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Saint-Martin-Vésubie, France

Soupremanien U.,LEGI | Person S.L.,LEGI | Favre-Marinet M.,LEGI | Bultel Y.,LEPMI
Experimental Thermal and Fluid Science | Year: 2011

This article presents experiments conducted with two single rectangular mini-channels of same hydraulic diameter (1.4mm) and different aspect ratios for conditions of horizontal boiling flow. The Forane® 365 HX used was subcooled (ΔTsub=15°C) for all the boiling curves presented in the paper. Local heat transfer coefficients were measured for heat flux ranging from 25 to 62kWm-2 and mass flux from 200kgm-2s-1 to 400kgm-2s-1. The boiling flows were observed with two different cameras (depending on the flow velocity) through a visualization window. The flow patterns in the two channels were compared for similar conditions. The results show that the boiling heat transfer coefficient and the pressure drop values are different for the two single mini-channels. For low heat flux condition, the channel with lowest aspect ratio (H/W=0.143) has a higher heat transfer coefficient. On the other hand, for high heat flux condition, the opposite situation occurs, namely the heat transfer coefficient becomes higher for the channel with highest aspect ratio (H/W=0.43). This is probably due to the earlier onset of dryout in the channel with lowest aspect ratio. For the two cases of heating, the pressure drop for the two-phase flow remains lower for the channel with lowest aspect ratio. These results show that the aspect ratio plays a substantial role for boiling flows in rectangular channels. As for single-phase flows, the heat transfer characteristics are significantly influenced (even though the hydraulic diameter remains the same) by this parameter. © 2010 Elsevier Inc.

Vivet A.,Limoges National Superior School of Industrial Ceramics | Vivet A.,Air Liquide | Geffroy P.M.,Limoges National Superior School of Industrial Ceramics | Coudert V.,Limoges National Superior School of Industrial Ceramics | And 3 more authors.
Journal of Membrane Science | Year: 2011

Gas dissociation with a ceramic membrane is an economical and environmental attractive process for methane gas conversion into syngas (mixture of H2 and CO). For this application, the membrane materials require mixed ionic and electronic conductivities in a large range of pO2 resulting in an excellent oxygen semi-permeation of the membrane to improve methane conversion. In this paper, particular attention is given to the influence of sealant materials on oxygen semi-permeation performances of membrane materials. For instance, oxygen semi-permeation measurements have been performed with La0.8Sr0.2Fe0.7Ga0.3O3-δ membranes under an oxygen partial pressure gradient at temperatures from 700°C to 1000°C with different sealing materials (glass or gold ring sealant) between the membrane and the support. The result leads to a better understanding of the effects of sealing on oxygen transport through the La0.8Sr0.2Fe0.7Ga0.3O3-δ membrane. Indeed, a gold sealing material is required for accurate measurements of oxygen semi-permeation flux. © 2010 Elsevier B.V.

Assumma L.,University of GrenobleF 38000Grenoble France | Iojoiu C.,University of GrenobleF 38000Grenoble France | Mercier R.,University of Lyon | Lyonnard S.,CNRS Structure and Properties of Molecular Architectures Laboratory | And 2 more authors.
Journal of Polymer Science, Part A: Polymer Chemistry | Year: 2015

Partially fluorinated poly(arylene ether sulfone) multiblock copolymers bearing perfluorosulfonic functions (ps-PES-FPES), with ionic exchange capacity (IEC) ranging between 0.9 and 1.5 meq H+/g, are synthesized by regioselective bromination of partially fluorinated poly(arylene ether sulfone) multiblock copolymers (PES-FPES), followed by Ullman coupling reaction with lithium 1,1,2,2-tetrafluoro-2-(1,1,2,2-tetrafluoro-2-iodoethoxy)ethanesulfonate. The PES-FPES are prepared by aromatic nucleophilic substitution reaction by an original approach, that is, "one pot two reactions synthesis." The chemical structures of polymers are analyzed by 1H and 19F NMR spectroscopy. The resulted ionomers present two distinct glass transitions and α relaxations revealing phase separation between the hydrophilic and the hydrophobic domains. The phase separation is observed at much lower block lengths of ps-PES-FPES as compared with the literature. AFM and SANS observations supported the phase separation, the hydrophilic domains are well dispersed but the connectivity to each other depends on the ps-PES block lengths. The thermomechanical behavior, the water up-take, and the conductivity of the ps-PES-FPES membranes are compared with those of Nafion 117® and randomly functionalized polysulfone (ps-PES). Conductivities close or higher to those of Nafion 117® are obtained. © 2015 Wiley Periodicals, Inc.

El Baradai O.,Electronic and microelectronic center | Beneventi D.,Greek National Center For Scientific Research | Alloin F.,French National Center for Scientific Research | Bultel Y.,LEPMI | And 2 more authors.
International Journal of Engineering and Technology Innovation | Year: 2015

Organic free electrodes for lithium ion batteries containing cellulose derivatives components as binding and disperser respectively, lithium iron phosphate as active material and carbon black as conductive agent were manufactured by means of a large scale technique as well as screen printing process onto a cellulosic based separator. Firstly a water based ink, was formulated and rheological properties were analyzed in order to investigate the role of each component in the ink. Electrical conductivity was tuned by adjusting the content of carbon black to insure electrical percolation. The electrode exhibits a capacity of 143 mAh/g at C/10, close to the nominal capacity of the lithium iron phosphate (150 mAh/g). At higher current rates a good retention capacity was observed with 107 mAh/g at C. Finally industrial scale printed electrodes were manufactured by means of an industrial printing machine onto a cellulose based separator. The electrodes exhibit a promising capacity of 129 mAh/g at C/10 and an electrical conductivity of 21 S/m. The industrial scale approach proposed here could be a viable route to the manufacturing of large scale and eco-sustainable electrodes. © 2015.

Leveque J.-M.,University of Savoy | Leveque J.-M.,Shiga University of Medical Science | Fujita M.,Shiga University of Medical Science | Bosson A.,University of Savoy | And 4 more authors.
Ultrasonics Sonochemistry | Year: 2011

The Molybdate-catalyzed bromination of various aromatic compounds in the presence of KBr/H2O2 in an aqueous/chloroform biphasic system occurred under ultrasonic irradiation, whereas the reaction did not take place under conventional mechanical stirring (1400 rpm). The sonochemical activation was found to be of secondary effect, attributed to lowering pH by sonolysis of CHCl3-H2O solvents mixture. © 2010 Elsevier B.V.

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