Thermal management of reversible solid oxide cells in the dynamic mode switching

Abstract

Reversible solid oxide cell (rSOC) can flexibly switch between fuel cell and electrolyzer, making it promising for power generation and storage. However, the dynamic mode switching causes reversed electrochemical reactions and severe temperature fluctuation, leading to performance decline and even cell failure. Herein, we propose a thermal management strategy that combines rSOC with thermochemical energy storage (TES) to store/supply heat during exothermic/endothermic processes. Performance of the integrated new system is evaluated by a 2D non-adiabatic dynamic model. It is found that the maximum temperature difference across the cell surface can be reduced by 75.7 % at 0.75 V, where 18.21 % of the fuel enthalpy is stored in the TES section. Besides, a small air flow rate of 10 SCCM is enough to maintain a hot standby state during the shutdown stage, which reduces the energy consumption by 99.5 % compared with the hot air purging method. The temperature change rate in the switching process between the fuel cell mode and the shutdown stage is also decreased by 69 % on average. This work identifies the key characteristics of rSOC during mode switching and provides a new method towards its safe and economic operation when combining with fluctuating renewable powers.