractive, energy-efficient strategy for small-scale, distributed water purification systems, as compared to conventional thermal desalination or reverse osmosis. Many incumbent electrochemical desalination cells feature a combination of sodium-intercalating electrodes and polymer-based anion-exchange membranes with non-ideal permselectivities. We propose a hybrid flow cell design that features a redox-active electrolyte separated by a cation exchange membrane from a solid, anion-converting or anion-intercalating electrode. This design makes use of a dense, ceramic membrane with a greater selectivity for sodium ion conduction than polymeric ion-exchange membranes, which are also susceptible to energy losses from water crossover between dilute and concentrated salt streams. We discuss considerations that will impact the relationship among electrode and electrolyte properties, operational parameters (e.g. current density, concentration factor and water recovery percentage) and the energetic cost of desalination.
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Lu, Daluh, Jiin-Shiung Horng, and Chia-Pao Tung. "Reduction of Europium in a Redox Flow Cell." JOM 40, no. 5 (May 1988): 32–34. http://dx.doi.org/10.1007/bf03258908.
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Ferrigno, Rosaria, Abraham D. Stroock, Thomas D. Clark, Michael Mayer, and George M. Whitesides. "Membraneless Vanadium Redox Fuel Cell Using Laminar Flow." Journal of the American Chemical Society 124, no. 44 (November 2002): 12930–31. http://dx.doi.org/10.1021/ja020812q.
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Leung, P., D. Aili, Q. Xu, A. Rodchanarowan, and A. A. Shah. "Rechargeable organic–air redox flow batteries." Sustainable Energy & Fuels 2, no. 10 (2018): 2252–59. http://dx.doi.org/10.1039/c8se00205c.
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Gong, Ke, Qianrong Fang, Shuang Gu, Sam Fong Yau Li, and Yushan Yan. "Nonaqueous redox-flow batteries: organic solvents, supporting electrolytes, and redox pairs." Energy & Environmental Science 8, no. 12 (2015): 3515–30. http://dx.doi.org/10.1039/c5ee02341f.
Full textDissertations / Theses on the topic "Redox Flow Cell"
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FACCHINETTI, IRENE. "Thermally Regenerable Redox-Flow Batteries." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2021. http://hdl.handle.net/10281/308694.
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Il calore a bassa temperatura (LTH), inferiore a 100°C, è una forma di energia largamente disponibile che viene dispersa nell’ambiente, senza alcun utilizzo. La conversione di questo tipo di energia in elettricità aprirebbe le porte allo sfruttamento di fonti energetiche come il calore solare, geotermico e di scarto industriale.
La conversione di LTH in elettricità non è però un processo efficiente a causa dei limiti posti dalla termodinamica, con la cosiddetta legge di Carnot, oltre che ai limiti tecnologici che riducono ulteriormente la conversione di questa forma di energia.
I dispositivi preposti per convertire LTH in elettricità devono poter operare con alte efficienze e potenze, e devono essere facilmente scalabili ed economici. Purtroppo, attualmente nessun dispositivo è in grado di effettuare questa conversione con potenze ed efficienze abbastanza elevate da giustificare gli alti costi (materiali, operazionali e manutenzione) e la complessità dei dispositivi stessi ed è per questo motivo che LTH non trova tutt’ora alcuna applicazione
Questo progetto di ricerca si è focalizzato sullo sviluppo di un dispositivo in grado di convertire LTH in maniera efficiente e con alte potenze. Tale dispositivo, chiamato Thermally Regnerable Redox-Flow Battery, TRB, è una batteria a flusso ricaricabile termicamente. Il dispositivo conta due diverse processi: la produzione energetica, che avviene in una cella elettrochimica in grado di produrre elettricità alle spese dell’energia libera di mescolamento di due soluzioni acquose dello stesso sale ma a diversa concentrazione. Quando le due soluzioni raggiungono la stessa concentrazione, la soluzione esausta viene mandata al secondo processo: un distillatore sottovuoto che rigenera il gradiente di concentrazione tra le due soluzioni sfruttando risorse di LTH. L’efficienza totale del dispositivo è quindi data dal prodotto tra l’efficienza della cella elettrochimica e l’efficienza del distillatore.
Studi termodinamici dimostrano che per incrementare tale efficienza è fondamentale lavorare sull’efficienza del distillatore, il cui valore dipende dalla scelta del soluto e del solvente. In particolare, per questo lavoro di ricerca si è scelto di operare con soluzioni acquose di NaI/I2 e LiBr/Br2.
I risultati raggiunti e le principali attività di ricerca vengono riportate brevemente in questo abstract:
Con la determinazione dei coefficienti di attività, si è calcolato l’energia libera di mescolamento e il potenziale a circuito aperto per entrambi i set di soluzioni (NaI e LiBr).
Le celle elettrochimiche sono state sviluppate specificamente per entrambi I sistemi studiati e test elettrochimici hanno permesso di valutare le performance dei due dispositivi, come potenza ed efficienza elettrochimica. La distillazione è stata modellizzata in modo da definire le condizioni ottimali di lavoro e determinare l’efficienza del processo.Low-Temperature Heat (LTH), below of 100°C, has elicited great interest among the scientific community, as a source of energy since it does not see any form of utilization as it is currently simply released into the environment. Its conversion would open the doors to the exploitation of a huge amount of energy as well, such as geothermal, solar, and industrial waste heat. The conversion efficiencies of LTH are low because of the limitations imposed by Carnot law, as well as the existence of technological limits which further reduce the efficiency of the conversion of LTH. In order to be suitable for extensive industrial production, LTH converters should show high power densities, scalable and efficient whilst being cost-effective; to this point, the devices proposed for this afore mentioned application all failed to achieve suitable efficiencies and power density, making the LTH conversion unfeasible. This PhD project was focused on the design of a device called Thermally Regenerable Redox-Flow Battery (TRB) consisting of a redox-flow battery that can be recharged by a thermal process. The device is based upon a two-stages technology composed by a “power production” stage and a “thermal” stage: power production happens in an electrochemical cell which release electricity at the expenses of the mixing free energy of two water solutions of the same salt at different concentrations, referred to as a concentration cell. When the two solutions reach the same concentration, the exhausted fluid is sent to the second stage, the thermal process, which regenerates the initial mixing free energy, by exploiting LTH sources, through vacuum distillation. The efficiency of the technology is the product between the efficiencies of the units in the device where both stages happen: the electrochemical cell, engineered for power production, and a distillation unit, designed to be responsible for thermal conversion. NaI/I2 and LiBr/Br2 water solutions will be the most discussed redox couple in this thesis, as result of thermodynamic analysis that have shown the importance related to the solvent and salt choice to ensure high energy conversion efficiencies. The achieved results, as well as the main research activities, are briefly reported here: starting from the determination of the activity coefficients, mixing free energy of the initial solutions, and the open circuit voltage of the electrochemical are calculated. Electrochemical cells are specifically designed for both systems while electrochemical tests are performed to evaluate the main performances of the devices, such as power density and electrochemical efficiency. Modeling of the operational conditions of the thermal stage allows to determine the distillation efficiency for both the solutions. The initial experiments prove an unprecedented heat-to-electricity efficiency for both the systems: 3% for TRB-NaI and 4-5% for TRB based on LiBr, depending on the thickness of the membrane with a power density output of almost 10 W m-2 for both technologies, which opens various possibilities to implement further improvements into this new class of energy storage/converter devices.
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Bae, C. H. "Cell design and electrolytes of a Novel Redox flow battery." Thesis, University of Manchester, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.509374.
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Poon, Grace Chemical Sciences & Engineering Faculty of Engineering UNSW. "Bromine complexing agents for use in vanadium bromide (V/Br) redox flow cell." Publisher:University of New South Wales. Chemical Sciences & Engineering, 2008. http://handle.unsw.edu.au/1959.4/41210.
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The Vanadium bromide (V/Br) flow cell employs the Br3-/Br- couple in the positive and the V(II)/V(III) couple in the negative half cell. One major issue of this flow cell is bromine gas formation in the positive half cell during charging which results from the low solubility of bromine in aqueous solutions. Bromine complexing agents previously used in the zinc-bromine fuel cell were evaluated for their applicability in V/Br flow cell electrolytes. Three quaternary ammonium bromides: N-ethyl-N-methyl-morpholinium bromide (MEM), N-ethyl-N-methyl-pyrrolidinium bromide (MEP) and Tetra-butyl ammonium bromide (TBA) were studied. It is known that aqueous bromine reacts with quaternary ammonium bromides to form an immiscible organic phase. Depending on the number of quaternary ammonium bromides used and the environmental temperature, the second phase formed will either be solid or liquid. As any solid formation would interrupt the flow cell operation, potential formation of such kind has to be eliminated. Stability tests of simulated V/Br electrolyte with added quaternary ammonium bromides were carried out at 11, 25 and 40 oC. In the absence of bromine, the addition of MEM, MEP and TBA were found to be stable in V/Br electrolytes. However, in the presence of bromine, solid formation was observed in the bromine rich organic phase when the V/Br electrolyte contained a single quaternary ammonium bromide (QBr) compound. For V/Br electrolytes with binary or ternary QBr mixtures containing TBA, the presence of bromine caused a viscous polybromide phase to form at room temperature and the release of bromine gas at higher temperature. Only a binary mixture of MEM and MEP formed a stable liquid organic phase between 11 ?? 40 oC. In this study it was found that V/Br electrolytes containing a binary QBr mixture (0.75M) of MEM and MEP gave the best combination that formed an orange oily layer in the presence of bromine without solidification between 11 ?? 40oC. Furthermore, it was found that samples of V/Br electrolytes containing a ternary QBr mixture, are less effective in bromine capturing if the total QBr concentration was less than 1 M at 40oC, where bromine gas evolution was observed. From electrochemical studies of V3+/V2+, it was found that the addition of MEM and MEP had a minimal effect on the formal potential of the V3+/V2+ couple, the V2+/V3+ transfer coefficient and the diffusion coefficient of V3+. Therefore, MEM and MEP can be added to the negative half-cell of a V/Br flow cell without major interference From linear sweep voltammetry, the kinetics of the Br-/Br3- redox couple was found to be mass transfer controlled. After the addition of MEM and MEP mixture, the exchange current density was found to decrease from 0.013 Acm-2 to 0.01 Acm-2. On the other hand the transfer coefficient before and after MEM and MEP addition was found to be 0.5 and 0.44 respectively. Since the kinetic parameters were not significantly affected by the addition of MEM and MEP mixture, they can be added to the positive half-cell of the V/Br flow cell as bromine complexing agents. The electrochemical studies of both V3+/V2+ and Br-/Br3- showed the addition of MEM and MEP has minimal interference with the redox reactions of the vanadium bromide flow cell. This thesis also investigated the effect of MEM and MEP addition on the cell performance of a lab scale V/Br flow cell using two different membranes (ChiNaf and VF11). Flow cell performance for 2 M V3.7+ + 0.19 M MEM + 0.56 M MEP electrolytes utilising ChiNaf membrane at 10 mAcm-2 produced an energy efficiency of 59%, and this decreased to 43% after 15 cycles. For the static cell utilising VF11 membrane, the addition of MEM and MEP reduced the energy efficiency from 59.7% to 43.4%. It is believed that this is caused by the mass transfer controlled Br-/Br3- couple in the complexed positive half-cell solution. Therefore, uniformity between the organic and aqueous phase is important for flow cells utilising electrolytes with MEM and MEP. Finally, the polarization resistance of a lab scale V/Br flow cell utilising ChiNaf membrane and 2 M V3.7+ electrolytes was found to be slightly higher during cell charging (3.9 cm2) than during the discharge process (3.6 cm2), which is opposed to that in the all-vanadium redox cell.
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Prifti, Helen Chemical Sciences & Engineering Faculty of Engineering UNSW. "Electrolyte and membrane studies of the novel vanadium bromide redox flow cell." Awarded by:University of New South Wales. Chemical Sciences & Engineering, 2008. http://handle.unsw.edu.au/1959.4/41478.
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The novel Vanadium Bromide (V/Br) redox flow cell employs a V (III)/V (II) couple in the negative half-cell and a Br/Br2 couple in the positive half-cell, with hydrobromic acid and hydrochloric acid as the supporting electrolyte. This study evaluated the chemical and electrochemical properties of the electrolytes and assessed experimental and commercial membranes for use in the V/Br flow cell. A number of techniques were employed to characterise the composition of the V/Br flow cell electrolytes. During charge, the conductivity of the positive half-cell electrolyte increased, whilst the density and viscosity increased. The reverse was observed for the negative half-cell. The UV-visible spectra of the electrolytes showed characteristic peak wavelengths of the vanadium oxidation states and provided and insight into the halogenated species forming during the operation of the V/Br flow cell. The electrochemical properties of the electrolytes were also examined using cyclic voltammetry. NMR studies examined the relationships between the 35CI and 79Br nuclei in the presence of halide and paramagnetic vanadium ions. It was established that the SOC and performance of the V/Br flow cell can be measured by changes in slllectral chemical shifts and line widths. Small-scale cycling experiments were conducted to evaluate the performance of ion exchange membranes in the V/Br redox flow cell. Of the membranes evaluated, a number were not suitable for use due to high membrane resistances or low chemical stability. The perfluorinated Nafion?? and Gore Select?? ion exchange membranes proved to be the most chemically inert and showed low resistances. The Gore Select?? membranes did however exhibit blistering during extended cycling. The chemical stability and cycling performance of the HiporeTM microporous separator showed promise for future studies to optimise the selectivity and ion exchange capacity of the membrane. Tests of membrane ion exchange capacity, diffusivity and conductivity mirrored the properties displayed in the cell cycling experiments. Results suggested that the structural characteristics of the membrane (including functionality and crosslinking) greatly influenced membrane properties and performance. Tests of long term stability showed a negative change in membrane properties. These changes did not however reflect measured changes during cell cycling experiments.
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Sapouna, Ioanna. "Development of cellulose-based membranes for Vanadium Redox Flow Cell Battery applications." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-235217.
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In this study, the development of a cellulose-based membrane for use in Vanadium Redox Flow Cell Batteries (VRFBs) was investigated. Cellulose is the most abundant biopolymer on earth and due to its versatility it finds multiple applications. However, cellulose and its derivatives can be easily hydrolyzed in the amorphous regions, under acidic conditions. In order to bypass this problem and use this tough material in the highly acidic and oxidative environment of a VRFB, two approaches were utilized. First, cellulose nanocrystals (CNCs) were employed, which basically lack amorphous regions, to minimize the effect of hydrolysis. An additional advantage is that CNCs can create films with specific stereochemistry, as they pack closely, in helical structures. Second, the surface of the CNCs was modified with the use of trichloro(1H,1H,2H,2H- perfluorooctyl)silane (TCPOS). This molecule has a long fluorocarbon chain, which acts protectively towards hydrolysis of the CNCs. The choice of silane was made in order to produce a material that can resemble Nafion, the most popular copolymer used in VRFBs. Nafion has a fluorocarbon, Teflon-like, backbone and a hydrophilic side chain that consists of a sulfonic acid groups. The first step was to make a material that is stable under the VRFB conditions. The membranes were characterized with AFM imaging, FTIR spectroscopy, contact angle measurements, and tensile testing. With the use of the product of alkoxylation of TCPOS (TMPOS), hydrophobic membranes were produced that exhibit contact angle with water larger than that of Nafion. Young’s modulus of the membranes with TMPOS was larger compared to the one of CNC membranes without TMPOS. To determine stability against acidic conditions, Dynamic Light Scattering (DLS) was used. Additionally, stability of the membranes after acid and Vanadium solution treatment was performed with gravimetric measurements. From the results, 67% of the samples tested remained intact under high ionic strength and acidic conditions. In addition, the effect of the amount of silane on the membranes was evaluated. The results of this study are promising and encourages further research on this direction.I denna studie undersöktes utvecklingen av ett cellulosabaserat membran för användning i Vanadin redoxflödesbatterier (VRFB, en.). Cellulosa är den mest förekommande biopolymeren på jorden och med dess mångsidighet finns många tillämpningar. Cellulosa, och dess derivat, kan dessvärre enkelt hydrolyseras i amorfa regioner under sura förhållanden. För att kringgå detta problem och för att kunna använda materialet i den sura och oxidativa miljö som förekommer i ett VRFB, användes två tillvägagångssätt. Först användes cellulosananokristaller (CNC, en.) för att minimera effekten av hydrolys, då de huvudsakligen saknar amorfa regioner. Ytterligare en fördel är att man med CNC kan skapa filmer med specifik stereokemi, då de packas tätt i spiralformade strukturer. Det andra tillvägagångssättet var att modifiera CNC-ytan med hjälp av trikloro(1H,1H,2H,2H-perfluoroktyl)silan (TCPOS, en.). Denna molekyl har en lång fluorvätekedja, som skyddar mot hydrolys av CNC. Silan valdes för att skapa ett material som liknar Nafion, som är den vanligaste co-polymeren i VRFB. Nafion har en huvudkedja av fluorväte, liknande Teflon, och en hydrofil sidokedja bestående av sulfonsyragrupper. Det första steget var att göra ett material som är stabilt under de förhållanden som råder i ett VRFB. Membranen karaktäriserades med hjälp av AFM, FTIR-spektroskopi, kontaktvinkelmätningar och dragprov. Alkoxyleringsprodukten som erhölls ifrån TCPOS- behandlingen användes för att tillverka hydrofoba membran med en kontaktvinkel mot vatten som är större än för Nafion. Youngs modul för membran med TMPOS var större än för CNC- membran utan TMPOS. För att klarlägga stabiliteten under sura förhållanden ändvändes DLS. Dessutom testades membranens stabilitet efter syra- och vanadinlösningsbehandling genom olika gravimetriska mätningar. Resultaten visade att 67 % av de testade proverna förblev intakta under förhållanden med hög jonstyrka och surhet. Effekten av mängden använt silan i membranen utvärderades också. Resultaten från denna studie är lovande och uppmuntrar till vidare forskning i denna riktning.
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Cazot, Mathilde. "Development of Analytical Techniques for the Investigation of an Organic Redox Flow Battery using a Segmented Cell." Thesis, Université de Lorraine, 2019. http://www.theses.fr/2019LORR0116.
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Les batteries à électrolyte circulant ou redox flow batteries (RFB) représentent une technologie prometteuse pour répondre aux besoins grandissants de stockage d'énergie. Elles seraient particulièrement adaptées aux réseaux électriques qui comptent une part grandissante d'énergie d'origine renouvelable, produite en intermittence. L'objet de ce travail est l'étude d'un nouveau type de RFB, actuellement développé par l'entreprise Kemiwatt. Il repose sur l'utilisation de molécules organiques, qui sont abondantes et recyclables. Le but de cette étude est d'améliorer la compréhension fondamentale de la batterie grâce à l'utilisation d'outils d'analyse précis et innovants. Chaque composant du système a d'abord été analysé via des moyens expérimentaux ex-situ. Les deux électrolytes composant la batterie ont ensuite été étudiés séparément en conditions réelles de circulation dans une cellule symétrique. Couplées à un modèle d'électrode volumique, les données ont été analysées pour identifier les facteurs limitants de chaque solution. La batterie entière a ensuite été étudiée dans un dispositif segmenté, permettant l'accès à la distribution interne du courant. Une étude paramétrique, réalisée avec la cellule segmentée a permis d'observer les effets du courant, du débit et de la température sur le fonctionnement de la cellule, puis d'établir une cartographie des conditions de fonctionnement idéales, suivant la puissance et l'état de charge de la batterie. L'aspect hydrodynamique du système a finalement été abordé en développant un modèle fluidique ainsi qu'une maquette expérimentale de cellule transparente pour visualiser l'écoulementRedox Flow Batteries (RFBs) are a promising solution for large-scale and low-cost energy storage necessary to foster the use of intermittent renewable sources. This work investigates a novel RFB chemistry under development at the company Kemiwatt. Based on abundant organic/organo-metallic compounds, this new technology promises the deployment of sustainable and long-lived systems. The study undertakes the building of a thorough knowledge base of the system by developing innovative reliable analytical tools. The investigation started from the evaluation of the main factors influencing the battery performance, which could be conducted ex-situ on each material composing the cell. The two electrolytes were then examined independently under representative operating conditions, by building a symmetric flow cell. Cycling coupled with EIS measurements were performed in this set-up and then analyzed with a porous electrode model. This combined modeling-experimental approach revealed unlike limiting processes in each electrolyte along with precautions to take in the subsequent steps (such as membrane pretreatment and electrolyte protection from light). A segmented cell was built and validated to extend the study to the full cell system. It provided a mapping of the internal currents, which showed high irregularity during cycling. A thorough parameter study could be conducted with the segmented platform, by varying successively the current density, the flow rate, and the temperature. The outcome of this set of experiments would be the construction of an operational map that guides the flow rate adjustment, depending on the power load and the state of charge of the battery. This strategy of flow rate optimization showed promising outcomes at the lab-cell level. It can be easily adapted to real-size systems. Ultimately, an overview of the hydrodynamic behavior at the industrial-cell level was completed by developing a hydraulic modeling and a clear cell as an efficient diagnostic tool
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Ke, Xinyou. "Fundamental Studies on Transport Phenomena in Redox Flow Batteries with Flow Field Structures and Slurry or Semi-Solid Electrodes: Modeling and Experimental Approaches." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1543883710323558.
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Pasquini, Luca. "Ion - conducting polymeric membranes for electrochemical energy devices." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4750.
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La recherche vise à proposer des membranes pour des dispositifs électrochimiques capables d'atteindre le bon compromis en terme de conduction ionique, de stabilité et de longue durée de vie pour une haute efficacité.Nous avons réalisé des membranes échangeuses des protons, d'anions ou amphotères à base de polymères aromatiques stables fonctionnalisés. Des groupes sulfonique on été introduit sur la squelette du PEEK, des groupes d'ammonium sur le PEEK et le PSU ou le deux au même temps pour échanger ensemble des protons et des anions.L'optimisation continue des paramètres de synthèse, le choix des différents polymères et/ou des groupes de fonctionnalisation et l'amélioration des procédures et des traitements des membranes coulée, a conduit à de bons résultats en termes de conductivité ionique, sélectivité et stabilité.L'étude des principaux paramètres des membranes démontre une stabilité thermique entre 140 et 200 ° C selon la membrane sélectionnée, un comportement mécanique caractérisé par une résistance à la traction et un module d'élasticité élevée et un relativement faible ductilité, influencé par le niveau d’ hydratation de la membrane ou l éventuelle présence de cross-link. En optimisant le degré de fonctionnalisation et les types de groupes de fonctionnalisation, nous avons obtenu une accordable absorption d'eau, une conductivité ionique élevé pour différent ions (jusqu'à ≃ 3 mS / cm pour le polymère conducteurs des anions) et une perméabilité aux ions vanadium très faible (applications dans RFB) jusqu'à ≃ 10-10 cm2/min, ce qui est bien au-dessous des données typiques de la littérature et un paramètre très important pour applications technologiquesThe research aims to propose membranes for electrochemical devices alternative to the commercial ones able to reach the right compromise in term of good ionic conduction, stability and long life time for an high efficiency. We realized proton exchange, anion exchange and amphoteric membranes based on stable functionalized aromatic polymers (PEEK, PSU). We thus introduced sulfonic groups on a PEEK backbone to exchange protons or ammonium groups on PEEK and PSU to exchange anions. We also realized amphoteric membranes able to exchange at the same time both kinds of ions. The continuous optimization of synthesis parameters, the choice of different polymers and/or functionalization groups and the improvement of casting procedures and treatments of membranes, led to good results in terms of ionic conductivity, selectivity and stability.The study of the main parameters of the synthesized membranes demonstrates a thermal stability between 140 and 200°C depending on the selected membrane, a mechanical behavior characterized by a high elastic modulus and tensile strength and a relatively low ductility strongly influenced on the degree of hydration of the membrane as well as the eventual presence of cross-linking. Working on the degree of functionalization and the type of functionalizing groups, we obtained a tunable water uptake, an elevated ionic conductivity for different ions (up to ≃ 3 mS/cm for anionic conducting polymers) and a very low ion permeability (vanadium ions for RFB applications) down to ≃ 10-10 cm2/min, which is much below typical literature data for cation- and anion separation membranes and a challenge parameters for technological applications
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Martino, Drew J. "Evaluation of Electrochemical Storage Systems for Higher Efficiency and Energy Density." Digital WPI, 2017. https://digitalcommons.wpi.edu/etd-dissertations/470.
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Lack of energy storage is a key issue in the development of renewable energy sources. Most renewables, especially solar and wind, when used alone, cannot sustain a reliably constant power output over an extended period of time. These sources generally generate variable amounts of power intermittently, therefore, an efficient electrical energy storage (EES) method is required to better temporally balance power generation to power consumption. One of the more promising methods of electrical energy storage is the unitized regenerative fuel cell (UFRC.) UFRCs are fuel cells that can operate in a charge-discharge cycle, similar to a battery, to store and then to subsequently release power. Power is stored by means of electrolysis while the products of this electrolysis reaction can be recombined as in a normal fuel cell to release the stored power. A major advantage of UFRCs over batteries is that storage capacity can be decoupled from cell power, thus reducing the potential cost and weight of the cell unit. Here we investigate UFRCs based on hydrogen-halogen systems, specifically hydrogen-bromine, which has potential for improved electrode reaction kinetics and hence cheaper catalysts and higher efficiency and energy density. A mathematical model has been developed to analyze this system and determine cell behavior and cycle efficiency under various conditions. The conventional H2-Br2 URFCs, however also so far have utilized Pt catalysts and Nafion membranes. Consequently, a goal of this work was to explore alternate schemes and materials for the H2-Br2 URFC. Thus, three generations of test cells have been created. The first two cells were designed to use a molten bromide salt, ionic liquid or anion exchange membrane as the ion exchange electrolyte with the liquids supported on a porous membrane. This type of system provides the potential to reduce the amount of precious metal catalyst required, or possibly eliminate it altogether. Each cell showed improvement over the previous generation, although the results are preliminary. The final set of results are promising for anion exchange membranes on a cost basis compared Nafion. Another promising energy storage solution involves liquid methanol as an intermediate or as a hydrogen carrier. An alternative to storing high-pressure hydrogen is to produce it on-board/on-site on demand via a methanol electrocatalytic reformer (eCRef), a PEM electrolyzer in which methanol-water coelectrolysis takes place. Methanol handling, storage, and transportation is much easier than that for hydrogen. The hydrogen produced via methanol eCref may then be used in any number of applications, including for energy storage and generation in a standard H2-O2 PEM fuel cell. The mathematical modeling and analysis for an eCref is very similar to that of the HBr URFC. In this work, a comprehensive model for the coelectrolysis of methanol and water into hydrogen is created and compared with experimental data. The performance of the methanol electrolyzer coupled with a H2-O2 fuel cell is then compared for efficiency to that of a direct methanol fuel cell data and was found to be superior. The results suggest that an efficient and small paired eCRef-fuel cell system is potentially be a cheaper and more viable alternative to the standard direct methanol fuel cell. Both the H2-Br2 URFC and the methanol eCref in combination with a H2-O2 fuel cell have significant potential to provide higher energy efficiency and energy density for EES purposes.
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DE, PORCELLINIS DIANA. "Materials for energy production and storage: fuel cells and redox flow batteries." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2016. http://hdl.handle.net/2108/201863.
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Stabilization and electrical contacting of redox enzymes with electrodes are fundamental requirements for the development of bioelectronics devices such as biosensors and EFCs. In the present work, we show that glucose oxidase (GOx) stability could be increased by immobilization with Nafion. The immobilization process affected GOx conformation but was not detrimental to its activity, which was maintained for over 120 days. The GOx/Nafion system was interfaced to a carbon cloth electrode and assembled in a prototype EFC fed with glucose. Polarization and power density curves demonstrated that GOx/Nafion system was able to generate power, exploiting a Nafion-assisted electron transfer process to the electrode. Our findings are consistent with the onset of pH-dependent conformational equilibrium for the enzyme secondary structure and its active site. Significantly, the protective effect by Nafion on the enzyme structure may be tuned by varying parameters such as pH, in order to fabricate durable EFCs with good performance in electricity and power production.
Book chapters on the topic "Redox Flow Cell"
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Wadley, Alex J., Rhys G. Morgan, Richard L. Darley, Paul S. Hole, and Steven J. Coles. "Using Flow Cytometry to Detect and Measure Intracellular Thiol Redox Status in Viable T Cells from Heterogeneous Populations." In Redox-Mediated Signal Transduction, 53–70. New York, NY: Springer US, 2019. http://dx.doi.org/10.1007/978-1-4939-9463-2_5.
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Zaffou, R., W. N. Li, and M. L. Perry. "Vanadium Redox Flow Batteries for Electrical Energy Storage: Challenges and Opportunities." In Polymers for Energy Storage and Delivery: Polyelectrolytes for Batteries and Fuel Cells, 107–27. Washington, DC: American Chemical Society, 2012. http://dx.doi.org/10.1021/bk-2012-1096.ch007.
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Baricci, Andrea, Andrea Casalegno, and Matteo Zago. "Redox Flow Batteries: Physics-Based Cell Modeling." In Reference Module in Earth Systems and Environmental Sciences. Elsevier, 2021. http://dx.doi.org/10.1016/b978-0-12-819723-3.00090-1.
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van der Heijden, Maxime, and Antoni Forner-Cuenca. "Transport Phenomena and Cell Overpotentials in Redox Flow Batteries." In Encyclopedia of Energy Storage, 480–99. Elsevier, 2022. http://dx.doi.org/10.1016/b978-0-12-819723-3.00132-3.
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Denno, Khalil. "The Economics of the Redox Flow Cell Energy Conversion System (RFEC)*." In Engineering Economics of Alternative Energy Sources, 137–72. CRC Press, 2018. http://dx.doi.org/10.1201/9781351071734-3.
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"Physical Properties of Negative Half-Cell Electrolytes in the Vanadium Redox Flow Battery." In Electrochemically Enabled Sustainability, 408–41. CRC Press, 2014. http://dx.doi.org/10.1201/b17062-14.
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Yeetsorn, Rungsima, and Yaowaret Maiket. "Hydrogen Fuel Cell Implementation for the Transportation Sector." In Hydrogen Implementation in Transportation Sector [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.95291.
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Global transportation possesses have compelling rationales for reducing the consumption of oil, emissions of carbon dioxide, and noise pollution. Transitions to alternative transportation technologies such as electric vehicles (EVs) have gained increased attention from the automotive industries. A fuel cell electric vehicle (FCEV) occupying a hydrogen engine is one of the most stupendous technologies, since it is suitable for a large-scale transportation. However, its performance limitations are in question due to voltage degradation in long term operations through steady conditions under constant load and dynamic working conditions. Other drawbacks of using fuel cells in EVs are energy balances and management issues necessary for vehicle power and energy requirements. An efficient solution to accommodate driving behavior like dynamic loads comprises of hybridizing PEMFCs with energy storage devices like supercapacitors and batteries. This opening chapter reviews the projected gist of FCEV status; considers the factors that are going to affect how FCEVs could enter commercialization, including the importance of fuel cells for EV technologies; the degradation diagnoses using accelerated stress test (AST) procedures; FCEV hybridization; and the contribution of an energy storage device for charging EVs. The article also addresses case studies relating to material degradation occurring from driving behavior. Information about material degradation can be compiled into a database for the improvement of cell component performance and durability, leading to the creation of new materials and new fuel cell hybridization designs. To support the growth of EV technologies, an energy storage is required for the integrated alternative electricity generations. A redox flow battery is considered as a promising candidate in terms of attractive charging station for EVs or HEVs.
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Oriakhi, Christopher O. "Fundamentals of Electrochemistry." In Chemistry in Quantitative Language. Oxford University Press, 2009. http://dx.doi.org/10.1093/oso/9780195367997.003.0027.
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Electrochemistry is the branch of chemistry that deals with the interconversion of chemical and electrical energy. A galvanic (or voltaic) cell is a chemical system that uses an oxidation–reduction reaction to convert chemical energy into electrical energy (hence it is also known as an electrochemical cell). This process is the opposite of electrolysis (explained in section 23.10), wherein electrical energy is used to bring about chemical changes. The two systems are similar in that both are redox processes; in both, the oxidation takes place at one electrode, the anode, while reduction occurs at the cathode. Figure 23-1 shows a galvanic cell, indicating the half-reactions at the two electrodes. Electrons flow through the external circuit from the anode (Zn) to the cathode (Cu). The overall reaction, which is obtained by adding the anodic and cathodic half-cell reactions, is: . . .Zn(s)+Cu2+(aq) → Zn2+(aq)+Cu(s). . . This cell has a potential of 1.10 V (see next section). The potential energy of electrons at the anode is higher than at the cathode. This difference in potential is the driving force that propels electrons through the external circuit. The cell potential (Ecell) is a measure of the potential difference between the two half-cells. It is also known as the electromotive force (emf) of the cell, or, since it is measured in volts, the cell voltage. An electrochemical cell consists of two half-reactions at different potentials, which are known as electrode potentials. The electrode potential for the oxidation half-reaction is called the oxidation potential. Similarly, for the reduction half-reaction, we have the reduction potential. The potential of a galvanic cell is determined by the concentrations of the species in solution, the partial pressures of any gaseous reactants or products, and the reaction temperature. When the electrochemical measurement is carried out under standard-state conditions, the cell potential is called the standard electrode potential and is given the symbol E0. The standard conditions include a concentration of 1 M, gaseous partial pressure of 1 atm, and a temperature of 25°C. It is impossible to measure the absolute potential value of a single electrode, since every oxidation is accompanied by a reduction. Therefore any measurement is carried out against a reference electrode.
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Neyhouse, Bertrand J., and Fikile R. Brushett. "From the Synthesis Vial to the Full Cell: Electrochemical Methods for Characterizing Active Materials for Redox Flow Batteries." In Reference Module in Earth Systems and Environmental Sciences. Elsevier, 2021. http://dx.doi.org/10.1016/b978-0-12-819723-3.00058-5.
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Nakamura, Hideaki. "Developmental Studies on Practical Enzymatic Phosphate Ion Biosensors and Microbial BOD Biosensors, and New Insights into the Future Perspectives of These Biosensor Fields." In Biomedical Engineering. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.104377.
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This chapter summarizes the developmental studies on environmental biosensors of enzymatic phosphate ion (Pi) biosensors for eutrophication and microbial biochemical oxygen demand (BOD) biosensors for organic pollution. In particular, an author focuses on the developmental studies that the author principally conducted, and describe the history and the insights into the future of these fields of environmental biosensors. In our developmental studies on the enzymatic Pi biosensors, we fabricated automatic instruments of a desktop-type and a submersible buoy-type, which was fabricated for remote biosensing of dam water. These instruments employed a luminol-chemiluminescence flow injection analysis (CL-FIA) system and enabled to have practical performances in precise Pi determination, operational stability, and accurate bioavailable Pi measurements. In the microbial BOD biosensor development, the author considered to apply the FIA concept enabling highly repeatable measurements to absorptiometric BOD measurements. Both precise temperature control and accurate time control to incubate measurement mixture of budding yeast cell suspension containing redox color indicator and sample enabled to obtain the highly repeatable results that led to highly sensitive BOD measurements. Looking back on our developmental studies, what the author was thinking at the time and the results obtained are described. Finally, the author discusses the developmental trends of these biosensor fields and new insights into the future perspectives.
Conference papers on the topic "Redox Flow Cell"
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Nagai, Yoshiki, Ryohei Komiyama, Hidetoshi Miyashita, and Sang-Seok Lee. "Miniaturization of Zn/Br redox flow battery cell." In 2016 IEEE 11th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS). IEEE, 2016. http://dx.doi.org/10.1109/nems.2016.7758237.
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Khabbazi, Ali Ebrahimi, and Mina Hoorfar. "Modeling of Microfluidic Fuel Cells With Flow-Through Porous Electrodes." In ASME 2010 8th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2010. http://dx.doi.org/10.1115/fuelcell2010-33220.
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This paper presents a modeling of a microfluidic fuel cell with flow-through porous electrodes using vanadium redox couples as the fuel and oxidant. There are advantages associated with the use of vanadium redox species in microfluidic fuel cell: 1) vanadium redox couples have the possibility of producing high open-circuit potential (up to 1.7 V at uniform PH [1]); 2) they have high solubility (up to 5.4 M) which causes more species available to the electrodes; 3) they do not require metal catalyst for electrochemical reactions so the reactions take place on the bare carbon electrodes. This characteristic of the vanadium redox couple make them a great candidate as reactants as they do not need expensive catalyst coatings on the electrodes. The fuel and the oxidant can be brought into contact with the electrode in two different ways: flowing over the electrodes or flowing through the electrodes. In the presented fuel cell design, the vanadium redox species are forced to flow through the porous electrodes. They finally come to meet each other in the middle microchannel and establish a side-by-side co-laminar flow traveling down the channel. In this paper, the effect of the inlet velocity and electrode porosity has been investigated. As it is expected, the higher velocity results in the higher power densities. For the porosity, however, there is an optimum value. In essence, there is a trade-off between the available electrode surface area and electric conductivity of the solid phase (i.e., the porous carbon electrode). The modeling shows that a porous electrode with a 67% porosity results in the highest power output.
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Tsushima, Shohji, Sho Sasaki, Takahiro Suzuki, Phengxay Deevanhxay, and Shuichiro Hirai. "Performance Improvement in Redox Flow Battery With Flow-Through Channel Geometry." In ASME 2013 11th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icnmm2013-73209.
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Redox Flow battery attracts much attention as one of the efficient rechargeable batteries because of its versatility for small and large scale energy storage. Although this battery has great potentials, further improvement on cell performance to achieve high current density is necessary for industrial implementation. In this study, we applied flow-through (interdigitated) channel geometry to a redox flow battery for enhancement of electrode utilization by advection transport. As a result, it is confirmed that the redox flow battery showed better performance by using interdigitated channels than ones with serpentine channels.
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Cook, Korey, Ethan Lau, Jordan Thayer, Shane Mann, Tom Guarr, and Andre Benard. "Development of a Membraneless Organic Redox Flow Battery." In ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-88024.
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The development of a novel electrochemical energy storage system, specifically a redox flow batteries (RFB), is discussed in this work. It has the distinction of not requiring an ion-selective membrane due to novel chemical compounds. The techno-economic aspects of a low-cost 3D printed flow cell and system design tailored for a novel chemistry is discussed. The organic compounds employed are inexpensive, have a long lifespan, and as mentioned enable the system to be membraneless. All these substantially decrease the capital and maintenance costs. Suitable systems were developed and tested using chemically compatible 3D printed materials for the flow cells. The estimated cost per kWh is lower than the Department of Energy’s target cost of $150/kWh for grid storage capacity. A commercial scale system, rated for a 1 MW, 5-hour discharge time, has an estimated cost of $65/kWh. The proposed technology could revolutionize the energy storage industry and help with the construction of a more stable and efficient energy grid.
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Islam, Rabiul, Benjamin Eckerson, Cameron Nolen, Kwangkook Jeong, and Roy McCann. "Experimental Study on Test-Bed Vanadium Redox Flow Battery." In ASME 2015 9th International Conference on Energy Sustainability collocated with the ASME 2015 Power Conference, the ASME 2015 13th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2015 Nuclear Forum. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/es2015-49493.
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An experimental study has been conducted to develop a test-bed for advanced vanadium redox flow battery (VRFB) for renewable energy applications. Lab scale experimental setup has been designed based on enhanced geometry of mechanical components and reduced power consumption in terms of fluid mechanics and thermodynamics. Two tests have been conducted with variations of flowrate, concentration of electrolytes and electrical input power. The VRFB project has been collaborated between Arkansas State University Jonesboro (ASUJ) and University of Arkansas Fayetteville (UAF) to integrate VRFB with micro-grid at UAF. To obtain comparable experimental data, a test bed made of two half cells was constructed and joined together by a permeable membrane designed to facilitate ion transfer between two separate vanadium electrolytes. This research aims to better understand and demonstrate the transient characteristics of VRFB in order to refine the system in hopes of improving efficiency. This paper will focus on the steps taken to experimentally validate preliminary performance of the VRFB test bed. An analytical model has been performed to validate design and test of VRFB. Future work will be addressed to develop a pilot-scale multiple cell stacks with enhanced efficiency and temperature limits.
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Nizam, N. M., M. H. Zulkhifli, A. C. Khor, M. R. Mohamed, and M. H. Sulaiman. "Design and Development of Vanadium Redox Flow Battery (V-RFB) Cell Stack." In 4th IET Clean Energy and Technology Conference (CEAT 2016). Institution of Engineering and Technology, 2016. http://dx.doi.org/10.1049/cp.2016.1286.
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Sujali, S., M. R. Mohamed, S. A. Mad Don, and N. Yusoff. "Method approaches to prevent leakage cell stack of vanadium redox flow battery (VRFB)." In 4th IET Clean Energy and Technology Conference (CEAT 2016). Institution of Engineering and Technology, 2016. http://dx.doi.org/10.1049/cp.2016.1289.
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Kjeang, Erik, Ned Djilali, and David Sinton. "Planar and Three-Dimensional Microfluidic Fuel Cell Architectures." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-42524.
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We propose planar and three-dimensional microfluidic fuel cell architectures based on the all-vanadium redox system. These fuel cells operate in a membraneless co-laminar flow configuration and are manufactured by economical microfabrication methods. Graphite rods, also known as mechanical pencil refills, are demonstrated as fuel cell electrodes in a three-dimensional array architecture with unique scale-up capabilities. We also demonstrate unprecedented power density levels by incorporation of porous electrodes in a planar microfluidic fuel cell.
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Wang, Yun, and Sung Chan Cho. "Advanced Modeling of the Dynamics of Vanadium Redox Flow Batteries." In ASME 2015 13th International Conference on Fuel Cell Science, Engineering and Technology collocated with the ASME 2015 Power Conference, the ASME 2015 9th International Conference on Energy Sustainability, and the ASME 2015 Nuclear Forum. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/fuelcell2015-49408.
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In this paper, a multi-dimensional dynamic model of vanadium Redox Flow Batteries (RFB) is employed to predict battery performance and internal operating condition during charge and discharge. The model consists of a set of partial differential equations of mass, momentum, species, charges, and energy conservation, in conjunction with the electrode’s electrochemical reaction kinetics. After validated against experimental data for a vanadium RFB, flow field, temperature distribution, and reactant evolution are presented. The developed numerical tool is extremely useful in optimizing RFB design and control.
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Sathisha, H. M., and Amaresh Dalal. "Simplified Mathematical Model to Evaluate the Performance of the All-Vanadium Redox Flow Battery." In ASME 2013 Heat Transfer Summer Conference collocated with the ASME 2013 7th International Conference on Energy Sustainability and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ht2013-17366.
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All-vanadium redox flow battery is one of the promising rechargeable battery since it is able to withstand average loads, high energy efficiency and high power output. The battery exhibits the excellent transient behaviour and sustains sudden voltage drop. The dynamics of the battery is governed by the conservation equations of mass and charge. The simplified mathematical model includes major resistances, electrochemical reactions and recirculation of electrolyte through reservoirs. The mathematical model is able to predict the performance of the battery. The cell performance can be increased by increasing the concentration of the vanadium ions, the flow rate and the temperature inside the cell. The model results are validated with the available experimental result which shows better agreement.
Reports on the topic "Redox Flow Cell"
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Delwiche, Michael, Boaz Zion, Robert BonDurant, Judith Rishpon, Ephraim Maltz, and Miriam Rosenberg. Biosensors for On-Line Measurement of Reproductive Hormones and Milk Proteins to Improve Dairy Herd Management. United States Department of Agriculture, February 2001. http://dx.doi.org/10.32747/2001.7573998.bard.
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The original objectives of this research project were to: (1) develop immunoassays, photometric sensors, and electrochemical sensors for real-time measurement of progesterone and estradiol in milk, (2) develop biosensors for measurement of caseins in milk, and (3) integrate and adapt these sensor technologies to create an automated electronic sensing system for operation in dairy parlors during milking. The overall direction of research was not changed, although the work was expanded to include other milk components such as urea and lactose. A second generation biosensor for on-line measurement of bovine progesterone was designed and tested. Anti-progesterone antibody was coated on small disks of nitrocellulose membrane, which were inserted in the reaction chamber prior to testing, and a real-time assay was developed. The biosensor was designed using micropumps and valves under computer control, and assayed fluid volumes on the order of 1 ml. An automated sampler was designed to draw a test volume of milk from the long milk tube using a 4-way pinch valve. The system could execute a measurement cycle in about 10 min. Progesterone could be measured at concentrations low enough to distinguish luteal-phase from follicular-phase cows. The potential of the sensor to detect actual ovulatory events was compared with standard methods of estrus detection, including human observation and an activity monitor. The biosensor correctly identified all ovulatory events during its testperiod, but the variability at low progesterone concentrations triggered some false positives. Direct on-line measurement and intelligent interpretation of reproductive hormone profiles offers the potential for substantial improvement in reproductive management. A simple potentiometric method for measurement of milk protein was developed and tested. The method was based on the fact that proteins bind iodine. When proteins are added to a solution of the redox couple iodine/iodide (I-I2), the concentration of free iodine is changed and, as a consequence, the potential between two electrodes immersed in the solution is changed. The method worked well with analytical casein solutions and accurately measured concentrations of analytical caseins added to fresh milk. When tested with actual milk samples, the correlation between the sensor readings and the reference lab results (of both total proteins and casein content) was inferior to that of analytical casein. A number of different technologies were explored for the analysis of milk urea, and a manometric technique was selected for the final design. In the new sensor, urea in the sample was hydrolyzed to ammonium and carbonate by the enzyme urease, and subsequent shaking of the sample with citric acid in a sealed cell allowed urea to be estimated as a change in partial pressure of carbon dioxide. The pressure change in the cell was measured with a miniature piezoresistive pressure sensor, and effects of background dissolved gases and vapor pressures were corrected for by repeating the measurement of pressure developed in the sample without the addition of urease. Results were accurate in the physiological range of milk, the assay was faster than the typical milking period, and no toxic reagents were required. A sampling device was designed and built to passively draw milk from the long milk tube in the parlor. An electrochemical sensor for lactose was developed starting with a three-cascaded-enzyme sensor, evolving into two enzymes and CO2[Fe (CN)6] as a mediator, and then into a microflow injection system using poly-osmium modified screen-printed electrodes. The sensor was designed to serve multiple milking positions, using a manifold valve, a sampling valve, and two pumps. Disposable screen-printed electrodes with enzymatic membranes were used. The sensor was optimized for electrode coating components, flow rate, pH, and sample size, and the results correlated well (r2= 0.967) with known lactose concentrations.
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Ohad, Itzhak, and Himadri Pakrasi. Role of Cytochrome B559 in Photoinhibition. United States Department of Agriculture, December 1995. http://dx.doi.org/10.32747/1995.7613031.bard.
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The aim of this research project was to obtain information on the role of the cytochrome b559 in the function of Photosystem-II (PSII) with special emphasis on the light induced photo inactivation of PSII and turnover of the photochemical reaction center II protein subunit RCII-D1. The major goals of this project were: 1) Isolation and sequencing of the Chlamydomonas chloroplast psbE and psbF genes encoding the cytochrome b559 a and b subunits respectively; 2) Generation of site directed mutants and testing the effect of such mutation on the function of PSII under various light conditions; 3) To obtain further information on the mechanism of the light induced degradation and replacement of the PSII core proteins. This information shall serve as a basis for the understanding of the role of the cytochrome b559 in the process of photoinhibition and recovery of photosynthetic activity as well as during low light induced turnover of the D1 protein. Unlike in other organisms in which the psbE and psbF genes encoding the a and b subunits of cytochrome b559, are part of an operon which also includes the psbL and psbJ genes, in Chlamydomonas these genes are transcribed from different regions of the chloroplast chromosome. The charge distribution of the derived amino-acid sequences of psbE and psbF gene products differs from that of the corresponding genes in other organisms as far as the rule of "positive charge in" is concerned relative to the process of the polypeptide insertion in the thylakoid membrane. However, the sum of the charges of both subunits corresponds to the above rule possibly indicating co-insertion of both subunits in the process of cytochrome b559 assembly. A plasmid designed for the introduction of site-specific mutations into the psbF gene of C. reinhardtii. was constructed. The vector consists of a DNA fragment from the chromosome of C. reinhardtii which spans the region of the psbF gene, upstream of which the spectinomycin-resistance-conferring aadA cassette was inserted. This vector was successfully used to transform wild type C. reinhardtii cells. The spectinomycin resistant strain thus obtained can grow autotrophically and does not show significant changes as compared to the wild-type strain in PSII activity. The following mutations have been introduced in the psbF gene: H23M; H23Y; W19L and W19. The replacement of H23 involved in the heme binding to M and Y was meant to permit heme binding but eventually alter some or all of the electron transport properties of the mutated cytochrome. Tryptophane W19, a strictly conserved residue, is proximal to the heme and may interact with the tetrapyrole ring. Therefore its replacement may effect the heme properties. A change to tyrosine may have a lesser affect on the potential or electron transfer rate while a replacement of W19 by leucine is meant to introduce a more prominent disturbance in these parameters. Two of the mutants, FW19L and FH23M have segregated already and are homoplasmic. The rest are still grown under selection conditions until complete segregation will be obtained. All mutants contain assembled and functional PSII exhibiting an increased sensitivity of PSII to the light. Work is still in progress for the detailed characterization of the mutants PSII properties. A tobacco mutant, S6, obtained by Maliga and coworkers harboring the F26S mutation in the b subunit was made available to us and was characterized. Measurements of PSII charge separation and recombination, polypeptide content and electron flow indicates that this mutation indeed results in light sensitivity. Presently further work is in progress in the detailed characterization of the properties of all the above mutants. Information was obtained demonstrating that photoinactivation of PSII in vivo initiates a series of progressive changes in the properties of RCII which result in an irreversible modification of the RCII-D1 protein leading to its degradation and replacement. The cleavage process of the modified RCII-D1 protein is regulated by the occupancy of the QB site of RCII by plastoquinone. Newly synthesized D1 protein is not accumulated in a stable form unless integrated in reassembled RCII. Thus the degradation of the irreversibly modified RCII-D1 protein is essential for the recovery process. The light induced degradation of the RCII-D1 protein is rapid in mutants lacking the pD1 processing protease such as in the LF-1 mutant of the unicellular alga Scenedesmus obliquus. In this case the Mn binding site of PSII is abolished, the water oxidation process is inhibited and harmful cation radicals are formed following light induced electron flow in PSII. In such mutants photo-inactivation of PSII is rapid, it is not protected by ligands binding at the QB site and the degradation of the inactivated RCII-D1 occurs rapidly also in the dark. Furthermore the degraded D1 protein can be replaced in the dark in absence of light driven redox controlled reactions. The replacement of the RCII-D1 protein involves the de novo synthesis of the precursor protein, pD1, and its processing at the C-terminus end by an unknown processing protease. In the frame of this work, a gene previously isolated and sequenced by Dr. Pakrasi's group has been identified as encoding the RCII-pD1 C-terminus processing protease in the cyanobacterium Synechocystis sp. PCC 6803. The deduced sequence of the ctpA protein shows significant similarity to the bovine, human and insect interphotoreceptor retinoid-binding proteins. Results obtained using C. reinhardtii cells exposes to low light or series of single turnover light flashes have been also obtained indicating that the process of RCII-D1 protein turnover under non-photoinactivating conditions (low light) may be related to charge recombination in RCII due to back electron flow from the semiquinone QB- to the oxidised S2,3 states of the Mn cluster involved in the water oxidation process.