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A study of ionic transfer in electrodialysis process with laminar flow
Author(s) -
Huang TingChia,
Wang JunHsien
Publication year - 1989
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.5450670306
Subject(s) - electrodialysis , laminar flow , schmidt number , reynolds number , mass transfer , limiting current , dimensionless quantity , chemistry , thermodynamics , analytical chemistry (journal) , nusselt number , mechanics , chromatography , membrane , physics , turbulence , electrode , biochemistry , electrochemistry
The concentration profile in a laminar flow of the diluent of a parallel‐plate electrodialysis stack is derived by assuming operation at the limiting current density. The Nusselt mass transfer number is found to depend on the Reynolds number, the Schmidt number and the dimensionless hydraulic equivalent diameter according to (Nu) theo. = 3.7 · (Re · Sc · de/L) 1/3 . An empirical correlation of the Reynolds number, the Schmidt number, and the shape factor of the electrodialysis cell, with the ionic mass transfer rate in ion exchange membrane electrodialysis is obtained by measuring the limiting current densities at various conditions. The resulting empirical mass‐transfer correlation, (Nu) exp. = 3.91 · Re 0.333 · Sc 0.328 · (de/L) 0.352 , holds for sodium acetate as dialysate at concentrations ranging from 0.0106 to 0.0508 kmol/m 3 , viscosities ranging from 0.608 to 0.926 mPa · s, temperatures ranging from 15 to 55°C, axial velocities ranging from 0.341 to 4.55 cm/s, and for cell thicknesses of 0.32 and 0.94 cm, and is found to be in agreement with the equation obtained from theory. The effects of concentration, flow rate and temperature on the limiting current density are also studied. The relationship between the thicknesses of the diffusion layer and the Reynolds number has been analyzed.