Abstract
The results of an experimental investigation of transport processes at the wall of an agitated vessel in a gas-liquid system are presented. Measurements were carried out by means of the electrochemical method. The experiments were performed in a standard agitated vessel of diameter 0.3 m, equipped with a Rushton disc turbine and baffles. The distributions of the diffusion current along the vessel wall were obtained for different values of agitator speed and superficial gas velocity. On the basis of these data, distributions of the shear rate, shear stress, dynamic velocity, friction coefficient and energy dissipated were evaluated. The mean values of the \(\overline {\gamma /n} \) variables were approximated analytically.
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Abbreviations
- A 1, A 2 :
-
exponents in Equations 7 and 11
- a :
-
length of agitator blade (m)
- B :
-
width of baffle (m)
- b :
-
width of agitator blade (m)
- C 1, C 2 :
-
coefficients in Equations 7 and 11
- D :
-
inner diameter of agitated vessel (m)
- d :
-
agitator diameter (m)
- e :
-
distance between dispersing ring and bottom of the vessel (m)
- f :
-
friction coefficient
- g :
-
gravitational acceleration (m s−2)
- H :
-
height of the liquid in the vessel (m)
- h :
-
distance between disc of the agitator and bottom of the vessel (m)
- I d :
-
diffusion current (A)
- n :
-
agitator speed (s−1)
- ν* :
-
dynamic velocity (m s−1)
- v * :
-
gas flow rate (m3 s−1)
- w og :
-
superficial gas velocity wog = V g/(πD 2/4) (m s−1)
- Z :
-
number of agitator blades
- z :
-
axial coordinate (m)
- α:
-
heat transfer coefficient (W m−2 K-1)
- γ:
-
shear rate (s-1)
- ϕ:
-
angular coordinate (deg)
- η:
-
dynamic viscosity (Pa s)
- ρ:
-
liquid density (kg m−3)
- τ:
-
shear stress (N m−2)
- ɛm :
-
energy dissipated (W kg−1)
- Nu = αD/λ:
-
Nusselt number
- Re = nd 2ρ/η:
-
Reynolds number
- Fr = w 2 og/gD :
-
modified Fronde number
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Karcz, J. Experimental studies of momentum transfer in a gas-liquid system in the vicinity of an agitated vessel wall. J Appl Electrochem 24, 602–606 (1994). https://doi.org/10.1007/BF00252083
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DOI: https://doi.org/10.1007/BF00252083