Transition to low emission environment: Proposing a multiple system using a gas turbine as a topping cycle

With the acceleration of industrialisation and the increase in energy demand, reducing inefficiencies in fossil fuel-based systems and utilising waste heat have become critical for sustainable energy management. This study examines the thermodynamic, environmental, and exergoeconomic performance of an integrated multi-generation power system comprising a gas turbine (GT), Kalina cycle (KC), and Organic Rankine cycle (ORC). The proposed configuration aims to increase energy recovery from high-temperature exhaust gases, reduce CO2 emissions, and improve economic efficiency. First, a KC system operating with an ammonia-water mixture containing 95 % ammonia was integrated into the GT to recover waste heat at 500 °C. Then, an ORC subsystem was added to utilise waste heat at 150 °C, and six different organic working fluids (OWFs) were analysed comparatively. Parametric optimisations were performed using Ebsilon® Professional software to determine the effects of turbine inlet temperature, pressure, and fluid selection on net power output, thermal efficiency, and exergy efficiency. The highest system efficiencies were achieved when the KC operated at 480 °C and 100 bar, and the ORC operated at 140 °C and 15 bar with R11. The results show that the system's total thermal and exergy efficiencies increased to 48.22 % and 47.39 %, respectively, and that approximately 13 966 tonnes of CO2 emissions were prevented annually. With a payback period of 2.15 years, the system was evaluated as a viable solution for sustainable waste heat recovery in industry.