Computational Fluid Dynamic evaluation of Solid Oxide Fuel Cell performances with biosyngas under co-flow and counter-flow conditions

摘要

Fuel cells, which convert the chemical energy stored in a fuel into electrical and thermal energy, offer an efficient solution for efficient and low pollution production of electricity and heat. These devices rely on the combination of hydrogen and oxygen into water: oxygen is extracted from the air while hydrogen can be obtained from either fossil fuels or renewable sources. Solid Oxide Fuel Cells (SOFCs) are often designed to operate with specific fuels, quite often natural gas. Hydrogen can also be internally produced inside the fuel cells from the reforming reaction of methane. Internal reforming has a crucial impact on the performance of SOFCs, especially on the current density, temperature distribution and the resulting thermal-stress. Computational Fluid Dynamic (CFD) modeling is often used to arrive at efficient and safe SOFC designs. An SOFC design developed by ECN together with Delft University of Technology is employed for the calculations. The impact of different fuels on the cell performance has been studied in our previous work. However, the performances under co-flow and counter-flow operations are still unknown. Model results provide detailed profiles of temperature, Nernst potential, anode-side gas composition, current density and hydrogen utilization over a range of operating conditions. Variations in temperature distribution and species concentration are discussed. Quite interesting results are observed for the current density variations when different fuels are used. Detailed results from the CFD calculations for a single channel are presented. Thermal predictions of nickel oxidation and carbon deposition and temperature gradients are employed to detect the operation safety. The fuel cell designed for methane as a fuel is also shown to be safe for operation with biosyngas both under co-flow and counter-flow conditions.