کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
660585 | 1458113 | 2011 | 7 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Dry-out CHF correlation for R134a flow boiling in a horizontal helically-coiled tube
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی شیمی
جریان سیال و فرایندهای انتقال
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
An experimental study was carried out to investigate the R134a dry-out critical heat flux (CHF) characteristics in a horizontal helically-coiled tube. The test section was heated uniformly by DC high-power source, and its geometrical parameters are the outer diameter of 10 mm, inner diameter of 8.4 mm, coil diameter of 300 mm, helical pitch of 75 mm and valid heated length of 1.89 m. The experimental parameters are the outlet pressures of 0.30-0.95 MPa, mass fluxes of 60-500 kg mâ2 sâ1, inlet qualities of â0.36-0.35 and heat fluxes of 7.0 Ã 103-5.0 Ã 104 W mâ2. A method based on Agilent BenchLink Data Logger Pro was developed to determine the occurrence of CHF with a total of 68 T-type thermocouples (0.2 mm) set along the tube for accurate temperature measurement. The characteristics of wall temperatures and the parametric effect on dry-out CHF showed that temperature would jump abruptly at the point of CHF, which usually started to form at the front and offside (270° and 90°) of the outlet cross-section. The CHF values decrease nearly linearly with increasing inlet qualities, while they decrease more acutely with increasing critical qualities, especially under larger mass flux conditions. The mass flux has a positive effect on CHF enhancement, but the pressure has negative one. A new dimensionless correlation was developed to estimate dry-out CHF of R134a flow boiling in horizontal helically-coiled tubes under current experimental conditions and compared to calculated results from Bowring and Shah correlations.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: International Journal of Heat and Mass Transfer - Volume 54, Issues 1â3, 15 January 2011, Pages 739-745
Journal: International Journal of Heat and Mass Transfer - Volume 54, Issues 1â3, 15 January 2011, Pages 739-745
نویسندگان
C.N. Chen, J.T. Han, T.C. Jen, L. Shao,