Determination of the heat transfer coefficient during annular flow condensation in smooth horizontal tubes

Bu çalışmada, iki fazlı akışlarda halka akış şartlarında taşınım katsayısını hesaplamak için basınç düşümü ve taşınım katsayısı arasında bir model geliştirilmiştir. Halka akış şartlarında, sıvı filmindeki hız ve sıcaklık dağılımlarına eşdeğer tek faz sıvı akışı belirlenerek yoğuşmadaki ısı taşınım katsayısı tek faz sıvı için verilen bağıntılardan yararlanarak hesaplandı. Geliştirilen modelden elde edilen sonuçlar deneysel çalışmadan elde edilen taşınım katsayısı değerleri ile karşılaştırıldı. Deneysel çalışmada R600a (İsobütan) soğutkanının iç çapı 4 mm olan yatay düz boru içerisinde yoğuşması incelendi ve elde edilen taşınım katsayısını değerlerinin mevcut korelasyonlarla ±20% uyumlu olduğu saptandı. Modelin doğruluğunu belirlemek için aynı şartlarda literatürde mevcut taşınım katsayıları ile analitik modelden hesaplanan taşınım katsayıları birbirleri ile mukayese edildi sonuçta ±% 25 lik bir sapma saptandı.

Halka akış şartlarında pürüzsüz yatay boruda yoğuşmada taşınım katsayısının belirlenmesi

In this study, a model describing the relationship between pressure drop and heat transfer coefficients was developed to calculate the heat transfer coefficient under two-phase annular flow conditions. According to these conditions, the single phase liquid flow with temperature distribution which is equivalent to velocity and temperature distributions in the liquid film was determined and the heat transfer coefficient during condensation was calculated from equations provided for the single-phase liquid. The results of the new analytical model were compared with the heat transfer coefficient obtained from experimental study. In this study, the refrigerant (R600a) was circulated inside a smooth horizontal tube with an inner diameter 4 mm and the experimental results were found to be consistent with the mentioned correlations within a range of ±20%. Consequently, to validate the model, the heat transfer coefficient data in the literature were compared with the heat transfer coefficient values of the analytical model study, under the same conditions. A deviation of ±25% was found as a result of the comparison.

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