فهرست مطالب

Hydrogen, Fuel Cell and Energy Storage - Volume:3 Issue: 2, Spring 2016

Journal of Hydrogen, Fuel Cell and Energy Storage
Volume:3 Issue: 2, Spring 2016

  • تاریخ انتشار: 1395/08/28
  • تعداد عناوین: 6
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  • Hassan Hassanzadeh*, Mohammad Ali Farzad, Ali Safavenejad, Mohammad Reza Agaebrahimi Pages 81-97
    It is expected that residential units may replace traditional heat and power production systems with cogeneration ones. Among the different cogeneration systems, fuel cell based systems are a suitable choice due to their high efficiency, high power density, low emission and low noise. In this paper, a cogeneration system based on solid oxide fuel cells is examined. The system, including the fuel and air compressors, desulphurizer, fuel reformer, fuel cell stack, etc., has been modeled from an energy and exergy viewpoint. An optimization algorithm with three different objective functions, including power production, heat production and the minimum exergy destruction, is applied. Then, the base system is utilized along with photovoltaic and electrolizer as a combined system. The results showed that an OP (Ordinary Photovoltaic) is the best configuration with emissions reduction in the heat production approach, while OP and OFPE (Ordinary Fuel cell Photovoltaic Electrolizer) configurations are the best configurations with excess energy in power production approach. The conditions of the numerical calculations were selected in accordance with a sample building located in eastern Iran.
    Keywords: Solid Oxide Fuel Cell, Exergy, Optimization, CHP
  • Ashkan Torkavannejad *, Nader Pourmahmoud Pages 99-112
    To simulate a new economical architecture for PEM fuel cell and investigate the effectiveness of the introduced structure on the performance, computational fluid dynamics (CFD) code is used to solve the equations for a single domain of the cell namely: the flow field, the mass conservation, the energy conservation, the species transport, and the electric/ionic fields under the assumptions of steady state and single phase. In this article, a new architecture of proton exchange membrane fuel cell (PEMFCs) stack with typical geometry is presented in which every anode channel is in connection with two cathode channel in the constant length and vice versa. The analyzed numerical results yield to observation the effect of this new structure on the distributions like current density oxygen, water, hydrogen mass fraction, current density and temperature. The introduced configuration has the same active area as the base model. Drawing the polarization curve for this new cell demonstrates that straight channel with dual connection in each channel shows considerably better performance and surpassed by a large amount the current density region of the polarization curves of a fuel cell using the base structure. The improved model can bring several advantages to the conventional PEMFC configuration which associated to the sufficient distribution of the reactants, to the flow field, improvement the concentration distribution along the channels and transport of the reactant gases through the gas diffusion layer (GDL), .
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    Keywords: Fuel cell, PEM fuel cells, Single, phase, geometry
  • Ali Saberimoghaddam*, Mohammad Mahdi Bahri Rasht Abadi Pages 113-125
    Heat exchangers are the critical components of refrigeration and liquefaction processes. Selection of appropriate operational conditions for cryogenic recuperative heat exchanger and expansion valve operating in Joule-Thomson cooling system results in improving the performance and efficiency. In the current study, a straightforward procedure is introduced to design an efficient Joule-Thomson cooling system. Determining the appropriate operational conditions and configuration of streams within the recuperative heat exchanger are discussed comprehensively. A Joule-Thomson cooling system including helically coiled tube in tube heat exchanger and expansion valve was considered as a case study. Simulation was performed by procedure different from conventional finite element method and the results were validated versus data obtained from small laboratory hydrogen liquefier. In accordance with mathematical modeling performed on the recuperative heat exchanger, it is better to flow low pressure hydrogen inside the inner tube and high pressure hydrogen within the annulus. This arrangement results in needing shorter length for heat exchanger tubes compared with reverse arrangement..
    Keywords: Refrigeration, Joule, Thomson, hydrogen liquefaction, heat exchanger, design, simulation
  • Ebrahim Alizadeh*, Majid Khorshidian, Seyed Majid Rahgoshay, Seyed Hossein Masrori Saadat, Mazaher Rahimi, Esbo Pages 127-136
    Electrochemical impedance spectroscopy (EIS) is a suitable and powerful diagnostic testing method for fuel cells (FCs) since it is non-destructive and provides useful information about FC performance and its components. In this study, for the first time, a 500W cascade type 4 cells stack with integrated humidifier, water separator and internal manifolds was designed, fabricated and tested. The diagnostic test was conducted by EIS. The effects of dead end and open end modes of the stack impedance spectra are studied. The results suggested that ohmic resistance of the single cell decreased with increasing current density due to the greater effect of hydration of membrane. The results of the electrochemical impedance revealed that the gas operating mode had significant impacts on electrochemical impedance of the stack. When the stack was tested on dead end mode, the charge transfer resistance of the stack decreases dramatically and its influences on mass transfer resistances are negligible.
    Keywords: PEM Fuel Cell (PEMFC), Cascade type stack, Electrochemical Impedance Spectroscopy (EIS), Dead, end Operation
  • Ali Hedayati, Saeed Asghari *, Amir Hosein Alinoori, Morteza Koosha, Esa Vuorinen Pages 137-149
    In the polymer electrolyte membrane fuel cells (PEMFCs), low corrosion resistance and high interfacial contact resistance (ICR) are two controversial issues in usage of AISI 316L stainless steel as a metallic bipolar plate. For solving these problems, investigation and development of different coatings and/or surface treatments are inevitable. Corrosion behavior and ICR of AISI 316L specimens coated with 1, 2, and 3 µm thick TiN were investigated. Potentiodynamic (PD), potentiostatic (PS) and electrochemical impedance spectroscopy (EIS) tests were conducted at 80 °C in pH3 H2SO4 ppm HF solution purged with either O2 or H2 under both simulated cathodic and anodic conditions. The PS corrosion test results revealed that the current densities of the specimens were below 1 µA cm−2. In the simulated cathodic condition, an increase of coating thickness from 1 to 3 µm led to a relatively large decrease of the current density from 0.76 to 0.43 µA cm−2. Furthermore, the ICR values of the coated specimens after the PS test were lower than that of the uncoated specimen before the PS. In general, the TiN coating decreases the ICR, and has enough corrosion resistance in simulated PEMFC conditions. However, none of the coatings achieved the DOE ICR targets.
    Keywords: Proton Exchange Membrane Fuel Cells, AISI 316L Stainless Steel, Bipolar Plates, PVD Coating, Titanium Nitride (TiN) Coating
  • Ali Reza Madram*, Samane Asadi Pages 151-158
    In this study Ni catalyst have been activated during hydrogen evolution reaction (HER) by adding Mo ions into the alkaline electrolyte. After dissolving different amounts of ammonium molybdate in the 1M NaOH as electrolyte, Ni catalyst was used as cathode for HER. Afterwards a comparison between hydrogen overpotential measured in Ni catalyst with and without in situ activation has been made; the in situ activation shows an improvement of electrocatalytic properties of Ni catalyst for hydrogen evolution reaction. In the other words impact increase of in situ activation of Mo ions on the Ni structure, show that extremely significant impact in improving the Ni catalyst activation during in situ activation. The values of Tafel slope for Ni catalyst without Mo is an average of about 141 mVdec-1, while by using in situ activation by activator Mo ion this value is about 172 mVdec-1. As well as the values of overpotential for Ni catalyst, are an average of about 625 mV, by using in situ activation, these values are about 482 mV at the current density of 250 mAcm-2 (η250). In this study electrochemical data obtained from linear sweep voltammetry (LSV), the steady state polarization Tafel curves, electrochemical impedance spectroscopy (EIS).
    Keywords: Hydrogen evolution reaction, In situ activation, Electrochemical impedance spectroscopy, electrocatalytic activity