Exergoeconomic Analysis of a Combined Cycle Gas Turbine Plant Based on Several Operational Parameters

The current investigation delved into the exergoeconomics of a combined cycle gas turbine system, employing the exergy costing method followed by 1st law analysis. Through exergy analysis, the study facilitated the determination of the exergy destruction rate across all components, subsystems, and the entire plant. Assigning a cost function to each exergy stream enabled the calculation of both the entire plant cost and the cost related with exergy destruction. Key operational factors for analyzing thermodynamic and cost-related performance included compression ratio, turbine inlet temperature, and the degree of inlet air cooling. The latter increases with ambient temperature, while the compressor inlet temperature remains constant at 288 K. Simulations were conducted to explore the effects of these variations and other input parameters. Notably, the combustion chamber emerged with the maximum cost rate of irreversibilities. Moreover, the cost rate of both exergy destruction and topping cycle work production increased with the degree of inlet air cooling. Importantly, the latter escalated at a more rapid pace, establishing the advantages of inlet air cooling from both thermodynamic and economic perspectives. Taking into account total capital cost and destruction cost, the study suggests greater pressure ratios (≥14) and lower turbine inlet temperatures. However, in scenarios with a high electricity price per unit, justifying increased capital investment for a combined cycle power plant with high turbine inlet temperature becomes reasonable.