Jean-Marie Klein

Modeling of a SOFC Fueled by Methane:Anode Barrier to Allow Gradual Internal Reforming Without Coking

Natural gas appears to be a highly attractive fuel for solid oxide fuel cell systems. To avoid the cooling effect occurring in direct internal reforming, gradual internal reforming (GIR) can be used. GIR is based on local coupling between steam reforming and hydrogen oxidation. The steam required for the reforming reaction is obtained from hydrogen oxidation on the anode side. Previous studies have demonstrated that the cooling effect has disappeared. However, with GIR, the risk of carbon formation is greater. To deal with this issue, a different cell configuration was studied. This configuration combines a catalyst layer with a cermet anode, allowing GIR without coking. The study comprised simulations, using the CFD Research Corporation software package, of the behavior of a tubular solid oxide fuel cell when using GIR. A thermodynamic study based on the partial pressure distributions within the cell was also carried out to investigate the occurrence of carbon formation. A parametric analysis of the reforming rate and the thickness of the layer were then performed. The simulations indicate that the risk of carbon deposition is strongly reduced if the configuration is used for a catalyst layer of 900 μm and at a reforming rate in the catalyst only ten times higher than the reforming rate in nickel.

Electrical Interaction Model of Planar SOFC Stack Fed with Natural Gas

Solid oxide fuel cells (SOFC) are energy conversion devices thatproduce electricity and heat directly from a fuel such asnatural gas. Little attention has been paid to the electricalbehaviour of a SOFC stack. This paper presents an electricalinteraction model of a planar anode supported intermediatetemperature SOFC stack with direct internal reforming. The SOFCstack model is built up of multiple single repeat units stackedon top of each other and takes into account, amongst otherparameters, contact resistances and gas flow. This assembly issandwiched between two end plates. A combined model with mass,charge and heat balances has been developed with a specialattention to the description of electrical behavior. Such anapproach can provide a picture of the two dimensionaldistribution of potential, current density, and temperature.Simulations are performed to analyse the impact of changes inmaterial conductivities, electrical configuration and operation conditions.

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.