کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
237660 465718 2010 6 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Wall effects on the velocities of a single sphere settling in a stagnant and counter-current fluid and rising in a co-current fluid
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی مهندسی شیمی (عمومی)
پیش نمایش صفحه اول مقاله
Wall effects on the velocities of a single sphere settling in a stagnant and counter-current fluid and rising in a co-current fluid
چکیده انگلیسی

Experimental results were obtained on the steady settling of spheres in quiescent media in a range of cylindrical tubes to ascertain the wall effects over a relatively wide range of Reynolds number values. For practical considerations, the retardation effect is important when the ratio of the particle diameter to the tube diameter (λ) is higher than about 0.05. A new empirical correlation is presented which covers a Reynolds number range Re = 53–15,100 and a particle to tube diameter ratio λ < 0.88. The absolute mean deviation between the experimental data and the presented correlation was 1.9%. The well-known correlations of Newton, Munroe and Di Felice agree with the presented data reasonably well. For steady settling of spheres in a counter-current water flow, the slip velocity remains practically the same as in quiescent media. However, for rising spheres in a co-current water flow, the slip velocity decreases with increasing co-current water velocity, i.e., the wall factor decreases with increasing co-current water velocity. Consequently, the drag coefficient for rising particles in co-current water flow increases with increasing water velocity.

The steady settling of spheres in quiescent media in different cylindrical tubes was investigated and a new wall factor empirical correlation is proposed. Wall factor was approximately constant for settling spheres in counter-current water flow, while decreased with increasing co-current water velocity for rising spheres in co-current water flow. Consequently, drag coefficient for rising particles increases with increasing water velocity.Figure optionsDownload as PowerPoint slide

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Powder Technology - Volume 203, Issue 2, 10 November 2010, Pages 237–242
نویسندگان
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