Integrated Energy–Exergy–Environmental Analysis and Optimization of a Heavy-Duty Gas Turbine in Hot-Dry Climates Using High-Pressure Inlet Fogging with Overspray

Gas turbine performance deteriorates markedly in hot and arid environments where high-temperature, low-density air enters the compressor, increasing specific compression work and lowering overall cycle efficiency. To mitigate these climate-driven losses, this work develops an integrated energy–exergy–environmental assessment for a heavy-duty Siemens SGT5-4000F gas turbine retrofitted with a high-pressure inlet fogging system incorporating overspray. A detailed Brayton-cycle model, coupled with a humidity-dependent evaporation formulation, is implemented in Engineering Equation Solver (EES), A comprehensive parametric study shows that an overspray level of 1.2% of the compressor inlet air mass flow provides the best compromise between thermodynamic enhancement and water consumption for severe ambient conditions of 52 °C and 12% relative humidity. At this operating point, the system recovers about 20% of lost power, corresponding to a 55.7 MW increase in net output, while thermal efficiency and exergy efficiency rise by approximately 3.4% and 4.5%, respectively, relative to the non-cooled configuration. These improvements translate into a reduction of roughly 200,000 tons of CO₂ emissions per year, highlighting the environmental benefit of fog- assisted wet compression. Overall, the findings demonstrate that high-pressure inlet fogging with optimized overspray is an effective, economical, and environmentally responsible solution for restoring heavy-duty gas-turbine performance in extreme hot-dry regions.