THREE-DIMENSIONAL CONJUGATE NUMERICAL ANALYSIS OF FIN AND TUBE HEAT EXCHANGERS WITH VARIOUS FIN THERMAL CONDUCTIVITY VALUES AND GEOMETRIC PARAMETERS

Isı değiştirici performansının, kanatçık malzemesinin ısıl iletkenliği ile yüksek bir alakası olduğu açıktır. Bu çalışmada, kanatlı borulu ısı değiştiricinin bütünleşik ısı transferi ve akış karakteristiklerini belirlemek için üç boyutlu modelleme ile sayısal hesaplamalar yapılmıştır. Kanatçık malzemesinin etkisi şu beş faktör ile birlikte incelenmiştir: Reynolds sayısı (Re), kanatçıklar arası mesafe (FP), kanatçık kalınlığı (FT), boru çapı (TD) ve kanatçık uzunluğu (FL). Bununla birlikte yüksek ısı iletim katsayılarına sahip malzemelerin gıda işleme gibi bazı proseslerde kullanılması uygun olmayabilmektedir. Malzemenin ısı iletim katsayısı, Re sayısının Nu sayısı üzerindeki etkisinde ufak bir artışa sebep olmakla birlikte boru çapının Nu sayısı üzerindeki etkisi incelendiğinde önemli bir parametre olduğu bulunmuştur. Benzer olarak kanatçık uzunluğunun ve kanatçık kalınlığının etkileri de kanatçık malzemesinden etkilenmektedir. Nu sayısının bulunması için bütün bu parametrelerin etkilerini içeren yeni bir korelasyon önerilmiştir.

FARKLI KANAT ISI İLETİM KATSAYILARI VE GEOMETRİK PARAMETRELER İÇİN KANATLI BORULU ISI DEĞİŞTİRİCİLERİN ÜÇ BOYUTLU BÜTÜNLEŞİK SAYISAL ANALİZİ

It is obvious that heat exchanger performance is highly related with fin material thermal conductivity. In this paper 3-D numerical simulations were performed for conjugate heat transfer and fluid flow characteristics of fin and tube heat exchanger. The effects of the fin materials interacting with five factors: Reynolds (Re) number, fin pitch (FP), fin thickness (FT), tube diameter (TD) and fin length (FL) were examined. However, high thermal conductivity materials may not be suitable under some operating conditions such as food processing. It is found that thermal conductivity of the material slightly increases the effect of the Re number on Nusselt (Nu) number and the thermal conductivity is becoming very important parameter while investigating the effect of tube diameter on Nu number. Similarly the effect of fin length and fin thickness is also affected by fin material. A new correlation is proposed to predict Nu number includes the effect of all these parameters.

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