Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Determination of Preparation Conditions for Membrane Electrode Assembly of Pem Electrolyzer(Izmir Institute of Technology, 2013) Düzgören, Derya; Şeker, Erol; Şeker, Erol; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe aim of this thesis is to investigate the effect of preparation conditions of Membrane Electrode Assembly (MEA) on the hydrogen production of a single cell Proton Exchange Membrane (PEM) electrolyzer operated at room temperature and atmospheric pressure. In the first part of the thesis, the catalyst ink, without the metal catalysts, coated membrane (MEA), with the 16 cm2 active area, were produced. For the proton exchange membrane Nafion-117 membrane was used. An experimental design (Small Central Composite Design) was done in order to investigate the optimum preparation conditions (such as temperature, pressure and holding time in the hot press) for MEA of PEM electrolyzer. The responses were water vapor permeability and the surface resistance of the catalyst ink coating. The optimum conditions that gave maximum permeability and lowest surface resistance were found at 135°C of the hot press temperature, 5000 pound of pressure and 3 minute of holding time. In the second part, Membrane Electrode Assembly containing Pt and Pt/Ru metals in the catalyst ink was produced using the optimum conditions found in the first part. Then the prepared MEA was compared with the commercial MEA containing Pt and Pt/Ru metals using our home made single PEM electrolyzer.Master Thesis Performance Assessment of Proton Exchange Membrane Fuel Cell (pemfc) Stack by Means of Semi-Empirical Model(Izmir Institute of Technology, 2011) Kalender, Eda; Özerdem, Barış; Özerdem, Mehmet Barış; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe charge transfer coefficient estimated around 0.4In this study, the performance of a 10 kW peak power proton exchange membrane fuel cell stack under different operating conditions was investigated experimentally by its i-V polarization curve. The stack has been fed with pure hydrogen and air and PEM fuel cell stack has active area 200 cm2 and is composed of 75 single cells. The stack was tested for different reactant inlet temperatures as from 50 °C to 65 °C with 5 °C intervals keeping constant other conditions and for different relative humidities as 75%, 85% and 95% again keeping constant other operation conditions. Then the analytical nonlinear model adapted to describe the polarization curve has been discussed. Model parameters have been simultaneously estimated by fitting data into model by using LABFIT nonlinear regression program. These parameters are the cathode exchange current density, charge transfer coefficient and polymer electrolyte membrane internal resistance. The polarization curve of the fuel cell stack showed the stack performance improved from 50 °C to 65 °C temperature with the decrease of voltage losses. However the decrease of relative humidity from 95% to 75% did not show any explicit effect onto stack performance. Data fitting was obtained with reasonable model parameters in accordance with literature and with high coefficient of determination (R2) values. The effect of temperature on model parameters was also investigated. The cathode exchange current density value increased from 2.247X10-6 A/cm2 at T=50 °C to 5.643X10-6 A/cm2 at T=65 °C. The charge transfer coefficient estimated around 0.4 coherently with literature. The membrane internal resistance value followed the slightly decreasing tendency with increasing temperature as the value around 0.1 cm2.