Multi-Objective Thermodynamic and Thermoeconomic Optimization of the Gas Turbine Cycle with Intercooling, Reheating, and Regeneration

There are numerous operating parameters that affect the thermodynamic and thermoeconomic performance of gas turbine cycles, and many studies based on energy, exergy, and economic analyses have been conducted in the literature by considering these parameters. However, the order of importance and contribution ratios of key operating parameters such as ambient temperature, compressor pressure ratio, combustion efficiency, regenerator effectiveness, and compressor and turbine isentropic efficiencies with respect to thermal efficiency, exergy efficiency, and the levelized cost of electricity (LCOE) have not been sufficiently investigated using statistical methods. Accordingly, a thermodynamic model of a gas turbine cycle improved with intercooling, reheating, and regeneration processes was developed in the study, and thermal efficiency, exergy efficiency, and LCOE values were calculated under different parameter levels. Taguchi analysis was carried out by using the L27 orthogonal array, in which six operating parameters were evaluated at three levels, and optimum parameter levels were determined for each performance indicator. Next, the contribution ratios of the parameters to the objective functions were calculated using the ANOVA method. The results showed that turbine isentropic efficiency was the most influential parameter in terms of thermal and exergy efficiencies, while compressor pressure ratio played the dominant role in terms of LCOE. Additionally, to simultaneously achieve the goals of maximizing thermal and exergy efficiencies and minimizing the LCOE value, the grey relational analysis (GRA) method was applied as a multi-objective optimization approach, and the optimum operating conditions were determined based on a single performance indicator. According to the GRA results, under the optimum conditions, the thermal efficiency was calculated as 0.5533, its exergy efficiency was 0.5772, and the LCOE value was 0.01751 USD/kWh.