Kabuk ve Sarmal Bobin Isı Eşanjörünün Termal Performansının İyileştirilmesi

Öz

Günümüzde enerji tüketimi arttığı için ısı enerjisi geçişinin verimliliğini ve performansını artırmak gerekmektedir. Delikli bükümlü bandın ısı transfer katsayısı, etkinlik, Nusselt sayısı ve basınç düşüşü üzerindeki etkileri sayısal olarak incelenmiştir. Kurulumu gerçekleştirmek ve çözümü tamamlamak için sonlu hacim yönteminin kullanıldığı ısı eşanjörünün delikli bükümlü bant ile modellenmesi uygulanmıştır. Sayısal sonuçlar önceki deneysel sonuçlarla doğrulanmıştır ve sayısal ve deneysel sonuçlar arasında aşırı bir uyum vardır. Reynolds sayılarının aralığı 3800 ila 18000 arasındadır. Sonuçlar, genel ısı aktarım katsayısının U’nun, Reynolds sayısının artmasıyla arttığını göstermiştir; burada delikli bükümlü bant, 965 ila 1250 W/ sayılarına ulaşarak ısı aktarım katsayısında maksimum artış sağlar. m2K. Delikli bükümlü bant, 65’ten 115’e kadar olan sayıların ardından Nusselt sayısını arttırma oranı en yüksek olanıdır ve bu, hız arttıkça türbülans seviyesi arttıkça açıklanabilir. Isı eşanjörünün etkinliği, delikli bükümlü bandın 0.35’ten 0.85’e ulaşan sayılara ulaşan üstün etkinlik geliştirmesine ulaştığı Reynolds sayısının büyümesiyle artar. Bükümlü bandın karmaşıklığı basınç düşüşünü artırdıkça, bükümlü bant konfigürasyonunun maksimum basınç düşüşü artış oranına sahip olduğu belirtilmektedir. Isı eşanjöründen geçen sıcak ve soğuk suyun hatları ve akış çizgileri sıcaklık, hız ve basınç dağılımlarını açıklar.

Anahtar Kelimeler

• Eşanjör
• Delikli bükümlü bant
• Termal performans

Thermal Performance Improvement of Shell and Helical Coil Heat Exchanger

Öz

Nowadays, energy consumption increases so it is necessary to enhance the efficiency and performance of heat energy transition. The effects of perforated twisted tape on heat transfer coefficient, effectiveness, Nusselt number, and pressure drop are studied numerically. Modeling of heat exchanger with the perforated twisted tape is applied where finite volume method is utilized to perform the setup and complete the solution. The numerical results are validated with previous experimental results and there is an excessive agreement between the numerical and experimental results. The range of Reynolds numbers is from 3800 to 18000. The results showed that the overall heat transfer coefficient U increases with the rise of Reynolds number where the perforated twisted tape achieves the maximum enhancement of heat transfer coefficient achieving the numbers from 965 to 1250 W/m2K. The perforated twisted tape has the highest ratio of enhancing Nusselt number following the numbers from 65 to 115 and this can be explained as the velocity rises, the turbulence level increases. Heat exchanger effectiveness increases with the growth of Reynolds number where the perforated twisted tape attained the supreme enhancement of effectiveness reaching the numbers from 0.35 to 0.85. It is indicated that the twisted tape configuration has the maximum ratio of pressure drop increase as the complicity of twisted tape rise the pressure drop. Contours and streamlines of hot and cold water cross the heat exchanger explains the distributions of temperature, velocity, and pressure.

Anahtar Kelimeler

• Heat exchanger
• Perforated twisted tape
• Thermal performance

Kaynakça

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