The main purpose of this thesis is to model power cycles especially steam power plant and combined cycle power plant and carry out exergy and exergoeconomic analysis for these cycles. For these reasons initially these cycles was modeled by IPSE Pro professional software of power plant modeling. By developing a code that gets output data from IPSE Pro, cost of flow and final cost of electricity is calculated. In the second section of thesis concentration is on developing of cycles by modifying the cycle configuration and changing performance parameters. In order to analysis steam power plant cycle, final cost of electricity is calculated and effects of key parameters such as condenser pressure, superheat steam temperature, reheat steam temperature and number of feed water heater on thermodynamic performance and exergoeconomic is considered. For analysis combined cycle power plant three configurations of heat recovery steam generator (HRSG) is studied. In the first case heat recovery steam generator is considered with out duct burner. In the second case duct burner is located before HP superheater and in the last one duct burner is located after HP superheater. In each case exergy and exergeconomic parameters are compared with each other and the final cost of electricity is found. Also effects of pressure ratio of compressor and variation of fuel mass flow on cycle performance are done. At the last feasibility of modifying Isfahan steam cycle power plant to combined cycle power plant is studied. Key Words Steam power plant, Combined power plant, Exergoeconomic, IPSE Pro
