کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
658832 1458087 2013 15 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Heat transfer augmentation in unsteady conjugate thermal systems - Part II: Applications
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی جریان سیال و فرایندهای انتقال
پیش نمایش صفحه اول مقاله
Heat transfer augmentation in unsteady conjugate thermal systems - Part II: Applications
چکیده انگلیسی
This paper, which follows on from its predecessor [1], is concerned with the phenomenon of augmentation in simple, one-dimensional, unsteady and conjugate fluid-solid systems. A simple semi-analytical one-dimensional model of heat transfer with a time-varying heat transfer coefficient, which was presented in Mathie and Markides [1], is applied herein to two different paradigm problems. Such a model can be an important tool in the design of improved heat exchangers and thermal insulation, through for example, the novel selection of materials to exploit these augmentation effects. The first flow considered is a thin, wavy fluid film flowing over a heated plate. This film flow exhibits a periodic fluctuation in the heat transfer coefficient, that is linked to the wavy interfacial deformations of free surface of the liquid film. The second flow considered concerns the heat transfer behind a backwards-facing step, which exhibits broadband fluctuations in the heat transfer coefficient due to the flow separation and turbulence behind the step. The model predictions of the augmentation ratio for these problems are also compared to direct measurements from each case. Good agreement is observed with the experimental results for the global heat transfer trends. In both cases the augmentation ratio was negative, reflecting a reduction in time-averaged heat transfer. For the backwards-facing step flow a low magnitude of augmentation ratio was observed, however, the thin film flows exhibited augmentation ratios of as high as 10%.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: International Journal of Heat and Mass Transfer - Volume 56, Issues 1–2, 1 January 2013, Pages 819-833
نویسندگان
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