Eliptik Boru Demeti Üzerinden Geçen Nanoakışkanların Laminer Akışının Isı Transferine Etkisi

Bu çalışmada, sabit duvar sıcaklığına sahip eliptik boru demeti üzerinden geçen CuOsu nanoakışkanın laminer akışının ısı transferine ve sürtünme faktörüne etkileri sayısal olarak incelenmiştir. Çalışmada, farklı kesit alanına sahip eliptik borular kademeli olarak yerleştirilmiş ve analizler iki boyutlu olarak gerçekleştirilmiştir. Kullanılan eşitlikler, sonlu hacimler metodu ile SIMPLE algoritması kullanılarak çözülmüştür. Sayısal incelemelerde, nanoakışkan tipi ve partikül hacim oranı (j) sabit tutulmuş, eliptik kanalın en/boy oranı (AR) ve Reynolds sayısı (Re) değiştirilerek incelemeler gerçekleştirilmiştir. Bu parametrelerin ısı transferi karakteristiği ve sürtünme faktörü üzerindeki etkileri taban akışkan ile de karşılaştırılmıştır. Boru demeti üzerinden nanoakışkanların laminer akışında anlık hız ve sıcaklık dağılımları elde edilmiştir. Sayısal sonuçlar, ısı transferindeki iyileşmenin eliptik kanal kesitinden ve Reynolds sayısından oldukça etkilendiğini göstermiştir. Nanoakışkan kullanımı ile ısı transferinin de arttığı, ancak bu artışın sürtünme faktöründe de bir miktar artışa sebep olduğu gözlemlenmiştir. En yüksek ısı transferi performansı, AR=1,0 ve Re=1000’de yaklaşık olarak %15 olarak elde edilmiştir. Çalışma sonucunda boru demetleri üzerinden nanoakışkanların laminer akışı için en iyi termo-hidrolik performansı sağlayan parametreler belirlenmiştir. En iyi termohidrolik performans Re=1000 için AR=0,5’te yaklaşık olarak %12 olarak elde edilmiştir.

The Effect on the Heat Transfer of LaminarNanofluid Flow over the Elliptic Tube Bundle

In this study, the effect of the laminar flow of CuO-water nanofluids through the elliptical tube bundle with constant wall temperature on the heat transfer and friction factor are investigated numerically. In the study, elliptical tubes with different cross-sectional area are placed staggered and the analyses are carried out for two dimensions. The governing equations are solved by using SIMPLE algorithm with finite volume method (FVM). In the studies, the nanofluid type and particle volume fraction (j) are kept constant, Reynolds number (Re) and aspect ratio of the elliptic channel (AR) are changed. The effects on the friction factor and the heat transfer characteristics of these parameters are also compared with the base fluid. In the laminar flow of the nanofluids over the tube bundle, instantaneous velocity and temperature distributions are obtained. Numerical results have shown that the improvement in heat transfer is highly affected by the elliptic channel cross-section and Reynolds number. It has been observed that the heat transfer increases with the use of nanofluid, but this increase also causes slightly increase in friction factor. The highest heat transfer performance is obtained as approximately 15% at AR=1,0 and Re=1000. As a result of the study, the parameters providing the best thermo-hydraulic performance for the laminar flow of the nanofluids on the tube bundles are determined. The best thermo-hydraulic performance is obtained as approximately 12% fort Re=1000 at AR=0,5.

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