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Hydrogen, Fuel Cell and Energy Storage - Volume:1 Issue: 2, Spring 2014

Journal of Hydrogen, Fuel Cell and Energy Storage
Volume:1 Issue: 2, Spring 2014

  • تاریخ انتشار: 1393/04/02
  • تعداد عناوین: 7
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  • Faramarz Hormozi, Elham Omidbakhsh Amiri, Hussein Jelveh Pages 65-74
    Steam reforming integrated with oxidation of methanol was considered with numerical simulation. The parallel micro-channels with circular cross sections were used. Because when the catalytic deposited inside the rectangular micro-channels, it fills up the edges. Hence, the approximation of a cylindrical channel is appropriate. Effect of this changing in cross section was considered and results show conversion is lower in circular model. Also, effects of operating conditions such as inlet temperature, feed flow rate, inlet composition (as steam/carbon ratio) and geometry parameters such as the distance between two rows and two columns were considered. The results show that with increasing inlet temperature and steam/carbon ratio, methanol conversion increases while with increasing feed flow rate, methanol conversion decreases. Geometry parameters are another consideration and the results show that with increasing t1 (the distance between oxidation and steam reforming micro-channels) methanol conversion decreases and with increasing t1/t2 ratio (t2 is the distance between two oxidation micro-channels or two steam reforming micro-channels), methanol conversion increases firstly and then keep almost constant.
    Keywords: steam reforming, oxidation, circular micro, channel, CFD model
  • Mehdi Kheirmand, Rasol Abdullah Mirzaie, Rahil Yazdanshenas, Ahmad Nozad Golikand Pages 75-82
    In this paper, the effect of surface area of reaction layers in gas diffusion electrodes on oxygen reduction reaction was investigated. For this purpose, various amounts (0.1, 0.2, 0.3, 0.4, 0.5, 1, 1.5 and zero %wt of total loading of reaction layer) of single walled carbon nanotube (SWCNT) were inserted in the reaction layer. The performance of gas diffusion electrodes for oxygen reduction reaction was studied in a three-electrode half-cell system, via linear sweep voltammetry (LSV), cyclic voltammetry (CV), chronoamperometry (CHA) and impedance analysis. The results show that, the existence of SWCNT in the reaction layer improves the exchange current density of ORR, the symmetry factor changed between 0.51 and 0.83, as a whole in the optimized condition (0.4% wt. SWCNT) tendency of gas diffusion electrode for ORR is increased. The addition, influences significantly in electrochemical surface area and the gas diffusion electrode with 0.4%wt SWCNT has lowest charge transfer resistance respect to other electrodes. Our results indicated that the best performance obtains for an electrode with 0.4% single walled carbon nanotube.
    Keywords: oxygen reduction reaction, gas diffusion electrode, surface area, reaction layer, single walled carbon nanotube
  • Seyyed Mojtaba Alavisadr, Hadi Arabi, Faiz Pourarian Pages 83-94
    The hydrogenation characterizations of the hydrogen storage alloy MmNi4.22Co0.48Mn0.15Al0.15 (Mm= mischmetal), and the effect of hydrogenation/dehydrogenation (H/D) cycling on its structural and morphological properties are investigated. The results indicate that after several H/D cycles the alloy was pulverized into fine particles, but it kept its hexagonal CaCu5-type structure. The pressure-composition (PC) isotherms for hydrogen absorption/desorption and absorption kinetic were measured in temperature range of 293-338 K. The absorption plateau pressures were determined to be ~ 0.51, 1.22 and 2.49 bar at 293, 313 and 33 K respectively, with a maximum hydrogen storage capacity of about 5.78 at 293 K. The enthalpy (H), entropy (S) and the activation energy of reactions (Ea) were also calculated. The results show that the hydrogenation reaction rate increases with an increase in the operating temperature or pressure. The Jander diffusion (JDM) and Johnson-Mehl-Avrami (JMA) models were employed and the kinetic of hydrogenation was analyzed in detail for hydriding reaction (rate controlling steps) mechanism. The obtained results indicate that the MmNi4.22Co0.48Mn0.15Al0.15 alloy has potential to be suitable for use in practical applications.
    Keywords: Hydrogen storage, Mm(NiCoMnAl)5 alloy, Structural properties, Pressure, composition isotherm, Hydriding kinetic
  • Saeed Olyaee, Reza Ebrahimpour, Somayeh Esfandeh Pages 95-104
    In this paper, a method for determination of refractive index in membrane of fuel cell on basis of three-longitudinal-mode laser heterodyne interferometer is presented. The optical path difference between the target and reference paths is fixed and phase shift is then calculated in terms of refractive index shift. The measurement accuracy of this system is limited by nonlinearity error. In this study, nonlinearity error is modeled by multi-layer perceptrons (MLPs) and stacked generalization method (Stacking), using two learning methods; back propagation (BP) and genetic algorithm. Training neural networks with genetic algorithm, improves modeling of nonlinearity error in this system. In the proposed technique, a real code version of genetic algorithm is used. Parameters and genetic operators are set and designed accurately. The results indicate that the nonlinearity error can be effectively modeled by training the stacking with the genetic algorithm which has minimum mean square error (MSE). Keywords: Fuel cell, Genetic algorithm, Heterodyne interferometer, Multi-layer perceptrons, Nonlinearity error, Refractive index, Stacked Generalization.
    Keywords: fuel cell, Genetic algorithm, Heterodyne interferometer
  • Mehran Javanbakht, Khadijeh Hooshyari, Morteza Enhessari, Hossein Beydaghi Pages 105-112
    Proton exchange membrane fuel cells (PEMFCs) are electrochemical devices that show the highest power densities compared to the other type of fuel cell. In this work, nanocomposite membranes used for proton exchange membrane fuel cells as poly(vinyl alcohol)/La2Ce2O7 (PVA-LC) with the aim of increasing the water uptake and proton conductivity. Glutaraldehyde (GA) was used as cross linking agent of PVA matrix. PVA-LC nanocomposite membranes have been prepared with solutions casting method. The significant improvement has been achieved via the synergetic combination of organic and inorganic phases. Nanocomposite membranes were structurally, morphologically and electrochemically considered by FTIR, SEM and ELS, respectively. The results exhibited that the proton conductivity and the water uptake of the nanocomposite membranes were higher than that of the PVA membrane. PVA-LC nanocomposite membranes containing 4 wt.% of La2Ce2O7 nanoparticles displayed a high proton conductivity (0.019 S/cm). The highest peak power density of the PEMFC using PVA-LC nanocomposite membrane at ambient temperature was 19 mW/cm2. The proposed PVA-LC nanocomposite membranes appear to be a viable candidate for future PEMFCs applications.
    Keywords: PEM fuel cell, Poly(vinyl alcohol), Nanocomposite membranes, Proton conductivity, La2Ce2O7 nanoparticles
  • Hosna Ghanbarlou, Soosan Rowshanzamir, Mohammad Javad Parnian, Bagher Kazeminasab Pages 113-119
    Development of efficient electrocatalysts for oxygen reduction reaction (ORR) is one of the most important issues for optimizing the performance of fuel cells and metal-air batteries. The introduction of nitrogen into carbon nanostructures has created new pathways for the development of non-precious electrocatalysts in fuel cells. In this work, nitrogen-doped graphene (NG) was synthesized by a low temperature solvothermal process to use as catalyst supports for oxygen reduction reactions (ORR). The morphology of the NG was studied using scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. X-ray photoelectron spectroscopy showed that graphitic (Quaternary), pyridinic and pyridinic oxidized nitrogen formed by designed reaction and these types of nitrogen configurations has been found to be responsible for the ORR catalytic activity of N-doped carbon material. Cyclic voltammetry and linear sweep voltammetry were used to measure electrocatalytic activity. Electrochemical characterization reveal that the produced NG not only as support but also as catalyst has good catalytic activity for oxygen reduction reaction in alkaline media.
    Keywords: nitrogen, doped graphene, solvothermal synthesis, oxygen reduction reaction, fuel cell
  • Reza Irankhah, Babak Raissi, Amir Maghsoudipour Pages 121-131
    In the present study, electrophoretic deposition (EPD) method in different electric fields (30 – 300 V / cm) was used to apply Co3O4 spinel coating to SUS 430 as SOFC interconnect. The coated and uncoated specimens were pre-sintered in air at 800 and 900 °C for 3 h followed by cyclic oxidation at 700 and 800 °C for 500 h, respectively. X-ray diffraction analysis (XRD), Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscopy (EDS) were used for characterization of the prepared samples. The results indicated that the electric field of 100 V was an effective voltage to obtain crack-free coating. A comparison between the oxidation resistance of coated and uncoated specimens indicated that the weight change of the coated specimen was larger than that of the uncoated one during the cyclic oxidation, so the Co3O4 coating is not effective for improving the oxidation resistance. According to the obtained results, the oxidation rate constant (Kp) for the coated specimens at 700 and 800 °C in air were 2.36×10-14 and 3.37×10-12gr2cm−4s−1, respectively.
    Keywords: Electrophoretic deposition, Co3O4 coating, SOFC interconnect, Oxidation resistance