Comparative Analysis of Loss Mechanism Localization in a Semi-2D SOEC Single Cell Modell: Non-Equilibrium Thermodynamics versus Monocausal-Based Approach

This study aims to theoretically analyze the local entropy production rate in a SOEC single cell at T = 1123.15 K and p = 1 bar. Local entropy rates signify loss mechanisms, crucial for cell design and optimization. A semi-2D SOEC model based on non-equilibrium thermodynamics is developed, supplemented by monocausal correlations for direct comparison. The model is validated using KeraCell III data and grid independence analysis. Simulations of electric current density, temperature, heat flow, and local entropy production for various SOEC operating modes are presented. Coupled transport mechanisms significance is discussed, highlighting the pronounced impact of the Peltier effect on heat flux and temperature. The importance of the Peltier effect in SOECs compared to SOFCs is emphasised. The effects of the Seebeck effect on the potential distribution are superimposed by the dominant ohmic losses in the electrolyte. The localization of entropy production rates shows for exothermic operation that 66.6% of the total losses are due to the predominantly dominant irreversible ion transport in the electrolyte, while the entanglements in the reaction layers contribute 33% and GDLs less than 1%.