Elucidating the sensitivity to key operating parameters of a commercial-scale solid oxide fuel cell stack with open cathode manifolds

Abstract

Solid oxide fuel cell (SOFC) is considered a promising eco-friendly energy conversion technology due to its high efficiency and fuel flexibility resulting from its high-temperature operation and ceramic structure. However, nonuniformities in thermal and electrochemical distribution within the SOFC stack can lead to performance degradation and hinder its market competitiveness. This study aims to identify optimal operating conditions to minimize these nonuniformities by investigating the effects of key operating conditions on the internal phenomena and local thermodynamic states of a commercial-scale stack. A highly reliable hydrocarbon-fueled SOFC model is developed and used to investigate the response of a 1-kW commercial-scale stack with open cathode manifolds to changes in key operating conditions. A parametric study is conducted on the air inlet temperature, air utilization, external reforming rate, and operating current density. Results show that increasing the air inlet temperature improves the uniformity of in-plane temperature distribution but deteriorates the uniformity of current density distribution. Air utilization and air inlet temperature have an identical mechanism to alter the internal distribution, thus showing a similar effect on local thermodynamic states. However, when altering the air utilization, the rate of decrease in uniformity of vertical temperature and current density is 5.39 times and 2.47 times larger than the change in the air inlet temperature. Increasing the external reforming rate exacerbates the overall distribution of local thermodynamic states. Among the selected operating parameters, the operating current density has the greatest influence on the in-plane temperature and current density distribution. This study provides guidance on the desired internal conditions inside the stack by quantitatively analyzing the effects of key operating conditions on the internal phenomena and local thermodynamic states of the stack through performance parameters and sensitivity analysis.