Effect of scales on overall heat transfer coefficient during nucleate pool boiling of water
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Date
1980-04
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Publisher
Turkish Atomic Energy Commission, Ankara Nuclear Research and Traning Center
Abstract
Bu çalışmada, kazan taşının platin bir şeritten elektrik akımı geçirmek suretiyle ısıtılan durgun su içerisinde kabarcıklı kaynama ile olan ısı transferine etkisi incelendi, iki elektrot arasına yerleştirilen test şeridi doyma sıcaklığında tutulan bir arı ve yumuşak su havuzuna daldırıldı ve önce şerit yüzeyi temiz olarak, daha sonra da üzerine çeşitli kalınlıklarda kazantaşı çökeltilerek deneyler yapıldı. Alınan sonuçlara göre ısı transferi katsayısı kazantaşı kalınlaştıkça azalmata ve test şeridi sıcaklığı ile su sıcaklığı arasındaki farka göre ısı transferi katsayısının değişimini ifade eden eğri, kazantaşı kalınlığı arttıkça sağa doğru kaymaktadır. Ufak sıcaklık farklarında ısı transferi katsayısı yavaş olarak artmakta, daha büyük sıcaklık farklarında ise katsayının değeri hemen hemen sabit kalmakta ve kabarcıklı kaynamanın daha sonraki kademelerinde ısı transfej-1 katsayısı hızlı olarak tekrar büyümeye başlamaktadır.
The effect of scales on overall heat transfer coefficient during nucleate pool boiling of water heated by a platinum strip was investigated. The platinum test strip, placed between two electrodes was submerged into a pool of distilled water which was kept at the saturation temperature by means of an immersion heater. The experiments were conducted with the bare test strip and v/ith Various scale thicknesses deposited on the strip. The results show that the overall heat transfer coefficient «h» decreases with the scale thickness and the «(h) versus wall superheat (Tw-Ts) curve» shifts to the right as the scale thickness increases. In the initial stage of nucleate boiling the overall heat transfer coefficient «h» increases slowly, then it becomes almost constant so that in some cases the slope of «(h) versus (Tw-Ts)» curve approaches to zero. In the later stages of the nucleate boiling the overall heat transfer coefficient starts to increase again steeply.
The effect of scales on overall heat transfer coefficient during nucleate pool boiling of water heated by a platinum strip was investigated. The platinum test strip, placed between two electrodes was submerged into a pool of distilled water which was kept at the saturation temperature by means of an immersion heater. The experiments were conducted with the bare test strip and v/ith Various scale thicknesses deposited on the strip. The results show that the overall heat transfer coefficient «h» decreases with the scale thickness and the «(h) versus wall superheat (Tw-Ts) curve» shifts to the right as the scale thickness increases. In the initial stage of nucleate boiling the overall heat transfer coefficient «h» increases slowly, then it becomes almost constant so that in some cases the slope of «(h) versus (Tw-Ts)» curve approaches to zero. In the later stages of the nucleate boiling the overall heat transfer coefficient starts to increase again steeply.
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Keywords
Overall heat transfer coefficient, Toplam ısı transfer katsayısı, Ölçeklerin etkisi, Effect of scales, Boiling, Kaynama, Water, Su, Nucleate pool, Çekirdek havuzu
Citation
Yeşin, O. ve Arısoy, Y. (1980). Effect of scales on overall heat transfer coefficient during nucleate pool boiling of water. Technical Journal, 7(1), 15-24.