A numerical simulation to effectively assess impacts of flow channels characteristics on solid oxide fuel cell performance

Abstract

Solid oxide fuel cells (SOFCs) introduce a promising electrochemical conversion technology to generate electricity directly from fuel oxidization. A three-dimensional (3D) numerical model is proposed to evaluate the SOFC performance by employing computational fluid dynamics (CFD) approach based on the finite element method. This research includes simultaneously solving momentum, energy, and mass transport equations linked with the electrochemical reactions. First, the modeling results of a SOFC system with a rectangular channel in the absence of obstacles are compared with the experimental data, showing very good agreement. The effects of different shapes and numbers of obstacles on fuel cell behavior (voltage and power) are then evaluated to determine the optimal performance in the SOFC system. The impacts of operating conditions such as inlet gas velocity in anode and cathode channels and porosity and permeability of electrodes on the SOFC electric output as well as integrated transport phenomena and electrochemical reactions are also investigated. It is concluded that the average current density (SOFC performance) increases by 15% upon using seven triangular obstacles in comparison with the reference case. Fuel cell power is enhanced by almost 35%, compared to a cell with direct flow channels. It is found that the fuel cell performance is increased by using the trapezoidal and rectangular obstacles in the flow channels. The amount of hydrogen consumption at the anode channel is an important parameter affecting the SOFC performance; by increasing the efficiency of the fuel cell, hydrogen conversion is increased. According to the results, the average overpotential in SOFC decreases with increasing fuel cell efficiency. The new SOFC design proposed in this study can be used for optimal design and operation purposes.