Comparative Analysis of Environmental Sustainability and Performance Indices of Different Gas Turbine Inlet Cooling Systems

Abstract

Background: A thermodynamic analysis was performed on the inlet air cooling system of a natural gas-fueled turbine at the Afam power plant in Nigeria. The objective was to identify optimal conditions for environmental sustainability, performance output, fossil fuel economy, and cost-effectiveness. Methods: Three cooling methods were evaluated: spray cooler with wetted media, fogging system, and mechanical chiller. Energy, exergy, and exergy-economic models for both the existing and modeled turbine units were compared. The developed program source code indicated that both sustainability and performance indices improved when the turbine inlet cooling system adhered to design specifications. Results: The refrigeration method achieved the lowest inlet temperature at 15 ℃ and a sustainability index (SI) of 2.243. The SI decreased with increasing ambient temperatures due to higher total exergetic destruction. Regarding performance indices—net turbine output, energy efficiency, and exergy efficiency—the spray cooler had the highest values at 98.845 WM, 29.05%, and 28.49% respectively. This was followed by the mechanical chiller at 100.692 WM, 29.25%, and 29.03%, and the fogging system at 98.695 WM, 29.03%, and 28.45%. The base system recorded the lowest values at 95.70 WM, 28.69%, and 27.58%, attributed to increased compressor work. Both the environmental effect factor (EEF) and waste exergy ratio (WER) decreased with rising ambient temperature due to total exergetic destruction. conclusion: The refrigeration cooling method is recommended due to its lower inlet conditions, minimal exergy destruction, and high environmental sustainability, performance efficiency, and cost-effectiveness. Inlet-air cooling remains an efficient technique for improved performance.

Keywords

• gas turbine
• environmental sustainability
• performance output
• cooling systems
• techno-economy