Numerical Investigation on Heat Enhancement Method with Using Circular Dimpled Tube

Öz

In this study, the effect of dimpled tube which is heated with constant heat flux on heat transfer enhancement is numerically investigated Using physically enhanced tube is one of the passive heat transfer enhancement methods. The reason of using dimpled tube is increase turbulence through the tube and destruct the thermal boundary layer. The numerical study is validated with an experimental study and configurations of cases are expanded with chancing pitch length. The considered cases are conducted in Reynolds number range of 3000 to 8000. Used fluid through the flow and its material copper are selected as water and copper, respectively. The k- ε RNG turbulence model is used to simulate turbulent flow adjacent the inner wall surface. The analyses are determined with Nusselt number (Nu), friction factor (f) and performance evaluation criteria (PEC).  The highest Nusselt number and the minimum friction factor is obtained when the Reynolds number of 8000, as 135.54 and 0.0599, respectively, for pitch length of 10 mm and 50 mm. The highest THP value is observed as 2.01 by the case of pitch length of 10 mm and Reynolds number of 3000.

Anahtar Kelimeler

• Dimpled tube,Numerical study,Heat transfer,Performance evaluation criteria

Dairesel Oyuntu ile Isı Transferi İyileştirilmesi Üzerine Sayısal Araştırma

Öz

Bu çalışmada sabit ısı akısı ile ısıtılmış bir boruya oyuntu yerleştirilmesinin ısı transferi iyileştirilmesi üzerindeki etkisi sayısal olarak araştırılmıştır. Fiziksel olarak boru üzerinde yapılan iyileştirme ısı transferi iyileştirilmesinin pasif metotlarından birisidir. Oyuntulaştırılmış boru kullanımının sebebi akış boyunca türbülansı arttırmak ve termal sınır tabakayı parçalamaktır. Sayısal çalışma, deneysel başka bir çalışma ile doğrulanmış ve incelenen değişen hatve uzunlukları genişletilmiştir. İncelenen analizler Reynolds sayısının 3000’den 8000’ e kadar gerçekleştirilmiştir. Akış boyunca kullanılan akışkan ve boru malzemesi sırasıyla su ve bakır olarak seçilmiştir. İç duvar etrafındaki türbülanslı akışın simülasyonu için k-ε RNG türbülans modeli kullanılmıştır. Analizlerin sonuçları Nusselt sayısı (Nu), sürtünme katsayısı (f) ve performans değerlendirme kriteri (PEC) ile değerlendirilmiştir. En yüksek Nu ve en düşük f Re sayısı 8000 iken, sırasıyla 130.54 ve 0.0453 olarak, hatve uzunluğunun sırasıyla 10 mm ve 50 mm olduğu durumlarda elde edilmiştir.

Anahtar Kelimeler

• Oyuntulaştırılmış boru,Sayısal çalışma,Isı transferi,performans değerlendirme kriteri

Kaynakça

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