Energy and Exergy Analysis of Gas Turbine – Fuel Cell Based Combined Cycle Power Plant

The newer power generation systems are becoming more important for the society due to increase in demand for the electrical energy utilization and higher energy conversion efficiencies. Though it is not new, fuel cell technology is one of the promising systems for cleaner and competitive alternate power generation system. When the fuel cells are integrated with the gas turbines, the total thermal efficiency of the combined cycle can be obtained greater than 60%. This is appreciably better exergetic performance when compared to traditional gas turbine cycle. In this work, thermodynamic analysis of SOFC-GT combined system (2.898MW) has been carried out, to evaluate energy efficiency, exergy efficiency and exergy destruction of each component is calculated. The effect of compression ratio (r_p), turbine inlet temperature (TIT), air fuel ratio and ambient temperature of air, on the performance of the system has been analyzed by adopting the different fuels. The outcome of the system modeling reveals that SOFC and combustion chamber are the main sources of exergy destruction. When the methane, natural gas and coal gas are used as fuels, at the optimum compression ratio 9, the total thermal efficiencies are found to be 63.3%, 62.12% and 61.02% respectively. The exergy efficiencies are obtained respectively as 60.85%, 59.16% and 60.06%.