Yazar "Kaska, Onder" seçeneğine göre listele

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    Öğe
    Investigations of flow structures and performances of heat transfer in semi-circular grooved ducts by applying field synergy principal analysis: An experimental and numerical study
    (Pergamon-Elsevier Science Ltd, 2023) Tokgoz, Nehir; Erdinc, Mehmet Tahir; Kaska, Onder; Sahin, Besir
    The present study aimed at investigating the flow structure and heat transfer mechanism through the corrugated channel experimentally and numerically. Particle imaging velocimetry (PIV), which can give detailed information about the wake and shear flow regions, was used for the experiments. The experimental and numerical works were performed considering Reynolds numbers in the range of 6 x 103 <= Re <= 12 x 103 and 3 x 103 <= Re <= 2 x 104, respectively. In the numerical part, aspect ratios (R/hp) of examined grooves have been chosen as 0.1, 0.2, and 0.3, and for the experiment, only one aspect ratio was chosen which was 0.3. The experimental studies were conducted regarding different Reynolds numbers as well as the distributions of instantaneous and timeaveraged velocity contours, Turbulence Kinetic Energy, Reynolds shear stress, and vorticity. The standard SST k-omega turbulent method was employed for the case of numerical study to predict the thermal performance (eta) along with Nusselt numbers (Nu) the friction factors (f) and local field synergy angles (alpha, beta) were calculated. As a result, the Nusselt number (Nu) values of the corrugated channels were higher than the parallel plate, and the increment in the Nusselt number initially increased and later decreased with Reynolds numbers for all aspect ratios considered.
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    Öğe
    Nanoakışkan Kullanımında Ani Daralma ve Ani Genişleme Bağlantı Elemanlarının Akış Karakteristiklerinin Sayısal Olarak İncelenmesi
    (2021) Tokgöz, Nehır; Avcı, Mürüvvet; Erdinç, Mehmet Tahir; Kaska, Onder
    Yapılan bu çalışmada endüstriyel sistemlerde en çok kullanılan iki farklı tesisat bağlantı elamanının (ani daralma ve ani genişleme) içerisinden nanoakışkan geçirilerek bu bağlantı parçalarının basınç düşüşleri ve kayıp katsayıları sayısal olarak incelenmiştir. Nanoakışkan, temel akışkan su alınarak içerisine farklı konsantrasyonlarda alüminyum, bakır ve titanyum esaslı nanoparçacıkların eklenmesiyle elde edilmiştir. Artan konsantrasyonun basınç kaybı ve akış yapısı üzerinde etkisini incelemek için farklı konsantrasyonlarda farklı nanoakışkanlar incelenmiştir. Nanoakışkanların termofiziksel özellikleri daha önce yapılmış olan çalışmalardan alınmıştır. Hesaplama sonuçları, literatürdeki sonuçlar ile doğrulanmıştır. Sayısal çözümlemelerde yaygın olarak tercih edilen Standart k- ε ve Standart k- ω türbülans modeli olmak üzere 2 farklı türbülans modeli kullanılmıştır. Elde edilen hesaplar sonucunda incelenen her akışkanda, konsantrasyon arttıkça viskozitenin artışı ile yerel kayıpların da arttığı ortaya konulmuştur. En uygun türbülans modelinin bütün bağlantı parçaları için k-ε olduğu belirlenmiştir.
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    Öğe
    Summer period analysis of the rotary desiccant - hybrid cooling system combined with solid oxide fuel cells using human waste fuel
    (Elsevier, 2024) Cerci, Kamil Neyfel; Silva, Ivo Rafael Oliveira; Kaska, Onder; Hooman, Kamel
    This paper proposes and simulates a desiccant air cooling system integrated with a vapor compression cooling unit and a heat recovery unit for an office building in & Ccedil;anakkale, Turkey, during the summer season. The required electrical energy for equipment of the proposed system is supplied by an Solid Oxide Fuel Cells (SOFC) unit using human waste as fuel. Moreover, some of the waste heat generated by the SOFC is used to regenerate the desiccant wheel. The simulation also includes the effects of three different refrigerants for the vapor compression cooling unit. Among the refrigerants, the highest electrical COP was obtained for the system using R1234ze(Z), which is 3.14% and 2.40% higher than the systems using R717 and R1233zd(E), respectively. Additionally, the system using R1234ze(Z) achieved electrical savings of 9.97% and 9.23% compared to the other systems. These electrical savings resulted in fuel savings of 1.19% and 0.90% for R1234ze(Z) compared to R717 and R1233zd(E), respectively. During the summer season, the electricity production from the existing SOFC unit met 82.00% of the total electricity consumption of the desiccant hybrid cooling system. Furthermore, a difference of 3984.56 kWh in primary energy consumption was identified between the desiccant hybrid cooling systems operating with the SOFC and without the SOFC during the summer season.