Electrocatalyst development and modeling of nonisothermal two-phase flow for PEM fuel cells

Fıçıcılar, Berker
A macro-homogeneous, nonisothermal, two-phase, and steady state mathematical model is developed to investigate water and thermal management in polymer electrolyte membrane (PEM) fuel cells. An original two-phase energy balance approach is used to catch the thermal transport phenomena in cases when there is a signi cant temperature di erence between the fuel cell temperature and the reactants inlet temperatures like during cold start-up. Model considers in depth electrode kinetics for both anode and cathode reactions. External and internal mass transfer resistances on fuel cell performance are accounted by means of a thin-film and agglomerate approach. Developed model accounts for all substantial transport phenomena including diffusion of multi-component gas mixtures in the porous media, electrochemical reactions in the catalytic regions, water and proton transport through the solid polymer electrolyte, transport of electrons within the solid matrix, heat transport in the gas and solid phases, phase change and transport of water through porous diffusion media and catalyst layers. In this study, it is truly shown how significant heat and water transport are to overall fuel cell performance. Model predictions are validated by comparison with experimental data, involving polarization curves, saturation and temperature gradients. For optimal electrode kinetics purposes, an alternative novel hollow core mesoporous shell (HCMS) carbon supported Pt and Pt-Pd electrocatalysts were synthesized by microwave irradiation. HCMS carbon spheres were produced by two different carbon precursors with the template replication of solid core mesoporous shell (SCMS) silica spheres. Compared to Pt/VX and ETEK electrocatalysts, HCMS carbon based Pt and Pt-Pd electrocatalysts showed promising cathode and anode electrodics performance in the fuel cell environment.


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DEVRİM, YILSER; Devrim, Huseyin (2015-06-29)
In this study, an air-cooled Proton Exchange Membrane Fuel Cell (PEMFC) short stack with Nafion/Silica nanocomposite membrane was designed and fabricated for net 100 W net power output to improve the stack performance at low relative humidity conditions. Composite membrane was prepared by solution casting method. Gas Diffusion Electrodes (GDE's) were produced by ultrasonic spray coating technique. Short stack design was based on electrochemical data obtained at 0.60 V was 0.45 A/cm(2) from performance tests...
PEM fuel cell degradation: numerical investigation and effects on the performance of solar-hydrogen based renewable energy systems
Özden, Ender; Tarı, İlker; Department of Mechanical Engineering (2015)
A hybrid (Solar-Hydrogen) renewable energy system consisting of Photovoltaic (PV) panels, Proton Exchange Membrane (PEM) fuel cells, PEM based electrolyzers and hydrogen storage has been investigated for a stand-alone application. A complete model of the hybrid renewable energy system has been developed using TRNSYS against a reference system, which was established for the emergency room of Keçiören Research and Training Hospital in Ankara. The main goal of the study is to verify that the system meets the e...
Nafion/titanium silicon oxide nanocomposite membranes for PEM fuel cells
DEVRİM, YILSER; Erkan, Serdar; BAÇ, NURCAN; Eroğlu, İnci (2013-04-01)
In the present study, Nafion/Titanium Silicon Oxide (TiSiO4) nanocomposite membranes were prepared by recasting method for proton exchange membrane fuel cells. The composite membrane containing 10wt% TiSiO4 had a membrane thickness of 80 mu m. The membrane was characterized by thermogravimetric analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM). SEM and XRD results have proven the uniform and homogeneous distribution of TiSiO4 in Nafion, and consequently, the crystalline character of ...
Development of self-humidifying nano-composite membrane for polymer electrolyte membrane fuel cell
Çaçan, Umut Baki; Özkan, Necati; Devrim, Yılser; Department of Polymer Science and Technology (2015)
Low humidity self-humidifying nano-composite membrane electrode assemblies (MEA) were developed for Polymer Electrolyte Membrane Fuel Cell (PEMFC) working at elevated temperatures. The nano-composite membranes were prepared by adding nano-sized silica particles (SiO2) or inorganic fillers with a size of approximately 20 nm to a polymeric material which is commercially named as Nafion (Perfluoro Sulfonic Acid/PFSA). The particle content of the nano-composite membranes were between 2.5 – 10 wt. %. In this man...
Modeling and sensitivity analysis of high temperature PEM fuel cells by using Comsol Multiphysics
Sezgin, Berna; Caglayan, Dilara Gulcin; DEVRİM, YILSER; Steenberg, Thomas; Eroğlu, İnci (2016-06-22)
The 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 ...
Citation Formats
B. Fıçıcılar, “Electrocatalyst development and modeling of nonisothermal two-phase flow for PEM fuel cells,” Ph.D. - Doctoral Program, Middle East Technical University, 2011.