Jonathan Deseure

Micromodeling of Functionally Graded SOFC Cathodes

One approach to improve the performances of a solid oxide fuel cell (SOFC) cathodes is to use a composite electrode that typically consists of a two-phase porous mixture of a solid electrolyte (yttria-stabilized zirconia) and an electrocatalytic material. The best electrochemical performances with such a type of cathode are obtained when the composition varies within the composite cathode called graded electrode. The present modeling has been performed in order to give a complete description of the electrode microstructure, as well as the process occurring therein. A one-dimensional, homogeneous model and a discrete element method was used. The present study proposes a one-dimensional dc and ac model that takes into account mass and charge conservation, transport of species, and reaction kinetics. The influence of transport parameters and microstructure on the shape of both polarization curves and impedance diagrams is discussed.

Optimization of SOFC interconnect design using Multiphysic computation

Abstract The aim of this work is to optimize an interconnect design. A three-dimensional model have been developed in order to investigate the effect of interconnect design on electrical performance and degradation process. Oxygen concentration, potential, current density and temperature distribution in interconnect and SOFC cathode have been calculated. Cathode degradation has been supposed to be due to temperature gradient non-uniformity. Our studies have demonstrated the impact of cathode/interconnect contact on thermal and electrical behavior. Thus, an optimization of the cathode/interconnect contact using COMSOL Multiphysics ® software has been investigated. In this investigation, the effects of the two geometrical parameters are considered. This paper presents the modification of cathode/interconnect contact area and electrical collecting pins size. Simulations show a decreasing power density and a reduction of temperature gradient for an increasing contact area. With a decreasing size of collecting pins, better temperature homogeneity and power density are recorded.

Modeling comparison of high temperature fuel cell performance: electrochemical behaviours of SOFC and PCFC

Fuel cells are highly efficient in terms of energy production, due to their high power efficiency. Solid Oxide Fuel Cells or Protonic Ceramic Fuel Cell are often proposed. The present paper aims to report on the electrochemical performance comparison between both systems by a Computational Fluid Dynamics approach. The developed model consists of mass, energy balances, and an electrochemical model that relates the fuel, air gas composition and temperature to voltage, current density, and other relevant fuel cell parameters. The electrochemical performances of SOFCs and PCFCs are analysed for several flow contigurations. The simulations show that, the flow management should be an essential key during the design optimization. In the PCFC operating conditions, steam is produced at the cathodic side and an excessive steam can involve clogging of PCFC cathode. As a result, electrochemical performance of PCFCs decreases more than SOFCs executions.