Sustainable pathways for double-stage compression gas turbine–based polygeneration via energy–exergy–environmental optimization and pinch-based heat recovery

This study investigates a gas turbine–based polygeneration system integrating a multi-effect desalination (MED) unit and an absorption chiller for simultaneous production of electricity, freshwater, and cooling. The system recovers waste heat from both the turbine exhaust and air compression processes to enhance overall efficiency. Five heat recovery scenarios are proposed and evaluated based on energy, exergy, and environmental performance indicators. A comprehensive multi-criteria decision-making approach, referred to as the Triple-E function, is introduced to identify the optimal configuration. Pinch analysis is employed to design efficient heat recovery pathways, and the models of key components are validated against manufacturer data and literature benchmarks. Results indicate that for the unrecuperated cycle, utilizing compression heat for the chiller and exhaust heat for desalination (Scenario 1) offers the best overall performance, achieving energy and exergy efficiencies of 70.79 % and 52.77 %, respectively, along with a fuel energy saving ratio of 30.02 %. Additionally, annual reductions in carbon dioxide, carbon monoxide, and nitrogen oxides emissions reach 103,173, 561, and 69 tons, respectively. These findings demonstrate the significant potential of thermally integrated gas turbine–based polygeneration systems to enhance energy utilization and environmental sustainability.