Thermodynamic modeling and performance analysis of a power generation system based on the solid oxide fuel cell

Performance analysis with detailed thermodynamic models of a power generation system based on the solid oxide fuel cell (SOFC) is presented. The proposed power system in this study is composed of an external reformer, a SOFC with an internal reformer, an afterburner, and preheaters. Natural gas (CH4) as supplied fuel to the SOFC is reformed to hydrogen (H-2) by external and internal reformers. Necessary steam for the use in reformers is either externally supplied or internally recirculated from exit of the SOFC. Exhaust gas of the SOFC containing steam and other chemical compositions is combusted in afterburner to raise its temperature to preheat supplied fuel and air. It is found from the results of performance analysis that the system performance can be enhanced by the use of internally recirculated steam from the exhaust gas of the SOFC. It is also found that the benefit of the high-pressure operation is not so secure if the power to compress supplied air is consumed from the produced power of the system. Installation of a turbine at the system exhaust produces necessary power to pressurize supplied air and, additionally, extra power to enhance total power density of the system.