Exergetic and Exergo-Economical Analyses of a Gas-Steam Combined Cycle System

Abstract

In this study, the results of an investigation of the performance of a gas-steam combined cycle system (GSCCS) under exergetic and exergo-economical criteria are reported. The effective power (P-ef), destroyed exergy (X), efficiency of exergy (epsilon), unit electric generation cost (C-elec) and exergy-dependent economic worth of electrical energy (C-ex,C-elec), which is novelly determined in this study, have been analyzed. The impacts of speed (N), pressure ratio of the gas cycle (lambda), equivalence ratio (phi), the flow rate of the air mass ((m) over dot(a)), the flow rate of the fuel mass ((m) over dot(f)), inlet temperature of the air into the compressor (T-1), steam temperature (T-6) and pressure (P-6) of the heat exchanger, outlet pressure (P-7) of the high pressure steam turbine and condenser pressure (P-9) on P-ef, epsilon, C-elec and C-ex,C-elec have been parametrically evaluated. It was revealed that the stream and component characteristics of the system have significant influences on the performance characteristics of the GSCCS.