An Optimized Strategy for Fuel Cell Degradation Control in SOFC Power Systems

Abstract

Solid Oxide Fuel Cell (SOFC) is an attractive energy conversion device due to its high efficiency and fuel flexibility. Key operation parameters such as current, temperature and fuel utilization are critical variables in SOFC systems that directly impact efficiency and longevity. The degradation of the SOFC performance not only limits the operating temperature range of the SOFC stack in the system, but also simultaneously generates Joule heat, which further causes the stack to deviate from its initial thermal balance.In this paper, a semi-empirical SOFC dynamic model with degradation is proposed and validated by experiment data. The degradation in the above model is developed based on current density, temperature and fuel utilization to simulate cell performance decay over time due to ohmic loss growth and the heat generation by cell resistance. The coupling between key parameters, stack performance and degradation during long-term load following and the impact of stack degradation on the entire system long-term performance is discussed and investigated. An optimized strategy uses both feedback and feed-forward control law is designed to track the desired power demand with the aim of mitigating the degradation and compensating the time differences between dynamics at different time-scale.