CFD Analysis of the Impact of Temperature Variation on Condensation and Phase Transition Performance in Heat Exchangers

Öz

This study investigates condensation in a rectangular copper heat exchanger with six circular tubes exposed to temperature variations. Three different temperature levels (380 K, 420 K and 460 K) were compared by examining heat transfer and phase change over a 5-second period with 1.25 s increments. A transient two-dimensional analysis model was developed. Physical modeling was performed using the Volume of Fluid (VOF) phase model and the Standard k-ε turbulence model. The analysis results were monitored along two horizontal lines at different heights on the plate. The simulation results show that rapid condensation occurs at low and medium temperature levels due to high heat transfer. At the high temperature level, a delayed phase change leads to a longer condensation duration. The study serves as a guide for thermal device design by emphasizing the need to select appropriate temperature ranges while considering both the amount and duration of condensation.

Anahtar Kelimeler

• CFD
• Phase Transition
• Heat Exchanger
• Temperature
• Condensation

Isı Eşanjörlerinde Sıcaklık Değişiminin Yoğuşma ve Faz Geçiş Performansı Üzerindeki Etkisinin CFD Analizi

Öz

Yürütülen bu çalışma, sıcaklık değişimine maruz 6 adet dairesel boru içeren dikdörtgen bir bakır ısı eşanjöründeki yoğuşma konusunu incelemektedir. Üç farklı sıcaklık seviyesi (380 K, 420 K ve 460 K) ve 1,25 s artımlarla 5 saniye boyunca gerçekleşen ısı transferi ve faz geçişi ortaya konularak karşılaştırılmıştır. Geçici rejimde 2 boyutlu bir analiz modeli oluşturularak VOF(Volume of Fluid) faz modeli ve Standart k-ε türbülans modeli ile fiziksel modelleme yapılmıştır. Analiz sonuçları plaka üzerinde oluşturulan farklı yüksekliklerdeki yatay iki çizgi boyunca grafikle izlenmiştir. Simülasyon sonuçlarına göre, düşük ve orta sıcaklık seviyesinde yüksek bir ısı transferi neticesinde yoğuşma işleminin hızlıca gerçekleştiği gözlemlenirken, yüksek sıcaklık seviyesinde faz değişiminin gecikerek yoğuşma süresinin diğer sıcaklık seviyelerine göre arttığı gözlenmiştir. Çalışma, ısıl cihaz tasarımı yapılırken uygun sıcaklık aralıkları seçilerek yoğuşma miktarı ve süresinin de gözönünde bulundurulmasını ortaya koyan rehber niteliğinde bir çalışmadır.

Anahtar Kelimeler

• CFD
• Faz Değişimi
• Isı Eşanjörü
• Sıcaklık
• Yoğuşma

Kaynakça

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