Exergy, exergoeconomic and combined pinch and exergy analysis are beneficial methods that can be applied for design or performance evaluation of process systems or thermal power plants; however, these methods are usually applied individually. In this paper, these methods have been applied for 423 MW NEKA combined cycle power plant located in NEKA at north of Iran and 315-MW RAMIN steam power plant located in Ahvaz at south of Iran as real cases to evaluation and comparison of performance of each component in different load conditions simultaneously. To perform these analysis for both plants, a computer program is developed from thermodynamic modeling of the plant as simulator. With the thermodynamic properties of the most significant mass and energy flow stream being obtained from the plant, the simulator can reproduce the cycle behavior for different operating conditions with relative errors less than 4.2%. The models of computer program are refined using data from designed performance test in these plants. After thermodynamic simulation, this program can calculate exergy of the flows. In addition, it can perform exergoeconomic analysis using thermoeconomic model of both plants that are defined based on the functionally of each component by the fuel-product definition. The costs of all flows in production structure can be calculated by solving a set equation including thermoeconomic modeling of each plant. Furthermore, it is helpful to display the system information graphically for one to visualize the performance of system in different conditions by applying combined pinch-exergy analysis. Meanwhile, due to importance of exergy destruction cost and better understanding plant performance, the new variables have been defined as Exergy Destruction Level (EDL) and Exergy Cost Destruction Level (ECDL). In this respect, new graphical representation has been developed for showing performance of each component based on exergoeconomic analysis. In this regard, this computer program can generate improved combined pinch-exergy and EDL/ ECDL representation.

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