کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4992723 1457393 2017 26 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Transition between nucleate and film boiling in rapid transient heating
ترجمه فارسی عنوان
انتقال بین نوکلئوتید و فیلم جوش در گرمای گذرا سریع
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی جریان سیال و فرایندهای انتقال
چکیده انگلیسی
This article presents an experimental study of rapid transient boiling regimes of distilled water at saturation on a thin tungsten wire of 50 μm diameter. The heating rate varied from ∼0.5 to 5 × 105 K/s. Heat supply was obtained by periodic pulses of constant voltage with a period large enough to avoid response overlap. Rapid video recording (14,000 fps) was associated with electrical measurements. Two transient phenomena were studied: pulse heating and thermal relaxation. During pulse heating, it was observed that, depending on heating rate, three kinds of behavior exist: (i) only nucleate boiling appears for small heating rates (≲105 K/s), (ii) transition from nucleate boiling to film boiling by bubble coalescence at intermediate heating rates (≲2.105 K/s), and (iii), at higher heating rates, transition to film boiling by vapor wave propagation (speed ∼20 m/s). This last mechanism is interpreted as homogeneous nucleation process and is qualitatively similar to an autowave process. In the relaxation stage, it is observed that film collapse is characterized by two mechanisms: film break up into nucleate boiling regime or continuous vapor receding. This second mechanism is compared to a conduction model of a temperature traveling wave in the wire. The time variation of the vapor film length predicted by the model is in the range of the experimental data.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Experimental Thermal and Fluid Science - Volume 83, May 2017, Pages 118-128
نویسندگان
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