Numerical investigation of the effect of functional layer thickness on solid oxide fuel cell performance

ABSTRACTIn this 3D numerical study, the effects of cathode and anode functional layer thicknesses on the performance of solid oxide fuel cells under different operating parameters are analysed and elucidated. The performance of the model is evaluated using direct ammonia and an equivalent amount of hydrogen fuel with functional layers ranging from 0 to 50 μm. The findings unveiled that the cathode functional layer has a stronger influence on cell performance than the anode functional layer. The parametric analysis also showed that the effect of temperature gradually weakened with the increase of the cathode functional layer which is the exact opposite of what anode functional layers do. This gives more promising result for the cathode functional layer than the anode functional layer, especially for hydrogen-powered cells. However, the anode functional layer works best when green ammonia is supplied directly to the solid oxide fuel cell. In this regard, the 10 μm functional layers of the anode and cathode layers achieved the highest possible power density using ammonia and hydrogen fuels under similar operating conditions. This suggests that the anode layer has outstanding performance than the cathode counterparts for ammonia-fuelled cells and the layers of the cathode have better performance for hydrogen-fuelled cells. It is also observed that the performance of the cell is decreasing while the thickness of the functional layer is increasing particularly after 10 μm. The study also confirmed that solid oxide fuel cells with functional layers have outstanding performance over corresponding cells without functional layers. Thus, the finding of this study concluded that the functional layer thickness is strongly dependent on the types of fuel and electrodes used in the cells.