应用机械工程学报

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Exergy Analysis for Brayton and Inverse Brayton Cycles with Steam Injection

Betelmal EH, Farhat S and Agnew B

Global economic and social development has led to the growth in demand for electrical power. Gas turbines play an essential role in many societies, and as the requirements for power generation increase, the power output and thermal efficiency of gas turbines must also increase. This paper presents one of the ways to improve the performance of the gas turbine with a study of exergy analysis of combined Brayton and inverse Brayton cycles with steam injected into the combustion chamber. The effect of variation of operating conditions (compression ratio and ambient temperature) on the performance of gas turbine (thermal efficiency, power) were investigated, the results were compared with the same cycle, but without injection with the analytical formulae of exergy and exergy destruction. The programming of performance model for gas turbine was developed utilizing the commercially available software IPSEpro. The analysis shows that the highest exergy destruction occurs in the combustion chamber. In addition, the performance has been improved by using steam injection by 11% in efficiency and 57% in power output and decrease linearly with the increase of the ambient temperature. However, steam injection increases the specific fuel consumption and heat rate. Thus, the thermodynamic parameters on cycle performance are economically feasible and beneficial for the gas turbine operations.