(186d) Hydrogen Production Using Electrolysis Process Modelling from the Bubble to the Laboratory Electrochemical Cell

During water electrolysis for hydrogen there are bubbles which are created at the two electrodes which imply a great hydrodynamic acceleration but also a quite important electrical field and electrochemical processes disturbance. This disturbance can lead to the modification of the local current density and to anode effects for example. There is few works concerning the local modelling of coupled electroactive species transport and electrochemical processes in a biphasic electrolyte. There are also few local experimental measurements in term of chemical composition, temperature or current density which will allow the numerical calculations validation. Nevertheless, effects like the anode effect, particularly expensive on the point of the process efficiency, should need a better understanding. Nowadays, the respective roles of the local temperature increases, the electroactive specie composition or the transport properties modification due to bubbles are not known. The goal of the present work is the modelling and the numerical simulation of the hydrogen production process for a vertical electrode configuration. Bubbles presence is supposed to modify the electrical properties, the thermal properties and then the electroactive specie diffusive transport and the current density. Bubbles are also motion sources for the electrolysis cell flow, and then hydrodynamic properties are strongly coupled with specie transport and electrical field [1,2]. The present work shows hydrodynamic, electrical, thermal and chemical composition properties in a laboratory scale electrolysis cell with a vertical electrode. The numerical algorithm used was the finite volume used in the computational fluid dynamic software Fluent®.

[1] Ph. Mandin Philippe, J. Hamburger, S. Bessou, G. Picard, Calculation of the current density distribution at vertical gas-evolving electrodes, Electrochimica Acta, accepted april 2005

[2] R Wüthrich, L.A. Hof, A. Lal, K. Fujisaki, H. Bleuler, Ph. Mandin, G. Picard, Physical principles and Miniaturization of Spark Assisted Chemical Engraving (SACE), J of Micromech. Microeng., 15 (2005) 1-8