INFLUENCE OF TEMPERATURE AND CONCENTRATION BOUNDARY LAYERS AT SEPARATION ON HEAT AND MASS TRANSFER IN SEPARATED FLOWS

1982 ◽  
Author(s):  
Volker Kottke
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Boundary Layers ◽  
Separated Flows ◽  
Concentration Boundary ◽  
Influence Of Temperature ◽  
Concentration Boundary Layers

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.

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