Power–Exergy Trade-Off in Simple and Two-Stage Intercooled Brayton Cycles: An Integrated Thermodynamic and Multi-Objective Assessment

Abstract Gas turbine cycles are widely employed for power generation and propulsion, yet their thermodynamic performance is strongly influenced by compressor pressure ratio, turbine inlet temperature, ambient temperature, and internal irreversibilities. Conventional performance assessments predominantly emphasize thermal efficiency and net power output, whereas the simultaneous effects of entropy generation, component-wise exergy destruction, operating feasibility, and multi-objective performance of simple and intercooled Brayton cycles remain insufficiently quantified. In particular, the thermodynamic trade-off associated with intercooling between enhanced specific power and increased irreversibility requires systematic investigation under variable operating conditions. This study addresses this gap through a comprehensive energy, entropy-generation, and exergy-destruction analysis of simple and two-stage intercooled gas turbine cycles. An ideal-gas air model with temperature-dependent specific heat for combustion products is developed, incorporating compressor and turbine isentropic efficiencies, combustor efficiency and heat loss, intercooler effectiveness, and variations in pressure ratio, turbine inlet temperature, and ambient temperature. Physical and chemical exergies of the fuel and combustion products are evaluated, while component-wise entropy generation and exergy destruction are quantified. The computational framework is numerically verified using analytical Brayton-cycle relations, exergy–entropy consistency, component-wise exergy balances, and the overall cycle exergy balance. A total of 1,274 operating cases are evaluated, followed by operating-feasibility, equal-weight multi-objective decision-index, and Pareto analyses. The results show that intercooling substantially increases maximum specific net work, reaching 532.91 kJ/kg air, compared with 459.00 kJ/kg air for the simple cycle, corresponding to an improvement of approximately 16.1%. However, the maximum thermal efficiency is higher for the simple cycle (41.85%) than for the intercooled cycle (40.59%), while the corresponding maximum second-law efficiencies are 40.37% and 39.16%, respectively. Combustion is identified as the dominant source of exergy destruction, accounting for approximately 76.6% of the total in the simple cycle and 75.0% in the intercooled cycle. Within the investigated operating domain, the intercooled cycle achieves higher maximum specific net work, while its minimum total exergy destruction remains higher than that of the simple cycle. The results therefore indicate a thermodynamic trade-off between the power benefit of intercooling and the additional irreversibility associated with the intercooled configuration. These findings highlight the importance of an integrated multi-objective thermodynamic assessment when selecting gas-turbine cycle configurations.