Yazar "Aydin, Ugur" seçeneğine göre listele

Listeleniyor 1 - 3 / 3
  • Küçük Resim Yok
    Öğe
    Development of titanium bipolar plates fabricated by additive manufacturing for PEM fuel cells in electric vehicles
    (Pergamon-Elsevier Science Ltd, 2022) Celik, Selahattin; Timurkutluk, Bora; Aydin, Ugur; Yagiz, Mikail
    Bipolar plates (BPs) are one of the main parts of proton exchange membrane (PEM) fuel cell stacks, which constitute a significant percentage of a PEM fuel cell system in terms of cost, weight, and structural strength. Although frequently used graphite BPs have low density, high conductivity, and high corrosion resistance, machining the desired flow channels on these plates is challenging. On the other hand, BPs made of various materials rather than graphite can be also fabricated by additive manufacturing methods. These methods can be considered as a reasonable alternative to conventional machining for the fabrication of graphite BPs in PEM fuel cells regarding material cost, fabrication of flow channels, and some post-processes in which the large-scale manufacturing of graphite BPs is more complex. This study offers a comparison of formed stainless-steel, additive manufactured titanium and machined composite graphite plates having the same flow-field geometry as a bipolar plate. In addition, titanium BPs are coated with gold and their performances are compared. Among the cells tested, the highest peak power of 639 mWcm-2 is measured from the cell with 450 nm gold coated titanium BP, whereas those of the cell with con-ventional graphite and stainless-steel BP are only around 322 mWcm-2 and 173 mWcm-2, respectively. Moreover, a new titanium bipolar plate design providing high specific power density is also presented. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
  • Küçük Resim Yok
    Öğe
    Experimental investigation on the effect of anode functional layer on the performance of anode supported micro-tubular SOFCs
    (Pergamon-Elsevier Science Ltd, 2022) Timurkutluk, Cigdem; Bilgil, Keremhan; Celen, Ali; Onbilgin, Sezer; Altan, Tolga; Aydin, Ugur
    In this study, anode supported micro-tubular solid oxide fuel cells (SOFCs) are fabricated by extrusion method and the effects of powder size, thickness and sintering temperature of the anode functional layer (AFL) on the electrochemical performance is experimentally investigated. For this purpose, four different commercial NiO powders are tested as initial powder for the fabrication of the anode functional layer. The thickness of AFL is also considered by varying the number of coatings. After deciding the optimum initial NiO powder size used in AFL and AFL thickness, the effect of pre-sintering temperature is examined. The performance tests are performed at an operating temperature of 800 degrees C under hydrogen and air. The microstructures of the samples are also investigated by a scanning electron microscope. The best peak power density is obtained as similar to 0.5 W/cm(2) from the cell having a single layer anode functional layer pre-sintered at 1250 degrees C prepared by NiO powders with 4 m(2)/g surface area. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
  • Küçük Resim Yok
    Öğe
    Investigation of formability of metallic bipolar plates via stamping for light-weight PEM fuel cells
    (Pergamon-Elsevier Science Ltd, 2020) Karacan, Kivanc; Celik, Selahattin; Toros, Serkan; Alkan, Mahmut; Aydin, Ugur
    Bipolar plates (BPs) are one of the main members which constitute a significant percentage of a fuel cell system in terms of cost, weight and structural strength. Although frequently used graphite BPs have low density, high conductivity and corrosion resistance, machining the desired flow channels on the graphite plates is an important issue. On the other hand, metallic BPs can be considered a reasonable alternative material to graphite in the view of the material cost, fabrication of flow channels and some post-processes in which the largescale manufacturing of graphite BPs is more complex compared to cutting and stamping processes for metal ones. This study offers a comparison of the formability of four different metals with four flow channel depths as bipolar plates formed by stamping. 304 Stainless Steel (SS 304), pure Titanium Grade2 (CP-Ti) and Aliminium (Al 6016 and Al 3104) are chosen as the BP materials. A serpentine type flow channel with two different channel widths are formed on to 0.1 mm thick sheets. The channel width is chosen as 1.2 mm and 1.8 mm for the channel depths of 0.36 mm-0.55 mm, and 0.54 mm-0.82 mm, respectively. The stamping processes of the BPs materials are simulated via commercially available eta/ Dynaform v5.9.4. software and formability characteristics are obtained for sixteen various cases. As a result, it is determined that SS 304 is the more appropriate material in the view of the formability for such a complex form. (c) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.