Modeling and Analysis of SOFC Thermal-Electrical Management System with an Air Bypass Valve

As a green, high efficient energy conversion technology, Solid Oxide Fuel Cell (SOFC) plays a crucial role in environmental enhancement and energy supply. For a stand-alone SOFC power system, maintaining temperature constraints and achieving high system efficiency during power tracing process is one of the biggest challenges for its application. In this work, a thermal-electrical SOFC system model considering the temperature distribution in SOFC is constructed based on a 5kW SOFC system with an air bypass valve. The Optimal Operation Points (OOPs) for different output powers that can maintain temperature constraints and achieve maximum system efficiency are obtained by model-based analysis under steady-state. Furthermore, the effects of bypass valve opening ratio (BP), voltage(U), fuel utilization(FU), air excess ratio(AR) in improving system efficiency and expanding feasible operating range are quantified. The analysis demonstrates that the design of the stand-alone SOFC system is feasible and the bypass valve can play a substantial role on improving the overall system performance and operationability.