• Title/Summary/Keyword: membrane performances

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Recent Advances in Polybenzimidazole (PBI)-based Polymer Electrolyte Membranes for High Temperature Fuel Cell Applications

  • Vijayakumar, Vijayalekshmi;Kim, Kihyun;Nam, Sang Yong
    • Applied Chemistry for Engineering
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    • v.30 no.6
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    • pp.643-651
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    • 2019
  • Polybenzimidazole (PBI), an engineering polymer with well-known excellent thermal, chemical and mechanical stabilities has been recognized as an alternative to high temperature polymer electrolyte membranes (HT-PEMs). This review focuses on recent advances made on the development of PBI-based HT-PEMs for fuel cell applications. PBI-based membranes discussed were prepared by various strategies such as structural modification, cross-linking, blending and organic-inorganic composites. In addition, intriguing properties of the PBI-based membranes as well as their fuel cell performances were highligted.

Effect of High-Temperature Spinning and PVP Additive on the Properties of PVDF Hollow Fiber Membranes for Microfiltration

  • Cha, Bong-Jun;Yang, Jung-Mok
    • Macromolecular Research
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    • v.14 no.6
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    • pp.596-602
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    • 2006
  • The effect of high-temperature spinning and poly(vinyl pyrrolidone) (PVP) additive on poly(vinylidene fluoride) (PVDF) hollow fiber membranes was investigated using differential scanning calorimetry, X-ray diffraction measurement, and scanning electron microscopy, together with the corresponding microfiltration performances such as water flux, rejection rate, and elongational strength. Using high-temperature spinning, porous hollow fiber membranes with particulate morphology were prepared through PVDF crystallization. The particulate structure of the membranes was further modified by the addition of miscible PVP with PVDF. Due to these effects, the rejection rate and strength of the fibers were increased at the expense of reduced water flux and mean pore size, which indicates that high-temperature spinning and PVP addition are vary effective to control the morphology of PVDF hollow fiber membranes for microfiltration.

Nonlinear Analysis of Shell Structures by Improved Degenerated Shell Element (개선된 degenerated 쉘요소를 사용한 쉘구조의 비선형해석)

  • 최창근;유승운
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1990.04a
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    • pp.18-23
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    • 1990
  • The paper is concerned with the elasto-plastic and geometrically nonlinear analysis of shell structures using an improved degenerated shell element. In the formulation of the improved degenerated shell element, an enhanced interpolation of transverse shear strains in the natural coordinate system is used to overcome the shear locking problems; the reduced integration technique in in-plane strains is applied to avoid membrane locking behavior; selective addition the nonconforming displacement modes improve the element performances. This element is free of serious locking problems and undesirable compatible or commutable spurious kinematic deformation modes and passes the patch tests. An incremental total Lagrangian formulation is presented which allows the calculation of arbitrarily large displacements and rotations. The resulting nonlinear equations are solved by the Newton-Raphson solution scheme. The versatility and accuracy of this improved degenerated shell element are demonstrated by solving several numerical examples.

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Enhancement of Catalytic Activity of Pt/Alumina by a Novel Pretreatment Method for the CO Oxidation for Fuel Cell Applications (연료전지용 CO의 산화를 위한 백금/알루미나 촉매의 성능향상에 관한 연구)

  • Jo, Myung-Chan
    • Journal of Environmental Science International
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    • v.17 no.12
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    • pp.1307-1314
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    • 2008
  • Hydrogen gas is used as a fuel for the proton exchange membrane fuel cell (PEMFC). Trace amount of carbon monoxide present in the reformate $H_2$ gas can poison the anode of the PEMFC. Therefore, preferential oxidation (PROX) of CO is essential for reducing the concentration of CO from a hydrogen-rich reformate gas. In this study, conventional Pt/$Al_2O_3$ catalyst was prepared for the preferential oxidation of CO. The effects of catalyst preparation method, additive, and hydrogen on the performances of PROX reaction of CO were investigated. Water treatment and addition of Ce enhanced catalytic activity of the Pt/$Al_2O_3$ catalyst at low temperature below $100^{\circ}C$.

Development of Porous Metal Materials and Applications

  • Fang, Y.;Wang, H.;Zhou, Y.;Kuang, C.
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.599-600
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    • 2006
  • This paper described the state of art of porous metal materials, the typical manufacturing technologies and performances of sintered metal porous materials, with emphasis on the recent research achievements of CISRI in development of porous metal materials. High performance porous metal materials, such as metallic membrane, sub-micron asymmetric composite porous metal, large dimensional and structure complicated porous metal aeration cones and tube, metallic catalytic filter elements, lotus-type porous materials, etc, have been developed. Their applications in energy industry, petrochemical industry, clean coal process and other industrial fields were introduced and discussed.

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Modeling of a PEM Fuel Cell Stack using Partial Least Squares and Artificial Neural Networks (부분최소자승법과 인공신경망을 이용한 고분자전해질 연료전지 스택의 모델링)

  • Han, In-Su;Shin, Hyun Khil
    • Korean Chemical Engineering Research
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    • v.53 no.2
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    • pp.236-242
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    • 2015
  • We present two data-driven modeling methods, partial least square (PLS) and artificial neural network (ANN), to predict the major operating and performance variables of a polymer electrolyte membrane (PEM) fuel cell stack. PLS and ANN models were constructed using the experimental data obtained from the testing of a 30 kW-class PEM fuel cell stack, and then were compared with each other in terms of their prediction and computational performances. To reduce the complexity of the models, we combined a variables importance on PLS projection (VIP) as a variable selection method into the modeling procedure in which the predictor variables are selected from a set of input operation variables. The modeling results showed that the ANN models outperformed the PLS models in predicting the average cell voltage and cathode outlet temperature of the fuel cell stack. However, the PLS models also offered satisfactory prediction performances although they can only capture linear correlations between the predictor and output variables. Depending on the degree of modeling accuracy and speed, both ANN and PLS models can be employed for performance predictions, offline and online optimizations, controls, and fault diagnoses in the field of PEM fuel cell designs and operations.

Effect of Force-field Types on the Proton Diffusivity Calculation in Molecular Dynamics (MD) Simulation (분자동역학 전산모사에서 force-field의 종류가 수소이온 확산도 계산에 미치는 영향)

  • Lee, Ji Hyun;Park, Chi Hoon
    • Membrane Journal
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    • v.27 no.4
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    • pp.358-366
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    • 2017
  • The most important factor in the performances of polymer electrolyte membranes for fuel cells is how fast hydrogen ions can be transported along the water channel formed inside the electrolyte membrane. Since the morphology of the water channel and the diffusivity of the protons are very important factors for the proton transport behavior, various molecular dynamics simulation studies are being carried out to clarify this. The force-field is an important variable parameterizing the movement and interaction of each atom in molecular dynamics simulation. In this study, proton diffusivities of the 3D models of polymer electrolyte membranes were calculated in order to analyze the effects of various types of force-fields on the molecular simulation. It has been found that the charge value determining the non-bonding interaction plays a very important role in the formation of the water channel morphology, and the COMPASS force-field can calculate the accurate proton diffusion behavior. Accordingly, for molecular dynamics simulation of polymer electrolyte membranes, the proper selection of the force-field is very important due to its great effect on the proton diffusion as well as the final molecular structure.

Characterization and Performance of MEA for Direct Methanol Fuel Cell Prepared with PFA Grafted Polystyrene Membranes via Radiation-Grafting Method (방사선 그라프트 PFA-폴리스티렌 멤브레인으로 제조한 직접 메탄올 연료전지용 MEA의 성능과 특성)

  • Kang, Se-Goo;Peck, Dong-Hyun;Kim, Sang-Kyung;Lim, Seong-Yop;Jung, Doo-Hwan;Park, Young-Chul;Shin, Jun-Hwa;Kang, Phil-Hyun;Nho, Young-Chang;Shul, Yong-Gun
    • Journal of the Korean Electrochemical Society
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    • v.12 no.2
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    • pp.173-180
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    • 2009
  • In order to develop a novel polymer electrolyte membrane for direct methanol fuel cell (DMFC), styrene monomer was graft-polymerized into poly(tetrafluoroethylene perfluoropropyl vinyl ether) (PFA) film followed by a sulfonation reaction. The graft polymerization was prepared by the $\Upsilon$-ray radiation-grafting method. Subsequently, sulfonation of the radiation-grafted film was carried out in a chlorosulfonic acid/1,2-dichloroethane (2 v/v%) solution. The chemical, physical, electrochemical and morphological properties of the radiation-grafted membranes (PFA-g-PSSA) were characterized by fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The water uptake, ionic conductivity, and methanol permeability of the PFA-g-PSSA membrane were also measured. The cell performances of MEA prepared with the PFA-g-PSSA membranes were evaluated and the cell resistances were measured by an impedance analyzer. The MEA using PFA-g-PSSA membranes showed superior performance for DMFCs in comparison with the commercial Nafion 112 membrane.

Pervaporation Separation of MTBE-Methanol Mixtures Using PVA/PAA Crosslinked Membranes (가교된 PVA/PAA 막을 이용한 MTBE-Methanol 혼합물에 대한 투과증발분리)

  • 임지원;김연국
    • Membrane Journal
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    • v.8 no.4
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    • pp.235-242
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    • 1998
  • Pervaporation separation of methyl tert-butyl ether (MTBE) and methanol (MeOH) mixture, of which the former compound is well known as the octane booster was carried out. Poly(vinyl alcohol) (PVA) membranes crosslinked with poly(acrylic acid) which have been successfully applied on the water-alcohol mixtures were used in this study. The PVA/PAA ratio in the crosslinked membranes was 95/5, 90/10, 85/15, 80/20, and 75/25 by weight. The operating temperatures were 30, 40, and 50$\circ$C, and the compositions of MTBE and MeOH to be separated were 95/5, 90/10, and 80/20 (MTBE/MeOH) solutions. PVA/PAA=85/15 membrane showed the separation factor $\alpha_{MeOH/MTBE}$=4000 and the permeation rate of 10.1 g/m$^2$hr for MTBE/MeOH=80/20 solution at 50$\circ$. When the same membrane was used, the separation factor and permeation rate for MTBE/MeOH=90/10 solution at 40$\circ$C were $\alpha_{MeOH/MTBE}$=6000 and 8.5 g/m$^2$hr, respectively. Also, the hydrophilic/hydrophobic balance of the membranes would take an important role in the relationships between the membranes and separation performances in terms of the flux and the separation factor.

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Template-free Hydrothermal Synthesis of High Phase Purity Mordenite Zeolite Particles Using Natural Zeolite Seed for Zeolite Membrane Preparation (제올라이트 분리막 제조를 위한 유기주형 없는 고순도 모데나이트 제올라이트 입자 수열합성에 관한 연구)

  • Lee, Du-Hyoung;Alam, Syed Fakhar;Lee, Hye-Rheon;Sharma, Pankaj;Cho, Churl-Hee;Han, Moon-Hee
    • Membrane Journal
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    • v.26 no.5
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    • pp.381-390
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    • 2016
  • In this study, the natural mordenite (MOR) zeolite seeds were used for the synthesis of high purity mordenite crystals. The effect of seed concentration and crystallization time on the phase purity and surface morphology of MOR crystals has also been reported. The diffraction, elemental and scanning analysis of MOR zeolite particles obtained from 100 g hydrothermal solution batch containing 3 g natural seed, hydrothermally treated at $140^{\circ}C$ for 72 h reveal the high phase-purity of as-synthesized sample having crystals of uniform size ($1-2{\mu}m$). Moreover, high seed concentration leads to the production of mesoporous MOR particles composed of needle shape primary nano crystallites. The gases adsorption performances of as-synthesized MOR particle were carried out at $25^{\circ}C$ and 0-1 bar. Surprisingly, MOR particles show good adsorption potential for $CO_2$ (97.19 mg/g) compared to other gases. Thus it confirms that high purity MOR particles can be synthesized without using any organic template which gives an advantage of separation performance at lower price.