Energy and Exergy Analysis of a Shell and Tube Heat Exchangers Having Smooth and Corrugated Inner Tubes

Abstract

Shell and tube heat exchangers are one of the most used heat exchanger types in applications and it is important to predict heat transfer capacity and pressure loss in both design stage. Heat transfer capacity of a heat exchanger can be enhanced by using tubes having enhanced surfaces instead of smooth ones. In this study, the usage of corrugated tubes in a shell and tube heat exchanger is investigated by using ε-NTU method, energy/exergy analysis. The impact of the usage of corrugated tubes on hot and cold fluid outlet temperatures, energy/exergy efficiencies, entropy generation and total exergy destruction are researched for various operation conditions. The results revealed that the difference between fluid outlet temperatures can be decreased by using tubes having corrugated surfaces instead of smooth ones because of fluid mixing and secondary flows obtained by means of the corrugations. Overall heat transfer coefficient of heat exchanger is enhanced up to 8% with the usage of corrugated tube in considered operation conditions. It is exhibited that the energy and exergy efficiencies of heat exchanger can be improved up to 18% and 16% with the usage of corrugated tubes instead of one having smooth tubes. Moreover, the entropy generation because of heat transfer and pressure loss and total exergy destruction of considered heat exchangers are determined to reveal the impact of corrugated tubes.

Keywords

• Heat exchanger design
• Exergy analysis
• Heat transfer enhancement
• Corrugated tubes

Pürüzsüz ve Koruge İç Borulara Sahip Bir Gövde Borulu Isı Değiştiricisinin Enerji ve Ekserji Analizi

Abstract

Gövde borulu ısı değiştiricileri uygulama en çok kullanılan ısı değiştirici türlerinden biridir ve tasarım aşamasında ısı transferi kapasitesi ve basınç kaybının tahmin edilmesi önemlidir. Bir ısı değiştiricisinin kapasitesi pürüzsüz yüzeyler yerinde iyileştirilmiş yüzeye sahip borular kullanılarak arttırılabilir. Bu çalışmada, koruge boruların bir gövde borulu ısı değiştiricisinde kullanımı ε-NTU method, enerji/ekserji analizleri kullanılarak araştırılmıştır. Koruge boru kullanımının sıcak ve soğuk akışkan çıkış sıcaklıklarına, enerji/ekserji verimlerine, entropi üretimine ve ekserji yıkımına etkisi farklı çalışma şartları için incelenmiştir. Sonuçlar koruge yüzeyler kullanılarak elde edilen akışkan karışması ve ikincil akışlar sebebiyle pürüzsüz yüzeyler yerine akışkan çıkış sıcaklıkları arasındaki farkın azaltılabileceğini ortaya çıkarmıştır. Göz önüne alınan çalışma şartlarında toplam ısı transfer katsayısı koruge borular kullanılarak %8’e kadar iyileşmiştir. Pürüzsüz boru yerine koruge boru kullanımıyla ısı değiştiricisinin enerji ve ekserji verimlerinin sırasıyla %18 ve %16’ya kadar arttırılabileceği ortaya konmuştur. Ayrıca, göz önüne alınan ısı değiştiricilerinin ısı transferi ve basınç kaybı kaynaklı entropi üretimi ve ekserji yıkımı koruge boru kullanımının etkisini açığa çıkarmak için belirlenmiştir.

Keywords

• Isı değiştiricisi tasarımı
• ekserji analizi
• ısı transferi iyileştirmesi
• Koruge borular

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