Artificial Neural Network Techniques for the Determination of Condensation Nusselt Number in Horizontal Smooth Tubes

Öz

In this study, using readily available experimental data in the literature, artificial neural networks (ANN) method is adopted to specify condensation Nusselt number in horizontal smooth tubes. Condensation heat transfer of R22, R134a and 50/50 and 60/40 of the R32/ R125 azeotropic refrigerant mixtures were examined with four different ANN methods. The experimental data is taken from the study of Dobson et al. [1]. The input parameters are mass flux, quality, hydraulic diameter, Soliman's modified Froude number, density of fluid phase and dynamic viscosity of liquid phase where the output parameter is the condensation Nusselt number. In this study the interval for tube diameters is between 3.14-7.04 mm, and the interval for mass flux is between 50-800 kg/m²s.  The training algorithms are tested using different neuron numbers and the best algorithm was found as Bayesian regularization having 8 neurons. It is observed that the Nu number evaluated using ANN is ± 15% error margin compared to experimental results. Furthermore, for increasing mass flux rates the error margin is around ± 5%.

Anahtar Kelimeler

• Condensation,Artificial neural networks,Refrigerant,Nusselt number,Horizontal smooth tube

Yatay Pürüzsüz Borularda Yoğuşmadaki Nusselt Sayısının Belirlenmesi için Yapay Sinir Ağ Teknikleri

Öz

Bu çalışmada, literatürdeki hazır deneysel veriler kullanılarak, yatay pürüzsüz borularda yoğuşmadaki Nusselt sayısını belirlemek için yapay sinir ağları (ANN) yöntemi kullanılmıştır. R32, R134a ve %50/%50 ve %60/%40 R32/R125 azeotropik soğutucu karışımlarının yoğuşma ısı transferi dört farklı ANN yöntemi ile incelendi; Levenberg-Marquardt, Bayes düzenlenmesi, ölçeklenmiş eşlenik değişim ve esnek geri yayılımı. Deneysel veriler Dobson ve ark.[1]’nın çalışmalarından alınmıştır. Giriş parametreleri kütle akısı, kalite, hidrolik çap, Soliman'ın değiştirilmiş Froude sayısı, akışkan faz yoğunluğu ve çıkış parametresinin yoğuşmadaki Nusselt sayısının olduğu sıvı fazın dinamik viskozitesidir. Bu çalışmada, boru çapları aralığı 3,14-7,04 mm arasında ve kütle akı aralığı 50-800 kg/m² arasındadır. Eğitim algoritmaları farklı nöron sayıları kullanılarak test edildi ve en iyi algoritma 8 nörona sahip Bayes düzenlenmesi olarak bulundu. ANN kullanılarak değerlendirilen Nu sayısının deney sonuçlarına göre ±%15 hata payı olduğu gözlenmiştir. Ayrıca, artan kütle akı oranları için hata payı ±%5 civarındadır.

Anahtar Kelimeler

• Yoğuşma,Yapay sinir ağları,Soğutucu akışkan,Nusselt sayısı,Yatay pürüzsüz boru

Kaynakça

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