Energetic and exergetic parametric study of a SOFC-GT hybrid power plant

A parametric study is conducted on a hybrid SOFC-GT cycle as part of a national program aiming to improve the efficiency of the actual gas turbine power plants and to better undertake the future investigations. The proposed power plant is mainly constituted by a Gas Turbine cycle, a SOFC system, and an ammonia water absorption refrigerating system. An external pre-reformer 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 for the combustion chamber. An extraction is performed on the gas Turbine in order to feed the SOFC cycle by thermal heat flux at medium pressure.The equations governing the electrochemical processes, the energy and the exergy balances of the power plant components are established. Numerical simulation using EES software is performed. The influences of key operating parameters, such as humidity, pre-reforming fraction, extraction fraction from the Gas Turbine and fuel utilization on the performances of the SOFC-GT hybrid system are analyzed. Obtained results show that the integration of the SOFC enhances significantly the hybrid overall cycle efficiency. The increase of the ambient temperature and humidity reduces the system efficiencies. The utilization factor has a negative effect on the SOFC temperature and voltage. That leads to a decrease in the power plant performances. While the pre-reforming fraction, has a positive effect on the indicated parameters.