Relevant bibliographies by topics / PEFCs

Academic literature on the topic 'PEFCs'

Author: Grafiati
Published: 10 December 2022
Last updated: 28 January 2023

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Journal articles on the topic "PEFCs"

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Mirfarsi, Seyed Hesam, Mohammad Javad Parnian, and Soosan Rowshanzamir. "Self-Humidifying Proton Exchange Membranes for Fuel Cell Applications: Advances and Challenges." Processes 8, no. 9 (September 1, 2020): 1069. http://dx.doi.org/10.3390/pr8091069.

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Polymer electrolyte fuel cells (PEFCs) provide efficient and carbon-free power by converting the hydrogen chemical energy. The PEFCs can reach their greatest performance in humidified condition, as proton exchange membranes (PEMs) should be humidified for their proton transportation function. Thus, external humidifiers are commonly employed to increase the water content of reactants. However, being burdened with external humidifiers can make the control of PEFCs complicated and costly, in particular for transportation application. To overcome this issue, self-humidifying PEMs have been introduced, with which PEFC can be fed by dry reactants. In fact, internal humidification is accomplished by produced water from the recombination of permeated hydrogen and oxygen gases on the incorporated platinum catalysts within the PEM. While the water production agent remains constant, there is a broad range of additives that are utilized to retain the generated water and facilitate the proton conduction path in the PEM. This review paper has classified the aforementioned additives in three categories: inorganic materials, proton-conductive materials, and carbon-based additives. Moreover, synthesis methods, preparation procedures, and characterization tests are overviewed. Eventually, self-humidifying PEMs endowed with platinum and different additives are compared from performance and stability perspectives, such as water uptake, proton conductivity, fuel cell performance, gas cross-over, and the overall durability. In addition, their challenges and possible solutions are reviewed. Considering the concerns regarding the long-term durability of such PEMs, it seems that further investigations can be beneficial to confirm their reliability for prolonged PEFC operation.
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Yang, Zehui, Xinxin Yu, Yunfeng Zhang, and Guodong Xu. "Remarkably durable platinum cluster supported on multi-walled carbon nanotubes with high performance in an anhydrous polymer electrolyte fuel cell." RSC Advances 6, no. 110 (2016): 108158–63. http://dx.doi.org/10.1039/c6ra19487g.

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Fushinobu, Kazuyoshi, Kenji Shimizu, Nariaki Miki, and Ken Okazaki. "Optical Measurement Technique of Water Contents in Polymer Membrane for PEFCs." Journal of Fuel Cell Science and Technology 3, no. 1 (August 22, 2005): 13–17. http://dx.doi.org/10.1115/1.2133801.

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The feasibility of an optical technique is examined for the measurement of the membrane water content in polymer electrolyte fuel cells (PEFCs). Transmission of the infrared light of 1.92 μm wavelength is used to measure the water content in the polymer electrolyte membrane. A calibration procedure is examined, and the technique is applied for the transient measurement of a Nafion membrane that gives the value of water diffusion coefficient, consistent with previous reports. The technique is then applied to an operating PEFC to show its applicability for in situ measurement.
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Pak, Chanho, Sangkyun Kang, Yeong Suk Choi, and Hyuk Chang. "Nanomaterials and structures for the fourth innovation of polymer electrolyte fuel cell." Journal of Materials Research 25, no. 11 (November 2010): 2063–71. http://dx.doi.org/10.1557/jmr.2010.0280.

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Polymer electrolyte fuel cells (PEFCs) are drawing attention as energy conversion devices for next generations because of their highly efficient, environmentally benign, and portable features. In the last five decades, three distinguishable innovations were achieved in terms of proton conductive membranes and electrodes: introduction of perfluorinated membranes into PEFCs, adoption of ionomers for electrodes, and increased toughness of membranes by reinforced membranes. The efficiency, cost, and durability achieved from the past three innovations are still not enough to replace competing technologies such as combustion engines. In this review, the authors would elucidate the three different methods based on nanotechnology to overcome the limits: nanoporous carbon-supported catalysts, nanocomposite membranes, and nanostructured membrane electrode assemblies, which will bring the fourth innovation to PEFCs. With the innovation, PEFCs will fulfill the goals of being clean-energy conversion devices in the major applications of stationary, portable, and vehicle markets.
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Meng, Hua, and Chao-Yang Wang. "Electron Transport in PEFCs." Journal of The Electrochemical Society 151, no. 3 (2004): A358. http://dx.doi.org/10.1149/1.1641036.

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Das, Prodip. "(Invited, Digital Presentation) Tuning Gas-Diffusion-Layer Surface Wettability for Polymer Electrolyte Fuel Cells." ECS Meeting Abstracts MA2022-01, no. 38 (July 7, 2022): 1709. http://dx.doi.org/10.1149/ma2022-01381709mtgabs.

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In the present scenario of a global initiative toward securing global net-zero by mid-century and keeping 1.5 degrees within reach, polymer-electrolyte fuel cells (PEFCs) are considered to play an important role in the energy transition, particularly for the decarbonization of transit buses, trucks, rail transport, ships and ferries, and the residential heating sector. However, PEFCs are not economically competitive with the internal combustion engine powertrains [1]. Moreover, their durability standards in widely varying conditions have yet to be established and water management remains a critical issue for performance degradation and durability [1-3]. Thus, the mission of my research team is to conduct original research to make PEFCs economically viable and optimize their performance and durability [4,5]. In this talk, I will highlight our research on PEFC’s gas diffusion layer (GDL), as its interfaces with the flow channel and microporous layer play a significant role in water management. This research was aimed at selectively modifying GDL surfaces with a hydrophobic pattern to improve water transport and water removal from flow channels; thus, improving the durability and performance of PEFCs. Sigracet® GDLs were used as a base substrate and two different monomers, polydimethylsiloxane (PDMS) added with fumed silica (Si) and fluorinated ethylene propylene (FEP) were used to print a selective pattern on the GDL surfaces [6]. Both the additive manufacturing and spray coating techniques were utilized for creating the hydrophobic pattern on the GDL surfaces. The results of this study demonstrated a novel but simple approach to tune GDL surfaces with selective wetting properties and superhydrophobic interfaces that would enhance water transport. I will discuss some of these results and highlight how these results will benefit the water management of next-generation high-power PEFCs. This work was funded by the Engineering and Physical Sciences Research Council (EP/P03098X/1) and the STFC Batteries Network (ST/R006873/1) and was supported by SGL Carbon SE (www.sglcarbon.com). References [1] A.Z. Weber et al., "A critical review of modeling transport phenomena in polymer electrolyte fuel cells," J. Electrochem. Soc., vol. 161, pp. F1254-F1299, 2014. [2] A.D. Santamaria et al., "Liquid-water interactions with gas-diffusion layers surfaces," J. Electrochem. Soc., vol. 161, pp. F1184-F1193, 2014. [3] P.K. Das and A.Z. Weber, "Water management in PEMFC with ultra-thin catalyst-layers," ASME 11th Fuel Cell Science, Engineering and Technology Conference, Paper No. FuelCell2013-18010, pp. V001T01A002, 2013. [4] L. Xing et al., "Membrane electrode assemblies for PEM fuel cells: A review of functional graded design and optimization," Energy, vol. 177, pp. 445-464, 2019. [5] L. Xing et al., "Inhomogeneous distribution of platinum and ionomer in the porous cathode to maximize the performance of a PEM fuel cell," AIChE J., vol. 63, pp. 4895-4910, 2017. [6] D. Thumbarathy et al., "Fabrication and characterization of tuneable flow-channel/gas-diffusion-layer interface for polymer electrolyte fuel cells," J. Electrochem. Energy Convers. Storage, vol. 17, pp. 011010, 2020.
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Koga, Maito, Hidetoshi Matsumoto, Mitsunori Kunishima, Masatoshi Tokita, Hiroyasu Masunaga, Noboru Ohta, Akihisa Takeuchi, et al. "Microstructure Investigation of Polymer Electrolyte Fuel Cell Catalyst Layers Containing Perfluorosulfonated Ionomer." Membranes 11, no. 7 (June 24, 2021): 466. http://dx.doi.org/10.3390/membranes11070466.

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Perfluorosulfonated ionomers are the most successful ion-exchange membranes at an industrial scale. One recent, cutting-edge application of perfluorosulfonated ionomers is in polymer electrolyte fuel cells (PEFCs). In PEFCs, the ionomers are used as a component of the catalyst layer (CL) in addition to functioning as a proton-exchange membrane. In this study, the microstructures in the CLs of PEFCs were characterized by combined synchrotron X-ray scattering and transmission electron microscopy (TEM) analyses. The CL comprised a catalyst, a support, and an ionomer. Fractal dimensional analysis of the combined ultrasmall- and small-angle X-ray scattering profiles indicated that the carbon-black-supported Pt catalyst (Pt/CB) surface was covered with the ionomer in the CL. Anomalous X-ray scattering revealed that the Pt catalyst nanoparticles on the carbon surfaces were aggregated in the CLs. These findings are consistent with the ionomer/catalyst microstructures and ionomer coverage on the Pt/CB surface obtained from TEM observations.
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Gamaleev, Vladislav, Kengo Kajikawa, Keigo Takeda, and Mineo Hiramatsu. "Investigation of Nanographene Produced by In-Liquid Plasma for Development of Highly Durable Polymer Electrolyte Fuel Cells." C 4, no. 4 (November 23, 2018): 65. http://dx.doi.org/10.3390/c4040065.

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Recently, polymer electrolyte fuel cells (PEFCs) are attracting a lot of attention owing to their small size and relatively low working temperature (below 80 °C), which enables their usage in automobiles and household power generation. However, PEFCs have a problem with decreased output caused by corrosion of amorphous carbon, which is commonly used as a catalytic carrier. This problem could be solved by the usage of carbon nanostructures with a stronger crystal structure than amorphous carbon. In this work, nanographene supported by Pt nanoparticles was synthesized and examined for possible applications in the development of PEFCs with increased durability. Nanographene was synthesized by in-liquid plasma generated in ethanol using alternating current (AC) high voltage. A membrane electrode assembly (MEA) was constructed, where Pt nanoparticle-supported nanographene was used as the catalytic layer. Power generation characteristics of the MEA were evaluated and current density for the developed MEA was found to be approximately 240 mA/cm2. From the electrochemical evaluation, it was found that the durability of Pt nanoparticle-supported nanographene was about seven times higher than that of carbon black.
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Mohamed, Hamdy F. M., Seiti Kuroda, Yoshinori Kobayashi, Bruno Tavernier, Ryoichi Suzuki, and Akihiro Ohira. "Study of Thin Nafion® Films for Fuel Cells Using Energy Variable Slow Positron Annihilation Spectroscopy." Materials Science Forum 733 (November 2012): 57–60. http://dx.doi.org/10.4028/www.scientific.net/msf.733.57.

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Nafion® is one of the most popular proton conducting membranes for polymer electrolyte fuel cells (PEFCs). For the integration of Nafion® to the catalyst layers, very thin layers of the polymer are often formed on the catalysts of PEFC from dilute solutions. We applied energy variable positron annihilation to characterizing the structure of thin Nafion® films prepared by spin and dip coating from ethanol/water solutions of Nafion® on Si substrates. Experimental data suggest that the nano-structure of 23 nm thick spin coated Nafion® film is different from 220 nm thick film and also from 26 and 227 nm thick dip coated films, possibly due to the preservation of the unique rod-like structure of Nafion® in the dilute solution.
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Tsuji, Naruki, Tetsuya Miyazawa, Takuma Kaneko, Yuki Orikasa, Yoichiro Tsuji, Yoshiharu Uchimoto, Hideto Imai, and Yoshiharu Sakurai. "Imaging Liquid Water in a PEFC with High-Energy X-Ray Compton Scattering." ECS Meeting Abstracts MA2022-02, no. 39 (October 9, 2022): 1384. http://dx.doi.org/10.1149/ma2022-02391384mtgabs.

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Water management is important for stable operation of PEFCs (Polymer Electrolyte Fuel Cells), since the proton conductivity depends on water content and excessive water hinders electrochemical reactions. As the durability of PEFC has become a major issue, the correlative behavior between liquid water and cerium oxides (radical scavengers) is drawing much attention. Till now, the water content and its inhomogeneous distributions have been reported by neutron radiography and X-ray computed tomography (CT). In this paper, we present a high-energy Compton scattering imaging (CSI) technique for non-destructive observation of liquid water in PEFC. The advantage of high-energy CSI over X-ray CT is that the CSI technique has direct access to a two-dimensional cross section inside a PEFC without its rotation. The radiation damage on polymer electrolyte membranes is negligibly small since the photoelectric absorption is substantially reduced at such high-energy X-rays. Although high-energy X-ray CT is not sensitive to light-element materials, X-ray Compton scattering has its sensitivity to light elements. Figure 1 shows the cross-sectional images of GDL (Gas Diffusion Layer) materials and liquid water [1]. The GDL materials are made of porous carbon fibers and carbon composites with Teflon treatment, TGP-H-300 (TORAY Industries, Inc., Tokyo, Japan). The area of the cross sections is 2mm x 2mm, and its thickness is 10μm. The spatial resolution is 75 μm. Figure 1(a) shows the image of dry GDL materials, displaying the distribution of carbon fibers and carbon composite, and Figure 1(b) does the difference image between dry and wet, representing the liquid water distribution. Negative contributions are observed in the carbon fiber and carbon composite region, which indicates possible interactions between the GDL materials and liquid water. In this presentation, applications to a model cell under operation are also presented, together with correlation mappings of liquid water and cerium. The capability of CSI for vehicles’ PEFCs (TOYOTA MIRAI) is also discussed. This work was performed under the NEDO FC-Platform project. [1] N. Tsuji et al., Appl. Sci. 11, 3851 (2021) Figure Caption: Fig.1: Cross-sectional images of GDL materials and liquid water. Figure 1
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Dissertations / Theses on the topic "PEFCs"

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Daniels, Simone Monique. "Water management strategies for polymer electrolyte fuel cells (PEFCs) employing microchannel flowfields." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/20033.

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Polymer electrolyte fuel cells (PEFCs) represent a promising energy conversion technology for automotive and portable applications. In order to achieve the high power densities required for these applications, the fuel cell needs to be operated in the high current density region where the rate of water production is at a maximum. This typically leads to the build-up of liquid water in the porous media and flowfield compartments of the fuel cell. The build-up of liquid water inhibits reactant gas transport to the catalyst layer, leading to a phenomenon called flooding. Flooding causes a rapid drop in cell voltage and is detrimental to fuel cell performance and durability. Microchannel flowfield designs possess characteristics which could potentially improve water removal from the fuel cell and also reduce the fuel cell system complexity. There is limited knowledge on the use of microchannels flow field designs in PEFCs, specifically how different operating conditions and different membrane electrode assembly (MEA) designs affect the overall performance and water management of a fuel cell using microchannel flow fields. This study investigated two water management strategies for PEFCs employing microchannel flowfields, namely manipulation of operating conditions and modification to the design of components within the MEA. Four different gas diffusion layer (GDL) cases were tested in a single cell environment at four different cathode flowrates and stoichiometric ratios. The cases consisted of a carbon GDL and three variants of a uniform structured metal GDL. The three metal GDL designs varied in terms of the wettability of the microporous layer coated on the surface of the metal GDL. Several in-situ diagnostic tests, namely polarisation curves, electrochemical impedance spectroscopy (EIS), pressure drop and voltage stability tests were conducted to determine the overall fuel cell performance and water management characteristics of the different GDL cases.
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Chen, Cheng. "Membrane degradation studies in PEMFCs." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29712.

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Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2010.
Committee Chair: Fuller, Thomas; Committee Member: Beckham, Haskell; Committee Member: Hess, Dennis; Committee Member: Koros, William; Committee Member: Meredith, Carson. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Hanna, Maha. "Étude physico-chimique de liquides ioniques pour PEMFCs." Phd thesis, Grenoble INPG, 2008. http://www.theses.fr/2008INPG0164.

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Les liquides ioniques pourront remplacer l'eau dans les électrolytes des PEMFCs opérant à 130°C. Les liquides ioniques résultant de la neutralisation des amines aliphatiques par l'acide trifluoromethanesulfonique montrent que les points de fusion dépendent de plusieurs critères, nature de l'anion, nature des substitutions sur l'amine. D'autre part, la majorité de ces sels sont thermiquement stables jusqu'à 400°C. L'étude par la voltamétrie cyclique a prouvé que les amines et les sels (HNR3+, A) s'oxydent à des potentiels très élevés (> 1,9 V/ESH), compatible avec leur utilisation dans les piles à combustible. D'autre part, les meilleures conductivités sont obtenues par les sels résultant de l'association acide trifluoromethanesulfonique et amines dissymétriques. Les conductivités à 130°C sont entre 5 mS. Cm-1 et 45 mS. Cm-1. L'incorporation de ces composés dans le Nafion a donné une bonne compatibilité LIP/Nafion. Cependant, l'effet plastifiant du LIP sur le polymère diminue les propriétés mécaniques du Nafion. Les conductivités sont aussi nettement réduites d'un facteur de 5 dans les meilleurs cas
Ionic liquids can replace water in the electrolytes of PEMFCs systems operating at 130°C. Ionic liquids resulting from the neutralization of aliphatic amines by trifluoromethanesulfonic acid show that the melting point depends on several criteria, nature of the anion, nature of the substitutions on the amine. Moreover, the majority of these salts are thermally stable upto 400°C. The study by cyclic voltammetry showed that the amines and the salts (HNR3+, A-) are stable towards very oxidative step (i. E. > 1. 9 V/HSE), compatible for their use in fuel cell. In the other hand, the best conductivity behaviour is observed for salts resulting from dissymmetric amines/ trifluoromethanesulfonic acid association. The conductivities at 130°C lie between 5 mS. Cm-1 and 45 mS. Cm-1. The incorporation of these compounds within Nafion shows good compatibility PIL/ Nafion. However, the plastizing effect of PIL in the polymer reduces the Nafion mechanical properties. The conductivities are also dramatically reduced by a factor of 5 in the best cases
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Jalilian, E. "Characterization of progenitors of endothelial cells (PECs)." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1560479/.

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There are a number of different stem cell sources that have the potential to be used as therapeutics in vascular degenerative diseases such as diabetic retinopathy. On the one hand, there are so called endothelial progenitor cells (EPCs), which are typically derived from adult blood. They carry the marker CD34, but the true nature and definition of EPCs is still controversial. On the other hand, there are embryonic precursors of endothelial cells (PECs), which also express CD34, and which can be differentiated from embryonic stem cells (ESCs) or induced pluripotent stem cells (iPSCs) in vitro. Furthermore, a subpopulation of human umbilical cord endothelial cells (HUVECs) has also been shown to express CD34. In this study, It was aimed to compare these three different CD34 positive cell populations by full genome transcriptional profiling (RNAseq). To this end I firstly optimised a PEC differentiation protocol and found that VEGF is critical for the transition from mesodermal precursors to PECs. Secondly, I found signalling pathways that regulate CD34 expression in HUVECs and showed a close correlation between CD34 expression and the endothelial tip/stalk cell phenotypes. Thirdly, principal component analysis (PCA) of RNAseq data showed that blood-derived EPCs are fundamentally different from iPS-derived PECs. Lastly, I also identified from RNAseq data number of potentially novel PEC markers. Once validated such novel markers of PECs and EPCs will be useful to better define these cell populations, facilitating the translation of regenerative approaches in this field as well as providing potentially novel diagnostic tools.
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Praillet, Thierry. "Caractérisation fonctionnelle du locus pecS d'Erwinia chrysanthemi." Lyon, INSA, 1997. http://www.theses.fr/1997ISAL0039.

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La macération des tissus végétaux provoquée par la bactérie phytopathogène Erwinia chrysanthemi est liée à la sécrétion par cette bactérie de nombreuses enzymes lytiques de la paroi végétale. La régulation de l'expression de ces enzymes fait intervenir différents loci génétiques. Parmi ceux-ci, le locus pecS contrôle à la fois la synthèse et la sécrétion des pectinases et des cellulases. Ce dernier est constitué de deux gènes pecS' et pecM transcrits de façon divergente, dont les produits sont tous deux impliqués dans la même voie de régulation. La caractérisation biochimique et fonctionnelle du régulateur PecS a fait l'objet de notre travail. Le régulateur PecS se caractérise par une masse moléculaire monomérique de 18 kDa, un point isoélectrique proche de la neutralité (pl= 6. 5) et semble actif sous forme dimérique. La comparaison de la séquence de la protéine PecS avec celles des banques de données révèle que PecS présente une homologie significative avec les protéines de la famille MarR, impliquées dans la régulation transcriptionnelle de l'expression de gènes de résistance ù des produits toxiques. Malgré l'absence d'un site classique d'interaction avec l'ADN, la protéine PecS interagit spécifiquement avec les régions régulatrices des gènes dont elle module l'expression in vivo. Malgré cette interaction spécifique entre la protéine PecS et l'ADN, aucune séquence consensus fixant la protéine PecS n'a pu être déterminée. La protéine PecS régule l'expression de son propre gène, ainsi que celle du gène pecM adjacent. Parallèlement, nous avons montré que la protéine PecM est nécessaire à la pleine activité régulatrice de PecS. Les analyses physiologiques antérieures permettent de supposer l'intervention du couple PecS/PecM dans la réception d'un signal émis au cours des réactions de défense de la plante peut être envisagée. Ainsi. Le couple PecS/PecM pourrait constituer un système régulateur de l'expression des facteurs de virulence d' E. Chrysanthemi au cours de l'infection en réponse à un signal non encore déterminé
The phytopathogenic bacterium Erwinia chrysanthemi is responsible for soft-rot diseases of many plants. This soft-rotting activity is mainly due to the ability of the bacterium to secrete large amounts of depolymerizing enzymes (pectinases, cellulases) attacking the middle lamella of the plant tissues. The regulation of these enzymes is subjected to a complex regulatory network. In this network, the PecS protein down-regulates the synthesis of cellulases and pectinases. In this thesis, we present the biochemical and functional characterization of the PecS repressor. After overproduction and purification of the PecS protein, biochemical analysis reveals that this protein is characterized by a molecular mass of 18 kDa, an isoelectric point next to 6. 5 and probably acts in the cell as a dimer. Computer assisted proteinic sequence comparison reveals that PecS is homologous to the MarR family of transcriptional regulator. This family of transcriptional regulators docs not present any classical DNA-binding domain in the primary sequence. Functionally, the PecS protein interacts specifically with the regulatory regions of the in vivo controlled genes. Meanwhile, no consensus for the PecS binding site was detected. The PecS protein downregulates the expression of its O\VD gene as these of the adjacent pecM gene. Reciprocally, the PecM protein is needed for the full regulatory activity of PecS. Preliminary physiological studies suggest that the PecS/PecM couple could be involved in the reception of a signal liberated by the plant defense reactions. So, these two regulators could constitute a regulatory system of virulence factor synthesis during plant infection
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Karlsson, Alexandra. "Attityder till certifieringssystemen FSC och PEFC i skogsbranschen." Thesis, Linnéuniversitetet, Institutionen för biologi och miljö (BOM), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-38481.

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Different groups in the forestry sector were likely to have different views regarding the responsibility for an environmentally sustainable forestry and the benefits of certification and this study aimed to examine the attitudes that existed in the forestry sector to the certification schemes FSC and PEFC. In the study a survey and a questionnaire were sent out to different groups. The investigation was made with respect to three groups: forest owners, forest contractors and employees working with the certification schemes on a daily basis at the forest company Södra. The groups agreed that the owner of the forest had the main responsibility for an environmentally sustainable forestry. The study revealed that all three groups highly valued the environmental aspect of certification. Forest owners also identified financial gain as a benefit. The forest contractors felt that the certification gave orderliness to their work but also saw an economic cost from being certified. The forest company employees found certification as an access to a widermarket with certified products. Half of the forest owners estimated their knowledge of the certification schemes to be inadequate while forest contractors and the employees of Södra valued their knowledge as sufficient. The forest owners had less education about the certification schemes than the other groups.
Olika grupper i skogsbranschen riskerar att ha olika syn när det gäller ansvaret för ett miljömässigt hållbart skogsbruk och nyttan med certifiering och den här studien gjordes för att undersöka vilka inställningar som fanns i skogsbranschen till certifieringssystemen FSC och PEFC. Arbetet gjordes med avseende på tre grupper: skogsägare, skogsentreprenörer och anställda som arbetar på skogsföretaget Södra med certifiering i sitt dagliga arbete. I studien skickades en enkät och ett frågeformulär ut. Undersökningen visade att de tre grupperna värderade miljömässigt hållbart skogsbruk med certifiering högt. Som skogsägare fick man en certifieringspremie för det certifierade virke som man sålde. Skogsägarna såg också en ekonomisk vinning med certifiering. Skogsentreprenörerna ansåg att certifiering i högre grad gav ordning och reda i deras arbete men att det fanns en ekonomisk kostnad med att vara certifierad. Skogsföretagsgruppen menade att certifierade produkter gav tillgång till en större marknad för skogsföretaget. Grupperna var överens om att ansvaret för ett miljömässigt hållbart skogsbruk låg på de/den som ägde skogsmarken. Samtidigt uppskattade hälften av skogsägarna att deras kunskaper om certifieringarna var otillräckliga medan skogsentreprenörerna och skogsföretagsgruppen ansåg att deras kunskaper var tillräckliga. Detta kunde bero på att skogsägarna fick mindre utbildning av certifiering än de andra två grupperna. Det här arbetet har visat att grupperna inte har olika syn när det gäller vikten av att ett miljömässigt hållbart skogsbruk bedrivs.
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Tessier, Béatrice Claire. "Preparation, characterisation and evaluation of core-shell electrocatalyst for PEMFCs." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/142773/.

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For oxygen reduction catalysis it has been shown that thin layers of platinum (shell) over a non-Pt core enhance the activity. In addition surface science studies have found that overlayers of one metal on another strongly modifies the electrocatalytic properties of the surface metal. The aim of this project is to develop this concept by the preparation of practical fuel cell catalysts based on the core-shell model and gain a fundamental understanding of their properties and behaviour. A key aspect of the work is to establish the physical characteristics required for a catalyst to show long-term stability as well as improved activity. Chapter 1 introduces the PEM fuel cells, ORR electrocatalysts and the preparation and characterisation of core-shell type electrocatalysts. The experimental techniques, procedures and apparatus used for this work will be described in Chapter 2. The mechanism of the synthetic controlled-surface reaction (CSR) used to prepare the coreshell electrocatalysts was studied in Chapter 3. Then the focus will be on the palladiumcore and platinum-shell system in Chapter 4 and 5, where the effects of the Pt shell and the Pd core size on the electrocatalysts properties are investigated. The electrocatalysts prepared for these studies were assessed for their electrochemical stabilities and their ORR activities. Finally, Chapter 6 presents preliminary results on the iridium-core and platinumshell system. The deposition of Pt on Pd and Ir cores using the CSR did not lead to a complete Pt coverage as Pt tended to deposit preferentially at the edges and corners on the core surface and then on Pt. Whereas an enhancement in the electrochemical stability of the Pt/Pd coreshell electrocatalysts was observed compared to a pure Pt electrocatalyst, the Pt/Ir coreshell showed poorer stability than Pt. Benefits in the ORR activity were gained with both the Pt/Pd and Pt/Ir core-shell electrocatalysts. This demonstrates that, due to the original properties of the core-shell-structured electrocatalysts, it is possible to use less Pt and still obtain an improvement in the ORR activity.
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Мороз, Людмила Василівна, and Liudmyla Vasylivna Moroz. "Розвиток комунікації дітей із розладами аутичного спектру засобами PECS." ФОП Цьома С. П, 2019. http://repository.sspu.sumy.ua/handle/123456789/7549.

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Останніми роками у спеціальній освіті спостерігається значна активізація інтересу до проблеми аутизму. Це зумовлено постійним збільшенням виявлення означеного розладу серед дітей, науковими даними щодо природи та сутності даного порушення, а також накопиченням практичного досвіду корекційно-логопедичної роботи із означеною категорією дітей та створенням можливостей для їх прийнятного функціонування у суспільстві.
In recent years, special education has seen a significant increase in interest in autism. This is due to the constant increase in the detection of the specified disorder among children, scientific data on the nature and essence of the violation, as well as the accumulation of practical experience of corrective speech therapy with the specified category of children and creating opportunities for their acceptable functioning in society.
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Nero, Hanna. "Traktdirektiv enligt PEFC – effektiv kommunikation från skogsägare till skogsbolag." Thesis, Linnéuniversitetet, Institutionen för skog och träteknik (SOT), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-65330.

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Skogen innehåller höga värden i form av naturvärden och forn- och kulturlämningar. Dessa måste skyddas när skogen brukas för ekonomisk vinning och hur det ska ske framgår främst i arbetsbeskrivningen för varje objekt, kallat traktdirektiv. För att se var bristerna finns har inköpare/planerare samt maskinförare/entreprenörer intervjuats. En mall för utformandet av traktdirektiven skulle underlätta för alla och gynna de höga värdena i skogen.
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Alayyaf, Abdulmajeed A. "Synthesis of Two Monomers for Proton Exchange Membrane Fuel Cells (PEMFCs)." Digital Commons @ East Tennessee State University, 2016. https://dc.etsu.edu/etd/3015.

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The overall goal of this research is to synthesize two different monomers for proton exchange membrane (PEM) Fuel Cells. Such monomers are proposed to be polymerized to improve the efficiency and compatibility of electrodes and electrolytes in PEM fuel cells. The first target is to synthesize 4-diazonium-3-fluoro PFSI zwitterionic monomer. Three steps were carried out in the lab. First one was the ammonolysis of 3-fluoro-4-nitrobenzenesulfonyl chloride. Second reaction was the bromination of Nafion monomer. The next coupling reaction, between brominated Nafion monomer and the 3-fluoro-4-nitrobenzenesulfonamide, was failed. The obstacles involve the harsh reaction condition and troublesome purification procedure. The second target is to synthesize 5-nitro-1, 3-benzenedisulfonamide. According to the literature, this synthesis was also designed as three steps: 1)nitration of sodium 1, 3-benzenedisulfonate salt; 2)chlorination of sodium 5-nitro-1, 3-benzenedisulfonate salt; and 3)ammonolysis of 5- nitro-1, 3- benzenedisulfonyl chloride. This monomer is expected to be copolymerized for membrane electrolyte in PEM fuel cells.
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Books on the topic "PEFCs"

1

Sarolta, Sellei. Pécs. [Pécs]: Pécs m. Város Tanácsa V.B. Művelődési Osztálya, 1985.

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Sarolta, Sellei. Pécs. [Budapest]: Magyar Távirati Iroda, 1990.

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Zsolnay, Pécs. [Budapest]: Helikon, 1996.

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Gábor, Szirtes. A millenniumi Pécs. Pécs: Molnár, 1996.

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Weinzettl, Franz. Prag, Pécs, Budapest. Graz: Leykam, 1993.

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Ernő, Tillai. A festői Pécs. Pécs: Alexandra, 1999.

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Tamás, Nádor. Pécs zenei krónikája. Pécs: Pro Pannonia Kiadói Alapítvány, 1995.

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Hámori, Istvánné. Pécs-Somogy története. [Pécs]: Pécs-somogyi Kulturális és Környezetvédelmi Egyesület, 2006.

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Weinzettl, Franz. Prag, Pécs, Budapest. Graz: Leykam, 1993.

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Ferenc, Fülep. Sopianae-Pécs ókeresztény emlékei. Budapest: Képzőművészeti Kiadó, 1988.

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Book chapters on the topic "PEFCs"

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Hayashi, Akari, Masamichi Nishihara, Junko Matsuda, and Kazunari Sasaki. "Polymer Electrolyte Fuel Cells (PEFCs)." In Green Energy and Technology, 301–11. Tokyo: Springer Japan, 2016. http://dx.doi.org/10.1007/978-4-431-56042-5_22.

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Scherer, Günther G. "Polymer Electrolyte Fuel Cells (PEFCs), Introduction." In Encyclopedia of Applied Electrochemistry, 1655–61. New York, NY: Springer New York, 2014. http://dx.doi.org/10.1007/978-1-4419-6996-5_211.

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Miyatake, Kenji, and Masahiro Watanabe. "Polyimide Ionomer Membranes for PEFCs and DMFCs." In Membranes for Energy Conversion, 47–59. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2008. http://dx.doi.org/10.1002/9783527622146.ch2.

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Lufrano, F., E. Passalacqua, G. Squadrito, and A. Patti. "Advanced CO Tolerant Anodes for Polymer Electrolyte Fuel Cells (PEFCs)." In Hydrogen Power: Theoretical and Engineering Solutions, 591–96. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-015-9054-9_77.

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Toriyama, T., N. Kawahara, Y. Maeda, T. Suruga, H. Wakabayashi, and Y. Takagi. "XRD and Mössbauer studies on Pt–Fe nano-particles synthesized by polyol method for cathode catalyst of PEFCS." In ICAME 2007, 401–5. Berlin, Heidelberg: Springer Berlin Heidelberg, 2008. http://dx.doi.org/10.1007/978-3-540-78697-9_50.

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Urban, Christoph. "PECS." In Deformable Avatars, 206–16. Boston, MA: Springer US, 2001. http://dx.doi.org/10.1007/978-0-306-47002-8_18.

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Im, Seongil, Youn-Gyoung Chang, and Jae Kim. "Instrumentations for PECCS." In SpringerBriefs in Physics, 17–29. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6392-0_2.

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Leasure, Bruce, David J. Kuck, Sergei Gorlatch, Murray Cole, Gregory R. Watson, Alain Darte, David Padua, et al. "PERCS System Architecture." In Encyclopedia of Parallel Computing, 1506–15. Boston, MA: Springer US, 2011. http://dx.doi.org/10.1007/978-0-387-09766-4_410.

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Jörissen, Ludwig, Werner Lehnert, Juergen Garche, and W. Tillmetz. "Lifetime of PEMFCs." In THERMEC 2006, 1303–8. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-428-6.1303.

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Im, Seongil, Youn-Gyoung Chang, and Jae Kim. "PECCS Measurements in Organic FETs." In SpringerBriefs in Physics, 31–58. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6392-0_3.

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Conference papers on the topic "PEFCs"

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Fu, Richard S., and Ugur Pasaogullari. "An Internal Water Management Scheme for Portable Polymer Electrolyte Fuel Cells." In ASME 2006 4th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2006. http://dx.doi.org/10.1115/fuelcell2006-97070.

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Performance of polymer electrolyte fuel cells (PEFCs) is highly dependent on water content of the membrane and a humidification scheme becomes a necessity to operate PEFCs at a high efficiency. However, conventional humidification schemes require external humidifiers, which are usually bulky and impractical for portable PEFCs. In this paper we propose an innovative approach for humidification of the polymer electrolyte membrane, using an internally built-in mass (water) exchanger (MX) embedded in the bipolar plates. We present the validation of the concept using a multi-dimensional, isothermal computational fluid dynamics (CFD) solution of the water transport in the proposed MX. An optimal range of operation of the MX is investigated and effects on PEFC performance are studied.
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Friedrich, Kaspar Andreas, Norbert Wagner, and Mathias Schulze. "In-Situ Diagnostics of PEFCs." In ASME 2009 7th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2009. http://dx.doi.org/10.1115/icnmm2009-82186.

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Polymer electrolyte fuel cells (PEFCs) are one of the most interesting alternatives for a pollution-free electrical energy production in many applications where a highly reliable source of electricity is needed. One of the major challenges in the development of PEFCs is to exploit the whole capacity that is inherent to a given membrane electrode assembly (MEA). In practice, certain obstacles remain to be overcome like local mass transport effects, non-uniformly manufactured MEAs, locally varying contact resistances, water management and temperature gradients. All these parameters lead to an inhomogeneous electrochemical activity over the electrode area. Consequently, a variation and a gradient of the current density over the cell area occurs which tends to result in inferior performance and low durability of a PEFC. For the determination of current density distribution different in-situ methods and measurement techniques are applied. Results can be used to improve cell components, to validate models and to detect inappropriate detrimental operating conditions of the fuel cell.
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Yoshida, Hideki, Shinji Amaha, and Hisataka Yakabe. "Hybrid Systems Using Solid Oxide Fuel Cell and Polymer Electrolyte Fuel Cell." In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-66213.

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In this paper, the concept of an SOFC (Solid Oxide Fuel Cell) and PEFC (Polymer Electrolyte Fuel Cell) hybrid system is presented. Large-scale SOFC systems operated in a thermally self-sustainable state produce excess heat. The excess heat can be used for producing hydrogen. Several variations of hydrogen production systems are presented here. One way is to produce the hydrogen by using an extra reformer. Another way is purifying the off-fuel of SOFCs. The produced hydrogen can be used as the fuel for PEFCs. The overall electrical efficiency of a combination of an SOFC and PEFCs is higher than that of a standalone SOFC. When the hydrogen produced by purifying the off-fuel of the SOFC is used as the fuel for PEFCs, the overall electrical conversion efficiency increases by around 20%.
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Fu, Richard S., and Ugur Pasaogullari. "Validation of a Computational Polymer Electrolyte Fuel Cell Model." In ASME 2008 Heat Transfer Summer Conference collocated with the Fluids Engineering, Energy Sustainability, and 3rd Energy Nanotechnology Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/ht2008-56408.

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Computational models of polymer electrolyte fuel cells (PEFCs) of various degrees of complexities have been reported in the recent years and are capable of simulating detail transport phenomena within the PEFCs where experimental methods cannot. A thorough model validation is necessary for the model results to be used in analysis and design. Water transport in PEFCs has a strong effect on the performance regardless of the operating conditions. In low humidity cases, especially, the amount of water exchange from anode to cathode has a strong role in governing the water content in the anode side of the polymer electrolyte membrane (PEM), consequently on the ionic conductivity of the anode side of the membrane and catalyst layer. In this work, we present results on validation of the previously developed CFD based PEFC model for low humidity conditions using current density and species distribution data along the flow direction provided in the open literature. An excellent current density profile was obtained and species profiles were found to capture the data trend well, especially for the first half of the flow distance. Our findings suggest that, an accurate water transport modeling is paramount in capturing the overall PEFC behavior.
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Ogawa, Kuniyasu, Yasuo Yokouchi, Tomoyuki Haishi, and Kohei Ito. "Measurement of Current-Density in PEFC With NMR Sensors." In ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44370.

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In order to improve the power generation performance of polymer electrolyte fuel cells (PEFC), it is necessary to maintain high current density over the whole area of the membrane electrode assembly (MEA) that includes the additional Pt-carbon particles loaded on the Polymer Electrolyte Membrane (PEM) as an electrocatalyst layer. However, the current density generated at the MEA is distributed unevenly due to a lack of hydrogen, flooding, and so on. Therefore, achieving a higher current density in a PEFC requires monitoring the local current density. The local current density in a PEFC can be measured by the frequency shift of the NMR signal received from planar surface coils inserted into the PEFC as sensors. This method is based on the relationship that the spatial gradient of the frequency shifts in NMR signals along the MEA is proportional to the magnetic field strength induced by local current density. In this study, two kinds of MEA were used. One MEA was with the platinum catalyst applied to an area of 50 mm * 50 mm. The other MEA was with platinum catalyst over half this area. The distributions of the frequency shift of NMR signals in PEFCs using these two MEAs were measured. These measured distributions of the spatial gradients were in agreement with those obtained by the theoretical-analysis of magnetic fields in PEFC. The spatial distributions of current density generated in PEFCs were obtained from the spatial gradients and theoretical result.
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Hasmady, Saiful, Manuel Philipp Wacker, Kazuyoshi Fushinobu, and Ken Okazaki. "Treatment of Heterogeneous Electrocatalysis in Modeling Transport-Reaction Phenomena in PEFCs." In ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference collocated with the ASME 2007 InterPACK Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ht2007-32581.

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Thermal and water management is a critical issue in PEFCs. In this research, the thermal behavior of PEFC is focused. The objective is to understand the influence of heat on cell performance both by experiment and theoretical analysis, as well as improving cell performance and reliability. In order to investigate the theoretical behavior, especially in the catalyst layer where the electrochemical reactions occur, a detailed modeling of heterogeneous surface reaction coupled with reactant transport is needed. In this paper, a theoretical model that improves the dependency of the exchange current density with reactant concentrations by applying data from a known surface reaction steps found in catalysis is developed. It served as a preliminary step before the thermal-electrochemical behavior of a PEFC can be fully understood.
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Wang, Yun, and Xiaoguang Yang. "Transients of Polymer Electrolyte Fuel Cell and Hydrogen Tank." In ASME 2009 3rd International Conference on Energy Sustainability collocated with the Heat Transfer and InterPACK09 Conferences. ASMEDC, 2009. http://dx.doi.org/10.1115/es2009-90242.

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This paper seeks to develop 3D dynamic models for polymer electrolyte fuel cells (PEFCs) and hydrogen tanks, respectively. The dynamic model of PEFCs consists of multiple layers of a single PEFC and couples the various dynamic mechanisms in fuel cells, such as electrochemical double-layer discharging/charging, species transport, heat transfer, and membrane water uptake. The one of hydrogen tanks includes a 3D description of the hydride kinetics coupled with mass/heat transport in the hydrogen tank. Transient of fuel cell during step change in current is simulated. Dynamic responses of the cell voltage and heat generation rate are discussed. Hydrogen absorption process in the tank is considered. Temperature, reaction rate and heat rejection in the fuel tank are presented. Efforts are also made to discuss the coupling of these two systems in practice and associated issues.
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Wang, Yun, Xuhui Feng, Ralf Thiedmann, Volker Schmidt, and Werner Lehnert. "Micro-Scale Transport in the Diffusion Media of Polymer Electrolyte Fuel Cells." In ASME 2009 Second International Conference on Micro/Nanoscale Heat and Mass Transfer. ASMEDC, 2009. http://dx.doi.org/10.1115/mnhmt2009-18201.

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This paper reports our recent work on the stochastic-model-based reconstruction of the gas diffusion layer (GDL) of PEFCs and direct numerical simulation and presented the pore-level transport within GDLs of polymer electrolyte fuel cell (PEFC). The carbon-paper-based GDL is modeled as a stack of thin sections with each section described by planar 2D random line tessellations which are further dilated to three dimensions. The reconstruction of the GDL structure is based on given GDL data provided by scanning electron microscopy (SEM) images. Based on the stochastically constructed digital GDL, we further conduct the DNS of the coupled transport processes, including gas flow and species transport, electronic current conduction, and heat transfer. Results indicate remarkable distinction in tortuosities of gas diffusion passage and solid matrix. The numerical tool can be applied to investigate the GDL microstructure and internal pore-level transport in PEFCs.
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Burford, Daniel J., and Matthew M. Mench. "Heat Transport and Temperature Distribution in PEFCs." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-59497.

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For detailed understanding of water and thermal management and degradation mechanisms, knowledge of the internal temperature distribution in a polymer electrolyte fuel cell (PEFC) is critical. Internal electrolyte temperature measurements as a function of current density and cathode inlet humidity were obtained using a specialized, 50cm2 fuel cell with micro-thermocouples embedded in the thin-film electrolyte at various locations. A simplified model of heat transport in the fuel cell materials was used to estimate the thermal conductivity in the gas diffusion layer media and polymer electrolyte membrane. At the same current and location in the fuel cell, steady state electrolyte temperature generally decreased with increasing humidity, a result of decreased internal resistance and/or latent heat effects. The diffusion media used had an estimated thermal conductivity 0.13–0.19 W/mK. The polymer electrolyte used (Nafion®) was estimated to have a thermal conductivity of 0.025–0.25 W/mK. The thermal conductivity and thickness of the diffusion media limits heat transfer, and opportunity exists for tailoring temperature profile in the PEFC through the diffusion layers.
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Dong, Q., J. Kull, and M. M. Mench. "Real-Time Species Distribution Profiling in PEFCs." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-59499.

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Knowledge of the species, current, and high frequency resistance distributions within a polymer electrolyte fuel cell (PEFC) is critical to enable prediction of the local performance and accurately quantify various species transport parameters. In micro and portable fuel cell systems, precise knowledge of steady state and dynamic water transport is especially important. This paper examines the distributed prifile of water vapor and other gas phase species in a PEFC, using a novel real-time technique for in situ species distribution measurement within the reactant flow channels of an operating PEFC. This is accomplished with an Agilent Real-Time Gas Analyzer (RTGA) that enables continuous profiling of changing species mole fractions at many locations along the anode and cathode flow paths, and enables detailed understanding of the time scales of the various multi-phase dynamic transport phenomena. Additionally, the periodic presence of liquid water droplets in the cathode can be observed at high current density with this technique.
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Reports on the topic "PEFCs"

1

Yoshitake, M., N. Yoshida, and T. Ishisaki. Flemion {reg_sign}S and PEFC. Office of Scientific and Technical Information (OSTI), December 1996. http://dx.doi.org/10.2172/460280.

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Fujita, Jun-ichi, Jitsuji Ohtsuki, and Yoshihiko Shindo. Performance evaluation of PEFC stack. Office of Scientific and Technical Information (OSTI), December 1996. http://dx.doi.org/10.2172/460309.

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Maeda, Hideo, Hisatoshi Fuklumoto, and Kenro Mitsuda. Development of PEFC for transportable applications. Office of Scientific and Technical Information (OSTI), December 1996. http://dx.doi.org/10.2172/460218.

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Komaki, Hideaki, and Syozo Tsuchiyama. Performance evaluation of 1 kw PEFC. Office of Scientific and Technical Information (OSTI), December 1996. http://dx.doi.org/10.2172/460227.

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Hiraide, Masataka, Eiichi Kaneda, and Takao Sato. Dynamic simulator for PEFC propulsion plant. Office of Scientific and Technical Information (OSTI), December 1996. http://dx.doi.org/10.2172/460232.

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Bevers, D., E. Guelzow, A. Helmbold, and B. Mueller. Innovative production technique for PEFC electrodes. Office of Scientific and Technical Information (OSTI), December 1996. http://dx.doi.org/10.2172/460319.

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Mukerjee, Sanjeev, Plamen Atanassov, Barr Zulevi, Ryan Pavlicek, Serge Pann, Emory De Castro, and Ludwig Lipp. Innovative Non-PGM Catalysts for High-Temperature PEMFCs. Office of Scientific and Technical Information (OSTI), December 2017. http://dx.doi.org/10.2172/1511038.

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Kawatsu, Shigeyuki, Satoshi Aoyama, and Masayoshi Iwase. PEFC R&D technology at Toyota. Office of Scientific and Technical Information (OSTI), December 1996. http://dx.doi.org/10.2172/460215.

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Hansen, Dr Christian Kruse, Dr Mette Dam, Dr Troels Dirch Poulsen, Dr Per-Arne Lönnqvist, and Dr Thomas Fichtner Bendtsen. Ultrasound-guided parasternal Pecs block: a new and useful supplement to Pecs I and serratus anterior plane blocks. The Association of Anaesthetists of Great Britain and Ireland, February 2016. http://dx.doi.org/10.21466/ac.aaaiiap.2016.

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Helmes, Roel, Tommie Ponsioen, Hans Blonk, Marisa Vieira, Pietro Goglio, Rick van der Linden, Paulina Gual Rojas, Daniël Kan, and Irina Verweij-Novikova. Hortifootprint Category Rules : Towards a PEFCR for horticultural products. Wageningen: Wageningen Economic Research, 2020. http://dx.doi.org/10.18174/526452.

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