Azize AKKOCA, Beşir ŞAHİN, Mustafa TUTAR

Effect of different wall functions on the prediction of flow and heat transfer characteristics in plate fin and tube heat exchangers

Bu çalışmada, Fluent yazılım programında mevcut bulunan duvar fonksiyonlarının, kanat borulu ısı eşanjörlerinde akım ve ısı transfer özelliklerinin belirlenmesindeki etkileri Reynolds Sayılarının 500$\leq$ Re $\leq$ 6000 aralığında ve $F_s$ = 0.233 boyutsuz plaka açıklığında araştırılmış ve sonuçlar deneysel çalışma ile karşılaştırılmıştır. Bilindiği üzere duvar fonksiyonları, viskoziteden etkilenmiş bölge ile tamamen türbülanslı akışın hakim olduğu bölge arasında bir köprü görevi kurmaktadır. Dö sıralı, saptırmak boru konfigürasyonuna ve dalgalı plakaya sahip bir kanat- borulu ısı eşanjöründeki akış ve ısı transfer özelliklerinin belirlenmesinde Standard $k-\varepsilon$ and RNG $k-\varepsilon$ türbülans modelleri kullanılmıştır. Bu ısı eşanjör modeli literatürdeki bir deneysel çalışmadan alınmış ve deneye en yakın sonucu veren duvar fonksiyonu iyileştirilmiş Duvar Fonksiyonu olarak belirlenmiştir.

Kanat-borulu ısı eşanjörlerinin akım ve ısı transfer özelliklerinin belirlenmesinde farklı duvar fonksiyonlarının etkisi

In the present study, effects of wall functions available in the Fluent software on the fluid flow and heat transfer characteristics of a plate fin and tube heat exchanger are investigated in the range of 500$\leq$ Re $\leq$ 6000 for a non-dimensional fin spacing of $F_s$ = 0.233 and the results are compared with experimental data. As it is well-known, wall functions are used to bridge the viscosity-affected region between the wall and the fully turbulent region in the flow domain. Both Standard $k-\varepsilon$ and RNG $k-\varepsilon$ turbulence models are employed in order to predict the flow and heat transfer characteristics inside the flow passage of the plate fin and tube heat exchanger comprised of four-row of staggered tube layout with wavy fin configuration. The test heat exchanger model is selected from the experimental work exists in the literature and the best wall function that has close agreement with the experimental data is chosen as Enhanced Wall Treatment.

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