Summary There are various methods to improve the gas turbine cycle efficiency. Bottoming cycles are exhaust heat recovery arrangements as a heat source for an essentially independent power cycle such as the combined cycle and the Kalina cycle [1]. Figure (1) shows that air bottoming gas turbine cycle (ABGTC) is an arrangement to recover the exhaust energy to drive bottoming gas turbine cycle. Najjar [2] has reported that the thermal efficiency of ABGTC improves 23% more than the simple gas turbine cycle. Also, Korobitsyn [3] has studied the capability of ABGTC for co-generation applications. In this study by using a computer simulation, a simple gas turbine cycle and ABGTC is modeled. Also ABGTC is optimized to obtain maximum power output and maximum second law efficiency. Optimized air bottoming cycle consists of a mass flow ratio (mass flow rate of main cycle to bottoming cycle) is equal to 1.02 and pressure ratio of main cycle equals to 10 while pressure ratio of bottoming cycle equals to 4.3. Exergy analysis of optimized ABGTC and simple gas turbine cycle have been performed at different intake air temperatures. For each component of cycles, properties of working fluid and flow exergy have been calculated. 10 species in products have been considered for modeling the combustion chamber. Exergy analysis for combustion chamberhas has been performed in term of thermomechanical dead state, while exergy analysis of exhaust gases has been calculated in form of unristricted dead state (equilibrium with the chemical species in the enviornment).

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