(510c) Multiscale Modeling of Gas Evolving Electrodes

Multiscale
Modeling of Gas Evolving Electrodes

Mehmet
Moralı¹, Palgat A. Ramachandran¹
and Milorad P. Duduković¹

¹Washington
University in St. Louis

Abstract

Gas evolving electrochemical systems are widely
used in industry, such as in chlorate, chlor-alkali
and hydrolysis of water. These systems might form bubbles on one or both of the
electrodes. Once bubbles depart from the electrode surface, they form a bubbly
layer. This layer presents resistance to current flown and demands higher cell
potential, requiring more energy to preserve fast reaction rates. The thickness
of the bubbly layer increases with increasing height, causing lower current
densities in the upper section of the electrode. This creates negative
feedback, reducing the formation rate of bubbles and affecting bubble layer
thickness. We present a multiscale model by which the
bubble layer thickness is calculated by a Eularian ? Lagrangian scheme for which the effective medium is
approximated by a submodel.  The accuracy of the submodel
is further investigated by Monte-Carlo simulations.  

Key
words

Multiscale modeling,
gas evolving electrodes, gas hold-up, effective medium approximation