Modelling of high temperature direct methanol solid oxide fuel cells

Abstract

Methanol is a promising fuel for solid oxide fuel cells (SOFCs). A 2D numerical model is developed to study a tubular direct methanol SOFC. The model fully considers the methanol decomposition reaction and water gas shift reaction in the anode, the electrochemical oxidations of H2 and CO, fluid flow and mass transfer in the cell. The model is validated by the direct methanol SOFC experiment. At a temperature of 1073 K, a peak power density of 1.2 W cm−2 is achieved, which is much higher than room temperature direct methanol fuel cells (typically less than 0.1 W cm−2). Subsequent parametric simulations are conducted to understand the effects of operating and structural parameters on the SOFC performance, such as temperature, potential, anode thickness and cell length. Increasing the temperature enhances chemical/electrochemical reaction rates and ion conduction, leading to improved cell performance. Increasing the anode thickness improves methanol conversion and increases the average current density to some extent. For comparison, a longer cell can also improve methanol conversion but decreases the average cell current density. The results form a basis for subsequent performance enhancement of direct methanol SOFC by optimization of the cell structure and operating parameters.