Inlet methane temperature effect at a planar sofc thermal field under direct internal reforming condition

Abstract

In this work, an Anode Supported Planar Solid Oxide Fuel Cell (ASP_SOFC) is applied. The thermal fields are shown for a standard SOFC: yttria stabilized zirconia for the electrolyte, nickel/zirconia cermet for the anode, anddoped lanthanum manganite (LSM) for the cathode. It is operating under direct internal reforming condition of methane gas. The present paper’s purpose is the thermal field visualization of an ASP_SOFC. The temperature fields are discussed under the influence of heat sources caused by the internal reforming reactions occurring at the SOFC anode side. The reforming reactions in the anode in this case are described by the endothermic steam reforming reaction, the exothermic water-gas shift reaction, and the endothermic overall chemical reaction. The SOFC thermal behavior is influenced by several parameters such as mole fractions, pressure and temperature, etc. In this work we focus on two parameters: the inlet methane temperature and pressure. This study requires coupling conservation equations; mass, energy, and species. To accomplish this study, it is necessary to calculate velocities. The latter is governed by Darcy’s law. The thermal fields are studied by a two-dimensional numerical simulation in the plane perpendicular to the methane flow. The method adopted for solving numerically a complex system of equations is the finite difference method. The thermal fields as results of this study are obtained by developing a program in FORTRAN language and the Tecplot software, respectively. The results show the thermal fields together with the application of the parameters studied in the literature. Methane and air inlet conditions are methane temperature values of 1,173 K or Tµ 1, 273 K and pressure values of 1 bar, 2 bar, or 3 bar. The inlet fuel is considered as a gas mixture of H2, CH4, CO, H2O, and CO2. Fuel and air inlet compositions are: CH4, 0.29; H2, 0.09; CO2, 0.01; CO, 0.01; H2O, 0.6; O2, 0.21; and N2, 0.79. The analysis of the thermal fields is based on the source term introduced in the energy equation. The influence of the heat source is shown by the decrease or increase in the temperature.