Electrochemical model for performance analysis of a tubular SOFC

Abstract

Tubular solid oxide fuel cells (SOFC) are promising candidates for future energy conversion systems and expected to be applied widely for small-scale distributed generation to large-scale central station power plants because of their high electrical efficiency and high temperature exhaust gas utilization. This study presents an electrochemical model to determine the performance characteristics of tubular solid oxide fuel cell. Activation, ohmic and concentration polarizations are regarded as the major sources of irreversibility. The Butler-Volmer equation, Fick's law and Ohm's law are used to determine the polarization terms. Performance curves are simulated for single cell voltage and power under variable current density and validated with published experimental data for given operating conditions. All the variations of tubular SOFC's operational conditions such as operating pressure and temperature in the electrochemical processes is taken into consideration. The contribution of each polarization term to voltage losses is analysed with local characteristics such as pore size, electrolyte thickness and activation energy for evaluating the relative changes. Cell performance represented by cell voltage, power, efficiency and heat generation are analysed at its complete operating range, aiming at finding the set of optimal operating conditions maximizing the overall cell performance. As a conclusion from this study, the developed model is a simple and effective tool to analyse tubular SOFC in obtaining insight information about cell performance characteristics under different conditions. Copyright (c) 2006 John Wiley & Sons, Ltd.