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T : 목차정보

International journal of hydrogen energy 51건

  1. [해외논문]   Influence of coating conditions on the H2 separation performance from H2/CH4 gas mixtures by the PDMS/PEI composite membrane   SCI SCIE

    Kargari, A. , Arabi Shamsabadi, A. , Bahrami Babaheidari, M.
    International journal of hydrogen energy v.39 no.12 ,pp. 6588 - 6597 , 2014 , 0360-3199 ,

    초록

    In the present study, the composite polyetherimide (PEI) membrane coated with poly dimethyl siloxane (PDMS) was synthesized and optimum conditions of coating were obtained for separation of hydrogen from methane. Three coating techniques ''pouring solution inclined by 45 o '', ''film casting'' and ''dip-coating'' were used. The effect of sequential coating for different methods on permselectivity of the membranes was investigated. In addition, the influences of coating conditions including coating solution concentration, coating and curing temperatures were examined. The results showed that when the concentration of PDMS coating solution was increased; the permeance of H 2 was initially declined rapidly and was then gradually leveled off. The optimum concentration of coating solution was 15 wt.%. The examination of the curing and coating temperatures showed no significant effect on H 2 permeance and selectivity. In the ''dip coating'' method, two times coating showed superior permeance and selectivity and in ''film casting'', the performance of triple coating was promising. Higher selectivities for the composite membrane prepared by ''dip-coating'' introduced this method as the best method. The sequential dip-coating with different PDMS concentrations was applied and the selectivity was enhanced significantly from 26 to 96 for pure gases and from 22 to 70 for the binary gas mixture. Finally, the influence of pressure on the separation performance of the fabricated membrane was investigated.

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  2. [해외논문]   Hydrogen atom absorption in hydrogen-covered Pd(110) (1 x 2) missing-row surface   SCI SCIE

    Padama, A.A.B. , Chantaramolee, B. , Nakanishi, H. , Kasai, H.
    International journal of hydrogen energy v.39 no.12 ,pp. 6598 - 6603 , 2014 , 0360-3199 ,

    초록

    The absorption of H atom in H-covered Pd(110) (1 x 2) missing-row surface is investigated using density functional theory based calculations. For 1.5 monolayer H coverage, interaction among the adsorbed H atoms is found to be negligible and was verified by analyzing the electronic structure of the system and by comparing the calculated binding energies with low H coverage case. Neither the monoatomic absorption of H nor the assistance from the initially adsorbed H atom explains the experimentally observed presence of subsurface H in Pd(110) at high H coverage. Instead, H absorption is realized through the assistance of incoming H atoms from vacuum. The absorption of H in the H-covered surface is non-activated while the dissociation of H 2 is the rate-limiting process. Dissociation on ridge site is energetically more preferred than on trough site and the difference in the activation barrier is elucidated by investigating the electronic structures of the system.

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  3. [해외논문]   Process simulation for hydrogen/deuterium exchange in a packed column   SCI SCIE

    Ye, L. , Luo, D. , Tang, T. , Yang, W. , Zhao, P.
    International journal of hydrogen energy v.39 no.12 ,pp. 6604 - 6609 , 2014 , 0360-3199 ,

    초록

    The hydrogen isotope exchange reaction between hydrogen and water is a key process in water detritiation and heavy water production. To determine the optimum operating parameters and predict the exchange performance in a packed column, the hydrogen/deuterium exchange process was simulated, and the experiment results were verified by the simulation. The optimum exchange temperature was found to decrease with increased hydrogen feed flow rate. The deuterium concentration at the top of the column exhibited nonlinearity throughout all stages. The pressure drop per stage was also observed to induce no significant change in the hydrogen/deuterium exchange performance. With increased temperature, the change trend of calculated results was consistent with that of the experimental values. However, the calculated results are somewhat higher than the experimental ones, and the reason for the difference was discussed.

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  4. [해외논문]   Adsorption of H2S on carbonaceous materials of different dimensionality   SCI SCIE

    Ashori, E. , Nazari, F. , Illas, F.
    International journal of hydrogen energy v.39 no.12 ,pp. 6610 - 6619 , 2014 , 0360-3199 ,

    초록

    The effect of the dimension of carbonaceous systems, from two to zero, on the adsorption strength of H 2 S is investigated by density functional theory based methods. To this end, a carbon nanocone (CNC), a (3, 3) carbon nanotube ((3, 3)-CNT), and graphene (G) are chosen as models for zero-, one- and two-dimensional systems, respectively. Pristine G and CNC have low tendency to adsorb H 2 S but on the (3, 3)-CNT the molecule adsorbs dissociatively and deforms the surface. The effect of doping the surface of these materials with Ti has also been investigated. The presence of Ti modifies H 2 S adsorption capability to the point that it is chemically adsorbed on the three decorated surfaces although H 2 S adsorption on Ti decorated graphene appears to be different from two other doped surfaces. Only in this case, the H 2 S molecule dissociates and releases hydrogen atoms which form H 2 molecule. The resulting H 2 molecule is physisorbed on the Ti-decorated graphene surface and the S atom adsorbs directly on the Ti atom. The density of states of pristine, Ti decorated and H 2 S adsorbed nanostructures demonstrate that the systems change their conductivity and magnetic properties.

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  5. [해외논문]   Two-phase flow in GDL and reactant channels of a proton exchange membrane fuel cell   SCI SCIE

    Kandlikar, S.G. , See, E.J. , Koz, M. , Gopalan, P. , Banerjee, R.
    International journal of hydrogen energy v.39 no.12 ,pp. 6620 - 6636 , 2014 , 0360-3199 ,

    초록

    Understanding the effect of two-phase flow in the components of proton exchange membrane fuel cells (PEMFCs) is crucial to water management and subsequently to their performance. The local water saturation in the gas diffusion layer (GDL) and reactant channels influences the hydration of the membrane which has a direct effect on the PEMFC performance. Mass transport resistance includes contributions from both the GDL and reactant channels, as well as the interface between the aforementioned components. Droplet-channel wall interaction, water area coverage ratio on the GDL, oxygen transport resistance at the GDL-channel interface, and two-phase pressure drop in the channels are interlinked. This study explores each factor individually and presents a comprehensive perspective on our current understanding of the two-phase transport characteristics in the PEMFC reactant channels.

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  6. [해외논문]   Optimization of a thermoelectric generator subsystem for high temperature PEM fuel cell exhaust heat recovery   SCI SCIE

    Gao, X. , Andreasen, S.J. , Kaer, S.K. , Rosendahl, L.A.
    International journal of hydrogen energy v.39 no.12 ,pp. 6637 - 6645 , 2014 , 0360-3199 ,

    초록

    In previous work, a thermoelectric (TE) exhaust heat recovery subsystem for a high temperature polymer electrolyte membrane (HT-PEM) fuel cell stack was developed and modeled. Numerical simulations were conducted and have identified an optimized subsystem configuration and 4 types of compact heat exchangers with superior performance for further analysis. In this work, the on-design performances of the 4 heat exchangers are more thoroughly assessed on their corresponding optimized subsystem configurations. Afterward, their off-design performances are compared on the whole working range of the fuel cell stack. All through this study, different electrical connection styles of all the thermoelectric generator (TEG) modules in the subsystem and their influences are also discussed. In the end, the subsystem configuration is further optimized and a higher subsystem power output is achieved. All TEG modules are now connected into branches. The procedures of designing and optimizing this TE exhaust heat recovery subsystem are drawn out. The contribution of TE exhaust heat recovery to the HT-PEM fuel cell power system is preliminarily concluded. Its feasibility is also discussed.

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  7. [해외논문]   Liquid water distribution in hydrophobic gas-diffusion layers with interconnect rib geometry: An invasion-percolation pore network analysis   SCI SCIE

    Lee, K.J. , Kang, J.H. , Nam, J.H.
    International journal of hydrogen energy v.39 no.12 ,pp. 6646 - 6656 , 2014 , 0360-3199 ,

    초록

    Water distribution in gas diffusion layers (GDLs) of polymer electrolyte membrane fuel cells (PEMFCs) is determined by the pore morphology of the GDL as well as the flow conditions between the GDL and the gas flow field, where interconnect ribs and gas channels are placed side-by-side. The present study employs a steady state pore network model based on the invasion-percolation (IP) process to investigate the water transport in the under-rib region, in the under-channel region, and in between those regions inside the GDL. The interconnect rib partially blocks the outlet surface of the GDL, which forces water transport paths from the under-rib region to grow towards the gas channel through an extra IP process. The pore network model predicts spatially non-uniform water distributions inside the GDL due to the interconnect ribs, especially with an increased saturation level in the under-rib region. Parametric studies are also conducted to investigate the effects of several geometrical factors, such as width of the rib and the channel, thickness of the GDL, and water intruding condition at the inlet surface of the GDL.

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  8. [해외논문]   A versatile strategy towards semi-interpenetrating polymer network for proton exchange membranes   SCI SCIE

    Zhao, Z. , Pu, H. , Chang, Z. , Pan, H.
    International journal of hydrogen energy v.39 no.12 ,pp. 6657 - 6663 , 2014 , 0360-3199 ,

    초록

    A universal method to prepare proton exchange membrane (PEM) with semi-interpenetrating polymer network (semi-IPN) via a versatile crosslinker 1,3-benzenedisulfonyl azide (1,3-BDSA) is proposed. Sulfonyl azide groups can react with any polymer with carbon-hydrogen bonds via hydrogen abstraction. Polyvinylidene fluoride (PVDF) and perfluorosulfonic acid (PFSA) polymer are selected as two precursors for semi-IPN. When 1,3-BDSA is heated to a sufficiently high temperature it can form the nitrene and connect with PVDF via hydrogen abstraction reaction, recombination, or CH-bond insertion. The crosslinking structure of PVDF is formed, and semi-IPN is constructed in the presence of PFSA at the same time. The mechanical properties, degree of crosslinking, water uptake, and proton conductivity of semi-IPN membranes are investigated. Compared with pure PFSA membrane, the mechanical properties and the dimensional stability of the semi-IPN membranes are improved significantly. The tensile strength of the composite membrane (27.2 MPa) is much higher than that of PFSA membrane (10.1 MPa). The maximum power density of the composite membrane can reach 382 mW cm -2 at 940 mA cm -2 . Sulfonyl azide based crosslinkers can be used to prepare semi-IPN or IPN PEMs from any paired polymers with carbon-hydrogen bonds.

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  9. [해외논문]   Numerical analysis of transport phenomena for designing of ejector in PEM forklift system   SCI SCIE

    Hosseinzadeh, E. , Rokni, M. , Jabbari, M. , Mortensen, H.
    International journal of hydrogen energy v.39 no.12 ,pp. 6664 - 6674 , 2014 , 0360-3199 ,

    초록

    In the present study, Computational Fluid Dynamics (CFD) technique is used to design an ejector for anode recirculation in an automotive PEMFC system. A CFD model is firstly established and tested against well-documented and relevant solutions from the literature, and then used for different ejector geometries under different operating conditions. Results showed that a single ejector with optimized geometry cannot cover the required recirculation in the entire range of the fuel cell current. Having two ejectors for different ranges of currents is thus proposed as an alternative solution in which the system can better take the advantage of ejectors for recirculation purpose. In addition, the operating mode of one variable nozzle ejector has been investigated and compared with aforementioned cases. The results showed that the variable nozzle ejector can work in the same operational mode as in the case with two ejectors. However, in practice, the latter one needs a more complicated control system and it is more difficult to manufacture.

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  10. [해외논문]   Electrochemical characterization of La0.6Ca0.4Fe0.8Ni0.2O3 cathode on Ce0.8Gd0.2O1.9 electrolyte for IT-SOFC   SCI SCIE

    Ortiz-Vitoriano, N. , Bernuy-Lopez, C. , Hauch, A. , Ruiz de Larramendi, I. , Rojo, T.
    International journal of hydrogen energy v.39 no.12 ,pp. 6675 - 6679 , 2014 , 0360-3199 ,

    초록

    For Solid Oxide Fuel Cells (SOFCs) to become an economically attractive energy conversion technology, suitable materials and structures which enable operation at lower temperatures, while retaining high cell performance, must be developed. Recently, the perovskite-type La 0.6 Ca 0.4 Fe 0.8 Ni 0.2 O 3 oxide has shown potential as an intermediate temperature SOFC cathode. An equivalent circuit describing the cathode polarization resistances was constructed from analyzing impedance spectra recorded at different temperatures in oxygen. A competitive electrode polarization resistance is reported for this oxygen electrode using a Ce 0.8 Gd 0.2 O 1.9 electrolyte, determined by impedance spectroscopy studies of symmetrical cells sintered at 800 o C and 1000 o C. Scanning electron microscopy (SEM) studies of the symmetrical cells revealed the absence of any reaction layer between cathode and electrolyte, and a porous electrode microstructure even when sintered at a temperature of only 800 o C. The performance of this cathode shows favorable oxygen reduction reaction (ORR) properties potentially making it an excellent choice for IT-SOFC application.

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