PEMFC Development at Asahi Glass Co., Ltd.

1999 ◽  
Vol 575 ◽  
Author(s):  
M. Yoshitake ◽  
E. Yanagisawa ◽  
T. Naganuma ◽  
Y. Kunisa
Keyword(s):  
Ion Exchange ◽  
Mechanical Strength ◽  
Water Content ◽  
Hydrogen Permeation ◽  
Specific Resistance ◽  
Gas Permeability ◽  
Cell Voltage ◽  
Free Cell ◽  
Gas Permeation ◽  
Membrane Thickness

ABSTRACTPerfluorinated ion exchange membranes were studied and the membrane technology for PEMFC has been developed. Thermal stability, mechanical strength, water content, AC specific resistance and gas permeability were measured. The influence of membrane thickness on gas permeability and the influence of incorporation of cations on water content and AC specific resistance of Flemion® and Nafion® 117 were estimated. Gas permeation rates of the membranes decreased in inverse proportion to the increase of the membrane thickness and gas permeability coefficients were nearly constant and independent of the thickness. Hydrogen permeation rates of Flemion®S at 70°C were converted to 2.1 mA/cm2 as cunent density. Flemion®R-electrode assembly showed to maintain stable perfonnance for over 3,500hr. Furthermore, it was found that usage of thinner membranes or one with higher ion-exchange capacity gave not only lower intemal cell voltage but also higher iR-free cell voltage. PTFE-yam embedded type membrane (Flemion®Mc and Sc) and PTFE-flbril dispersed type (Flemion®R12) was examined to afford improvement in mechanical strength at moist and high temperature atmosphere. Flemion®Sc (80!am) was examined to give high cell performance of 0.67V at 0.5A/cm2, 80°C, I ata. Flemior®Mc-electrode assembly was examined to keep stable performance during the life test of over 1,500hr.

Evaluation of Gas Permeability in Microfluidic Device by Confocal Micro-PIV Combined With LIF Technique

2011 ◽  
Author(s):  
Mitsuhisa Ichiyanagi ◽  
Keita Sakai ◽  
Shinya Kidani ◽  
Yasuhiro Kakinuma ◽  
Yohei Sato ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Area ◽  
Liquid Flow ◽  
Gas Permeability ◽  
Gas Permeation ◽  
Membrane Thickness ◽  
Micro Machining ◽  
Dissolved Gas ◽  
Gas Concentration ◽  
Elastomeric Material

Microfluidic devices with the gas permeability through polymer membranes were developed for further high-efficiency of gas-liquid chemical reactions and high-accuracy of environmental diagnosis. The devices were composed of a cover glass and a polydimethylsiloxane (PDMS) chip which has the ability to permeate various gases, because PDMS is made of the elastomeric material. In the chip, microchannels with a width ranging from a few micrometers to a few hundred micrometers were manufactured by using the cryogenic micro machining. The gas permeation phenomena in microchannels are dominated by several factors, such as the gas and liquid flow rates, the membrane thickness between gas and liquid flow, and the surface area of membranes. The advantage of the present work is to realize the simple control of the gas permeability by changing the surface roughness of PDMS, because the cryogenic micro machining enables to control the surface roughness of microchannels and the increase in its roughness yields that in the surface area of membranes. For the evaluation of the gas permeability, the velocity and dissolved gas concentration distribution in the liquid flow field were measured by utilizing micron-resolution particle image velocimetry combined with laser induced fluorescence, and the measurement system was based on the confocal microscope to improve the depth resolution drastically. The experiments were performed under the several conditions with a change in the gas flow rate, the PDMS membrane thickness and the surface roughness, which affect the gas permeation phenomena. The results indicate that the velocity-vector distributions in the liquid flow have a similar pattern and the magnitudes of the velocity are approximately the same values under all conditions, while the dissolved gas concentration distributions have different patterns. It was quantitatively clear that the gas permeability through PDMS membranes was increased with an increase in the surface roughness and has the linearity to the surface area of membranes. The important conclusion is that the proposed device achieves to control the gas permeability by using the elastomeric material and changing the surface roughness.

Preparation and Characterization of AgA Zeolite/Polysulfone Membranes

2012 ◽  
Vol 549 ◽  
pp. 401-405
Author(s):  
Tian Ming Zhang ◽  
Zhen Huang ◽  
Xiao Hong Zhang ◽  
Li Ying Guo
Keyword(s):  
Ion Exchange ◽  
Gas Permeability ◽  
Composite Membranes ◽  
Gas Permeation ◽  
Silver Ion ◽  
Interfacial Interactions ◽  
Polysulfone Membrane ◽  
Characterization Methods ◽  
Permeation Test

In present study, a few polysulfone composite membranes with the introduction of silver ion-exchange treated zeolite were prepared and evaluated by several characterization methods. Regularly-ordered zeolite particles were generally finely dispersed in the continuous PSF phase with appreciated organic-inorganic interfacial interactions as reflected by SEM and FTIR results. Gas permeation test shows that after incorporating zeolite the polysulfone membrane exhibits significantly decreased gas permeability for H2, N2, and CO2 whereas they show increased permselectivity for CO2/N2, H2/CO2 and H2/N2 gas pairs as compared to neat polysulfone membrane.

scholarly journals The Influence of Concentration and Temperature on the Membrane Resistance of Ion Exchange Membranes and the Levelised Cost of Hydrogen from Reverse Electrodialysis with Ammonium Bicarbonate

Membranes ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 135
Author(s):  
Yash Dharmendra Raka ◽  
Robert Bock ◽  
Håvard Karoliussen ◽  
Øivind Wilhelmsen ◽  
Odne Stokke Burheim
Keyword(s):  
Ion Exchange ◽  
Waste Heat ◽  
Ammonium Bicarbonate ◽  
Operating Efficiency ◽  
Membrane Thickness ◽  
Ion Exchange Membranes ◽  
Reverse Electrodialysis ◽  
Ohmic Resistance ◽  
Production Of Hydrogen ◽  
The Impact

The ohmic resistances of the anion and cation ion-exchange membranes (IEMs) that constitute a reverse electrodialysis system (RED) are of crucial importance for its performance. In this work, we study the influence of concentration (0.1 M, 0.5 M, 1 M and 2 M) of ammonium bicarbonate solutions on the ohmic resistances of ten commercial IEMs. We also studied the ohmic resistance at elevated temperature 313 K. Measurements have been performed with a direct two-electrode electrochemical impedance spectroscopy (EIS) method. As the ohmic resistance of the IEMs depends linearly on the membrane thickness, we measured the impedance for three different layered thicknesses, and the results were normalised. To gauge the role of the membrane resistances in the use of RED for production of hydrogen by use of waste heat, we used a thermodynamic and an economic model to study the impact of the ohmic resistance of the IEMs on hydrogen production rate, waste heat required, thermochemical conversion efficiency and the levelised cost of hydrogen. The highest performance was achieved with a stack made of FAS30 and CSO Type IEMs, producing hydrogen at 8.48× 10−7 kg mmem−2s−1 with a waste heat requirement of 344 kWh kg−1 hydrogen. This yielded an operating efficiency of 9.7% and a levelised cost of 7.80 € kgH2−1.

Transient Water Transport in Nafion Membranes Under Activity Gradients

2010 ◽  
Author(s):  
T. Romero ◽  
W. Me´rida
Keyword(s):  
Water Content ◽  
Water Transport ◽  
Water Activity ◽  
Thickness Variation ◽  
Membrane Thickness ◽  
Membrane Interface ◽  
Rational Representation ◽  
Transport Measurements ◽  
Nafion Membranes ◽  
The Time Domain

Transient water transport experiments on Nafion of different thicknesses were carried out in the temperature range of 30 to 70 °C. These experiments report on water transport measurements under activity gradients in the time domain for liquid and vapour equilibrated Nafion membranes. Using a permeability test rig with a gated valve, the water crossover was measured as a function of time. The typical response is shown as a time dependent flux, and it shows the dynamic transport from an initially dry condition up to the final steady state. Contrarily to previous reports from dynamic water transport measurements, where the activity gradient across the membrane is absent; in this work, the membrane was subjected to an activity gradient acting as the driving force to transport water from an environment with higher water activity to an environment with lower water activity through the membrane’s structure. Measurements explored temperature and membrane thickness variation effect on the transient response. Results showed dependency on temperature and a slower water transport rate across the vapour-membrane interface than for the liquid-membrane interface. These measurements showed the transport dependency on water content at the beginning of the experiment when the membrane was in a close-to-dry condition suggesting a transport phenomenon transition due to a reached critical water content value. The new protocol for transient measurements proposed here will allow the characterization of water transport dependency on membrane water content with a more rational representation of the membrane-environment interface.

Capillary suction time (CST) as a measure of sludge dewaterability

1996 ◽  
Vol 34 (3-4) ◽  
pp. 443-448 ◽  
Author(s):  
G. W. Chen ◽  
W. W. Lin ◽  
D. J. Lee
Keyword(s):  
Water Content ◽  
Specific Resistance ◽  
Bound Water ◽  
The Other ◽  
Solid Concentration ◽  
Capillary Suction ◽  
Good Index ◽  
Other Hand ◽  
Sludge Dewaterability ◽  
Bound Water Content

The feasibility of employment of capillary suction time (CST) for characterizing the dewaterability of excess activated sludges was examined. The CST was shown as a good index for sludge filterability, if only the product of solid concentration and average specific resistance is of interest. On the other hand, the bound water content cannot be directly evaluated from the CST data.

scholarly journals Fabrication of Porous Al2O3 Ceramics with Submicron-Sized Pores Using a Water-Based Gelcasting Method

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1784 ◽  
Author(s):  
Zhihong Yang ◽  
Nan Chen ◽  
Xiaomei Qin
Keyword(s):  
Mechanical Strength ◽  
Water Content ◽  
Sintering Temperature ◽  
Al2o3 Content ◽  
Volume Fractions ◽  
Pore Sizes ◽  
Water Based ◽  
Low Levels ◽  
Median Pore

The gelcasting method is usually employed to fabricate relatively dense ceramics. In this work, however, porous Al2O3 ceramics with submicron-sized pores were fabricated using the water-based gelcasting method by keeping the Al2O3 content at low levels. By controlling the water content in the ceramic slurries and the sintering temperature of the green samples, the volume fractions and the size characteristics of the pores in the porous Al2O3 can be readily obtained. For the porous Al2O3 ceramics prepared with 30 vol.% Al2O3 content in the slurries, their open porosities were from 38.3% to 47.2%, while their median pore sizes varied from 299.8 nm to 371.9 nm. When there was more Al2O3 content in the slurries (40 vol.% Al2O3), the porous Al2O3 ceramics had open porosities from 37.0% to 46.5%, and median pore sizes from 355.4 nm to 363.1 nm. It was found that a higher sintering temperature and Al2O3 content in the slurries increased the mechanical strength of the porous Al2O3 ceramics.

scholarly journals Gas Permeation Through Single-Crystal ZIF-8 Membranes

2019 ◽  
Author(s):  
Chen Chen ◽  
Aydin Ozcan ◽  
A. Ozgur Yazaydin ◽  
Bradley Ladewig
Keyword(s):  
Single Crystal ◽  
Grain Boundaries ◽  
Gas Permeability ◽  
Metal Organic Framework ◽  
Gas Permeation ◽  
Microstructural Feature ◽  
Polycrystalline Metal ◽  
Transmission Electron ◽  
Metal Organic ◽  
Separation Performances

<b>Abstract</b><div>Grain boundaries are an unavoidable microstructural feature in intergrown polycrystalline metal-organic framework (MOF) membranes. They have been suspected to be less size-selective than a MOF’s micropores, resulting in suboptimal separation performances – a speculation recently confirmed by transmission electron microscopy of MOF ZIF-8. Single-crystal membranes, without grain boundaries, should confine mass transport to micropores and reflect the intrinsic selectivity of the porous material. Here, we demonstrate the feasibility of fabricating single-crystal MOF membranes and directly measuring gas permeability through such a membrane using ZIF-8 as an exemplary MOF. Our single-crystal ZIF-8 membranes achieved ideal selectivities up to 28.9, 10.0, 40.1 and 3.6 for gas pairs CO<sub>2</sub>/N<sub>2</sub>, CO<sub>2</sub>/CH<sub>4</sub>, He/CH<sub>4</sub> and CH<sub>4</sub>/N<sub>2</sub> respectively, much higher than or reversely selective to over 20 polycrystalline ZIF-8 membranes, unequivocally proving the non-selectivity of grain boundaries. The permeability trend obtained in single-crystal membranes aligned with a force field that had been validated against multiple empirical adsorption isotherms.<br></div>

scholarly journals Porous Medium Equation in Graphene Oxide Membrane: Nonlinear Dependence of Permeability on Pressure Gradient Explained

Membranes ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 665
Author(s):  
Lukáš Mrazík ◽  
Pavel Kříž
Keyword(s):  
Porous Medium ◽  
Graphene Oxide ◽  
Governing Equation ◽  
Pressure Difference ◽  
Gas Permeability ◽  
Porous Medium Equation ◽  
Gas Permeation ◽  
Nonlinear Dependence ◽  
Medium Equation ◽  
Oxide Membrane

Membrane performance in gas separation is quantified by its selectivity, determined as a ratio of measured gas permeabilities of given gases at fixed pressure difference. In this manuscript a nonlinear dependence of gas permeability on pressure difference observed in the measurements of gas permeability of graphene oxide membrane on a manometric integral permeameter is reported. We show that after reasoned assumptions and simplifications in the mathematical description of the experiment, only static properties of any proposed governing equation can be studied, in order to analyze the permeation rate for different pressure differences. Porous Medium Equation is proposed as a suitable governing equation for the gas permeation, as it manages to predict a nonlinear behavior which is consistent with the measured data. A coefficient responsible for the nonlinearity, the polytropic exponent, is determined to be gas-specific—implications on selectivity are discussed, alongside possible hints to a deeper physical interpretation of its actual value.

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