Grafen-Demir Oksit Hibrit Nanoakışkanı Kullanılan Bir Isı Değiştirici Borusunun Entropi Üretim Analizi

Öz

Bu çalışmada, türbülanslı akış koşullarında bir ısı değiştirici borusunda % 0.5-1 aralığında altı farklı hacimsel karışım oranına sahip Grafen-Demir Oksit-Su hibrit nanoyakışkanın entropi üretim analizi sayısal olarak incelenmiştir. Boru üzerine sabir ısı akısı sınır şartı uygulanmış ve Reynolds sayısı çalışma aralığı 10000-50000 olarak belirlenmiştir. Sayısal analizde k − ε RNG çözüm metodu seçilmiş ve ağ bağımsızlığı çalışması gerçekleştirilmiştir. Boyutsuz entropi üretimini incelendiği sonuçlara göre, entropi üretimi, hibrit nanoakışkan hacimsel karışım oranının artmasıyla düşen bir eğilim göstermiştir. Artan Reynolds sayısı ile artış gösteren boyutsuz entropi üretim sayısı 0,5, 0,6, 0,7 ve 0,8 % hacimsel karışım oranında birim değer üzerinde daha fazla konfigürasyonda gerçekleşirken, 0,9 ve 1 % hacimsel karışım oranlasında entropi üretim sayısı için tüm değerler 40000 Reynolds sayısına kadar birim değerin altında gerçekleşmiştir. Bu sonuç, hibrit nanoakışkanın Grafen-Demir oksitinin ısı değiştiricilerde kullanılmasının termodinamik açıdan büyük avantajlar sağladığını göstermiştir.

Anahtar Kelimeler

• Nanoakışanlar
• Entropi üretimi
• Isı transferi

Entropy Generation Analysis of a Heat Exchanger Tube with Graphene-Iron Oxide Hybrid Nanofluid

Abstract

In this study, the entropy generation analysis of the Graphene-Iron Oxide-Water hybrid nanofluid with six different volumetric fractions in the range of 0.5-1% in a heat exchanger tube under turbulent flow conditions was numerically investigated. The constant surface heat flux was applied to the tube and the Reynolds number was obtained in the range of 10000-50000. The k − ε RNG solver method was selected for the turbulence method and grid independence was checked. According to the results examining the dimensionless entropy production, entropy production showed a descending trend with the increment of hybrid nanofluid volume fraction. For the dimensionless entropy generation number, which increased with the increasing Reynolds number, configurations above unity were found at the volumetric fractions of 0.5, 0.6, 0.7 and 0.8 %, in addition, all values for entropy generation number with the volume fractions of 0.9 and 1 % were realized below unity up to the Reynolds number of 40000. This result showed that the use Graphene-Iron oxide of hybrid nanofluid in heat exchangers provides great advantages in terms of thermodynamics.

Keywords

• nanofluids
• entropy generation
• heat transfer

Kaynakça

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