EFFECTS OF RECTANGULAR-SHAPED TURBULATORS ON HEAT TRANSFER, FRICTION FACTORS, AND ENTROPY

Abstract

In this study, the effects of turbulators with different P ratios placed in a circular cross-section test pipe under turbulent flow conditions using water as the working fluid on heat transfer, friction factor (f), and entropy production were investigated using Ansys-Fluent 2021. The lowest Nu was calculated as 111 at Re=11825 for P=6, while the highest Nu was calculated as 219 at Re=19133 for P=1. The increase in Nu values for P = 6, 3, 2, 1.5, 1.2, and 1 compared to the plain pipe is 10.34%-11.64%; 17.39%-18.78%; 25.31%-26.56%; 34.42%-35.88%; 43.53%-44.87%; and 50.36%-51.47%, respectively. In turbulent situations, the highest entropy production rate was found to be 0.3631 W/mK at Re=11825 for P=6, while the lowest entropy production rate was found to be 0.2215 W/mK at Re=19133 for P=1. The minimum and maximum Ns reduction compared to the empty pipe was calculated as 7.13% for Re=19133 at P=6 and 46.62% for Re=11825 at P=1, respectively. In turbulent conditions, the highest Bejan number was found to be 0.9931 at Re=11825 for P=6. As a result, it was concluded that a ratio of P=1 provides maximum benefit in terms of heat transfer, while a ratio of P=6 is ideal in terms of total entropy production.

Keywords

• Entropy
• Heat transfer
• Friction factor
• Turbulator
• Reynolds number

Dikdörtgen Şekilli Türbülatörlerin Isı Transferi, Sürtünme Faktörü ve Entropi Üzerindeki Etkileri

Abstract

Bu çalışmada, çalışma akışkanı olarak su kullanılan, türbülanslı akış şartlarında dairesel kesitli bir test borusuna yerleştirilen farklı P oranlarına sahip türbülatörlerin ısı transferi, sürtünme faktörü (f) ve entropi üretimi üzerindeki etkileri Ansys-Fluent 2021 kullanılarak incelenmiştir. En düşük Nu, P=6 için Re=11825'te 111 olarak hesaplanırken, en yüksek Nu, P=1 için Re=19133'te 219 olarak hesaplanmıştır. P=6, 3, 2, 1,5, 1,2 ve 1 için Nu değerlerindeki artış düz boruya göre sırasıyla %10,34-%11,64; %17,39-%18,78; %25,31-%26,56; %34,42-%35,88; %43,53-%44,87; ve %50,36-%51,47 olarak gerçekleşmiştir. Türbülanslı durumlarda, en yüksek entropi üretim oranının P=6 için Re=11825'te 0,3631 W/mK olduğu, en düşük entropi üretim oranının ise P=1 için Re=19133'te 0,2215 W/mK olduğu bulunmuştur. Boş boruya kıyasla minimum ve maksimum Ns azaltımı, P=6'da Re=19133 için %7,13 ve P=1'de Re=11825 için %46,62 olarak hesaplanmıştır. Türbülanslı durumlarda, en yüksek Bejan sayısı, P=6 için Re=11825'te 0,9931 olarak bulunmuştur. Sonuç olarak, P=1 oranının ısı transferi açısından maksimum fayda sağladığı, P=6 oranının ise toplam entropi üretimi açısından ideal olduğu sonucuna varılmıştır.

Keywords

• Entropi
• Isı transferi
• Sürtünme faktörü
• Türbülatör
• Reynolds sayısı

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