Yazar "San, Fatma Gul Boyaci" seçeneğine göre listele

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    Experimental scale up techniques for PEMFC: Fluid mechanics approach
    (Pergamon-Elsevier Science Ltd, 2026) Tol, Guneyhan; Turkmen, Anil Can; Celik, Cenk; San, Fatma Gul Boyaci
    This study designs and manufactures three fuel cell sizes, varying only the active area, to evaluate the scaling effect on PEM fuel cell performance. Produced fuel cells with active areas of 50 cm2, 100 cm2 and 225 cm2 are experimentally tested under identical conditions. All cells are made of materials with identical properties. Flow rate calculations are based on the current density obtained from the active area size. A single-phase isothermal fluid mechanics model based on the finite element method is developed for all fuel cells to ensure that hydrogen flows at the same average linear velocity throughout channels of equal depth. Velocity calculations and pressure drops are analysed in the model for different stoichiometries. The model is validated by comparing pressure drops in the produced cells with model predictions. The performance of cells with the same active area as the only variable is compared under the same conditions.
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    Regenerative Fuel Cell Systems for Aerospace Applications: A Short Review
    (Asme, 2026) Sozbir, Nedim; Bulut, Murat; San, Fatma Gul Boyaci
    Hydrogen has emerged as a promising energy carrier for aerospace applications due to its high specific energy and suitability for long-duration missions. Fuel cells (FCs), electrolyzers, and regenerative fuel cell systems (RFCSs) represent key electrochemical technologies within aerospace energy architectures, enabling power generation, gas production, and energy storage. This review examines these three classes of electrochemical systems within a unified, system-level framework tailored to aerospace applications. Fuel cell technologies are reviewed for power generation in applications such as landers, aircraft, unmanned aerial vehicles (UAVs), auxiliary power units (APUs), and stationary backup systems. Proton exchange membrane (PEM) electrolysis is discussed as a viable approach for hydrogen and oxygen production to support both terrestrial infrastructure and onboard aerospace operations. Regenerative fuel cell systems, which integrate an electrolyzer and a fuel cell to enable cyclic energy storage, are then evaluated as advanced energy storage solutions. A system-level comparison between RFCSs and state-of-the-art, space-qualified lithium-ion battery systems is presented based on reported specific energy, system mass, and discharge-duration data. The analysis highlights that RFCSs offer advantages in specific energy and total system mass under long discharge-duration conditions, making them particularly suitable for extended aerospace missions. Key technical challenges and design considerations, including system integration, energy density, and operational performance, are also discussed. Overall, this review provides a coherent assessment of electrochemical energy systems and clarifies the potential role of regenerative fuel cell technologies in future long-duration and sustainable aerospace energy applications.
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    Synergistic effects of temperature, gas flow, and clamping force on fuel cell performance
    (Pergamon-Elsevier Science Ltd, 2026) Yilgin, Busra; San, Fatma Gul Boyaci; Celik, Cenk
    Fuel cells are recognized for their high efficiency and environmentally friendly characteristics, with applications ranging from portable devices to transportation systems. The performance of fuel cells is significantly influenced by operating parameters and the mechanical design of components. This study investigates the effects of key operating conditions, including cell temperature, anode and cathode flow rates, and torque applied to the end plate, on fuel cell performance using Response Surface Methodology (RSM). A stainless steel end plate and a centered bolt arrangement configuration were employed to ensure homogeneous pressure distribution. The analysis included 27 experiments to evaluate current density, power density, and internal resistance under varying operating conditions. The findings highlight that cell temperature and cathode flow rate are critical factors influencing performance. At the optimal cell temperature, enhancements in reaction kinetics and proton conductivity resulted in a maximum current density of 513.93 A/cm2 and power density of 307.20 W/cm2, while the internal resistance was minimized. The cathode flow rate was also observed to play a decisive role in performance. In contrast, torque applied to the end plate exhibited a negligible influence on performance within the investigated range, confirming the effectiveness of the closure design. Furthermore, maintaining the cell temperature at an optimal level in a fuel cell has enhanced the impact of gas flow rates on performance. These results emphasize that in fuel cell design and operation, optimizing individual parameters alone is insufficient; the interactions and synergistic effects between parameters must also be considered.