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Effect of surface roughness on the rate of mass transfer to a pipe wall in the mass transfer entry region
Author(s) -
Sedahmed G. H.,
Soliman M. Nagy,
ElKholy N. S.
Publication year - 1981
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450590607
Subject(s) - mass transfer , surface roughness , reynolds number , potassium ferricyanide , surface finish , materials science , limiting current , analytical chemistry (journal) , mechanics , chemistry , electrochemistry , composite material , electrode , chromatography , turbulence , physics , inorganic chemistry
Rates of mass transfer between a turbulently flowing solution and the inner wall of a rough tube were measured using an electrochemical technique involving the measurement of the limiting current of the cathodic reduction of potassium ferricyanide in a large excess of sodium hydroxide. Roughness was made by cutting V‐threads in the inner surface of the pipe. Four degrees of surface roughness with peak to valley height ranging from 0.047 to 0.833 mm were used. Reynolds number ranged from 5000 to 40000. Under these conditions it was found that surface roughness increases the rate of mass transfer by an amount ranging from 10% to 115% depending on the degree of roughness and Reynolds number. The data were correlated in the mass transfer entry region by the equation:\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm St} = 0.183\,\,{\rm Sc}^{ - 2/3} \,\,{\rm Re}^{ - 0.15} \,\,\left( {{\rm e}/{\rm d}} \right)^{0.313} \,\,\left( {{\rm L}/{\rm d}} \right)^{ - 1/3} $$\end{document}