The Effect of Fouling on the Baffle Spacing of a Shell and Tube Heat Exchanger

Öz

In this study, shell-side fouling of the shell and tube heat exchanger (STHE) designed for a textile firm was examined. The economic baffle spacing was determined for clean and fouled conditions. The energy and pressure loss analysis was performed using Bell –Deleware method. To predict the fouling thickness (FT), a prototype tube bundle was installed in the chimney of the stenter machine to expose to the exhaust gases. The FT on tubes reached to about 0.5 mm within three months. Fuel saving (FS) due to recovered heat and fan power consumption (FPC) due to pressure drop were calculated by assuming that FT varies linearly with time. In the result of the cost analysis, it was seen that economic baffle spacing was affected by R value which is the ratio of unit cost of natural gas to that of electricity but the effect of fouling on the optimum baffle spacing was not significant. Fouling affected optimum baffle spacing when R is greater than 15. In this study optimum baffle spacing was determined as 1.16 m for both fouled and clean condition, because of that R is 3.52 in Turkey at the time of the study.

Anahtar Kelimeler

• Heat exchanger
• Baffle spacing
• Fouling

Kirlenmenin Bir Gövde-Boru Isı Eşanjörünün Şaşırtma Levhası Aralığı Üzerindeki Etkisi

Öz

Bu çalışmada, bir tekstil firması için tasarlanan gövde borulu ısı eşanjörünün gövde tarafındaki kirlenmenin etkileri incelenmiş, temiz ve kirli koşullar için ekonomik şaşırtma levhası aralığı belirlenmiştir. Enerji ve basınç kaybı analizi Bell-Deleware yöntemi kullanılarak yapılmıştır. Kirlenme kalınlığını tahmin etmek için, ramöz makinesinin bacasına egzoz gazlarına maruz kalması için bir prototip boru demeti yerleştirilmiş ve üç ay içinde borulardaki kirlenme kalınlığının yaklaşık 0.5 mm’ye ulaştığı görülmüştür. Hesaplarda, kirlenme kalınlığının zamanla doğrusal olarak değiştiği varsayılmıştır. Maliyet analizi sonucunda, ekonomik şaşırtma levhası aralığının, doğal gazın birim maliyetinin elektriğin birim maliyetine oranı olan R değerinden etkilendiği, ancak optimum şaşırtma levhası aralığı üzerinde kirlenmenin etkisinin önemli olmadığı görülmüştür. Kirlenme, R nin 15’den büyük olduğu durumlarda optimum şaşırtma levhası aralığını etkilemiştir. Çalışmanın yapıldığı zamanda Türkiye’de R değerinin 3.52 olması nedeniyle hem kirli hem de temiz durumda optimum şaşırtma levhası aralığı 1.16 m olarak belirlenmiştir.

Anahtar Kelimeler

• Isı değiştiricisi
• Şaşırtma levhası aralığı
• Kirlenme

Kaynakça

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