Yazar "Acar, Mahmut Caner" seçeneğine göre listele

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    A MODELING STUDY ON USING VARIOUS BASE MATERIALS AS COOLING PLATE IN PROTON EXCHANGE MEMBRANE FUEL CELLS
    (Begell House Inc, 2023) Acar, Mahmut Caner
    Heat management in proton exchange membrane fuel cells is seen as one of the most important issues for their control, durability and performance. In this work, a detailed three-dimensional thermal analysis for the cooling plate of proton exchange membrane fuel cells is carried out by using the computational fluid dynamics method. In this context, the thermal performance of different cooling plate materials, viz., graphite, titanium alloy, stainless steel, and aluminum that are commonly used as the base material for bipolar plates, is investigated based on the temperature uniformity index, temperature difference between the maximum and minimum temperatures, maximum temperature, and average temperature. Comparing with other materials, the minimum values for the temperature uniformity index (1.03 degrees C), temperature difference (3.74 degrees C), and maximum surface temperature (68.77 degrees C) are obtained with aluminum at the heat flux and Reynolds number of 3250 W/m(2) and 1200, respectively. Since a quite small difference is observed between the maximum and minimum surface temperatures, the highest average surface temperature value of 67.29 degrees C is obtained in the case of aluminum. Therefore, it can be concluded that the best cooling performances can be achieved by using aluminum. Since the highest value for temperature uniformity index is estimated with titanium alloy, this material exhibits the worst cooling performance.
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    Channel to rib width ratio effect on thermal performance of cooling plate in polymer electrolyte membrane fuel cell
    (Wiley-V C H Verlag Gmbh, 2022) Acar, Mahmut Caner
    Ensuring a homogeneous temperature distribution inside a polymer electrolyte membrane fuel cell stack is crucial to fuel cell performance and durability, and cooling channels are responsible for this. In this study, a three-dimensional numerical investigation is performed on a channel to rib width ratio (CR) based on serpentine flow field design. The cooling performance of various designs having different CR values is considered and compared according to the temperature uniformity index, the temperature difference between the maximum and minimum temperature, average bottom temperature, and pressure drop between the inlet and outlet of the cooling channels. Results demonstrate that the average temperature, temperature uniformity index, temperature difference, and pressure drop decrease by about 5%, 40%, 37%, and 79%, respectively, when CR is increased from 0.33 to 3.00. More uniform temperature distribution and thus, better cooling performance is achieved for CR = 3.00, especially at low Reynolds numbers and high heat fluxes. Also, the lowest pressure drops are obtained when CR is 3.00 under all considered operating conditions.
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    Computational Thermal Analysis of Divergent and Convergent Flow Channels for Cooling Plates in PEM Fuel Cells
    (2023) Acar, Mahmut Caner
    During the operation of polymer electrolyte membrane fuel cells excess heat is generated as a result of electrochemical reactions. This heat raises the temperature of the polymer electrolyte membrane fuel cells, which can damage the membrane. Homogeneity of the temperature through the fuel cell is important in terms of stability and performance. Thermal management is therefore essential and is provided by the cooling channels formed on the bipolar plates or cooling plates. In this paper, a three-dimensional computational analysis of the cooling plate with divergent and convergent flow field designs is carried out. In this context, heat transfer and fluid flow performances of these two different flow fields are considered in terms of temperature uniformity, maximum temperature and pressure drop. Numerical results demonstrated that the more uniform temperature distribution along the fuel cell could be achieved with divergent flow field design. Furthermore, when a divergent design is used, the maximum surface temperature of the cooling plate and the pressure drop between the inlet and outlet of the channel are reduced.
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    Elektrokimyasal hidrojen kompresörünün performansına etki eden parametrelerin deneysel incelenmesi
    (Niğde Üniversitesi / Fen Bilimleri Enstitüsü, 2012) Acar, Mahmut Caner; Mat, Mahmut D.
    Tez kapsamında, hidrojen gazını mekanik kompresörlere ihtiyaç duymadan yüksek basınçlara çıkarabilen, sessiz ve gürültüsüz çalışan ve yüksek saflık değerlerinde hidrojen gazının elde edilebilmesine olanak sağlayan tek hücreli bir elektrokimyasal hidrojen kompresörü (EHK) geliştirilmiş ve performansa etki eden parametreler deneysel olarak incelenmiştir. Deneylerin daha kontrollü ve güvenli bir şekilde gerçekleştirilebilmesi için EHK sistemine uyumlu özel bir elektronik kontrol ünitesi (data logger/kontrolör) ve yüksek basınç test istasyonu imal edilmiştir. EHK sisteminin performansına etki eden basınç, sıcaklık, hidrojen debisi, nemlilik ve akım yoğunluğu gibi parametreler deneysel olarak incelenmiştir. Sıcaklığın artmasıyla hücre performansının arttığı gözlemlenirken debi değişimimin belirli bir değerden sonra performansa etki etmediği tespit edilmiştir.
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    Experimental determination of NiFe2O4-water nanofluid thermophysical properties and evaluation of its potential as a coolant in polymer electrolyte membrane fuel cells
    (Pergamon-Elsevier Science Ltd, 2024) Sahin, Fevzi; Acar, Mahmut Caner; Genc, Omer
    Heat is generated as a byproduct of the electrochemical reactions of a polymer electrolyte membrane fuel cell. This heat raises the temperature of the system, and if it is not properly removed from the cell, it can cause membrane damage and overheating. Thermal management is thus critical for PEM fuel cell stability, efficiency, and safety. This paper investigates the potential use of NiFe2O4-water nanofluid as a novel coolant for PEM fuel cells. To determine the nanofluid thermophysical properties, an experimental study for different mass% concentrations of NiFe2O4-water nanofluid is first performed. Then, a three-dimensional CFD model is built to demonstrate the effect of nanofluid use on the thermal performance of a cooling plate. Simulation results show that replacing water with 0.5% NiFe2O4 nanofluid improves temperature uniformity by 11.97%. Furthermore, nanofluid cooling reduces maximum surface temperature by up to 0.75 degrees C while increasing pressure drop by 5.6%, implying higher pumping power.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Modeling the influence of coolant flow directions on thermal performance of PEM fuel cell cooling plates with serpentine and straight flow channels
    (Elsevier, 2023) Acar, Mahmut Caner
    The flow direction of the coolant in cooling channels relative to the reactant gasses is critical for thermal performance. Here, four different flow patterns for the serpentine channel and three different flow patterns for the straight channel are numerically studied based on index of uniform temperature (IUT), maximum temperature, and pressure drop. For the serpentine flow channel, the left-cross pattern has the lowest index of uniform temperature and maximum temperature, while the right-cross pattern has the highest. The parallel and left-cross patterns exhibits best and worst performances, respectively, in terms of cooling performance for the straight channel. Nearly the same pressure drops are obtained for all flow patterns of both channel configurations. When the parallel pattern is used instead of the counter pattern in the straight channel and the left-cross pattern is used instead of the right-cross pattern in the serpentine channel, the IUT improves by 55.45% and 27.39%, respectively.