Flow-through and flow-by porous electrodes of nickel foam Part IV: experimental electrode potential distributions in the flow-through and in the flow-by configurations |
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Authors: | S Langlois F Coeuret |
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Affiliation: | (1) Laboratoire de Génie des Procédés, CNRS-ENSCR, Avenue du Général Leclerc, 35700 Rennes Beaulieu, France |
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Abstract: | Experimental distributions of the solution potential in flow-through and flow-by porous electrodes of nickel foam operating in limiting current conditions are presented. These are in good agreement with the corresponding theoretical distributions. In the case of a flow-by configuration used in a two-compartment cell, the experiments confirm the validity of the models, presented in Part III, which take into account the presence of a separator (ceramic porous diaphragm or ion exchange membrane).Nomenclature
a
e
specific surface area per unit volume of electrode
-
C
0
entrance ferricyanide concentration (y=0)
-
D
molecular diffusion coefficient of ferricyanide
-
E
e
cathode potential
-
F
Faraday number
-
mean (and local) mass transfer coefficient
-
L
electrode thickness
-
L
s-L
separator thickness
-
m
number of sheets of foam in a stack
-
n
number of terms in Fourier series
-
Q
volumetric flow-rate
-
r
s
ohmic specific resistance of the separator
-
mean flow velocity based on empty channel
-
V
constant potential
-
X
conversion
-
x
coordinate for the electrode thickness
-
y
coordinate for the electrode length
-
y
0
length of the porous electrode
-
z
number of electrons in the electrochemical reaction
Greek symbols
parameter
-
parameter
-
ionic electrolyte conductivity
-
sc
solution potential in the pores of the cathode
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M
matrix potential (
sc = constant)
-
parameter =n /y
0]
-
electrolyte density
-
mean porosity
-
kinematic viscosity
- E
c
potential drop in the porous cathode
- ![Delta](/content/w2225h13410m501w/xxlarge916.gif)
potential drop defined in Fig. 5
Indices c
cathodic
- o
electrolyte alone
- s
separator |
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Keywords: | |
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