Department of Manufacturing Engineering
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Browsing Department of Manufacturing Engineering by Author "Devrim, Yılser"
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Item DESIGN, MANUFACTURING AND TESTING OF HIGH TEMPERATURE PEM FUEL CELL STACK(2022-02-15) Budak, Yağmur; Devrim, YılserIn recent years, the need for energy has been increasing with the developing of technology and population. The proton exchange membrane fuel cell (PEMFC) considered to be the preferred alternative energy technology in recent years due to its high efficiency, low emission, high power density, quiet operation and short start-up period. High Temperature PEMFC (HT-PEMFC) type PEMFC provide easy water management and high carbon monoxide (CO) tolerance thanks to over 100 oC of operation temperature. PEMFC must have high CO tolerances for PEMFC commercialization and usage of reformed gases obtained from a short process of gases such as natural gas and methane, which are frequently used today. In this thesis, the design, manufacturing and testing of a nominal 300 W HT-PEMFC stack which has 150 cm2 active area and 12 cells were performed. The materials chosen to manufacture this stack are composite graphite bipolar plates, eloxal coated aluminum plates, Gold-coated copper plate current collectors, stainless steel connections, Viton® gasket, Pt/C coated carbon paper gas diffusion layer and PBI membranes. In the scope of the thesis, the current test station was upgraded in order to test HT PEMFC stack by reformate gas mixture. Firstly, a single HT-PEMFC performance test was performed with Hydrogen (H2) gas and reformate gas mixture supply at 160oC in order to obtain the design parameters of the stack would be produced. The current density value at 0.6 V was obtained as 0.33 A/cm2 with H2 supply, and 0.28 A/cm2 was obtained with reformate gas mixture supply. Then, according to single HT-PEMFC test result, the stack of HT-PEMFC was designed. After the design of the stack, the pressure drop on the bipolar plate was analyzed for 3 different gas flow rates using Solid Works® Flow Simulation program. The pressure losses were determined maximum 83.5 Pa for H2 at 0.5 slpm and 129.83 Pa to reformate gas mixture (H2/CO2/CO;75/22/3) at 0.56 slpm. After that, the performance of stack produced were tested by pure H2 and reformate gas mixture supply. The stack power with pure H2 feed was 320 W at 7.2 V operation voltage, it was 218 W at 7.2 V for reformate gas mixture. In addition, with the H2 supply, the total efficiency of the stack was 79 %, while this efficiency decreases to 76 % with its reformate gas mixture supply. These losses can be ignored considering the advantages of reformate gas mixture use and the importance of fuel cell for commercialization.