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Effects of laminar/turbulence modelling on the prediction of flow characteristics and heat transfer data in plate fin and tube heat exchangers

Bu çalışmada; kanat-borulu ısı eşanjörlerinin akış ve ısı transfer özelliklerinin belirlenmesinde, laminar ve türbülans modellemenin etkileri detaylı olarak araştırılmıştır. Günümüzde, hala kanat-borulu ısı eşanjörlerindeki akımın laminar veya düşük Reynolds sayılı türbülanslı akım olarak değerlendirilmesine tam olarak karar verilememiştir. Bu nedenle bu çalışmada hem laminar, hem de türbülans modelleri kullanılarak, farklı Reynolds sayılarında, dört-borulu, saptırmalı dizilişe sahip, dalgalı plakadan oluşan bir kanat-borulu ısı eşanjörü pasajında meydana gelen akış yapısı, alt plakaca yakın ve pasajın tam ortasındaki kesitlerde araştırılmış ve sonuçlar değerlendirilmiştir. Reynolds sayısı değişim aralığı 100 $\leq$ Re $\leq$ 4000 ve boyutsuz plaka açıklığı $F_s$ =0.233 olarak seçilmiştir. LES ve RANS simülasyon sonuçları deneysel sonuçlarla karşılaştırıldığında, deneye en yakın sonucu veren modelin LES türbülans modeli olduğu görülmüştür.

Kanat-borulu ısı eşanjörlerinin akış ve ısı transfer özelliklerinin belirlenmesinde laminar ve türbülans modellemenin etkisi

Present investigation provides detailed, information on effects of laminar and. turbulence modelling on the prediction of flow and heat transfer characteristics in plate fin and tube heat exchangers. In plate fin and. tube heat exchangers, there is no clear understanding on whether the flow in the heat exchanger passage is laminar or low Reynolds number turbulent flow. Therefore, in the present investigation, both laminar and turbulence models are employed in order to understand the flow and. heat transfer characteristics inside the flow passage of a. plate fin and tube heat exchanger comprised of four-row of staggered tube layout with wavy fin configuration. The flow patterns and heat transfer data in the middle of the flow passage and close to the lower plate are investigated in detail for the Reynolds number range 100$\leq$ Re $\leq$ 4000 and non-dimensional fin spacing of $F_s$ = 0.233. It is found that LES simulation gives better agreement with the experimental data comparing to the RANS equations based turbulence model simulations.

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