Iranian Research Organization for Science and Technology (IROST)Hydrogen, Fuel Cell & Energy Storage2980-85373320161227The effect of vertical injection of reactants to the membrane electrode assembly on the performance of a PEM fuel cell16718246510.22104/ijhfc.2016.465ENFarzinRaminFaculty of Mechanical Engineering, University of TabrizSimaBaheri IslamiFaculty of Mechanical Engineering, University of TabrizSiamakHossainpourMechanical Engineering Faculty, Sahand University of TechnologyJournal Article20160915In order to present a new and high performance structure of PEM fuel cell and study the influence of the flow direction and distribution on the rate of reactants diffusion, three novel models of vertical reactant flow injection into the anode and cathode reaction area field have been introduced. They consist of one inlet and two inlets and also a continuous channel. The governing equations on the steady, three dimensional non-isothermal flow have been discretized using finite volume method. These 3D simulations are going to evaluate the effectiveness of flow direction on the transportation and chemical phenomena inside the PEM fuel cell by applying computational fluid dynamics (CFD) method to the transportation and conservation equations with the suppositions of steady state and one phase flow. The numerical results are validated with experimental ones for available common fuel cells. The results show that the presented geometries have several mechanical and chemical benefits such as extra diffusion of reactants because of flow direction, improvement of species distributions, enhancement in temperature management and more effective water removal due to the number of outlets and uniform current distribution. Furthermore, the continuous channel inlet due to cover more reaction area and high rate of reactants diffusion presents substantial higher performance than others. With regard to the polarization curve along with other advantages, the so-called design can be strongly recommended for obtaining high operating efficiency and can be considered for the manufacturing of new generation of PEM fuel cells in the form of high performance stacks.Iranian Research Organization for Science and Technology (IROST)Hydrogen, Fuel Cell & Energy Storage2980-85373320170205Experimental Study on a 1000W Dead-End H2/O2 PEM Fuel Cell Stack with Cascade Type for Improving Fuel Utilization18319742110.22104/ijhfc.2017.421ENEbrahimAlizadehMalek Ashtar University of Technology, Fuel Cell Technology Research LaboratoryMajidKhorshidianMalek Ashtar University of Technology, Fuel Cell Technology Research Laboratory0000-0001-5700-1918Seyed HosseinMasrori SaadatMalek Ashtar University of Technology, Fuel Cell Technology Research LaboratorySeyed MajidRahgoshayMalek Ashtar University of Technology, Fuel Cell Technology Research LaboratoryMazaherRahimi-EsboMalek Ashtar University of Technology, Fuel Cell Technology Research LaboratoryJournal Article20161107Proton exchange membrane fuel cells (PEMFCs) with a dead-ended anode and cathode can obtain high hydrogen and oxygen utilization by a comparatively simple system. Nevertheless, the accumulation of the water in the anode and cathode channels might cause a local fuel starvation degrading the performance and durability of PEMFCs. In this study, a brand new design for a polymer electrolyte membrane (PEM) fuel-cell stack is presented which can achieve higher fuel utilization without using hydrogen and oxygen recirculation devices such as hydrogen pumps or ejectors that consume parasitic power and require additional control schemes. In this manuscript the basic concept of the proposed design is presented. Concept of the proposed design is to divide the cells of a stack into several stages by conducting the outlet gas of each stage to a separator and reentering it into the next stage in a multistage construction of anode and cathode electrodes. In this design, a higher gaseous flow rate is maintained at the outlet of the cells, even under dead-end conditions resulting in a reduced purge-gas emissions by avoiding the accumulation of liquid water in the cells. Moreover, fluctuation of voltage in hydrogen and oxygen cells at dead-end mode is investigated. Furthermore the utilization factor of hydrogen and oxygen at different power is presented. Overall, the result shows that the proposed design has the same polarization curve as open-end mode one, resulting in a higher PEMFC performance.Iranian Research Organization for Science and Technology (IROST)Hydrogen, Fuel Cell & Energy Storage2980-85373320170211Influence of unsuitable operational conditions on the transient performance of a small hydrogen liquefier19921243010.22104/ijhfc.2017.430ENAliSaberimoghaddamMalek Ashtar University of TechnologyMohammad MahdiBahri Rasht AbadiDepartment of Chemistry and Chemical Engineering, Faculty of Chemical Engineering,
Malek Ashtar University of Technology (MUT), Lavizan 158751774, Tehran, IranJournal Article20161002Joule-Thomson cooling systems are used in refrigeration processes such as cryogenic gas liquefaction. Although extensive studies have been carried out by researchers, most of them include cryogenic heat exchangers and their associated fields. In the current study, an attempt was made to indicate the effect of using inappropriate operational conditions in a cryogenic Joule-Thomson cooling system including recuperative heat exchanger, expansion valve and collector. Mass flow rate and operational pressure were selected as design parameters while cool-down time and final temperature of high-pressure gas at heat exchanger outlet were considered as responses. The results showed that using mass flow rate smaller than the design value led to considerable decrease in performance. Operational pressure had lesser effect on cool-down time. Increasing the pressure had no significant effect on the gas temperature at expansion valve inlet for high mass flow rates. Using unsuitable values for mass flow rate and operational pressure might lead to fail liquefaction despite using heat exchanger with high effectiveness.Iranian Research Organization for Science and Technology (IROST)Hydrogen, Fuel Cell & Energy Storage2980-85373320170212Modeling and experimental study on the sealing gasket of proton exchange membrane fuel cells21322041610.22104/ijhfc.2017.416ENMohammad HosseinFiliDepartment of Mechanical Engineering, Sari Branch, Islamic Azad University, Sari, IranMostafaHabibniaDepartment of Mechanical Engineering, Joybay Branch, Islamic Azad University, Jouybar, IranPeymanGhasemi TamamiDepartment of Mechanical Engineering, Tarbiat Modares University, Tehran, IranJournal Article20160927In this study cross section geometry and material of gasket in proton exchange membrane (PEM) fuel cells have been investigated to achieve optimized fuel cell in terms of energy efficiency. The role of gaskets in fuel cells is sealing of gas flow channels and preventing from combination of them. In a PEM stack, gasket with approved geometry that suffers more stress has better sealing. For this investigation, at first experimental leakage tests have been done and after gaskets manufacturing, stack assembly, putting setup under press and studying leakage values in terms of time and various pressures, results showed that sealing gasket with width of 3mm and thickness of 0.4mm in pressure of 2MPa seals well according to standards, To access to optimal results, width of 3mm and thickness of 0.4mm has been considered for numerical simulation. After leakage test, some materials have been tested and results showed that gasket with hyper elastic properties is the best choice for sealing. After experimental tests 6 shapes of gasket cross section profile in fuel cell stack have been modeled in Abaqus software and with attention to results and analyzing them, the best material and profile shape for gasket in fuel cell has been selected. Results of simulations showed good uniform pressure distribution in stack.Iranian Research Organization for Science and Technology (IROST)Hydrogen, Fuel Cell & Energy Storage2980-85373320170220Studies on the SPEEK membrane with low degree of sulfonation as a stable proton exchange membrane for fuel cell applications22123242810.22104/ijhfc.2017.428ENMohammad JavadParnianSchool of Chemical Engineering, Iran University of Science and Technology, Narmak, Tehran 16846-13114, IranFatemehGashoulSchool of Chemical Engineering, Iran University of Science and Technology, Narmak, Tehran 16846-13114, IranSoosanRowshanzamirGreen Research Center (GRC) & School of Chemical Engineering (SChE)
Iran University of Science & TechnologyJournal Article20161114Sulfonated poly (ether ether ketone) (SPEEK) with a low degree of sulfonation (DS = 40%) was prepared for proton exchange membrane fuel cells (PEMFC). Poly (ether ether ketone) (PEEK) was sulfonated in concentrated H<sub>2</sub>SO<sub>4</sub> under N<sub>2</sub> atmosphere and characterized by the hydrogen nuclear magnetic resonance (H-NMR) technique. After preparation of the SPEEK polymer, the obtained polymer was dissolved in dimethylacetamide (DMAC) solvent and then the solution casting method was applied for the fabrication of membranes. Water uptake behavior, ion exchange capacity (IEC), and the proton conductivity at different temperatures and different relative humidity were determined and compared with a commercial Nafion 117 membrane. The IEC and the proton conductivity results showed that the sulfonation process successfully created proton conduction channels. In addition, the thermal, mechanical, chemical, and hydrolytic stabilities were thoroughly investigated for the prepared membrane. The low degree of sulfonation SPEEK showed a desirable chemical durability with a higher dimensional, mechanical, and thermal stability than Nafion-117 but lower water uptake and proton conductivity.Iranian Research Organization for Science and Technology (IROST)Hydrogen, Fuel Cell & Energy Storage2980-85373320170222The Impact of Wettability on Effective Properties of Cathode Catalyst Layer in a Proton Exchange Membrane Fuel Cell23324546710.22104/ijhfc.2017.467ENHosseinFathiDepartment of Mehcanical Engineering, Shahid Bahonar University of Kerman, Kerman, IranSeyed HosseinMansouriDepartment of Mechanical Engineering, Shahid Bahonar University of Kerman, Kerman, IranAmirRaoofDepartment of Earth Sciences, Utrecht University, Utrecht, NetherlandsJournal Article20161116The produced liquid water in cathode catalyst layer (CCL) has significant effect on the operation of proton exchange membrane fuel cell (PEMFC). To investigate this effect, the transport of oxygen in CCL in the presence of immiscible liquid water is studied applying a two-dimensional pore scale model. The CCL was reconstructed as an agglomerated system. To explore the wettability effects, different contact angles were considered at the surface of agglomerates. The effective diffusivity of oxygen was calculated under different contact angles at various saturation levels. The same effective diffusivity was obtained for hydrophilic and hydrophobic domains at lower saturations, however, at saturation above 0.4, hydrophobic domain provided higher effective diffusivity values. The effect of water coverage at reaction surface areas was investigated. The results showed that, at the saturation of 0.4, the hydrophobic domain with the contact angle of 150 has about 2 times more available surface area, due to different distribution of water phase compared to the hydrophilic domain with the contact angle of 20.