کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
654678 885260 2007 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Heat transfer characteristics in a tube fitted with helical screw-tape with/without core-rod inserts
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی جریان سیال و فرایندهای انتقال
پیش نمایش صفحه اول مقاله
Heat transfer characteristics in a tube fitted with helical screw-tape with/without core-rod inserts
چکیده انگلیسی
Effects of insertion of a helical screw-tape with or without core-rod in a concentric double tube heat exchanger on heat transfer and flow friction characteristics are experimentally investigated. The heat exchanger has the outer and the inner tube diameters of 50 mm (Do) and 25 mm (D) where the cold and the hot waters used as the test fluids are in shell and tube sides, respectively. The stainless steel helical screw-tape has the geometrical dimensions of width (W) 17 mm with the clearance to the tube wall (D − W) / 2 = 4 mm. Thus, the insertion of the screw-tape in the tube is considered as a loose-fit. In the experiment, the loose-fit helical tape with or without core-rod, is inserted in the inner tube of the heat exchanger and the hot water enters the tube based on its Reynolds number in a range of 2000 to 12,000. The experimental results show that the increases in average Nusselt number of using the loose-fit, helical tape with and without core-rod are found to be 230% and 340%, respectively, over the corresponding plain tube. It is worth noting that for the loose-fit, helical tape without core-rod, the friction factor is around 50% less than that for the one with core-rod while the Nusselt number is about 50% higher. Furthermore, the enhancement efficiency of the helical screw-tapes varies between 1.00 and 1.17, 1.98 and 2.14, for the tapes with and without core-rod, respectively.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: International Communications in Heat and Mass Transfer - Volume 34, Issue 2, February 2007, Pages 176-185
نویسندگان
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