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Conference Object Citation - WoS: 44Citation - Scopus: 56Three-Dimensional Modeling of a High Temperature Polymer Electrolyte Membrane Fuel Cell at Different Operation Temperatures(Pergamon-elsevier Science Ltd, 2016) Caglayan, Dilara Gulcin; Sezgin, Berna; Devrim, Yilser; Eroglu, InciA three-dimensional model for a high temperature polymer electrolyte membrane (PEM) fuel cell having an active area of 25 cm(2) is developed. Triple mixed serpentine flow channel single cell with phosphoric acid doped polybenzimidazole (FBI) membrane is used in the model. Steady-state, isothermal, single phase assumptions are defined for the system. The model is simulated at different temperatures ranging from 100 to 180 degrees C to investigate the influence of operation temperature on the performance of the cell. It is seen that there is an improvement in the performance of the cell as the operation temperature increases. Experimental data are used to validate the model both for single channel and triple mixed serpentine flow channel. Current density distribution is obtained at different operating voltages. The predicted results show that at high operating voltages the local current density is almost uniform; whereas, decreasing operating voltage causes non-uniformities in the local current density. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Conference Object Citation - WoS: 134Citation - Scopus: 148Polybenzimidazole/Sio2< Hybrid Membranes for High Temperature Proton Exchange Membrane Fuel Cells(Pergamon-elsevier Science Ltd, 2016) Devrim, Yilser; Devrim, Huseyin; Eroglu, InciPolybenzimidazole/Silicon dioxide (PBI/SiO2) hybrid membranes were prepared and characterized as alternative materials for high temperature proton exchange membrane fuel cell (HT-PEMFC). The PBI/SiO2 membranes were cast from a PBI polymer synthesized in the laboratory and contained 5 wt. % SiO2 as inorganic filler. Scanning electron microscopy (SEM) analysis showed that the uniform and homogeneous distribution of SiO2 particles in the hybrid membrane. The existence SiO2 has improved the acid retention and proton conductivity properties. A maximum conductivity of 0.1027 S/cm at 180 degrees C was obtained for the PBI/SiO2 hybrid membrane. Gas diffusion electrodes (GDE) were fabricated by ultrasonic coating technique with 1 mg Pt/cm(2) catalyst loading for both anode and cathode. The membranes were tested in a single HT-PEMFC with a 5 cm(2) active area operating at the temperature range of 140 degrees C-180 degrees C. Single HT-PEMFC tests indicated that PBI/SiO2 hybrid membrane was more stable and also performed better than pristine PBI membrane. Maximum current density was observed for PBI/SiO2 membrane at 165 degrees C and cell voltage of 0.6 V as 0.24 A/cm(2). The results suggested that PBI/SiO2 hybrid membrane is promising electrolytes for HT-PEMFC with improved fuel cell performance. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Article Citation - WoS: 55Citation - Scopus: 63Development of 500 W Pem Fuel Cell Stack for Portable Power Generators(Pergamon-elsevier Science Ltd, 2015) Devrim, Yilser; Devrim, Huseyin; Eroglu, InciPolymer Electrolyte Membrane Fuel Cell (PEMFC) portable power generators are gaining importance in emergency applications. In this study, an air-cooled PEMFC stack was designed and fabricated for net 500 W power output. Gas Diffusion Electrodes (GDE's) were manufactured by ultrasonic spray coating technique. Stack design was based on electrochemical data obtained at 0.60 V was 0.5 A/cm(2) from performance tests of a single cell having the same membrane electrode assemblies (MEA) that had an active area of 100 cm(2). Graphite bipolar plates were designed and machined by serpentines type flow. The stack comprising of 24 cells was assembled with external fixing plates. The stack temperature was effectively regulated by the cooling fan based on on-off control system. A maximum power of 647 W was obtained from the stack. The PEMFC stack was stable during start-up and shutdown cycling testing for 7 days at 65 degrees C in H-2/air at a constant cell voltage. Copyright (c) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Conference Object Citation - WoS: 90Citation - Scopus: 107Modeling and Sensitivity Analysis of High Temperature Pem Fuel Cells by Using Comsol Multiphysics(Pergamon-elsevier Science Ltd, 2016) Sezgin, Berna; Caglayan, Dilara Gulcin; Devrim, Yilser; Steenberg, Thomas; Eroglu, InciThe objective of this study is to observe the effect of the critical design parameters, velocities of inlet gases (hydrogen and air) and the conductivity of polymer membrane, on the performance of a high temperature PEM fuel cell. A consistent and systematic mathematical model is developed in order to study the effect of these parameters. The model is applied to an isothermal, steady state, three-dimensional PEM fuel cell in order to observe concentration profiles, current density profiles and polarization curves. The model includes the transport of gases in anode and cathode gas flow channels, diffusion in the catalyst layers, the transport of water and hydronium ion in the polymer electrolyte and in the catalyst layers, and the transport of electrical current in the solid phase. The model is considered as having a single flow channel. The simulation is performed by using licensed Comsol Multiphysics 5.0, Fuel Cells &Batteries Module. The results compare well with the experimental polarization data obtained at 160 degrees C for ohmic and activation regions. The best match with the experimental data is obtained when the inlet hydrogen gas velocity is 0.133 m/s whereas inlet air velocity is 1.3 m/s for proton conductivity of 10 S/m. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Article Citation - WoS: 18Citation - Scopus: 20Three-Dimensional Non-Isothermal Model Development of High Temperature Pem Fuel Cells(Pergamon-elsevier Science Ltd, 2018) Caglayan, Dilara Gulcin; Sezgin, Berna; Devrim, Yilser; Eroglu, InciA three-dimensional non-isothermal mathematical model is developed in a triple mixed serpentine flow multichannel domain for a high temperature PEM Fuel Cell having a phosphoric acid doped PBI membrane as electrolyte and an active area of 25 cm(2) within Comsol Multiphysics. The inlet temperatures of cathode and anode reactants are taken as 438 K. Model predicts pressure, and temperature distribution along the channels and membrane current density distribution over the membrane electrodes. The model results are obtained at two different operation voltages, 0.45 V and 0.60 V. Resulting average current densities are respectively 0.313 A cm(-2) and 0.224 A cm(-2). The non-isothermal model results are compared to isothermal model results from a previous study and various other single channel non-isothermal model results available in the literature. The pressure drop at cathode compartment is predicted to be 6500 Pa, whereas it is found to be 6400 Pa for the isothermal model. The temperature difference within the system is found to be 0.18 K for the operation voltage of 0.6 V, whereas this value increases to 0.31 K for the operation voltage of 0.45 V. The temperature difference isocontours are illustrated for the whole cell. Considering changes in temperature, one can employ isothermal operation assumption for this system as an approximation and simplification for the governing equations, since the variation in the temperature within the cell is less than 1 K. It should be emphasized that multichannel model predictions are more realistic compared to single channel models. The model developed here can be extended to larger electrode active area and different multichannel configurations. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Article Citation - WoS: 44Citation - Scopus: 52Hydrogen energy systems for underwater applications(Pergamon-elsevier Science Ltd, 2022) Sezgin, Berna; Devrim, Yilser; Ozturk, Tayfur; Eroglu, InciThe most critical development in conventional underwater applications in recent years is to use hydrogen energy systems, including Air Independent Propulsion (AIP) systems. Proton Exchange Membrane (PEM) fuel cell-powered AIP systems increase interest worldwide. They offer many advantages such as longer endurance time without going to the surface for 2-3 weeks or without snorkeling with an average speed, perfectly silent operation, environmentally friendly process, high efficiency, and low thermal dissipation underwater. PEM fuel cells require a continuous source of hydrogen and oxygen as reactants to sustain a chemical reaction to produce electrical energy. Hydrogen storage is the critical challenge regarding the quality of supplied hydrogen, system weight, and volume. This paper reviewed hydrogen/oxygen storage preferences coupled with PEM Fuel Cell applications in the literature for unmanned underwater vehicles. Since underwater vehicles have different volume and weight requirements, no single hydrogen storage technique is the best for all underwater applications.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
