Thermodynamic and exergoeconomic analysis of an innovative cogeneration of power and freshwater based on gas turbine cycle

Abstract

The gas turbine cycle's ability to incorporate various waste heat recovery systems, diversify product output, and optimize the performance of standalone power plants is a topic of great interest. This study aims to propose a multi-level waste heat recovery system designed for a modified gas turbine cycle. This study employs a double-flash organic flash cycle, a Kalina cycle, and a modified single-flash desalination unit to generate power and freshwater simultaneously. The double-flash organic flash cycle derives its input energy from recuperating the cooling process associated with the initial air compression phase, while the Kalina cycle's condenser serves as the energy source for the desalination subsystem. The performance of this innovative system is assessed using energy, exergy, and economic analyses. Additionally, various multi-objective optimization techniques are applied to identify the optimal operational conditions. The findings indicate that when input fuel costs exceed $8/GJ, and the electricity sale price falls below $0.08/kWh, the payback period extends beyond the system's expected lifetime. Furthermore, the effectiveness of the air preheater is identified as the most influential factor affecting system performance. In its optimal state, the designed system delivers a total net power output of 22,328 kW, produces freshwater at a rate of 3.09 kg/s, achieves an exergetic efficiency of 43.087 %, and yields a net present value of $38.53 M.