Mass transfer in a laminar-flow parallel plate electrolytic cell with simultaneous development of velocity and concentration boundary layers

1990 ◽  
Vol 20 (6) ◽  
pp. 885-892 ◽  
Author(s):  
Jian Qi ◽  
R. F. Savinell
Keyword(s):  
Mass Transfer ◽  
Laminar Flow ◽  
Boundary Layers ◽  
Parallel Plate ◽  
Electrolytic Cell ◽  
Concentration Boundary ◽  
Concentration Boundary Layers ◽  
Simultaneous Development

Experimental determination of the dissolved oxygen boundary layer and mass transfer resistance near the fluid-biofilm interface

1994 ◽  
Vol 30 (11) ◽  
pp. 47-58 ◽  
Author(s):  
Tian C. Zhang ◽  
Paul L. Bishop
Keyword(s):  
Boundary Layer ◽  
Mass Transfer ◽  
Dissolved Oxygen ◽  
Boundary Layers ◽  
Mass Transfer Resistance ◽  
External Mass Transfer ◽  
Transfer Resistance ◽  
Concentration Boundary ◽  
Concentration Boundary Layers ◽  
Do Concentration

The thickness of the dissolved oxygen (DO) concentration boundary layer and the external mass transfer in a biofilm system were investigated using a microelectrode technique. Theoretical analysis was conducted to elucidate the mechanisms of the technique and to interpret the experimental measurements. The measured thicknesses of dissolved oxygen (DO) concentration boundary layers under different conditions demonstrated directly the effect of several factors on external mass transfer resistance. The experimental results indicated that (a) increasing substrate loading rate, (b) increasing fluid streamwise velocity and (c) increasing the roughness of the biofilm surface would decrease the external mass transfer resistance. The measured thickness of the DO concentration boundary layer was not in full agreement with theoretical correlations because the nonuniform biofilm created velocity and concentration fluctuations which resulted in the compression of concentration boundary layers. The microelectrode technique is a useful tool to study the external mass transfer resistance.

scholarly journals The Role of Gravity in the Evolution of the Concentration Field in the Electrochemical Membrane Cell

Entropy ◽  
2020 ◽  
Vol 22 (6) ◽  
pp. 680 ◽  
Author(s):  
Kornelia M. Batko ◽  
Andrzej Ślęzak ◽  
Wioletta M. Bajdur
Keyword(s):  
Boundary Layers ◽  
Concentration Polarization ◽  
Concentration Field ◽  
Membrane System ◽  
Volume Transport ◽  
Cellulose Acetate Membrane ◽  
Concentration Boundary ◽  
Concentration Boundary Layers ◽  
Mechanical Stirring

The subject of the study was the osmotic volume transport of aqueous CuSO4 and/or ethanol solutions through a selective cellulose acetate membrane (Nephrophan). The effect of concentration of solution components, concentration polarization of solutions and configuration of the membrane system on the value of the volume osmotic flux ( J v i r ) in a single-membrane system in which the polymer membrane located in the horizontal plane was examined. The investigations were carried out under mechanical stirring conditions of the solutions and after it was turned off. Based on the obtained measurement results J v i r , the effects of concentration polarization, convection polarization, asymmetry and amplification of the volume osmotic flux and the thickness of the concentration boundary layers were calculated. Osmotic entropy production was also calculated for solution homogeneity and concentration polarization conditions. Using the thickness of the concentration boundary layers, critical values of the Rayleigh concentration number ( R C r ), i.e., the switch, were estimated between two states: convective (with higher J v i r ) and non-convective (with lower J v i r ). The operation of this switch indicates the regulatory role of earthly gravity in relation to membrane transport.

Sign in / Sign up

Export Citation Format

Share Document