The main stated objectives have been reached such that now two different numerical methods exist enabling the solution of the 'dilute solution model' that describes in a general way transport of mass and charge in a computed velocity field. In regions where no concentration variation is observed, the equations reduce to the so called potential model describing only charge transport in the solution.
The numerical results are in perfect agreement with theoretical solutions. When comparing numerical results with experiments, it is observed that determination and application of the proper physical constants is of major importance.
Comparison of the numerical results with measurements reveals that limiting current densities can be modelled with sufficient accuracy (10-20%). When secondary current densities are considered, the reaction model has to deal with all phenomena occurring at the electrodes in order to meet sufficient accuracy.
In this Fundamental Research Project new, complementary and generally applicable numerical methods to predict current density distributions in electrochemical cells will be developed, compared and validated with experiments.
Models for dilute solutions describing mass and charge transfer of a maximum of four ions will be solved in practical situations where hydrodynamics may be complex.
The project considers steady-state, two-dimensional and axisymmetrical problems. Attention will be given to possible future extensions to three space dimensions, to time dependent problems, to problems involving more species and homogeneous reactions.
A multidisciplinary cooperation allows a combined and integrated approach of fluid flow and ion transport. Advantage will be taken from common data structures, grids, discretisation and iteration techniques. In one method multi-dimensional upwinding schemes are used for both the fluid flow and the ion transport. The second method applies upwinding schemes for the fluid flow and an integral formulation for the ion transport.
The methods are validated with own measurement performed in a parallel plate cell with baffles, a constricted cell and in a jet cell.
The resulting codes will be applicable to actual industrial processes 4 to 5 years after project start. They will yield helpful design tools to many branches of electrochemical industry. Further improvement of the process design and its subsequent performances may be expectable within two years of completion.
Funding SchemeCSC - Cost-sharing contracts
1640 Rhode St Genese
EX4 4QF Exeter
SO4 2AA Southampton