Three-Dimensional Numerical study of the effect of converging and diverging channels on SOFC performance

Main important roles of bipolar plates in SOFCs are the uniform distribution of reactants to the reaction sites, the collection of current and the separation of each cell from another. Therefore, the performance of a SOFC is highly dependent on air and fuel flow channel design. In order to investigate how the geometry of air and fuel flow channels affects performance, current and power density, simulation results are discussed to evaluate the performance of two types of fuel cells with direct ducts, and converging and diverging ducts. In this research, a three-dimensional model of an anode-supported SOFC with a hydrocarbon fuel is presented. The results show that the pressure difference between the converging and diverging channels produces a transverse flow in the channels and ribs which is favor of better distribution of the reactants in the fuel cell with the converging and diverging channels. This transverse velocity causes a 6% increase in fuel consumption in the cell with converging and diverging channels than the cell with direct channels at voltage of 0.7V, but due to the reduction of the reaction area of this cell compared to the usual cell, the current density is 10% lower. At voltages below 0.55V, fuel cells with direct-channel perform better than the cells with converging and diverging channels due to higher current and power density and fuel consumption.