Abstract
Analytic study based on energy analysis is conducted on a solid oxide fuel cell (SOFC) integrated in a gas turbine power plant GT. The Tunisian natural gas is used as fuel for the SOFC and the GT cycle. An external pre-reforming system is installed before the SOFC. Heat recovery systems are adopted to valorize the waste heat at the SOFC and GT exhausts. The gas from the SOFC exhaust is also used as additional supply of the combustion chamber. The equations governing the electrochemical processes and the energy balances of the power plant components are established. Numerical simulations using EES software are performed. The influences of key operating parameters, such as ambient temperature, air flow, pre-reforming fraction and fuel utilization on the performance of the SOFC–GT hybrid system, are analyzed. The integration of the SOFC enhances the hybrid cycle efficiency of about 50%. The increase of the ambient temperature reduces the system efficiencies. The utilization factor has a negative effect on the SOFC temperature and voltage which leads to a decrease in the system performances, while the pre-reforming fraction has a positive effect on the indicated parameters. The SOFC voltage increases with the air molar flow rate. However, required air compressor power becomes important. That reduces significantly the SOFC efficiency. A small improvement of about 2% is obtained for the hybrid cycle efficiency SOFC–GT.